Measurements of flow conductivity and density fluctuations in supersonic nonequilibrium magnetohydrodynamic flows

• Published in: AIAA journal 2005-09, Vol.43 (9), p.1923-1930
• Main Authors: MEYER, Rodney, NISHIHARA, Munetake, HICKS, Adam, CHINTALA, Naveen, CUNDY, Michael, LEMPERT, Walter R, ADAMOVICH, Igor V, GOGINENI, Sivaram
• Format: Article
• Language: English
• Subjects: Aerodynamics; Air flow; Exact sciences and technology; Fluid dynamics; Fundamental areas of phenomenology (including applications); Instrumentation for fluid dynamics; Magnetic fields; Magnetohydrodynamics and electrohydrodynamics; Nonequilibrium gas dynamics; Physics; Reactive, radiative, or nonequilibrium flows; Weights & measures; Wind tunnels
• ISSN: 0001-1452; 1533-385X
• DOI: 10.2514/1.13736

A new blowdown nonequilibrium plasma magnetohydrodynamic (MHD) supersonic wind tunnel operated at complete steady state has been developed and tested at Ohio State. The wind tunnel can be operated at Mach numbers up to M = 3 4 and mass flow rates of up to 45 g/s at a stagnation pressure of 1 atm. Pitot tube and schlieren measurements in a M = 3 test section showed reasonably good flow quality, up to 80% inviscid core across the larger dimension and up to 50% inviscid core across the smaller dimension of the flow. Stable and diffuse transverse rf discharges (rf power up to 1 kW) have been sustained in M = 3 nitrogen flows, at magnetic fields of up to B = 1.5 T. Operation at higher magnetic fields produced a more uniform rf plasma in the MHD test section. Hall parameter and electric conductivity of the flow have been inferred from the dc (MHD) current and voltage measurements at different values of the magnetic field. At B = 1.5 T and rf power of 500 W, the Hall parameter is beta is congruent to 3 and the conductivity is sigma is congruent to 0.05 mho/m. At the rf power of 1 kW, the extrapolated conductivity is equivalent to 0.1 mho/m. The results of the present work demonstrate the Lorentz force effect on the supersonic boundary laver in M = 3 flows of nitrogen ionized by a high power transverse rf discharge in the presence of the magnetic field. Boundary laver density fluctuation spectra are measured using the laser differential interferometry diagnostics. In particular, decelerating Lorentz force applied to the flow produces a well reproduced increase of the density fluctuation intensity by up to 10 20% (1 2 dB), compared to the accelerating force of the same magnitude applied to the same flow. The effect is produced for two possible combinations of the magnetic field and MHD current directions producing the same Lorentz force direction (both for accelerating and decelerating force). The effect is observed to increase with the flow conductivity. On the other hand, the effect of Joule heating on the density fluctuation spectra appears insignificant. [PUBLICATION ABSTRACT]