Methodoloty Investigation Of Scramjet Performance Evaluation

Scramjet is the perfect propulsive device to hypersonic vehicle, and is a hot issue in current hypersonic technology area. The scramjet engine is highly integrated with the airframe of airbreathing hypersonic vehicle, which makes the performance evaluation very difficult. It's urgent to develop a kind of scramjet performance evaluation method which can take full advantages of data acquired in experiments. The means of domestic performance evaluation of scramjet segments and integrated model is analyzed synthetically in this paper. Then, based on current domestic experiment level, the method of scramjet performance evaluation is studied via adopting methods of theoretic analyse and numerical simulation. The results attained are as follows.On account of the strongly coupling character of parameters which have an effect on scramjet performance, the approximate evaluation models of scramjet inlet diffusion performance and the ignition problem in direct-connected experiments are established by neural network methodology.From the point of evaluating scramjet performance as a whole, the thrust increment and combustion efficiency are discarded, and the internal thrust is selected as a criterion of scramjet performance based on present free-jet experimental conditions. Five kinds of internal thrust calculation methods are educed from the definition of internal thrust combined with the experimental measuring means. The method of thrust increment by cold internal drag deducting is applied in full free-jet experiment. At last, some particular examples are calculated and some quantificational conclusion is obtained.Above all, the research of this paper is very important for comparing different scramjet performance, predicting experimental result and guiding scramjet design.