Shock Tube Investigation of Pressure and Ion Sensors Used in Pulse Detonation Engine Research

摘要

Shock tubes utilize a difference in pressures between gases separated by a diaphragm to create a shock wave when the diaphragm ruptures. The AFIT 2- inch shock tube was reassembled and tested to ensure proper and safe operation. A high-speed data acquisition system was configured to take data at 2 MS/s. This research showed that the Mach number of the shock waves produced in this shQCk tube fall within 7% of theoretical values at speeds under Mach 3 and within 9% at higher speeds. The peak velocity of each shock wave was shown to occur at approximately 3 meters from the diaphragm. The second portion of the research focused on the testing of sensors used to evaluate the performance of the pulse detonation engine (PDE) for research and developmental purposes. Two alternatives were developed to standard sensors to withstand the heat of the engine: coat the sensors with an insulating, 0.6 mm thick silicone that protects it from the heat and use spark plugs as ion sensors to detect the ions in the combustion inside the PDE tubes. This researched proved that no degradation in response time, rise time, or sensitivity results from coating the pressure transducers with silicone. The research also found that the ion sensors are unable to consistently detect ions created by a Mach 8 shock wave through air.