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  • 1
    Publication Date: 2011-08-18
    Description: Helicopter drop tests were made of models of the Pioneer Venus probe descent configurations to characterize their unsteady forces and angular dynamics in equilibrium descent. The axial and normal forces were found to be unsteady in magnitude by about 10 and 5% of the mean axial force, respectively. A cycle of the axial variation takes place in flight distances of from 15 to 40 diameters. The unsteadiness almost certainly is associated with the wake. Angular motions which do not converge to zero angle of attack even in very long duration descent are excited by the unsteady pitching moments. The nearly spherical large probe model was aerodynamically more unsteady than the round-nosed conical small probe model. Data returned from Venus by the Pioneer Venus probes show unsteady axial forces and angular motions similar to those seen in the drop tests.
    Keywords: SPACECRAFT DESIGN, TESTING AND PERFORMANCE
    Type: Journal of Spacecraft and Rockets; 19; Sept
    Format: text
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  • 2
    Publication Date: 2011-08-17
    Description: Wind-tunnel tests were performed on a scale model of a cab-over-engine tractor-trailer vehicle and several modifications of the model. Results from two of the model configurations were compared with full-scale drag data obtained from similar configurations during coast-down tests. Reductions in fuel consumption derived from these tests are presented in terms of fuel quantity and dollar savings per vehicle year, based on an annual driving distance of 160,900 km (100,000 mi.). The projected savings varied from 13,001 (3435) to 25,848 (6829) liters (gallons) per year which translated to economic savings from $3435 to about $6829 per vehicle year for an operating speed of 88.5 km/h (55 mph) and wind speeds near the national average of 15.3 km/h (9.5 mph). The estimated cumulative fuel savings for the entire U.S. fleet of cab-over-engine tractor, van-type trailer combinations ranged from 4.18 million kl (26.3 million bbl) per year for a low-drag configuration to approximately twice that amount for a more advanced configuration.
    Keywords: URBAN TECHNOLOGY AND TRANSPORTATION
    Type: Journal of Energy; 3; Sept
    Format: text
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  • 3
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    In:  CASI
    Publication Date: 2016-06-07
    Description: Optimization of L/D through minimizing induced drag through a detailed flow study together with force, pressure and vorticity measurements is considered. Flow visualization with neutral helium bubbles provides an excellent means of observing the effects of configuration changes.
    Keywords: AERODYNAMICS
    Type: Proc. of the NASA, Ind., Univ., Gen. Aviation Drag Reduction Workshop; p 215-233
    Format: application/pdf
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  • 4
    Publication Date: 2019-06-28
    Description: A wind tunnel investigation was conducted to determine the influence of several physical variables on the aerodynamic drag of a trailer model. The physical variables included: a cab mounted wind deflector, boattail on trailer, flow vanes on trailer front, forced transition on trailer, and decreased gap between tractor and trailer. Tests were conducted at yaw angles (relative wind angles) of 0, 5, 10, 20, and 30 degrees and Reynolds numbers of 3.58 x 10 to the 5th power 6.12 x 10 to the 5th power based upon the equivalent diameter of the vehicles. The wind deflector on top of the cab produced a calculated reduction in fuel consumption of about 5 percent of the aerodynamic portion of the fuel budget for a wind speed of 15.3 km/hr (9.5 mph) over a wind angle range of 0 deg to 180 deg and for a vehicle speed of 88.5 km/hr (55 mph). The boattail produced a calculated 7 percent to 8 percent reduction in fuel consumption under the same conditions. The decrease in gap reduced the calculated fuel consumption by about 5 percent of the aerodynamic portion of the fuel budget.
    Keywords: URBAN TECHNOLOGY AND TRANSPORTATION
    Type: NASA-CR-163104 , KU-FRL-406-1
    Format: application/pdf
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  • 5
    Publication Date: 2019-06-28
    Description: The influence of physical variables on the aerodynamic drag of a box shaped vehicle model was studied. The physical variables included built-in rounded front corners, and two different designs of add on flow vanes for the front of box shaped vehicle with 67 deg and 90 deg of arc. For a diesel powered vehicle, only slightly larger than a family van, the built in rounded front corners provide a calculated fuel saving of about 6.0 liters per hour of driving (1.6 gallons per hour) at 88.6 km per hour (55 mph) in national average winds, as compared to the baseline vehicle having all square corners. The corresponding savings for a baseline vehicle to which front mounted flow vanes were added is competitive. For a gasoline powered vehicle the volumetric fuel savings would be larger by a factor of about 1.7. The fuel savings for a standard size motor home would be greater for the diesel or gasoline powered vehicles by from 30 to 35 percent because of the larger frontal area. Thus projected fuel savings for a standard size motor home powered by gasoline can approach 12.5 to 13.5 liters (3.3 to 3.6 gallons) for each hour driving at highway speeds.
