Design And Analysis Of A New-type Variable Geometry Solid Rocket Ramjet Inlet

The 2-D inlet was inversely designed using caved shock compression in this paper.Meanwhile,in order to make the inlet to work efficiently in a wide range,a variable geometry scheme has been explored.First,at the design Mach number,the wall pressure distribution function of compression surface was given and then according to the method of characteristic,we calculated the coordinates of points on wall surface and finally determined compression surface of inlet.Study suggests that a shock comtession is generated at each point of the compression surface and the efficiency of the compression of inlet has improved.Secondly,in 2-D model,a adjustment scheme of variable geometry inlet was explored.The results show that the performance of variable geometry inlet is better than that of original geometry.At the case of Mach number 2,its mass flow rate increased by 15.9% and its total pressure recovery coefficient increased by 4%.At the design Mach number,its Anti-pressure capacity increased by 6.6%.Finally,the 3-D model is used to compare and analyze the flow field characteristics and performance features of the fixed/variable geometry inlet.The results show that the fixed geometry can’t be started at Mach number 2 and variable geometry inlet can be started successfully.At Mach number 4,the performance of variable geometry inlet is superior to that of the fixed geometry.Its total pressure recovery coefficient、mass flow rate and Anti-pressure capacity rised by 3.9% 、10% and 14.2% respectively.At Mach number 4.5,the performance of variable geometry inlet is also superior to that of the fixed geometry.Its total pressure recovery coefficient、mass flow rate and Anti-pressure capacity rised by 3.6% 、9% and 28.5% respectively.Increasing the design Mach number is advantageous for improving the performance of the inlet at high Mach numbers,but it also reduces the performance of the inlet at low Mach numbers.