Scramjet Engine Intake And Exhaust System Design And Numerical Simulation Of Flow Field

The design method for hypersonic forebody/inlet with isolator of integrated scramjet is researched. The design point of the designed forebody/inlet is flight Mach number M=6 and flight attitude H=25km. The three-ramp, mixed external and internal compression hypersonic/inlet is chosen as representative geometry to be designed. Nine types of hypersonic/inlet model with difference forebody length and total turning angle are obtained that the incidence angle of the first ramp and height of isolator are given. One of these models is chosen as a better scheme based on the one-dimensional calculation results. With account for the effect of temperature and shock-boundary layer interaction, the forebody/inlet with plane lip and wedge lip are designed by using the design methods of constant shock wave intensity and constant shock wave angle. In the design, the incidence angle of the first ramp, height of isolator, length of forebody and total turning angle of the designed forebody/inlet models are given. The software FLUENT was employed and the two-dimensional flow field and performance parameters of four hypersonic/inlet models at design and off-design condition are obtained. The calculation results indicate that the starting performance of forebody/inlet with wedge-shaped lip is better than that with plane lip at low flight Mach number. At high flight Mach number, the performance of the forebody/inlets designed by the two methods is approximate. At low flight Mach number, the starting performance of forebody/inlet designed by the method of constant shock wave intensity is better.The effect of exit back pressure and length/height ratio of isolator on forebody/inlet flow field is analyzed and discussed in the paper. The results show the exit back pressure and length/height ratio of isolator have great impact on exit flow field and starting performance of inlet. High back pressure of inlet will result in unstart. In final section of this paper, the flow field of two types of supersonic nozzle for scramjet is simulated and analyzed.