燃烧室压力对潜入式喷管喉衬热应力的影响

为了研究燃烧室压力对固体火箭发动机潜入式喷管热应力影响规律的问题,采用商业流体软件,基于压力求解器,求解了喷管纯气相的流场,确定了燃气温度、压力、壁面对流换热系数;采用有限元软件,依据流场计算的非均布壁面压力与非均布对流换热,求解了燃烧室压力为6 MPa下的潜入式喷管热结构问题;通过地面点火试验验证了仿真模型与数值方法的有效性与准确性;采用相同计算模型与数值方法,求解了在燃烧室压力为9 MPa、12 MPa下的喷管热结构问题,揭示了燃烧室压力对喉衬热应力的影响规律。结果表明:整个工作过程,喉衬环向应力最大值为103.9 MPa,位于内表面,且随时间增大,先增大后减小;喉衬环向拉应力也随时间先增大后减小;随压力增大,对流换热系数增大,喉衬温度升高,喉衬环向拉应力增大,喉衬环向压应力减小。

Influence of chamber pressure on thermal stress for submerged nozzle insert throat

In order to study the influence of chamber pressure on thermo-structural response for the submerged nozzle of solid rocket motor, a simulation was carried out. By means of the commercial fluid software, based on the pressure solver, the flow field of pure gas in the nozzle was conducted and the temperature, pressure, and wall convective heat coefficients were obtained in the nozzle; according to the non-uniform pressure and non-uniform heat transfer coefficients obtained from the above flow field, using the finite element software, the thermo-structural problem of the submerged nozzle was solved at the pressure 6 MPa. Then, the ground firing test of solid rocket motor with the submerged nozzle was carried out, and the proposed numerical method is effective and accurate. By means of the same model and numerical method, the thermo-structural response of the submerged nozzle was solved at the pressure 9 MPa and 12 MPa, and the influence of combustion pressure on the thermal stress of throat insert was obtained. The simulation results show that during the entire operation process of solid rocket motor, the maximum hoop stress of throat insert is 103.9 MPa, which locates on the inner surface, and increases at first and then decreases with time; the hoop tensile stress increases at first and then decreases with the increasing of time for the throat insert, as well; with the increasing of pressure, the convective heat coefficients, the temperature and the hoop tensile stress increases, and the hoop compressive stress decreases for the throat insert.