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  • Fluid Mechanics and Thermodynamics  (44)
  • 2020-2020
  • 1945-1949  (44)
  • 1
    facet.materialart.
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    In:  Other Sources
    Publication Date: 2019-07-12
    Description: The rate of heat transfer between a fluid stream in turbulent flow and a smooth, solid wall is largely controlled by the relatively high resistance of the laminar sublayer next to the wall. Although this laminar layer ii extremely thin, heat can be transferred through it only by molecular diffusion. Hence the resistance of this layer is very much greater than for a layer the same thickness farther out in the stream where turbulent exchange is the controlling factor. The thickness of the laminar layer is difficult to define precisely, since there is a gradual transition to the turbulent flow outside, but for the usual scale of many engineering applications almost half the temperature difference between the fluid and the wall occurs in a layer of a few thousands of an inch in thickness. When the wall is made of porous material and a coolant gas is forced through the wall into the stream, it has been found that a very small flow rate of the coolant is remarkably effective in keeping the wall at a low temperature. The coolant flow rate required is such as to give an average velocity normal cooling wall of the order of 1 per cent of the main stream velocity. This flow rate is so low that clearly the injected gas must act as an insulator rather than as a normal coolant. Because of its relatively low velocity, the injected gas can have very little influence on heat convection or momentum transfer in the turbulent stream, and its effect must be confined to the laminar sublayer. The possible influence of the coolant flow on the thickness of the laminar layer will be discussed in Section V.
    Keywords: Fluid Mechanics and Thermodynamics
    Type: JPL-PR-4-50
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  • 2
    Publication Date: 2019-07-11
    Description: A large number of papers have been devoted to the problem of integration of equations of two-dimensional steady nonvertical adiabatic motion of a gas. Most of these papers are based on the application of the hodograph method of S. A. Chaplygin in which the plane of the hodograph of the velocity is taken as the region of variation of the independent variables in the equations of motion; the equations become linear in this plane. The exact integration of these equations is, however, obtained in the form of infinite series containing hypergeometric functions. The obtaining of such solutions and their investigation involves extensive computations. As a result, methods have been developed for the approximate integration of the equations of motion first transformed to a linear form. S. A. Chaplygin first pointed out such an approximate method applicable to flows in which the Mach number does not exceed 0.4.
    Keywords: Fluid Mechanics and Thermodynamics
    Type: NACA-TM-1239 , Prikladnaia Matematika I Mekhanika, Tom XI
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  • 3
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    In:  CASI
    Publication Date: 2019-07-11
    Description: A study is made herein of the irrotational adiabatic motion of a gas in the transition from subsonic to supersonic velocities. A shape of the de Laval nozzle is given, which transforms a homogeneous plane-parallel flow at large subsonic velocity into a supersonic flow without any shockwaves beyond the transition line from the subsonic to the supersonic regions of flow. The method of solution is based on integration near the transition line of the gas equations of motion in the form investigated by S. A. Christianovich.
    Keywords: Fluid Mechanics and Thermodynamics
    Type: NACA-TM-1236 , Prikladnaia Matematika I Mekhanika, Tom XI
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  • 4
    Publication Date: 2019-07-11
    Description: By means of characteristics theory, formulas for the numerical treatment of stationary compressible supersonic flows for the two-dimensional and rotationally symmetrical cases have been obtained from their differential equations.
    Keywords: Fluid Mechanics and Thermodynamics
    Type: NACA-TM-1211 , ZWB Forschungsbericht; Rept-1581
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  • 5
    Publication Date: 2019-07-11
    Description: The turbulent flow in a conical diffuser represents the type of turbulent boundary layer with positive longitudinal pressure gradient. In contrast to the boundary layer problem, however, it is not necessary that the pressure distribution along the limits of the boundary layer(along the axis of the diffuser) be given, since this distribution can be obtained from the computation. This circumstance, together with the greater simplicity of the problem as a whole, provides a useful basis for the study of the extension of the results of semiempirical theories to the case of motion with a positive pressure gradient. In the first part of the paper,formulas are derived for the computation of the velocity and.pressure distributions in the turbulent flow along, and at right angles to, the axis of a diffuser of small cone angle. The problem is solved.
    Keywords: Fluid Mechanics and Thermodynamics
    Type: NACA-TM-1137 , Central Aero-Hydrodynaical Institute Reports; Rept-462
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  • 6
    Publication Date: 2019-07-12
    Description: Strain gages were used to measure blade vibrations possibly causing failure in the 10-stage compressor of the 19XB jet-propulsion engine. The seventh and tenth stages were of great concern as a result of failures experienced by the manufacturer. Strain-gage records were obtained from all stages during acceleration, deceleration, and constant speed runs. Curves are presented herein showing the maximum allowable vibratory stress for a given speed, the change of the damping coefficient with the mounting of a strain gage at the base of the blade, the effect of rotor speed, on blade natural frequency, and the effect of the order of first bending-mode vibration on stress. It was found that for all stages the lower the order of vibration the higher the stress but no destructive vibrations were detected.
