Optimized performance of arc heated shock tubes

An analysis of the performance of a transient discharge electric arc driven shock tube has been carried out using three computer codes. These determine the arc energy, circuit response and gas dynamic performance respectively. When a range of experiments on the NASA-Ames Research Center shock tube were examined, it was found that about 93 percent of the capacitor bank energy was transferred to the arc and that optimizing the electrical circuit maintained this energy transfer efficiency as capacitor bank energy rose. Gas dynamic calculations based on the time distributions of arc energy input for these cases showed that about 30 percent of the arc energy was actually used in shock wave production. The experimental shock velocity was approximately 65 percent that calculated for the full energy input. A scaling law relating shock Mach number to the one third power of the energy density has been confirmed which allows the designer to simply establish shock tube performance.