| In this dissertation, a comprehensive experimental platform was designed and completed in order to study the effect of fuel flow on the performance parameters and stability of the engine. Through the experimental study and numerical simulation of the working process of a valve pulse jet engine, the theoretical research foundation and data support were provided for the development process.First, a engine experiment bench including fuel supply system, test collection system, ignition system, TR-PIV test system had been designed and built to provide the experimental platform and test environment for the working characteristic test of a small jet engine.Secondly, a series of experimental studies on the valve type pulse jet engine were carried out. The characteristics of the engine including wall temperature, the concentration of the combustion products, the gas temperature and the pulse pressure were measured by the infrared thermal imaging system,the flue gas analyzer and other equipments. The influence of fuel flow on the above parameters were studied. The results show that with the increase of fuel flow rate, the peak value of pulse pressure is increased and the pulse period decreases.The transient velocity field of the nozzle exit was measured by the TR-PIV test system. The results show that the maximum value of the engine exhaust velocity is not in the exit of the nozzle, but at the outside of the nozzle, the distance from the nozzle exit is about 0.15m.In the end, the numerical simulation was carried out by using CFX to simulate the periodic pulse combustion of the pulse jet engine. The numerical simulation results were in agreement with the experimental data, which verifies the correctness of the numerical model. The dynamic characteristics of the pulse combustion flow field were analyzed by using the contour images of a pulse period.The influence of the length of the nozzle on the operating frequency was analyzed by CFX.The experimental study and numerical simulation analysis are very important to analyze the mechanism of pulse combustion and optimize the structure and performance of the pulse jet engine. |