    Keywords: Fluid Mechanics and Thermodynamics
    Type: NACA-RM-SE8A28
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  • 7
    Publication Date: 2019-07-12
    Description: An investigation has been conducted on a one-sixth segment of an annular turbojet combustor to determine the effects of modification in air-flow distribution and total-pressure loss on the performance of the segment. The performance features investigated during this series of determinations were the altitude operational limits and the temperature-rise efficiency. Altitude operational limits of the combustor segment, for the 19XB engine using the original combustor-basket design were approximately 38,000 feet at 17,000 rpm and 26,000 feet at 10,000 rpm. The altitude operational limits were approximately 50,000 feet at 17,000 rpm and 38,000 feet at 10,000 rpm for a combustor-basket design in which the air-passage area in the basket was redistributed so as to admit gradually no more than 20 percent of the air along the first half of the basket. In this case the total pressure loss through the combustor segment was not appreciably changed from the total-pressure loss for the original combustor basket design. Altitude operational limits of the combustor segment for the 19XB engine were above 52,000 feet at 17,000 rpm and were approximately 23,000 feet at 10,000 rpm for a combustor-basket design in which the distribution of the air-passage area in the basket was that of the original design but where the total-pressure loss was increased to 19 times the inlet reference kinetic pressure at an inlet-to-outlet density ratio of 2.4. The total-pressure loss for the original design was 14 times the inlet kinetic reference pressure at an inlet-to-outlet density ratio of 2.4.
    Keywords: Fluid Mechanics and Thermodynamics
    Type: NACA-RM-SE7K16
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  • 8
    Publication Date: 2019-08-13
    Description: A heat-transfer investigation was conducted with air flowing through an electrically heated silicon carbide tube with a rounded entrance, an inside diameter of 3/4 inch, and effective heat-transfer length of 12 inches over a range of Reynolds numbers up to 300,000 and a range of average inside-tube-wall temperatures up to 2500 R. The highest corresponding local outside-tube-wall temperature was 3010 R.
    Keywords: Fluid Mechanics and Thermodynamics
    Type: NACA/RM-E9D12
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  • 9
    Publication Date: 2019-07-11
    Description: The calculation of the phenomena within the boundary layer of bodies immersed in a flow underwent a decisive development on the basis of L. Prandtl's trains of thought, stated more than forth years ago, and by numerous later treatises again and again touching upon them. The requirements of the steadily improving aerodynamics of airplanes have greatly increased with the passing of time and recently research became particularly interested in such phenomena in the boundary layer as are caused by small external disturbances. Experimental results suggest that, for instance, slight fluctuations in the free stream velocities as they occur in wind tunnels or slight wavelike deviations of outer wing contours from the prescribed smooth course as they originate due to construction inaccuracies may exert strong effects on the extent of the laminar boundary layer on the body and thus on the drag. The development of turbulence in the last part of the laminar portion of the boundary layer is, therefore, the main problem, the solution of which explains the behavior of the transition point of the boundary layer. A number of reports in literature deal with this problem,for instance, those of Tollmien, Schlichting, Dryden, and Pretsch. The following discussion of the behavior of the laminar boundary layer for periodically oscillating pressure variation also purports to make a contribution to that subject.
    Keywords: Fluid Mechanics and Thermodynamics
    Type: NACA-TM-1228 , Ludwig Prandtl zum 70. Geburtstage, Schriften der Deutschen Akademie der Luftfahrtforschung, Publications of the Germany academy for Aviation Research; 247-255
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  • 10
    Publication Date: 2019-07-11
    Description: Some aerodynamic relations are derived which exist between two infinitely long airfoils if one is in a straight flow and the other in oblique flow, and both present the same profile in the direction of flow.
    Keywords: Fluid Mechanics and Thermodynamics
    Type: NACA-TM-1158 , Deutsche Luftfahrtforschung, Forschungsbericht; Rept-1497
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  • 11
    Publication Date: 2019-07-11
    Description: At the request of the Junkers Aircraft and Engine Construction Company, Engine Division, Dessau Main Plant, an investigation was made using the interferometer method on the two turbine-blade profiles submitted. The interferometer method enables making visible the differences in density and consequently the boundary layers that develop when a flow is directed on the profile. Recognition of the points on the profile at which separation of flow occurs is thus possible. By means of the interference photographs the extent of the dead-water region may be ascertained. The size of the dead-water region provides evidence as to the quality of the flow and allows a qualitative estimate of the amount of the flow losses. Interference photographs thus provide means of judging the utility of profiles under specific operating conditions and provide suggestions for possible changes of profile contours that might help to improve flow relations. Conclusions may be drawn concerning the influence of the blade-spacing ratio, the inlet-air angle, and the connection between the curvature of the profile contour and the point of separation of the flow from the profile surface.
