吸热型碳氢燃料再生冷却性能评估方法

吸热型碳氢燃料作为吸气式高超声速飞行器的再生冷却剂,冷却剂出口温度可达到750℃以上。碳氢燃料的冷却能力和抗结焦特性指标,是再生冷却剂的关键参数。在工程应用参数范围内,建立了吸热型碳氢燃料再生冷却性能综合评估体系,实现燃料热沉、结焦和流动传热性能的综合评估。燃料热沉采用热平衡法测量。作为参考:燃料温度600℃,热沉约2.0 MJ/kg;燃料温度750℃,热沉约3.5 MJ/kg。结焦采用层流流动阻力法进行定量测量,应用泊肃叶定律计算碳氢燃料结焦前后通道的当量内径,从而得到通道内结焦层的平均厚度。流动换热性能的评估方法是比较相同出口流体温度条件下不同燃料壁面温度沿轴向的分布趋势。以上吸热型碳氢燃料评估方法的建立,为研制吸热型碳氢燃料提供了有效的初步筛选途径。

Evaluation methods on regenerative cooling performance for endothermic hydrocarbon fuel

The endothermic hydrocarbon fuel as the coolant in the airbreathing hypersonic vehicles,its working temperature could be up to 750℃.The effective cooling capacity and coking characteristics of hydrocarbon fuel at high temperature conditions are crucial for the regenerative cooling technology.An experimental evaluation system for the regenerative cooling performance of endothermic hydrocarbon fuel was constructed to realize the measurement and evaluation of heat sink,coking characteristics and heat transfer characteristics.The heat sink was measured by the thermal balance method.Basically,the heat sink could be 2.0 MJ/kg for fuel at temperature of 600℃ and 3.5 MJ/kg at 750℃.Coking propensity was measured by hydraulic resistance method at laminar conditions.The equivalent inner diameter of the test tube before and after coking test could be obtained by the poiseulle’s law.Then the average coking thickness could be obtained from the inner diameter before and after coking test.Heat transfer characteristics were evaluated by comparing the wall temperature behavior at the same outlet fluid temperature for different fuels.The above experimental evaluation methods provide an effective evaluation mean for the selection and development of endothermic hydrocarbon fuel.