Engineering topics

Thompson, H. Doyle

Publications and source records attributed to Thompson, H. Doyle.

5 records

NASA NTRS1992

Hypervelocity scramjet combustor-nozzle analysis and design

The progress report for the grant entitled 'Hypervelocity of Scramjet Combustor-Nozzle Analysis and Design' is presented. The three main tasks in the program are combustor modeling study, development of anaylsis capabilities for hypersonic scramjet nozzles, and development of optimum design methods for hypersonic scramjet nozzles. The research performed was documented in a series of technical publications and presentations at various conferences. A brief description of the research in each of the above three areas and a list of the resulting technical publications are included.

Thompson, H. Doyle↗

NASA NTRS1990

Investigation of turbulent transport in an axisymmetric sudden expansion

Simultaneous two-component laser velocimeter measurements were made in the incompressible turbulent flowfield following an axisymmetric sudden expansion. Mean velocities, Reynolds stresses, and triple products were measured and are presented at axial positions ranging from x/H = 0.2-14. A balance of the turbulent kinetic energy in the flow was performed. The production, convection, and diffusion of turbulent kinetic energy were computed directly from the experimental data using central differencing. A specially designed correction lens was employed to correct for optical aberrations introduced by the circular tube. This lens system allowed the accurate simultaneous measurement of axial and radial velocities in the test section. The experimental measurements were compared to predictions generated by a code that employed the k-epsilon turbulence model. Agreement was good for mean axial velocities, turbulent kinetic energy, and turbulent shear stresses. However, the modeled turbulent normal stresses where in poor agreement with the measured values. The modeled diffusion of turbulent kinetic energy was underpredicted in the region between the shear layer and the centerline of the flow giving lower values of turbulent kinetic energy downstream of the potential core than measured.

Gould, Richard D.↗

NASA NTRS1989

Parametric study of statistical bias in laser Doppler velocimetry

Analytical studies have often assumed that LDV velocity bias depends on turbulence intensity in conjunction with one or more characteristic time scales, such as the time between validated signals, the time between data samples, and the integral turbulence time-scale. These parameters are presently varied independently, in an effort to quantify the biasing effect. Neither of the post facto correction methods employed is entirely accurate. The mean velocity bias error is found to be nearly independent of data validation rate.

Gould, Richard D.↗

NASA NTRS1988

The turbulence characteristics of a separated flow with combustion

The effects of combustion on the turbulent structure of a flow and vice versa were studied by making simultaneous two-component laser velocimeter measurements in the turbulent flow field following an axisymmetric sudden expansion with and without combustion. Mean axial and radial velocities and Reynolds stresses were measured. In addition, simultaneous time resolved temperature measurements were made in the reacting flow using fast response thermocouples. Velocity-temperature correlations were formed from the velocity and temperature measurements.

Gould, Richard D.↗

NASA NTRS1986

Two component laser velocimeter measurements of turbulence parameters downstream of an axisymmetric sudden expansion

Simultaneous two-component laser velocimeter measurements were made in an axisymmetric sudden expansion flowfield. A specially designed correction lens was employed to correct optical aberrations introduced by the circular tube. This lens system allowed the accurate simultaneous measurement of axial and radial velocities in the test section. The experimental measurements were compared to predictions generated by a code which employed the k-epsilon turbulence model. Possible sources of differences observed between model predictions and the measurements are discussed.

Gould, Richard D.↗