Investigation of row past a sphere in free flight

Sonic and shock waves in gas-discharge plasma

“…14 In ballistic range experiments, 13 the drag coefficient of a sphere was shown to be slightly higher in plasma than in unionized air at supersonic speeds. In unionized air at the same initial pressure, temperature, and velocity, a value of ( P s / P 0 ) AIR ϭ5.45 is obtained, so the stagnation pressure in the presence of the plasma is 7.2% lower than the corresponding case in unionized air.…”

“…13 We shall estimate the gas dynamic properties across the bow shock wave and in the stagnation zone for a case in which the model velocity v 0 ϭ1320 m/s, corresponding to a flight Mach number M ϭ2. Experimental measurements of drag in weakly ionized air generated by rf discharge were conducted at a gas temperature of 1140 K ͑gas kinetic sound speedϭ660 m/s; ␥ id ϭ1.33͒ and pressure P 0 ϭ15 Torr.…”

“…In unionized air at the same initial pressure, temperature, and velocity, a value of ( P s / P 0 ) AIR ϭ5.45 is obtained, so the stagnation pressure in the presence of the plasma is 7.2% lower than the corresponding case in unionized air. 13 It is clear that part of the drag decrease results from a reduction in the stagnation pressure that takes place in the isentropic compression that occurs in front of the sphere. 14 In ballistic range experiments, 13 the drag coefficient of a sphere was shown to be slightly higher in plasma than in unionized air at supersonic speeds.…”

Effect of electron density on shock wave propagation in optically pumped plasmas

“…Shock wave propagation in weakly ionized glow discharge plasmas ͑with an ionization fraction of n e /N ϳ10 Ϫ8 -10 Ϫ6 ͒ has been extensively studied over the last 15 years, both in Russia [1][2][3][4][5][6][7][8][9][10][11] and in the U.S. [12][13][14][15][16][17][18][19][20] A number of anomalous effects occurring at these conditions, such as shock acceleration, weakening, and dispersion, have been reported. These effects have been observed in discharges in various gases ͑air, N 2 , Ar͒ at pressures up to Pϭ30 Torr, and for shock wave Mach numbers Mϭ1.5-4.5.…”

Gasdynamic Flow Control by Ultrafast Local Heating in a Strongly Nonequilibrium Pulsed Plasma

“…Another interesting experimental study was presented in [13]. Ballistic experiments were carried out to measure the drag force when a sphere with a diameter of 15 mm moves at a velocity of 200 to 1350 m/s in a nonequilibrium plasma created in air by an RF discharge.…”