并联通道中超临界RP-3航空煤油流量分配特性数值研究

Numerical research on flow distribution characteristics of supercritical RP-3 aviation kerosene in parallel channels

针对热流偏差下空-油换热器的应用,进行了三种类型并联通道中超临界压力RP-3航空煤油流量分配数值研究,探究了进口压力、进口温度、进口总流量、进出口布置对双通道流量分配的影响机制。通过摩擦压降和加速压降的演变机制揭示了流量非对称分配的原因,讨论了通道质量流速和温度的分布特征及其对换热的影响,进行了(火积)耗散效应分析。根据热流密度比值和运行参数提出了流量偏差的预测准则,预测偏差处于±15%范围内。结果表明:随着双通道热流差别增大,两者流量偏差增大,源于加速压降和摩擦压降的平衡机制。热流比值小于1时,摩擦压降主导流量分配;热流比值大于1时,加速压降主导流量分配。热流比值等于1时,双通道流量等量分配。提高进口压力、进口温度、进口总流量双通道流量偏差均受到抑制。高热流偏差下通道出现流量不连续和偏差管温度反向分层问题。相对流量偏差和(火积)耗散偏差的变化规律一致,I型布置相比U型和Z型布置更好。

Based on the application of air-fuel heat exchanger under heat flux deviation,the flow distribution of supercritical-pressure RP-3 aviation kerosene in three types of parallel channels were numerically studied.The effect mechanisms of inlet pressure,inlet temperature,inlet total mass flux and inlet-outlet arrangement modes on flow distribution of dual channels were analyzed.The reason of asymmetric flow distribution was revealed by the evolution mechanisms of frictional pressure drop and accelerated pressure drop.The distribution characteristics of mass velocity and temperature in the channel and its influence on heat transfer were discussed.The entransy dissipation effect was analyzed.A prediction criterion for flow deviation was proposed based on the heat flux density ratio and operating parameters,the prediction deviation was within±15%.Results show that with the increase of heat flux difference between the two channels,the dual-channel mass flux deviation increases,which is due to the balance mechanism between accelerated pressure drop and friction pressure drop.When the heat flux density ratio is less than 1,the frictional pressure drop dominates the flow distribution,while when the heat flux density ratio is greater than 1,the accelerated pressure drop dominates the flow distribution.When the heat flux density ratio is equal to 1,the dual-channel mass flux is equally distributed.The mass flux deviation of dual-channel is suppressed by increasing the inlet pressure,the inlet temperature and the inlet total mass flux.Under the high heat flux deviation,the channel experiences flow discontinuity and temperature reverse stratification in the deviation channel.The variation of relative flow deviation and entransy dissipation deviation is consistent,and the I-type arrangement is better than the U-type and Z-type arrangements.