对流边界条件下超临界流体层流边界层相似解  

Similarity solutions of supercritical fluids laminar boundary layers with convective boundary conditions

作　　者：李桢[1] 杨瑞 赵玉新[2] 汪元 LI Zhen;YANG Rui;ZHAO Yuxin;WANG Yuan(Hypersonic Technology Laboratory,College of Aerospace Science and Engineering,National University of Defense Technology,Changsha 410073,China;College of Aerospace Science and Engineering,National University of Defense Technology,Changsha 410073,China)

机构地区：[1]国防科技大学空天科学学院高超声速技术实验室,湖南长沙410073 [2]国防科技大学空天科学学院,湖南长沙410073

出　　处：《推进技术》2025年第1期50-59,共10页Journal of Propulsion Technology

基　　金：国家自然科学基金(12272405);国家留学基金委(202306110026)。

摘　　要：在超燃冲压发动机中,燃烧室和尾喷管内的高温燃气使再生冷却通道中的流体达到超临界状态,即在对流边界条件下形成超临界流体边界层,但其基本特性尚未明晰。为此,本文通过相似性解法计算了具有对流边界条件的超临界二氧化碳(SCO_(2))平板层流边界层,来流压力为8 MPa。文中定义了热对流系数Mθ和局部对流换热常数c,它们分别与平板下表面热流体的温度及对流换热系数呈正相关,并分析了Mθ和c对边界层速度及温度剖面的影响。当c极小时,该问题可退化为绝热壁工况;相反,当c足够大时,它的表征类似于等温壁工况。随着Mθ和c的增大,壁面热流也增大;若来流温度为亚临界,此时边界层将出现跨临界机制,使壁面努塞尔数加剧降低。In a scramjet engine,the high-temperature gas in the combustor and nozzle causes the fluid in the regenerative cooling channel to reach the supercritical state.This results in the formation of a supercritical fluid boundary layer under convective boundary conditions,yet its fundamental theory remains unclear.To this end,the similarity solution was established to calculate the supercritical carbon dioxide(SCO_(2))flat-plat laminar boundary layers with convective boundary conditions.The free-stream pressure is 8 MPa.Thermal convection coefficient Mθand local convective heat transfer constant c were proposed in this paper.They are positively correlated with the temperature and convective heat transfer coefficient of the hot fluid on the bottom surface of the plate,respectively.The effects of Mθand c on velocity and temperature profiles are analyzed.When c is extremely small,the problem can be simplified to the adiabatic boundary condition.Conversely,when c is large enough,it exhibits behavior similar to an isothermal boundary condition.As Mθand c increase,the wall heat flux also increases,leading to a transcritical regime if the free-stream temperature is subcritical.This exacerbates the decrease in Nusselt number.

关 键 词：超临界流体 对流边界条件 层流边界层 相似解 壁面传热 

分 类 号：V231.1[航空宇航科学与技术—航空宇航推进理论与工程]