    Keywords: Fluid Mechanics and Thermodynamics
    Type: NACA-TM-1171 , Deutsche Luftfahrtforschung, Untersuchungen und Mitteilungen; Rept-2096
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  • 12
    Publication Date: 2019-07-11
    Description: The cavitation in nozzles on airfoils of various shape and on a sphere are experimentally investigated. The limits of cavitation and the extension of the zone of the bubbles in different stages of cavitation are photographically established. The pressure in the bubble area is constant and very low, jumping to high values at the end of the area. The analogy with the gas compression shock is adduced and discussed. The collapse of the bubbles under compression shock produces very high pressures internally, which must be contributory factors to corrosion. The pressure required for purely mechanical corrosion is also discussed.
    Keywords: Fluid Mechanics and Thermodynamics
    Type: NACA-TM-1078 , Eidgenoessische Technische Hochschule
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  • 13
    Publication Date: 2019-07-11
    Description: This paper includes the following topics: 1) Characteristic differential equations; 2) Treatment of practical examples; 3) First example: Diffuser; and 4) Second Example: Nozzle.
    Keywords: Fluid Mechanics and Thermodynamics
    Type: NACA-TM-1244 , Chapter 4, Technische Hoschschule Dresden, Archives No. 44; Rept-44/4
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  • 14
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    In:  CASI
    Publication Date: 2019-07-11
    Description: This paper contains a tabulation of functions of the Mach number which are frequently used in high-speed aerodynamics. The tables extend from M = 0 to M = 10.0 in increments of 0.01 and are based on the assumption that air is a perfect gas having a specific heat ratio of 1.400.
    Keywords: Fluid Mechanics and Thermodynamics
    Type: NACA-RM-L7K26
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  • 15
    Publication Date: 2019-08-14
    Description: The conference on Turbojet-Engine Thrust-Augmentation Research was organized by the NACA to present in summarized form the results of the latest experimental and analytical investigations conducted at the Lewis Flight Propulsion Laboratory on methods of augmenting the thrust of turbojet engines. The technical discussions are reproduced herewith in the same form in which they were presented. The original presentation in this record are considered as complementary to, rather than substitutes for, the committee's system of complete and formal reports.
    Keywords: Fluid Mechanics and Thermodynamics
    Type: NACA Conference on Turbojet-Engine Thrust - Augmentation Research; Oct 28, 1948; Cleveland, OH; United States
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  • 16
    facet.materialart.
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    In:  CASI
    Publication Date: 2019-07-13
    Description: The condensation of water vapor in an air consequences: acquisition of heat (liberated heat vaporization; loss of mass on the part of the flowing gas (water vapor is converted to liquid); change in the specific gas constants and of the ratio k of the specific heats (caused by change of gas composition). A discontinuous change of state is therefore connected with the condensation; schlieren photographs of supersonic flows in two-dimensional Laval nozzles show two intersecting oblique shock fronts that in the case of high humidities may merge near the point of intersection into one normal shock front.
    Keywords: Fluid Mechanics and Thermodynamics
    Type: NACA-TM-1174 , Heeres-Versuchsstelle; 66/72
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  • 17
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    In:  CASI
    Publication Date: 2019-07-13
    Description: The recent experiments by Jakob and Erk, on the resistance of flowing water in smooth pipes, which are in good agreement with earlier measurements by Stenton and Pannell, have caused me to change my opinion that the empirical Blasius law (resistance proportional to the 7/4 power of the mean velocity) was applicable up to arbitrarily high Reynolds numbers. According to the new tests the exponent approaches 2 with increasing Reynolds number, where it remains an open question whether or not a specific finite limiting value of the resistance factor lambda is obtained at R = infinity. With the collapse of Blasius' law the requirements which produced the relation that the velocity in the proximity of the wall varied in proportion to the 7th root of the wall distance must also become void. However, it is found that the fundamental assumption that led to this relationship can be generalized so as to furnish a velocity distribution for any empirical resistance law. These fundamental assumptions can be so expressed that for the law of velocity distribution in proximity of the wall as well as for that of friction at the wall, a form can be found in which the pipe diameter no longer occurs, or in other words, that the processes in proximity of a wall are not dependent upon the distance of the opposite wall.
