Flow Rate Measurement Method for Gaseous Fuel Injection for Pulse Detonation Engines

Abstract

A mass-flow model was developed to calculate the flow rates of a gaseous fuel and oxidizer injected intermittently into a pulse detonation engine. The procedure used the mass-flow parameter of the gas to estimate the ideal mass-flow rate. The ideal mass-flow rate calculation incorporated determination of the time-varying injection surface area, supply pressure, and temperature and specific heat ratio of the gas considering choked flow at the injecting surface. This value of ideal mass flow was multiplied by an experimentally determined discharge coefficient to account for losses. The calculated mass-flow rates and valve opening time duration were used to calculate the total mass of reactants injected per pulse for a typical pulse detonation engine. In addition, a scheme for the change in injection surface area for different types of valve openings was presented. Results indicated the practicality of the developed mass-flow model to calculate the intermittent gas mass injection into a pulse detonation engine. The results also showed that the experimentally determined discharge coefficient via steady-state calibration held true for valve operation at 1, 10, and 20 Hz.