Engineering topics

Menees, G. P.

Publications and source records attributed to Menees, G. P..

26 records · Page 2

NASA NTRS1976

Nitric oxide formation by meteoroids in the upper atmosphere

The process of nitric oxide formation during atmospheric entry of meteoroids is analyzed theoretically. An ablating meteoroid is assumed to be a point source in a uniform flow with a continuum regime evolving in its wake. The amount of nitric oxide produced by high-temperature reactions of air in the continuum regime is calculated by numerical integration of chemical-rate equations. The results, when summed over the observed mass, velocity, and entry-angle distributions of meteoroids, provide annual global production rates of nitric oxide as a function of altitude. The peak production of nitric oxide is found to occur at altitudes between 90 and 100 km, the total annual rate being about 40 million kg. The present results suggest that the large concentration of nitric oxide observed below 95 km could be attributed to meteoroids instead of photodissociation of nitrogen.

Menees, G. P.↗

NASA NTRS1974

Nitric oxide formation by meteoroids in the upper atmosphere

The process of nitric oxide formation during atmospheric entry of meteoroids is analyzed theoretically. An ablating meteoroid is assumed to be a point source in a uniform flow with a continuum regime evolving in its wake. The amount of nitric oxide produced by high-temperature reactions of air in the continuum regime is calculated by numerical integration of chemical-rate equations. This is accomplished by assuming that flow properties are constant across the reacting region, its radius being determined from considerations of shock-wave formation and molecular diffusion. The results, when summed over the observed mass, velocity, and entry-angle distributions of meteoroids, provide annual global production rates of nitric oxide as a function of altitude. The peak production is found to occur between 90- and 100-km altitude, the total annual rate being around 40 million kg.

Menees, G. P.↗

NASA NTRS1972

Experimental study of wall boundary layer growth in the 10 deg half angle conical nozzle of a reflected shock tunnel

Calibration studies of shock-tunnel nozzle flow were made in both N2 and Ar for a reservoir temperature of 2000 deg K and reservoir pressures of 15, 85, and 130 atm. The results for both test gases showed that the boundary layer was turbulent and the growth nonlinear, with the thickness being greater in Ar than N2 at comparable reservoir conditions. The boundary-layer thickness decreased with increasing reservoir pressure, but only small differences occurred between the two largest reservoir pressures. Good correlations of the boundary layer and displacement thickness were obtained for both N2 and Ar in terms of Reynolds number based on a reference temperature.

Menees, G. P.↗

NASA NTRS1971