    Keywords: Fluid Mechanics and Thermodynamics
    Type: NACA-TM-1231 , Zeitschrift fuer Angewandte Matematik und Mechanik; 5; 2; 136-139
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  • 18
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    In:  CASI
    Publication Date: 2019-07-13
    Description: The flow about a conical body of an ideal compressible fluid is considered. Assume that the velocity of the oncoming flow at infinity W is directed along the z-axis. The system of Cartesian coordinates x, y, z with origin at the vertex of the cone O is shown. From the considerations,of the dimensional theory, it may be found that along any ray issuing from O the components of the velocity u, v, W+w along the coordinate axes will maintain a constant value. It is further assumed that the conical body has such shape and disposition relative to the flow that u, v, and w are small in comparison with W.
    Keywords: Fluid Mechanics and Thermodynamics
    Type: NACA-TM-1245 , Prikladnaya Matematika I Mekhanika; X; 513-520
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  • 19
    Publication Date: 2019-07-13
    Description: For a certain Mach number of the oncoming flow, the local velocity first reaches the value of the local velocity of sound (M = 1) at some point on the surface of the body located within the flow. This Mach number is designated the critical Mach number M(sub cr). By increasing the flow velocity, a supersonic local region is formed bounded by the body contour and the line of transition from subsonic to supersonic velocity. As is shown by observations with the Toepler apparatus, at a certain flow Mach number M 〉 M(sub cr) a shock wave is formed near the body that closes the local supersonic region from behind. The formation of the shock wave is associated with the appearance of an additional resistance defined as the wave drag. In this paper, certain features are described of the flow in the local supersonic region, which is bounded by the contour of the body and the transition line, and conditions are sought for which the potential flow with the local supersonic region becomes impossible and a shock wave occurs. In the first part of the paper, the general properties of the potential flow in the local supersonic region, bounded by the contour of the profile and the transition line, are established. It is found that at the transition line, if it is not a line of discontinuity, the law of monotonic variation of the angle of inclination of the velocity vector holds (monotonic law). An approximation is given for the change in velocity at the contour of the body. The flow about a contour having a straight part is studied. In the second part of the paper, an approximation is given of the magnitudes of the accelerations at the interior points of the supersonic region. With the aid of these approximations, it is shown that for profiles convex to the flow the breakdown of the potential flow,associated with an increase of the Mach number of the oncoming flow, cannot be due to the formation of an envelope of the characteristics within the supersonic region. On the basis of the monotonic law, the transitional Mach number M is found, beyond which the potential flow with local supersonic region becomes impossible.
    Keywords: Fluid Mechanics and Thermodynamics
    Type: NACA-TM-1213 , Prikladnaya Matematika i Mekhanika; 10; 4; 481-502
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  • 20
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    In:  CASI
    Publication Date: 2019-07-13
    Description: In the present paper, the motion of a gas in a plane-parallel Laval nozzle in the neighborhood of the transition from subsonic to supersonic velocities is studied. In a recently published paper, F. I. Frankl, applying the holograph method of Chaplygin, undertook a detailed investigation of the character of the flow near the line of transition from subsonic to supersonic velocities. From the results of Tricomi's investigation on the theory of differential equations of the mixed elliptic-hyperbolic type, Frankl introduced as one of the independent variables in place of the modulus of the velocity, a certain specially chosen function of this modulus. He thereby succeeded in explaining the character of the flow at the point of intersection of the transition line and the axis of symmetry (center of the nozzle) and in studying the behavior of the stream function in the neighborhood of this point by separating out the principal term having, together with its derivatives, the maximum value as compared with the corresponding corrections. This principal term is represented in Frankl's paper in the form of a linear combination of two hypergeometric functions. In order to find this linear combination, it is necessary to solve a number of boundary problems, which results in a complex analysis. In the investigation of the flow with which this paper is concerned, a second method is applied. This method is based on the transformation of the equations of motion to a form that may be called canonical for the system of differential equations of the mixed elliptic-hyperbolic type to which the system of equations of the motion of an ideal compressible fluid refers. By studying the behavior of the integrals of this system in the neighborhood of the parabolic line, the principal term of the solution is easily separated out in the form of a polynomial of the third degree. As a result, the computation of the transitional part of the nozzle is considerably simplified.
    Keywords: Fluid Mechanics and Thermodynamics
    Type: NACA-TM-1212 , Prikladnaya Matematika I Mekhanika; 10; 4; 503-512
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  • 21
    Publication Date: 2019-07-13
    Description: There are investigated the problems of the flow of a supersonic jet out of a vessel with plane side walls and the problem of the supersonic flow about a wedge when there is a zone of local subsonic velocities ahead of the wedge.
