基于雷诺时均模型的高温空气流动传热数值研究

Numerical Simulation on Flow and Heat Transfer Characteristics of High-Temperature Air Based on RAS Model

核涡轮发动机反应堆其堆芯通常采用高温空气作为冷却剂,高温空气的流动传热特性直接关系到涡轮发动机的运行性能。本文基于开源CFD软件OpenFOAM,对直径为4.24 mm、长度为760mm的圆形通道内均匀加热和非均匀加热情况下高温空气的流动传热进行了研究。首先评估了均匀加热情况下k-ωSST湍流模型的适用性;之后分析了均匀加热情况下进口雷诺数等对其流动传热的影响。最后将非均匀加热情况下模拟结果与经验关系式进行对比。结果表明,k-ωSST湍流模型适用于均匀加热下高温空气流动传热模拟;均匀加热情况下,进口雷诺数对努塞尔数影响比较大;非均匀加热情况下,k-ωSST湍流模型模拟结果与Taylor关系式计算结果偏差较大,需要进一步研究和完善。

High-temperature air is taken as the coolant of nuclear turbine engine reactor.The flow and heat transfer characteristics of it are directly related to the running performance of the turbine engine.Based on the open source CFD software OpenFOAM,the flow and heat transfer of high-temperature air in a circular channel with a diameter of 4.24 mm and a length of 760 mm were studied.Firstly,the applicability of thek-ωSST turbulence model under uniform heating was evaluated;then the effects of wall heat flux,fluid inlet temperature,and inlet velocity on the flow and heat transfer under uniform heating were analyzed.Finally,the simulation results under non-uniform heating were compared with empirical relations.Under uniform heating,the Reynolds number of inlet has a large effect on the Nusselt number,and the heat flux and inlet temperature have small effect on it.The k-ωSST turbulence model is suitable for the simulation of high-temperature air flow and heat transfer under uniform heating.Under non-uniform heating the error between simulated results of the k-ωSST turbulence model and the results calculated by Taylor relationship is large and needs further research and improvement.