Design for throat length of mix-compression supersonic inlet with numerical analysis

To enhance the performance of mixed-compression axisymmetric supersonic inlet with fixed-geometry, the performances of designing Mach number 4 mixed-compression inlet of ramjet are investigated. The numerical calculation is carried out for the performance of inlet with the different length of throat. The research shows that it is necessary that the length of throat is less than the length of shock chain in the inlet of constant length. Especially for the shorter length of throat, total pressure recovery coefficient is enhanced at higher Mach number condition. When Mach number equals to 3.5 and 4.0, the total pressure recovery coefficient is enhanced by 6.15% and 5.04% for length-to-height ratio of throat 3.75 and 10 respectively. The longer the length of throat, the shorter the length of diffuser for given inlet length. Simultaneously, the performance of inlet will be deduced. When length-to-height ratio of inlet throat equals to 3.75, the total pressure recovery coefficient and the ability of resistance backpressure of the inlet are highest under design Mach number 4 condition. This result provides a reference for the design of the mixed-compression axisymmetric inlet with high designing Mach number.