    Keywords: Fluid Mechanics and Thermodynamics
    Type: NACA-TM-1155 , Bulletin de L'Academie des Sciences de L'URSS; 9; 121-143
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  • 22
    Publication Date: 2019-07-11
    Description: This paper makes the following assumptions: 1) The flowing gases are assumed to have uniform energy distribution. ("Isoenergetic gas flows," that is valid with the same constants for the the energy equation entire flow.) This is correct, for example, for gas flows issuing from a region of constant pressure, density, temperature, end velocity. This property is not destroyed by compression shocks because of the universal validity of the energy law. 2) The gas behaves adiabatically, not during the compression shock itself but both before and after the shock. However, the adiabatic equation (p/rho(sup kappa) = C) is not valid for the entire gas flow with the same constant C but rather with an appropriate individual constant for each portion of the gas. For steady flows, this means that the constant C of the adiabatic equation is a function of the stream function. Consequently, a gas that has been flowing "isentropically",that is, with the same constant C of the adiabatic equation throughout (for example, in origination from a region of constant density, temperature, and velocity) no longer remains isentropic after a compression shock if the compression shock is not extremely simple (wedge shaped in a two-dimensional flow or cone shaped in a rotationally symmetrical flow). The solution of nonisentropic flows is therefore an urgent necessity.
    Keywords: Fluid Mechanics and Thermodynamics
    Type: NACA-TM-1187 , Rept-44/1
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  • 23
    Publication Date: 2019-07-11
    Description: The authors regret that due to the lack of time the investigations could not be carried out to a more finished form. Especially in the first part it was intended to include a few further applications and to use them in the general considerations of this part. In spite of the fact that the intentions of the authors could not be realized, the authors felt that it would serve the aims of the competition to present part I in its present fragmentary form. The topics include: 1) A Few General Remarks Covering the Prandtl-Busemann Method; and 2) Effect of Compressibility in Axially Symmetrical Flow around an Ellipsoid.
    Keywords: Fluid Mechanics and Thermodynamics
    Type: NACA-TM-1233 , Lilienthal-Gesellschaft fuer Luftfahrtforschung Bericht S 13/1, Part 1; 40-68; Rept-13/1
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  • 24
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    In:  CASI
    Publication Date: 2019-07-11
    Description: In the present paper which deals with the heat transfer between the gas and the wall for large temperature drops and large velocities use is made of the method of Dorodnitsyn of the introduction of a new independent variable, with this difference, however, that the relation between the temperature field (that is, density) and the velocity field in the general case considered is not assumed given but is determined from the solution of the problem. The effect of the compressibility arising from the heat transfer is thus taken into account (at the same time as the effect of the compressibility at the large velocities). A method is given for determining the coefficients of heat transfer and the friction coefficients required in many technical problems for a curved wall in a gas flow at large Mach numbers and temperature drops. The method proposed is applicable both for Prandtl number P = 1 and for P not equal to 1.
    Keywords: Fluid Mechanics and Thermodynamics
    Type: NACA-TM-1229 , Prikladnaya Matematika I Mekhanika, Tom X; 449-474
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  • 25
    Publication Date: 2019-07-11
    Description: The present report consists of two parts. The first part deals with the two-dimensional stationary flow in the presence of local supersonic zones. A numerical method of integration of the equation of gas dynamics is developed. Proceeding from solutions at great distance from the body the flow pattern is calculated step by step. Accordingly the related body form is obtained at the end of the calculation. The second part treats the relationship between the displacement thickness of laminar and turbulent boundary layers and the pressure distribution at high speeds. The stability of the boundary layer is investigated, resulting in basic differences in the behavior of subsonic and supersonic flows. Lastly, the decisive importance of the boundary layer for the pressure distribution, particularly for thin profiles, is demonstrated.
    Keywords: Fluid Mechanics and Thermodynamics
    Type: NACA-TM-1189 , Lilienthal-Gesellschaft fuer Luftfahrtforschung Bericht S13/1 Teil; 7-24
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  • 26
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    In:  CASI
    Publication Date: 2019-07-11
    Description: There has been under development for the high-speed wind tunnel of the LFA an optical measuring arrangement for the qualitative and quantitative investigation of flow. By the use of interference measurements, the determination of density at the surface of the bodies being tested in the air stream and in the vicinity of these bodies can be undertaken. The results obtained so far in the simple preliminary investigations show that it is possible, even at a low Reynolds number, to obtain the density field in the neighborhood of a test body by optical means. Simple analytical expressions give the relation between density, pressure, velocity, and temperature. In addition to this, the interference measurement furnishes valuable data on the state of the boundary layer, that is, the sort of boundary layer (whether laminar or turbulent), as well as the temperature and velocity distribution.
    Keywords: Fluid Mechanics and Thermodynamics
    Type: NACA-TM-1253 , Forschungsbericht; Rept-1167
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  • 27
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    In:  CASI
    Publication Date: 2019-07-11
    Description: It is known that compression shocks which lead from supersonic to subsonic velocity cause the flow to separate on impact on a rigid wall. Such shocks appear at bodies with circular symmetry or wing profiles on locally exceeding sonic velocity, and in Laval nozzles with too high a back pressure. The form of the compression shocks observed therein is investigated.
