Performance and structural scheme design of the diffuser for attitude and orbit control engines with high chamber pressure and large flow rate in mid-high-altitude simulation test
The thermodynamic calculation method,normal shock wave theory,heat transfer theory,and strength theory were adopted to carry out the matching design and theoretical analysis of the performance and structural scheme of liquid attitude and orbit control engines and cylindrical diffusers.A design calculation method and procedure for determining the performance and structural scheme of diffusers was presented from the aspects of its performance,main dimensions,heat transfer mode,strength and stability verification.Influence curves of the area ratio of cylindrical diffusers,combustion chamber pressure ratio,vacuum chamber pressure ratio,and gas isentropic index on the main dimensions and operating characteristics of diffusers were obtained.A cylindrical diffuser with an inner diameter of 1.1 m,a length of 8 m,and an inner wall thickness and cooling jacket width of 10 mm was designed for the testing requirements of a certain NTO/MMH liquid attitude and orbit control engine with a thrust of 5 000 N.The working envelope demonstrated the ability to conduct relevant tests within the engine combustion chamber pressure range of 1-5 MPa,maximum flowrate range of 1-3 kg/s,and simulated working altitude range of 30-60 km.The research showed that using the design method for gas thermodynamic calculation introduced into the diffuser inflow before and after the normal shock wave,more accurate gas thermodynamic parameters required for cooling calculations can be obtained.In consideration of the chemical reaction of high-temperature gas,a more reasonable performance and structural matching scheme can be obtained using the method,making it convenient to determine the test capacity range of existing diffusers.
attitude and orbit control enginehigh-altitude simulation testcylindrical diffuserperformance calculationscheme design
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