Electrical conductivity channel for a shock tube

Abstract

The design of an electrical conductivity measurement channel for a shock tube is described. This measurement channel is used for the study of weakly ionized, high-enthalpy flows of gases seeded with alkali salts. The theory for determining the dimensions of the measurement channel and the electrical power supply for the channel is based on Ohm's law. Data are shown which demonstrate that the channel performs well. However, the measured electrical conductivity was one or two orders less than theoretical values. The current traces for each case show that the peak current occurred behind the contact surface, which indicates that some of the seed was entrained behind the test gas originally in the driven tube. An analysis of the effect of Joule heating on the measured conductivity was conducted. The result of increased temperature due to Joule heating in the measurement channel is believed to be minimal. Reasons for the discrepancy are given.

Detection of shock and detonation wave propagation by cross correlation

“…From the t M -surface, E(t M ) X and s(t M ) X were found to be 0.208 and 0.006 ms, respectively, as listed in Table 2. The propagation time using the TOF method was 0.22 ms [6], which is within two standard deviations of the averaged t M obtained by XCOR.…”

Electromagnetic Boundary Layer Flow Control Facility Development Using Conductive Particle Seeding

“…For example, cesium carbonate powder has been previously used to achieve conductivities of 1-10 mho/m in high-pressure aerodynamic plasmas. 17 This level of conductivity can be contrasted to the low value of 0.06 mho/m found in unseeded air plasmas at high-speed flight conditions. 14 Conversely, some of the theoretical and numerical work that demonstrates EMFC requires conductivities of up to 100 mho/m.…”

“…Assuming a value of conductivity for the seeded flow makes the Lorentz force generator plate design fairly independent of the other components. Based on previous conductivity results after ionization of a pure gas 14 and one seeded with potassium carbonate, 17 the design of the actuator was based around 1 = σ mho/m. This value can change significantly depending on the success of the ionization actuator plate.…”

Numerical Simulation of External MHD Generator on Board Reentry Vehicle

“…An external MHD generator based on a blunt-coneshaped vehicle configuration was first conceptually considered by Bityurin, Bocharov, and Lineberry [8]. In several recent papers [9]- [12], computational fluid dynamics was employed to explore the power density level of external MHD generators during planetary reentry. Results showed that megawatt power levels can be generated with a small amount of potassium seed (~1%) and modest values of magnetic field (0.1~0.2Tesla) [9].…”

“…In several recent papers [9]- [12], computational fluid dynamics was employed to explore the power density level of external MHD generators during planetary reentry. Results showed that megawatt power levels can be generated with a small amount of potassium seed (~1%) and modest values of magnetic field (0.1~0.2Tesla) [9]. However, a systematic deduction for generator design factors and their influences on the generated power have not been founded at the present stage.…”