    Keywords: Fluid Mechanics and Thermodynamics
    Type: NACA-TM-1150 , Deutsche Luftfahrtforschung; Rept-1850
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  • 28
    Publication Date: 2019-07-11
    Description: The characteristics of the position and form of the transition surface through the critical velocity are computed for flow through flat and round nozzles from subsonic to supersonic velocity. Corresponding considerations were carried out for the flow about profiles in the vicinity of sonic velocity.
    Keywords: Fluid Mechanics and Thermodynamics
    Type: NACA-TM-1147 , Deutsche Luftfahrtforchung; Rept-1992
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  • 29
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    In:  CASI
    Publication Date: 2019-07-11
    Description: The flow laws of the actual flows at high Reynolds numbers differ considerably from those of the laminar flows treated in the preceding part. These actual flows show a special characteristic, denoted as turbulence. The character of a turbulent flow is most easily understood the case of the pipe flow. Consider the flow through a straight pipe of circular cross section and with a smooth wall. For laminar flow each fluid particle moves with uniform velocity along a rectilinear path. Because of viscosity, the velocity of the particles near the wall is smaller than that of the particles at the center. i% order to maintain the motion, a pressure decrease is required which, for laminar flow, is proportional to the first power of the mean flow velocity. Actually, however, one ob~erves that, for larger Reynolds numbers, the pressure drop increases almost with the square of the velocity and is very much larger then that given by the Hagen Poiseuille law. One may conclude that the actual flow is very different from that of the Poiseuille flow.
    Keywords: Fluid Mechanics and Thermodynamics
    Type: NACA-TM-1218
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  • 30
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    In:  CASI
    Publication Date: 2019-07-11
    Description: Contents include the following: Characteristic differential equations - initial and boundary conditions. Integration of the second characteristic differential equations. Direct application of Meyer's characteristic hodograph table for construction of two-dimensional potential flows. Prandtl-Busemann method. Development of the pressure variation for small deflection angles. Numerical table: relation between deflection, pressure, velocity, mach number and mach angle for isentropic changes of state according to Prandtl-Meyer for air (k = 1.405). References.
    Keywords: Fluid Mechanics and Thermodynamics
    Type: NACA-TM-1243 , Chapter 3,Technische Hochschule Dresden, Archives No. 44/3; Rept-44/3
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  • 31
    Publication Date: 2019-07-11
    Description: Six, 3-inch-chord symmetrical airfoil sections having systematic variations in thickness and thickness location were tested at Mach numbers near flight values for propeller-shank sections. The tests, the results of which are presented in the form of schlieren photographs of the flow past each model and pressure-distribution charts for two of the model, were performed to illustrate the effects of compressibility on the flow past thick symmetrical airfoil sections. Representative flow photographs indicated that at Mach numbers approximately 0.05 above the critical Mach number a speed region was reached in which the flow oscillated rapidly and the separation point and the location of the shock wave were unstable. Fixing the transition on both surfaces of the airfoil was effective in reducing these rapid oscillations. The pressure distributions showed that the section normal-force coefficients for thick airfoils were very erratic at subcritical speeds; at supercritical speeds the section normal-force coefficients for the thick airfoils became more regular. Drag coefficients showed that considerable drag decreases can be expected by decreasing the model thickness ratio.
    Keywords: Fluid Mechanics and Thermodynamics
    Type: NACA-RM-L6J17a
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  • 32
    Publication Date: 2019-07-11
    Description: A heat-transfer investigation was conducted with air flowing through an electrically heated silicon carbide tube with a rounded entrance, an inside diameter of 3/4 inch, and an effective heat-transfer length of 12 inches over a range of Reynolds numbers up to 300,000 and a range of average inside-tube-wall temperature up to 2500 R. The highest corresponding local outside-tube-wall temperature was 3010 R. Correlation of the heat-transfer data using the conventional Nueselt relation wherein physical properties of the fluid were evaluated at average bulk temperature resulted in a separation of data with tube-wall-temperature level. A satisfactory correlation of the heat-transfer data was obtained, however, by the use of modified correlation parameters wherein the mass velocity G (or product of average air density and velocity evaluated at bulk temperature P(sub b)V(sub b)) in the Reynolds number was replaced by the product of average air velocity evaluated at the bulk temperature and density evaluated at either the average inside-tube-wall temperature or the average film temperature; in addition, all the physical properties of air were correspondingly evaluated at either the average inside-tube-wall temperature or the average film temperature.
