The effects of the inertia of a particle on its flow-tracking accuracy and particle dispersion are studied using direct numerical simulations of 2D compressible free shear layers in convective Mach number (Mc) range of 0.2 to 0.6. The results show that particle response is well characterized by tau, the ratio of particle response time to the flow time scales (Stokes' number). The slip between particle and fluid imposes a fundamental limit on the accuracy of optical measurements such as LDV and PIV. The error is found to grow like tau up to tau = 1 and taper off at higher tau. For tau = 0.2 the error is about 2 percent. In the flow visualizations based on Mie scattering, particles with tau more than 0.05 are found to grossly misrepresent the flow features. These errors are quantified by calculating the dispersion of particles relative to the fluid. Overall, the effect of compressibility does not seem to be significant on the motion of particles in the range of Mc considered here.

Motion of particles with inertia in a compressible free shear layer

We present a direct numerical simulation database of supersonic and hypersonic turbulent boundary layers. The systematic procedure for initializing the turbulent flow fields at controlled Mach number and Reynolds number conditions is described. It is shown that simulation transients are less than 10% of the time required for gathering statistical data of the turbulent flows. The experimental conditions of Debieve and Elena are simulated. The magnitude of velocity and temperature fluctuations, as well as the turbulent shear stresses given by the direct numerical simulations are in excellent agreement with the experimental data. Using the direct numerical simulation database we perform parametric studies varying freestream Mach number in the range of 3 to 8 and wall-temperature condition for wall-to-freestream-temperature ratio of 2 to 5.5.

/pdf/dns-of-hypersonic-turbulent-boundary-layers-2ysy7vazlc.pdf

DNS of Hypersonic Turbulent Boundary Layers

http://croccolab.umd.edu/publications/journal-docs/05-MartinCandler_JCP06_vol215_no1.pdf

A parallel implicit method for the direct numerical simulation of wall-bounded compressible turbulence

The current status of basic research in hypersonic turbulent flows is reviewed. We consider free shear layers, boundary layers, internal flows and shock-wave boundary layer interactions, and discuss experiments as well as computations, including DNS, LES, RANS and RANS-LES hybrid approaches. Important research challenges in external and internal hypersonic flows are identified and some possible future directions are explored. Some recent experimental and computational contributions are summarized.

Current status of basic research in hypersonic turbulence

Quadrant analysis was performed with instantaneous velocities measured by laser Doppler velocimetry in a zero pressure gradient supersonic turbulent boundary layer on an adiabatic or heated plate The distributions obtained were close to those for subsonic flows, and were not modified by the wall heating Moreover, this heating made it possible to extend the analysis to a part of the buffer layer that is characteristic of the turbulence process (y+∼15) This led to a differentiation between the effects of Reynolds and Mach numbers in the various regions of the boundary layer

Quadrant analysis in a heated‐wall supersonic boundary layer

This book presents the papers given at a conference on the use of measuring instruments in energy applications. Topics considered at the conference included instrumentation for the measurement of two-phase flows in gas turbine engines, laser doppler velocimeter signal quality in a spark ignition engine, measurements of flow from a fuel nozzle, anemometers for loss of coolant measurements, two-phase flow in pipelines, flame propagation, shock wave-turbulent boundary layer interaction, and open-channel flow.

International symposium on laser anemometry

Fluid flow and heat transfer over rod or tube bundles : presented at the winter annual meeting of the American Society of Mechanical Engineers, New York, New York, December 2-7, 1979

Proceedings of the 3rd ASME・JSME Joint Fluids Engineering Conference : presented at the 3rd ASME・JSME Fluids Engineering Conference, July 18-23, 1999, San Francisco, California

P. A. Pfund

Papers

International symposium on laser anemometry

Fluid flow and heat transfer over rod or tube bundles : presented at the winter annual meeting of the American Society of Mechanical Engineers, New York, New York, December 2-7, 1979

Proceedings of the 3rd ASME・JSME Joint Fluids Engineering Conference : presented at the 3rd ASME・JSME Fluids Engineering Conference, July 18-23, 1999, San Francisco, California