下挂式空中发射运载火箭机箭分离后至运载火箭一级分离前火箭历经亚音速、跨音速、超音速和小、大攻角多个飞行状态,因此研究不同飞行状态下运载火箭的气动特性是实现下挂式空射成功的基础。针对下挂式空射特点设计构建了运载火箭三维模型;根据运载火箭的飞行状态将机箭分离过程划分为无动力飞行段、跨音速突破至超音速段和加速飞行段,运用CFD仿真技术研究了不同马赫数和攻角状态下火箭气动特性;为研究机身长度和平尾上反角对火箭气动特性的影响,在原设计火箭基础上增加了箭体长度+0.5m、+1.0m、+1.5m、+2.0m和水平安定面上反角-5°、-10°、-15°、-20°、-25°,结果表明,不同机身长度会与机翼产生不同的气动干扰而影响到整个火箭的升阻特性,平尾上反角基本不影响火箭的升阻特性,同时,改进后的火箭模型俯仰稳定性得到了增强。

The hanging type air launch vehicle has complex flight experience of sonic, transonic, supersonic and low, high attack angle from separation of rocket and carrier to first stage separation of rocket. Therefore, the aerodynamics investigation in different flight conditions is the foundation of a successful launch. The three-dimensional model of rocket was designed and built according to the features of hanging type air launch vehicle. Based on the flight state of rocket, the separation process was divided into unpowered flight stage, transonic into supersonic flight stage and accelerated flight stage. The aerodynamic characteristics of rocket were studied in different flight conditions of mach and angle of attack by using CFD. To study the influence of fuselage length and horizontal tail anhedral on aerodynamic characteristics, fuselage length and horizontal tail anhedral were increased by +0.5 m, +1.0 m, +1.5 m, +2.0 m and -5°, -10°, -15°, -20°, -25°. The simulation results show that the different fuselage length and the wing generate different aerodynamic interference, which would influence the lift resistance of the rocket; while the horizontal tail anhedral has no influence on rocket lift resistance characteristic, moreover, the pitching stability of the improved rocket model has been enhanced.