Engineering topics

Passamaneck, R. S.

Publications and source records attributed to Passamaneck, R. S..

3 records

NASA NTRS1977

Monopropellant thruster exhaust plume contamination measurements

The potential spacecraft contaminants in the exhaust plume of a 0.89N monopropellant hydrazine thruster were measured in an ultrahigh quartz crystal microbalances located at angles of approximately 0 deg, + 15 deg and + or - 30 deg with respect to the nozzle centerline. The crystal temperatures were controlled such that the mass adhering to the crystal surface at temperatures of from 106 K to 256 K could be measured. Thruster duty cycles of 25 ms on/5 seconds off, 100 ms on/10 seconds off, and 200 ms on/20 seconds off were investigated. The change in contaminant production with thruster life was assessed by subjecting the thruster to a 100,000 pulse aging sequence and comparing the before and after contaminant deposition rates. The results of these tests are summarized, conclusions drawn, and recommendations given.

Baerwald, R. K.↗

NASA NTRS1977

Small monopropellant thruster contamination measurement in a high-vacuum low-temperature facility

The contamination that results from the exhaust plume of small thrusters used for attitude control maneuvers can pose severe problems for long-life satellite systems. In order to assess this type of contamination problem, analytical and experimental techniques must be developed. Mass deposition rate measurements of a representative 0.44-N thrust hydrazine thruster were made in a space simulation chamber using five appropriately placed variable-temperature quartz crystal microbalances. The mass deposition rates within the thruster plume were measured while operating the thruster over a wide range of operating parameters, including duty cycles, catalyst bed start temperatures, propellant water variation, as well as thruster aging effects. The contamination measurements were made over a temperature range of 144 to 256 K for all duty cycles. In addition, the nominal duty cycle of 100 msec on and 10 sec off was run at a temperature of 106 K. These data will make possible better prediction of deposition rates of contaminants from thrusters used in satellite systems.

Passamaneck, R. S.↗

NASA NTRS1974

Viscous, radiating hypersonic flow about a blunt body

The viscous, radiating hypersonic flow past an axisymmetric blunt body is analyzed based on the Navier-Stokes equations, plus a radiative equation of transfer derived from the Milne-Eddington differential approximation. The fluid is assumed to be a perfect gas with constant specific heats, a constant Prandtl number of order unity, a viscosity coefficient varying as a power of the temperature, and an absorption coefficient varying as the first power of the density and as a power of the temperature. The gray gas assumption is invoked, thereby making the absorption coefficient independent of the spectral frequency. Limiting forms of the solutions are studied as the freestream Mach number freestream Reynolds number and the temperature ratio across the shock wave, go to infinity, and as the Bouguer number and the density ratio across the shock wave go to zero. The method of matched asymptotic expansions is used in the analysis, and it is shown that there is a far-field precursor, composed of two regions, in which the fluid mechanics can be neglected for all practical purposes but included for completeness.

Passamaneck, R. S.↗