Two-way Fluid-structure Interaction Analysis And Optimization Of Automotive Air-conditioning Centrifugal Fan Aerodynamic Noise

The level of the vehicle noise is an important indicator of the quality of the car.Excessive vehicle interior noise not only increases driver and passenger’s fatigue,affects passenger’s comfort, and even affects the car’s driving safety. Vehicle noisereflects the design and the technological level of the automobile manufacturers, so thecar producers and consumers have more concerned about the interior noise. As themechanical noise controlled of the vehicle, the application of new absorption materialand the improvement of the performance of seal chamber, air conditioning systemnoise become the main source of vehicle interior noise. Centrifugal fan as the powersource of the air conditioning system, is one of the largest noise sources of the wholesystem.So research the aerodynamic noise of air conditioning centrifugal fan has avery practical significance.The traditional method of calculate the centrifugal fan aerodynamic noise, settedsolid as smooth wall, did not consider the impact of solid deformation and vibrationof the flow field. When centrifugal fan operates, that exists interaction between thehigh-speed air flow and impeller and volute: air apply an unsteady force on the voluteand impeller, makes the solid deform and vibrate, the deformation and vibration ofvolute and impeller, in turn, act on the air, affect the distribution of the air flow field,and thus change the distribution and size of the fluid loads. Therefore, only calculatethe flow field, may cause centrifugal fan internal flow does not match the actual flowfield analysis results so consider the fluid-structure interaction (FSI) is necessary.Main contents of the research are as follows:1. Air flow of an automotive air-conditioning centrifugal fan was simulated. Theflow field and sound field characteristics of centrifugal fan are analyzed. Therelationship between the flow characteristic and aerodynamic noise is on discussion.It provides references for the following work of noise reduction.2. The method for solving fluid-structure interaction includes one-way andtwo-way fluid-structure interaction. This paper used two-way fluid-structureinteraction calculation. To verify the accuracy of the two-way fluid-structureinteraction method, a simple geometric model is calculated by one-way and two-wayfluid-structure coupling and non-coupling method simultaneously, then compared thecalculate results with the wind tunnel experiment. It showed that two-way fluid-structure coupling numerical method is more accurate and reliable than theone-way fluid-structure interaction and non-coupling calculation.3. Two-way fluid-structure coupling method was used to calculate a car airconditioning centrifugal fan, and compared with the non-coupling calculation result,analyzed the influence of deformation and vibration of volute and impeller tocentrifugal fan flow field and sound field. The results showed that, after consideringfluid-structure coupling, the centrifugal fan flow field turbulence is more disordered,fluctuating pressure is more unstable and strength, the aerodynamic noise increases.4. Optimized aerodynamic noise of centrifugal fan. In this paper, through theoptimization of related parameters of the impeller design, by constructingapproximate model and using genetic algorithm to optimize the design variables andthe design goal, obtained the ideal impeller parameters and target value. The resultsshow that compared with the original fan impeller, under the condition that does notaffect the performance of centrifugal fan after optimization, the aerodynamic noisewas reduced8.43%.