高热流密度燃烧室壁面阵列空气射流-燃油组合冷却结构研究

Integrated Cooling Configuration of Array Air Jets and Fuel Cooling for High-Heat-Flux Combustor Wall

关键词:  空气阵列射流  燃油冷却肋板  集成冷却结构  综合传热性能  数值模拟

Key words:  Array air jets  Fuel-cooled ribs  Integrated cooling structure  Overall heat transfer performance  Numerical simulation

摘要:

针对高热流密度燃烧室壁面热防护需求，提出了一种空气阵列射流冲击和燃油冷却肋板的集成冷却方式，在射流平均雷诺数Re_j为1×10⁴~3×10⁴，燃油进口流速v_f为2.33～5.23m/s内，采用数值模拟方法对其传热特性进行了研究，并基于壁面加热侧当量对流换热系数的概念，分析了基准肋板以及燃油冷却肋板的传热增强作用。与无肋板靶面的阵列射流冲击相比，带肋板阵列射流冲击的面积平均当量对流换热系数是前者的1.6倍，压力损失系数相对提高了约25%；采用燃油冷却肋板，加热壁面综合传热能力进一步增强，在Re_j=1×10⁴时，采用燃油冷却肋板的面积平均当量对流换热系数是基准肋板的1.5倍以上，即使在Re_j=3×10⁴时，燃油冷却肋板的传热增强比也可以达到1.2；燃油冷却肋板的出口温度相对进口温度的提升在20~50K内，其提升幅度随着射流雷诺数或燃油进口流速的增大而减小。

Abstract:

An integrated cooling configuration was proposed by using array air-jets and fuel-cooled ribs to meet the thermal protection requirement in the high-heat-flux combustor wall. Numerical simulations were performed to characterize its heat transfer performance under a certain jet Reynolds number range （1×10⁴≤Re_j≤3×10⁴） and fuel inlet velocity range （2.33m/s≤v_f≤5.23m/s）. Based on the equivalent convective heat transfer coefficient on the heated side of target plate， the overall heat transfer enhancement by using baseline ribs and fuel-cooled ribs is illustrated. With respect to the no-rib situation， the presence of ribs in array-jet impingement makes the area-averaged equivalent convective heat transfer coefficient 1.6 times of the former. At the same time， the pressure loss coefficient otherwise increased about 25% relatively. By using the fuel-cooled ribs， the overall heat transfer capacity is further promoted. When compared to the baseline-rib situation， the heat transfer enhancement ratio in the viewing of area-averaged convective heat transfer coefficient is up to 1.5 under Re_j=1×10⁴. Even under Re_j=3×10⁴， the heat transfer enhancement ratio for the fuel-cooled ribs is 1.2 at least. Totally， the temperature rise of the fuel at outlet with respect to the inlet temperature increased about 20~50K. This temperature rise is reduced with the increase of jet Reynolds number and fuel inlet velocity.