Dynamic characteristics of hydrocarbon fuel within the channel at supercritical and pyrolysis condition

Regenerative cooling with fuel as the coolant is used in the scramjet engine.In order to grasp the dynamic characteristics of engine fuel supply processes,this article studies the dynamic characteristics of hydrocarbon fue lwithin the channel.A one-dimensional dynamic model was proved,the thermal energy storage effect,fuel volume effect and chemical dynamic effect have been considered in the model,the ordinmy differential equations were solved using a 4th order Runge-Kutta method.The precision of the model was validated by three groups of experimental data.The effects of input signal,working condition,tube size on the dynamic characteristics of pressure,flow rate,temperature have been simulated.It is found that cracking reaction increased the compressibility of the fuel pyrolysis mixture and lead to longer responding time of outlet flow.The responding time of outlet flow can reach 3s when tube is 5m long which will greatly influence the conmo1 performance of the engine thrust system.Meanwhile,when the inlet flow rate appears the step change,the inlet pressure leads to overshoot,the overshoot can reach as much as 100％,such highly transient impulse will result in detrimental effect on fuel pump.