不同倾角下管流中超临界CO₂对流换热特性的数值研究

Numerical Study on Convective Heat Transfer Characteristics of Supercritical CO₂ in Tube Flow at Different Inclinations

摘要: 针对高超声速飞行器面临的严苛工作环境，近年来利用超临界CO₂作为冷却介质对飞行器进行传热保护成为一种很有发展前景的方法，本文结合高超声速飞行器飞行过程中有可能出现的不同迎角，采用了一种基于k-ω SST模型的湍流Prt模型(TWL模型)，选择9个特殊角度(0˚ ≤ θ ≤ 180˚)，定义流动方向和重力方向相同时倾斜角为0˚，对加热管内超临界CO₂的流动传热进行了数值模拟。研究结果表明：相同工况下，流动方向对超临界CO₂与壁面间的换热特性影响较大，当倾斜角大于90˚时将伴随传热恶化现象，且随着倾斜角的增大传热恶化现象愈发明显；当倾斜角小于等于90˚时将强化传热，但并非随着角度的减小传热现象持续改善，在30˚时获得最佳的传热表现而非0˚，所以重力是影响超临界CO₂传热的重要因素，但并非唯一因素。

Abstract: In view of the harsh working environment faced by hypersonic aircraft, in recent years, the use of supercritical CO₂ as a cooling medium for heat transfer protection of aircraft has become a promising method. This paper combines the different angles of attack that may occur during the flight of hypersonic aircraft, adopts a turbulence Prt model (TWL model) based on the k-ω SST model, selects 9 special angles (0˚ ≤ θ ≤ 180˚), defines the flow direction and gravity direction at the same time the tilt angle is 0˚. The flow heat transfer of supercritical CO₂ in the heating tube is numerically simulated. The results show that under the same working conditions, the flow direction has a greater influence on the heat transfer characteristics between supercritical CO₂ and the wall surface; when the inclination angle is greater than 90˚, it will be accompanied by heat transfer deterioration, and with the increase of the inclination angle, the heat transfer deterioration phenomenon will become more and more obvious; when the inclination angle is less than or equal to 90˚, the heat transfer phenomenon will be strengthened, but not with the reduction of the angle; the best heat transfer performance is obtained at 30˚, so gravity is an important factor affecting supercritical CO₂ heat transfer, but it is not the only factor.