ALBERT

All Library Books, journals and Electronic Records Telegrafenberg

X
feed icon rss

Your email was sent successfully. Check your inbox.

An error occurred while sending the email. Please try again.

Proceed reservation?

Export
Filter
  • FLUID MECHANICS AND HEAT TRANSFER  (12)
  • 1
    facet.materialart.
    Unknown
    Development of a two-stream mixing layer from tripped and untripped boundary layers (1990)
    In:  Other Sources
    Details
    Publication Date: 2019-06-28
    Description: The effects of the state of the initial boundary layers on the development of a two-stream, plane mixing layer, with a velocity ratio of 0.6 are experimentally investigated. Spanwise-average profiles are compared for the first time. The results indicate that both the near and far-field growth rates for the untripped case are significantly higher than the tripped case. The maximum Reynolds stresses and higher-order products for the two cases behave very differently in the near-field, but asymptote to approximately the same constant levels far downstream. The mean velocity and turbulence profiles in this region also collapse adequately for the two cases when plotted in similarity coordinates. The distance required to achieve self-similarity is distinctly shorter for the tripped case, in contrast to previous observations. The higher growth rate for the untripped case is attributed to the presence of streamwise vortices which result in additional entrainment by the mixing layer.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: AIAA PAPER 90-0505
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 2
    facet.materialart.
    Unknown
    An experimental study of secondary vortex structure in mixing layers (1990)
    In:  CASI
    Details
    Publication Date: 2019-06-28
    Description: This report covers the first eight months of an experimental research project on the secondary vortex structure in plane mixing layers. The aim of the project is to obtain quantitative data on the behavior of the secondary structure in a turbulent mixing layer at reasonable reynolds numbers (Re(sub delta(sub w)) approx. 50,000). In particular, we hope to resolve the questions of how the scale of the secondary vortex structure changes with the scale of the mixing layer, and whether the structures are fixed in space, or whether they 'meander' in the spanwise direction.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: Annual Research Briefs, 1989; p 59-79
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 3
    facet.materialart.
    Unknown
    Contraction design for small low-speed wind tunnels (1988)
    In:  CASI
    Details
    Publication Date: 2019-06-28
    Description: An iterative design procedure was developed for two- or three-dimensional contractions installed on small, low-speed wind tunnels. The procedure consists of first computing the potential flow field and hence the pressure distributions along the walls of a contraction of given size and shape using a three-dimensional numerical panel method. The pressure or velocity distributions are then fed into two-dimensional boundary layer codes to predict the behavior of the boundary layers along the walls. For small, low-speed contractions it is shown that the assumption of a laminar boundary layer originating from stagnation conditions at the contraction entry and remaining laminar throughout passage through the successful designs if justified. This hypothesis was confirmed by comparing the predicted boundary layer data at the contraction exit with measured data in existing wind tunnels. The measured boundary layer momentum thicknesses at the exit of four existing contractions, two of which were 3-D, were found to lie within 10 percent of the predicted values, with the predicted values generally lower. From the contraction wall shapes investigated, the one based on a fifth-order polynomial was selected for installation on a newly designed mixing layer wind tunnel.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: NASA-CR-177488 , NAS 1.26:177488
    Format: application/pdf
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 4
    facet.materialart.
    Unknown
    Three-dimensional structure of a plane mixing layer (1989)
    In:  Other Sources
    Details
    Publication Date: 2019-06-28
    Description: An experimental study is reported which shows the spanwise structure of a plane mixing layer originating from laminar boundary layers. Quantitative measurements are obtained for the first time which show the origin and evolution of streamwise vortices within the mixing layer. After the first spanwise vortex rollup occurs, streamwise structures are triggered in clusters within the braid region of the mixing layer. Further downstream, they realign to form pairs of counterrotating vortices. The maximum vorticity diffuses rapidly with increasing downstream distance while the vortices grow, scaling with the mixing layer vorticity thickness. The presence of the streamwise vortices leads to significant spanwise distortions in the mean and turbulence properties of the mixing layer. A consistent peak in the secondary shear stress exists for each streamwise vortex.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: AIAA PAPER 89-0124
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 5
    facet.materialart.
    Unknown
    Spanwise averaging of plane mixing layer properties (1992)
    In:  Other Sources
    Details
    Publication Date: 2019-07-12
