三轴承旋转喷管矢量偏转规律及流场特性研究

Three Bearing Swivel Nozzle Vector Deflection Law Study and Fluid Field Calculation

关键词:  短距/垂直起降  矢量喷管  偏转规律  气动特性  数值模拟

Key words:  Short takeoff and vertical landing  Vector nozzle  Deflection law  Dynamic performance  Numerical simulation

摘要:

基于短距/垂直起降战斗机用三轴承旋转喷管的特殊设计要求，通过几何约束条件开展了三轴承旋转喷管型面设计方法及运动规律推导与研究，研究了非线性和线性两种喷管矢量角控制规律下的三段筒体随时间的旋转规律。根据小型涡轮喷气发动机的几何尺寸，利用发展的型面设计方法和喷管筒体旋转规律，设计了小尺寸三轴承旋转喷管，并利用CFD数值模拟技术对该喷管的流场特性进行了计算与分析。通过CFD数值模拟技术得到了不同矢量角下喷管的三维流动特性及不同落压比下的气动特性。结果表明:采用喷管矢量角非线性控制规律可以减少非线性控制变量，保证喷管机动性的前提下减小了喷管的设计难度和控制复杂度；基于小型涡轮喷气发动机设计的三轴承旋转喷管0°的推力系数较理想喷管低，90°的推力系数较理想喷管高，喷管在地面最大落压比下0°比90°推力系数高约1%。

Abstract:

Based on the special design requirements for the three bearing swivel nozzle (3BSN) applied to short takeoff and vertical landing fighter，the 3BSN profiling method and motion law research were developed by geometry constraint condition. The three segment rotation law of time controlled linear and nonlinear regulations for the nozzle is deduced and studied. According to the size of a small turbojet engine，a scaled 3BSN is designed by the development profiling method and the nozzle segment rotation law，the nozzle flow field characteristics is calculated and analyzed by CFD numerical simulation technology. By means of the CFD numerical simulation technology，the nozzle flow characteristic in three dimensions at the different vector angle and the aerodynamic performance at different nozzle pressure ratio are obtained. The results show that adopting the nonlinear control law for the nozzle vector angle can reduce the nonlinear control variables and overcome the nozzle design difficulty and control complexity on the premise of ensuring the nozzle’s mobility. The thrust coefficient of the 3BSN designed based on a small turbojet engine is lower than the ideal nozzle at 0° state and higher than that at 90° state，the thrust coefficient of the nozzle at 0° state is higher about 1% than at 90° state when the nozzle is working at the maximum pressure ratio on the ground.