Optimization Of Cross Flow Fan For Air-conditioner Based On CFD And Applicability Analysis Of SAS Turbulence Model

Due to the compact structure with airflow is flat and uniform,it can adjust the flow rate simply only by changing the axial length,so Cross Flow Fan(CFF)are widely used in household indoor units of split type air-conditioner,but there have an unique eccentric vortex in internal flow field,it is likely to worsen flow field when slightly change the structure of CFF,results the decrease of its aerodynamic performance.People generally hope large flow rate and relatively low noise of air-conditioner at the same time,the structure of an existing CFF is changed to improve its aerodynamic performance based on CFD technology in this paper,and testing of SAS turbulence model performance applying for the CFF.Flow field as the carrier of aerodynamic noise propagation,so study flow field is the basis of the aerodynamic analysis and structural optimization in CFF.This paper establishes a three-dimensional model of the CFF firstly,Large eddy turbulence model(LES)is used to study the characteristics of axial flow field,and then carrying out two-dimensional of flow field and far-field noise calculation and optimization based on symmetry characteristics of the axial flow field.The main research contents are as follows:1)A two-dimensional model of the CFF is estblished,the heat exchanger is treated as a porous medium,static and dynamic interference by using sliding mesh technique,using LES method to simulate internal flow field and far field aerodynamic noise of the CFF,analyzed internal transient complex flow field and far field aerodynamic noise spectrum characteristics in detail;2)Study the key structure parameters(tongue clearance,tongue width,volute gap,volute shape)influence for flow rate and noise of the CFF,it can providing a reference for optimization of the air duct system;3)With large flow rate and low noise as optimization target,a four factor and three level orthogonal test scheme is established,the influence of structural parameters on flow rate and noise is obtained by using the weight matrix methods,and determined the optimization scheme,numerical simulation results showed that the performance of optimization model is significantly improved compared with the original model under three different rotation speed;4)In view of the strict quality of grid and high computation costs,an attempt is made to calculate the aerodynamic characteristics of the CFF by using adaptive scale simulation(SAS)turbulence model based on SAS successfully in calculation of Carmen vortex and wing spoiler so as to testing it's performance,and explore its applicability.It showed that SAS calculating performance was significantly higher than that of RNG k-?,slightly inferior to LES through comparative analysis of RNG k-? and LES results,the aerodynamic characteristics of the CFF can be considered with SAS.