Various R&D programs for hypersonic propulsion system have progressed worldwide for the space development and the defense applications. Many CFD analyses, ground tests and flight tests were conducted for basic technology about hypersonic flight. During the studies, hypersonic flight tests could be cheaper by using a residual missile or a sounding rocket as a booster of the test, than before. Some leading countries, like USA, Australia, France and Russia, did or are doing hypersonic flight test programs. Australia completed HyShot flight test program, and USA has HIFiRE program in progress. This paper includes a mission design, flow-path modeling, an internal flow analysis and performance estimation of a sub-scale RBCC engine which can conduct a hypersonic flight test. The results will be used as analytic data compared with experimental data of the flight test in future.
First, the performance of overseas flight test boosters was investigated, and compared with it of domestic small launch vehicles. The results are shown that KSR-II is appropriate for the flight test, which is in Mach 6.0 with a maximum 230 kg RBCC engine. Operating conditions of the RBCC engine are altitude 10~30 km and Mach 3.0~7.0, and a 7-tonf gas generator on a 3rd stage of KSLV-II is used as a pre-burner of the RBCC engine.
Governing equations are an organized form of quasi one dimensional ODEs along x-axis, and the ODEs are calculated by a 4th-order Runge-Kutta method. A fuel-air reaction is applied by 10-species chemical equilibrium of hydrocarbon fuel, and the reaction results are verified with NASA CEA code. The Q1D analysis method, which includes quasi one dimensional ODEs and a chemical equilibrium reaction, secured the reliability of the results by comparing pressure data with those of HyShot II flight experiment and Q1D preceding research by C. Brizer.
Analysis results at design points are shown that thrust and specific impulse on a scramjet mode are 595 N and 646 s, and those on a ramjet mode are 9.07 kN and 1,543 s. Along angle of attack, specific impulse at zero degree is a highest value, and thrust at positive degree is decreased because of a loss of inlet mass flow rate. Along altitude, a lower altitude condition has higher propulsion performance with addition of inlet mass flow rate. Along Mach number, specific impulse around a design point is highest on each mode. To compare propulsion performance by friction effect, flow characteristics are assumed to be inviscid, viscid laminar and viscid turbulent. As a results, specific impulse of inviscid flow is 68% higher and it of viscid laminar flow is 60% higher than it of viscid turbulent flow. A performance loss by friction force runs to nearly 40%.