    Keywords: Fluid Mechanics and Thermodynamics
    Type: NACA-RM-E9D12-Pt-3 , Rept-1115-Pt-3
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  • 33
    Publication Date: 2019-07-10
    Description: In the lecture series starting today author want to give a survey of a field of aerodynamics which has for a number of years been attracting an ever growing interest. The subject is the theory of flows with friction, and, within that field, particularly the theory of friction layers, or boundary layers. A great many considerations of aerodynamics are based on the ideal fluid, that is the frictionless incompressibility and fluid. By neglect of compressibility and friction the extensive mathematical theory of the ideal fluid, (potential theory) has been made possible. Actual liquids and gases satisfy the condition of incomressibility rather well if the velocities are not extremely high or, more accurately, if they are small in comparison with sonic velocity. For air, for instance, the change in volume due to compressibility amounts to about 1 percent for a velocity of 60 meters per second. The hypothesis of absence of friction is not satisfied by any actual fluid; however, it is true that most technically important fluids, for instance air and water, have a very small friction coefficient and therefore behave in many cases almost like the ideal frictionless fluid. Many flow phenomena, in particular most cases of lift, can be treated satisfactorily, - that is, the calculations are in good agreement with the test results, -under the assumption of frictionless fluid. However, the calculations with frictionless flow show a very serious deficiency; namely, the fact, known as d'Alembert's paradox, that in frictionless flow each body has zero drag whereas in actual flow each body experiences a drag of greater or smaller magnitude. For a long time the theory has been unable to bridge this gap between the theory of frictionless flow and the experimental findings about actual flow. The cause of this fundamental discrepancy is the viscosity which is neglected in the theory of ideal fluid; however, in spite of its extraordinary smallness it is decisive for the course of the flow phenomena.
    Keywords: Fluid Mechanics and Thermodynamics
    Type: NACA-TM-1217
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  • 34
    Publication Date: 2019-07-12
    Description: Wind-tunnel tests of a full-scale model of the Republic XF-91 airplane having swept-back wings and a vee tail were conducted to determine both the stability and control characteristics of the model longitudinally, laterally, and directionally. Configurations of the model were investigated involving such variables as external fuel tanks, a landing gear, trailing-edge flaps, leading-edge slats, and a range of wing incidences and tail incidences.
    Keywords: Fluid Mechanics and Thermodynamics
    Type: NACA-RM-SA9C04
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  • 35
    Publication Date: 2019-08-16
    Description: Characteristic methods for nonstationary flows have been published only for the special case of the isentropic flow up until the present, althought they are applicable in various places to more difficult questions too. This report derives the characteristic method for the flows which depend only on the position coordinates and time. At the same time the treatment of compression shocks is shown.
    Keywords: Fluid Mechanics and Thermodynamics
    Type: NACA-TM-1196 , Zentrale fuer Wissenschaftliches Berichtswesen der Luftfahrtforschung des Generalluftzeugmeisters (ZWB); 1744
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  • 36
    facet.materialart.
    Unknown
    In:  CASI
    Publication Date: 2019-08-16
    Description: The investigation of the flow in a centrifugal pump indicated that the flow patterns in frictional fluid are fundamentally different from those in frictionless fluid. In particular, the dead air space adhering to the section side undoubtedly causes a reduction of the theoretically possible delivery head. The velocity distribution over a parallel circle is also subjected to a noticeable change as a result of the incomplete filling of the passages. The relative velocity on the pressure side of the vane, which for passages completely filled with active flow would differ little from zero even at comparatively lower than normal delivery volume, is increased, so that no rapid reverse flow occurs on the pressure side of the vane even for smaller delivery volume. It was established, further, that the flow ceases to be stationary for very small quantities of water. The inflow to the impeller can be regarded as radial for the operating range an question. The velocity triangles at the exit are subjected to a significant alteration in shape ae a result of the increased peripheral velocity, which may be of particular importance in the determination of the guide vane entrance angle.
    Keywords: Fluid Mechanics and Thermodynamics
    Type: NACA-TM-1089 , Mitteilungen des Hydraulischen Instituts der Technischen Hochschule; 4; 1-27
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  • 37
    facet.materialart.
    Unknown
    In:  CASI
    Publication Date: 2019-08-15
    Description: On the basis of certain formulas recently established by L. Prandtl for the turbulent interchange of momentum in stationary flows, various cases of "free turbulence" - that is, of flows without boundary walls - are treated in the present report. Prandtl puts the apparent shearing stress introduced by the turbulent momentum interchange. This present report deals first with the mixing of an air stream of uniform velocity with the adjacent still air, than with the expansion or diffusion of an air jet in the surrounding air space.
