旋流动力稳定性对传热影响的研究

Effect of Dynamic Stabiliy of Swirl Flow on Heat Transfer

旋流动力稳定性是影响旋流传热和流动性能的重要因素, 今提出了基于旋流稳定性基本判据的瑞利判据和失稳指标b,分析旋流动力稳定性的影响因素及其对传热效果的影响作用。结果表明旋流强度、轴向分量速度和旋转流道的几何尺寸均会对旋流稳定性产生重要影响。随着旋流失稳指标b 的提高传热系数明显增加,对于Vz=2.14ms-1的旋流, b 由0增至500时传热系数提高100%以上。旋流动力稳定性的研究结果为旋流强化传热研究的深入提供重要的手段。

Swirl flow can effectively form instability flow and secondary flow to intensify micro-flow mixing and reduce thickness of boundary layer, which leads to the heat transfer enhancement of swirl flow. Dynamic stability of swirl flow is an important factor to influence the heat transfer characteristics. Based on Rayleigh criterion and instability index b, the influence factors of swirl flow stability and its heat transfer characteristics were analyzed in detail. It was found that the stability of swirl flow decreases with swirl intensity and axial velocity raise and obviously depends on geometrical dimension of swirl sprue. The experimental results indicate that heat transfer coefficient is increased with instability index b. Under a constant axial velocity of swirl flow Vz = 2.14ms-1, when the instability index increases to b =500, the swirl flow heat transfer coefficient increases by more than 100% as compared with that of when instability index b =0.