Homogeneous turbulence generated by uniform fluxes of round glass beads (0.5, 1.0 and 2.0 mm dia) falling through stagnant (in the mean) air was studied for particle Reynolds numbers in the range 100-800 and particle volume fractions <0.0004%. Moments, probability density functions, spatial correlations and temporal spectra of air velocity fluctuations were measured using two-point phasediscriminating laser velocimetry. Predictions based on a simplified stochastic analysis, involving linear superposition of randomly-arriving particle velocity fields, were used to help interpret the measurements. Guided by the theory, correlations of turbulence properties were achieved for both the present particle/air and earlier particle/water measurements. Turbulence intensities (referenced to mean particle relative velocities) and integral scales are functions of the rate of dissipation of particle mechanical energy and particle drag properties; however, normalized probability density functions, spatial correlations and temporal spectra are largely independent of particle properties.

The supersonic diffuser of a Mach 2.68 bifurcated, rectangular, mixed-compression inlet was analyzed using a two-dimensional (20) Navier-Stokes flow solver. Parametric studies were performed on turbulence models, computational grids and bleed models. The computed flowfield was substantially different from the original inviscid design, due to interactions of shocks, boundary layers, and bleed. Good agreement with experimental data was obtained in many aspects. Many of the discrepancies were thought to originate primarily from 3D effects. Therefore, a balance should be struck between expending resources on a high fidelity 20 simulation, and the inherent limitations of 20 analysis. The solutions were fairly insensitive to turbulence models, grids and bleed models. Overall, the k-e turbulence model, and the bleed models based on unchoked bleed hole discharge coefficients or uniform velocity are recommended. 20 Navier-Stokes methods appear to be a useful tool for the design and analysis of supersonic inlets, by providing a higher fidelity simulation of the inlet flowfield than inviscid methods, in a reasonable turnaround time.

This paper presents pertinent results and assessment of propellant feed system leak detection as applied to the Linear Aerospike SR-71 Experiment (LASRE) program flown at the NASA

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The Mars Science Laboratory (MSL) is NASA's next major mission to Mars, to be launched in September 2009. It is a nuclear powered rover designed for a long duration mission, with an extensive suite of science instruments. The descent and landing uses a unique 'skycrane' concept, where a rocket-powered descent stage decelerates the vehicle, hovers over the ground, lowers the rover to the ground on a bridle, then flies a safe distance away for disposal. This descent stage uses a regulated hydrazine propulsion system. Performance requirements for the pressure regulator were very demanding, with a wide range of flow rates and tight regulated pressure band. These indicated that a piloted regulator would be needed, which are notoriously complex, and time available for development was short. Coincidentally, it was found that the helium regulator used in the Space Shuttle Orbiter main propulsion system came very close to meeting MSL requirements. However, the type was out of production, and fabricating new units would incur long lead times and technical risk. Therefore, the Space Shuttle program graciously furnished three units for use by MSL. Minor modifications were made, and the units were carefully tuned to MSL requirements. Some of the personnel involved had built and tested the original shuttle units. Delta qualification for MSL application was successfully conducted on one of the units. A pyrovalve slam start and shock test was conducted. Dynamic performance analyses for the new application were conducted, using sophisticated tools developed for Shuttle. Because the MSL regulator is a refurbished Shuttle flight regulator, it will be the only part of MSL which has physically already been in space.