    Keywords: Fluid Mechanics and Thermodynamics
    Type: NACA-TM-1085 , Zeitschrift fuer angewandte Mathematik und Mechanik; 6; 1-12
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  • 38
    Publication Date: 2019-08-15
    Description: As a turbine rotor turns, the blades traverse the wake zones of the nozzle vanes. A periodic fluctuation of the pressure distribution around the circumference of the rotor blade is therefore caused. It was desired to investigate quantitatively this effect. At the same time, the magnitude of the force acting upon one profile of the rotor-blade lattice at various positions of this lattice relative to the nozzle lattice was to be determined.
    Keywords: Fluid Mechanics and Thermodynamics
    Type: NACA-TM-1173 , Reports of the Lattice Conference: Berichte der Gittertagung; Mar 27, 1944 - Mar 27, 1944; Brunswick,; Germany|Berichte der Gittertagung; 95-100; M325/44g
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  • 39
    Publication Date: 2019-07-12
    Description: The heat losses from the envelope surface of a U.S. Navy K-type airship are evaluated to determine if the use of heat is a feasible means of preventing ice and snow accumulations on lighter-than-air craft during flight and when moored uncovered. Consideration is given to heat losses in clear air (no liquid water present in the atmosphere) and in probable conditions of icing and snow. The results of the analysis indicate that the amount of heat required in flight to raise the surface temperature of the entire envelope to the extent considered adequate for ice protection, based on experience with tests of heavier-than-air craft, is very large. Existing types of heating equipment which could be used to supply this quantity of heat would probably be too bulky and heavy to provide a practical flight installation. The heat requirements to provide protection for the nose and stern regions in assumed mild to moderate icing conditions appear to be within the range of the capacity of current types of heating equipment suitable for flight use. The amount of heat necessary to prevent snow accumulations on the upper surface of the airship envelope when moored uncovered under all conditions appear to be excessive for the heating equipment presently available for flight use, but could possibly be achieved with auxiliary ground heating equipment.
    Keywords: Fluid Mechanics and Thermodynamics
    Type: NACA-RM-SA6L20
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  • 40
    Publication Date: 2019-07-13
    Description: Test results are present for cascades of airfoils in retarded flow and increasing pressure as corresponds to the case of the impeller of an axial propeller pump and propeller fan.
    Keywords: Fluid Mechanics and Thermodynamics
    Type: NACA-TM-1190 , Transactions of the Society of Mechanical Engineers; 3; 13; 334-344
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  • 41
    facet.materialart.
    Unknown
    In:  CASI
    Publication Date: 2019-07-13
    Description: With water as driving medium and delivered medium in a device similar to a simple jet apparatus, the pressure and velocity fields of the mixing zone were explored with a pitot bar; the ratio of delivered to driving volume ranged between the values 0, 1, 2, and 4. An attempt was also made to analyze the mixing flow mathematically by integration of the equation of motion, with the aid of conventional formulas for the turbulent shearing stress, but this succeeded only approximately for the very simplified case that a driving jet is introduced in an unlimited parallel flow, while the pressure over the whole mixing field is assumed to be constant. In spite of these dissimilar assumptions for the theory and the experiment, the form of the measured and the computed velocity profiles indicates a very high degree of approximation. The pressure rise, which was approximated by Flugel's formulas, disclosed good agreement with the measured values.
    Keywords: Fluid Mechanics and Thermodynamics
    Type: NACA-TM-1096 , Forschung auf dem Gebiete des Ingenieurwesens; 12; 1; 16-30
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  • 42
    facet.materialart.
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    In:  CASI
    Publication Date: 2019-07-13
    Description: The characteristics introduced by the turbulence in the process of the flame propagation are considered. On the basis of geometrical and dimensional considerations an expression is obtained for the velocity of the flame propagation in a flow of large scale of turbulence.
    Keywords: Fluid Mechanics and Thermodynamics
    Type: NACA-TM-1110 , Journal of Technical Physics; 13; 10-Sep
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  • 43
    Publication Date: 2019-07-13
    Description: On the basis of photographic pictures the laminar flow at a pipe inlet was measured and compared with other measurements and computational results. The test setup is described in detail, and a series of the pictures obtained for turbulent flow is given.
    Keywords: Fluid Mechanics and Thermodynamics
    Type: NACA-TM-1109 , Forschung auf dem Gebiete des Ingenieurwesens; 8; Pt 1; 42-47
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  • 44
    Publication Date: 2019-07-13
    Description: The present report deals with the effect of turbulence on the propagation of the flame. Being based upon experiments with laminar as well as turbulent Bunsen flames, both the physico-chemical and the hydro-dynamical aspects of the problem are analyzed. A number of new deductions, interesting from the point of view of engine combustion and other very rapidly changing flame reactions, are made.
    Keywords: Fluid Mechanics and Thermodynamics
    Type: NACA-TM-1112 , Zeitschrift fuer Elektrochemie und Angewandte Physikalische Chemiw; 46; 11; 601-626
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