半周加热螺旋管中超临界RP-3燃料换热特性研究

Research on Heat Transfer Characteristics of Supercritical RP-3 Fuel in a Half-circle Heating Helical Tube

针对航空燃气涡轮发动机的冷却防护问题,基于RNG k-ε湍流模型进行了外表面半周加热螺旋管中超临界RP-3燃料换热数值研究,采用螺旋度定量分析了二次流对换热的影响,着重考察了运行压力和热质比值对换热的影响,探究了温度场、速度场、二次流和湍动能的分布情况并阐述了沿流动方向和沿螺旋管周向的换热机制。数值结果表明:半周加热时具有显著的周向非均匀热传导,加剧了离心力作用,产生了强的二次流,螺旋管内侧和外侧存在突出的换热差别。高温区观察到传热恶化问题,提高压力致使传热恶化加剧,高温区最大螺旋度由700 m·s^(-2)减小到360 m·s^(-2),热流密度下降和质量流速提高均使螺旋度减小。建立了半周加热螺旋管航空煤油换热的关联式,换热关联式的预测偏差处于±15%的范围,预测精度较高。

Aiming at the cooling protection problem of aviation gas turbine engine,numerical research on heat transfer of supercritical RP-3 fuel in a helical tube with the half-circle heat flux imposed on the outer surface is performed based on RNG k-εturbulence model,and effects of the operating pressure and heat-to-mass ratio on heat transfer are studied.The heat transfer mechanisms along the flow direction and the circumferential direction of the channel are studied as well.The distributions of temperature field,velocity field,secondary flow and turbulent kinetic energy are investigated.The effect of secondary flow on heat transfer is quantitatively analyzed by helicity.The heat transfer correlation of aviation kerosene in a half-circle heating helical tube is established.The numerical results show that the half-circle heating condition has a significant circumferential non-uniform heat conduction,aggravates the centrifugal force,which generates a strong secondary flow and leads to a prominent heat transfer difference between the inner and outer of helical tube.The heat transfer deterioration is observed in the high-temperature region.Increasing the pressure aggravates the heat transfer deterioration,the maximum helicity decreases from 700 m·s^(-2)to 360 m·s^(-2)in the high temperature region.Decreasing the heat flux or increasing the mass flux reduces the helicity.A correlation equation for heat transfer of aviation kerosene using a half cycle heating spiral tube has been established,and the prediction deviation of the proposed heat transfer correlation is within the range of±15%,with high prediction accuracy.