不同湍流模型在小尺寸换热器CFD计算中的应用与比较

Application and comparison of different turbulence models to small size heat exchanger CFD calculations

为了研究不同湍流模型在换热器流场和传热计算中的适用性,运用计算流体力学软件对粘性流场中小尺寸换热器性能进行了计算研究.分别采用Spalart-Allmaras湍流模型、标准模型k-ε和可实现k-ε方程模型模拟了换热器在不同质量流率下的出口温度、总换热量、壳程压降等有关参数.由3种湍流模型的CFD计算结果与Bell-Delaware理论计算值的对比得出:Spalart-Allmaras单方程湍流模型对换热器性能的数值计算存在明显的缺陷,表明该模型不适合于模拟计算换热器壳程的流动;标准k-ε湍流模型和可实现k-ε湍流模型下的CFD分析相对于SpalartAllmaras单方程湍流模型有所改进,但这种改进仍然没有抛弃物质粘性零影响的假设的基础,因此其对湍流精度的改进是有限的;可实现k-ε湍流方程模型下的CFD计算值与Bell-Delaware理论值最为接近,可实现k-ε湍流方程模型对于小尺寸的换热器仿真具有较其他两种模型更强的数值模拟能力.

In order to study the ap calculations, the calculating study plicability of different turbulence has been done by using the tom the performance of small and medium viscous flow heat exchanger. models in heat flow and heat transfer putational fluid dynamics software for By using Spalart-Allmaras turbulence model, the standard κ-ε model and achievable κ-εmodel respectively, some related parameters like outlet temperature, total heat exchange and the pressure drop of shell-side of the heat exchanger in different mass flow rates are simulated. It＇s derived from the comparison between the CFD calculations and the Bell-Delaware theoretical value of 3 turbulent flow models. Spalart-Allmaras one equation turbulence model exists obvious defects for the numerical calculation of heat exchanger performance indicating that the model is not suitable for the simulation change heat flow in shell; the analysis under standard κ-ε turbulence model and achievable CFD κ-ε turbulence model has improved respect to the Spalart-Allmaras one equation turbulence model which is limited without abandon the foundation assuming zero impact of viscous substances; the CFD calculations and the Bell-Delaware theoretical value is closest under the achievable turbulence equations κ-ε model with more strongger numerical simulation capability than the other two models.