    Keywords: AERODYNAMICS
    Type: NASA-CR-163111 , KU-FRL-406-3
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  • 6
    Publication Date: 2019-06-28
    Description: Models of both the small and large Pioneer Venus probes were dropped from a helicopter to simulate the conditions of Mach and Reynolds numbers to be encountered by the probes upon entry into the Venus atmosphere. The models were dropped at an average Mach number of .10 and at an average Reynolds number of 2.84 million for the small probe and 2.90 million for the large probe. After the large amplitude launching oscillations were damped, the small probe oscillations in angle of attack and in sideslip were generally less than 2 degrees. The large probe oscillations were generally less than 10 degrees. Both exhibited distinct frequencies. The motion of the small probe in a place perpendicular to the z axis was random while the large probe rotated (corkscrewed) at 1.1 cycles per second about the z axis. The average drag coefficients of the probe models were .714 for the small probe and .663 for the large probe.
    Keywords: LAUNCH VEHICLES AND SPACE VEHICLES
    Type: NASA-CR-164298 , KU-FRL-333-1
    Format: application/pdf
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  • 7
    Publication Date: 2019-06-28
    Description: A wind tunnel investigation was conducted to determine the influence of several physical variables on the aerodynamic drag of a standard truck model. The physical variables included: a cab mounted air deflector; a boattail on the rear of the cargo compartment; flow-vanes on the front of the cargo compartment; and a forebody fairing over the cab. Tests were conducted at yaw angles (relative wind angle) of 0, 5, 10, 20, and 30 degrees and Reynolds numbers of 3.4 x 100,000 to 6.1 x 100,000 based upon the equivalent diameter of the vehicles. The forebody fairing and the flow-vane with the closed bottom were very effective in improving the flow over the forward part of the cargo compartment. The forebody fairing provided a calculated fuel saving of 5.6 liters per hour (1.5 gallons per hour) over the baseline configuration for a ground speed of 88.6 km/hr (55 mph) in national average winds.
    Keywords: AERODYNAMICS
    Type: NASA-CR-163107 , KU-FRL-406-2
    Format: application/pdf
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  • 8
    Publication Date: 2019-06-28
    Description: Wind tunnel tests were conducted on a one-tenth scale model of a conventional tractor trailer livestock hauler to determine the air flow through the trailer and the drag of the vehicle. These tests were conducted with the trailer empty and with a full load of simulated cattle. Additionally, the drag was determined for six configurations, of which details for three are documented herein. These are: (1) conventional livestock trailer empty, (2) conventional trailer with smooth sides (i.e., without ventilation openings), and (3) a stream line tractor with modified livestock trailer (cab streamlining and gap fairing). The internal flow of the streamlined modification with simulated cattle was determined with two different ducting systems: a ram air inlet over the cab and NACA submerged inlets between the cab and trailer. The air flow within the conventional trailer was random and variable. The streamline vehicle with ram air inlet provided a nearly uniform air flow which could be controlled. The streamline vehicle with NACA submerged inlets provided better flow conditions than the conventional livestock trailer but not as uniform or controllable as the ram inlet configuration.
    Keywords: URBAN TECHNOLOGY AND TRANSPORTATION
    Type: NASA-CR-170400 , NAS 1.26:170400 , KU-FRL-541-2
    Format: application/pdf
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  • 9
    Publication Date: 2019-06-27
    Description: The nature of intense air vortices was studied and the factors which determine the intensity and rate of decay of both single and pairs of vortices were investigated. Vortex parameters of axial pressure differential, circulation, outflow rates, separation distance and directions of rotation were varied. Unconfined vortices, generated by a single rotating cage, were intensified by an increasing axial pressure gradient. Breakdown occurred when the axial gradient became negligible. The core radius was a function of the axial gradient. Dual vortices, generated by two counterrotating cages, rotated opposite to the attached cages. With minimum spacing only one vortex was formed which rotated in a direction opposite to the attached cage. When one cage rotated at half the speed of the other cage, one vortex formed at the higher speed cage rotating in the cage direction.
    Keywords: AERODYNAMICS
    Type: NASA-CR-145261 , CRINC-FRL-260-1
    Format: application/pdf
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  • 10
    Publication Date: 2019-06-27
    Description: The capabilities of the Kansas University- Flight Research Center for investigating panel sound transmission as a step toward the reduction of interior noise in general aviation aircraft were discussed. Data obtained on panels with holes, on honeycomb panels, and on various panel treatments at normal incidence were documented. The design of equipment for panel transmission loss tests at nonnormal (slanted) sound incidence was described. A comprehensive theory-based prediction method was developed and shows good agreement with experimental observations of the stiffness controlled, the region, the resonance controlled region, and the mass-law region of panel vibration.
    Keywords: ACOUSTICS
    Type: NASA-CR-156170 , KU-FRL-317-6
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