    Description: An attempt is made to demonstrate the effects of streamwise vorticity on such mixing layer global properties as layer thickness and peak Reynolds stresses. Attention is given to differences between results obtained from spanwise averaging over a number of velocity profiles and those given by the more conventional approach of analyzing a single profile measured along the test section centerline. It is found that the growth rate and streamwise development of peak Reynolds stresses in the near field can be significantly affected by spanwise variations in the mixing layer.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: AIAA Journal (ISSN 0001-1452); 30; 835-837
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 6
    facet.materialart.
    Unknown
    Measurements of the streamwise vortical structures in a plane mixing layer (1992)
    In:  Other Sources
    Details
    Publication Date: 2019-07-12
    Description: The 3D structure of a plane two-stream mixing layer of velocity ratio 0.6 and originating from laminar initial boundary layers was investigated through direct measurements made in a specially constructed mixing-layer wind tunnel. The main objective of the study was to establish quantitatively the presence and the role of the secondary streamwise vortex structure (of the kind that has been shown in past flow visualization investigations to ride among the primary spanwise vortices) in the development of a plane turbulent mixing layer at relatively high Reynolds numbers. Results indicate that the instability leading to the formation of streamwise vortices is initially amplified just downstream of the first spanwise roll-up. The streamwise vortices, which first appear in clusters containing vorticity of both signs, realign further downstream to form counterrotating pairs. Due to the amalgamation of like-sign vortices, the streamwise vortex spacing increases in a stepwise fashion.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: Journal of Fluid Mechanics (ISSN 0022-1120); 239; 213-248
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 7
    facet.materialart.
    Unknown
    Boundary-layer predictions for small low-speed contractions (1989)
    In:  Other Sources
    Details
    Publication Date: 2019-07-12
    Description: The present scheme for the prediction of boundary-layer development in small, low-speed wind tunnel contraction sections proceeds by calculating the wall pressure distributions, and hence the wall velocity distributions, by means of a three-dimensional potential-flow method. For the family of contractions presently treated, the assumption of a laminar boundary layer appears to be justified; the measured boundary layer momentum thicknesses at the exit of the four contractions were found to lie within 10 percent of predicted values.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: AIAA Journal (ISSN 0001-1452); 27; 372-374
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 8
    facet.materialart.
    Unknown
    Effects of initial conditions on the development of curved wakes (1993)
    In:  Other Sources
    Details
    Publication Date: 2019-07-13
    Description: An experimental investigation has been conducted on the three-dimensional structure of curved plane wakes developing from tripped and untripped initial boundary layers. The effects of mild stream-wise curvature on a wake generated at the trailing edge of a slowly tapering splitter plate were investigated at a Reynolds number of about 30,000. With the initial boundary layers turbulent, spatially-stationary streamwise vorticity was not observed. The curvature affected the wake growth and defect-decay rates, but in different ways for each of the two initial conditions. The effects of curvature were also apparent in the Reynolds stress results, especially in the primary shear stress distributions, which showed that the levels on the unstable side were increased significantly compared to those for a straight wake, while those on the stable side were decreased, with the effect stronger in the initially laminar wake.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: AIAA PAPER 93-0655 , AIAA, Aerospace Sciences Meeting and Exhibit; Jan 11, 1993 - Jan 14, 1993; Reno, NV; United States|; 11 p.
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 9
    facet.materialart.
    Unknown
    An experimental study of forced streamwise vortical structures in a plane mixing layer (1989)
    In:  Other Sources
    Details
    Publication Date: 2019-07-13
    Description: Streamwise structures have been shown to ride among the primary spanwise vortices in past flow visualization investigations of plane mixing layers. More recently, quantitative measurements were obtained which showed the origin and evolution of streamwise vortices within a mixing layer. In the present study, the effects of perturbing the mixing layer using two different mechanisms are investigated. A serration on the splitter plate trailing edge was found to have a relatively small effect, confined to the near-field development of the streamwise structures. The installation of cylindrical pegs in the high-speed side boundary layer, however, not only generated a regular array of vortex pairs, but also affected the mean development of the mixing layer far downstream. In both cases, the mean streamwise vorticity was found to decay rapidly with increasing downstream distance.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: Australasian Fluid Mechanics Conference; Dec 11, 1989 - Dec 15, 1989; Melbourne; Australia
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 10
    facet.materialart.
    Unknown
    Development of a two-stream mixing layer from tripped and untripped boundary layers (1990)
    In:  Other Sources
    Details
    Publication Date: 2019-07-12
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: AIAA Journal (ISSN 0001-1452); 28; 2034-204
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
Close ⊗
This website uses cookies and the analysis tool Matomo. More information can be found here...