Research On The Wind Tunnel Noise Influence Exerted By Some Wind Tunnel Main Structure Parameters

As countries paying more attention to aerodynamic noise to meet the increasingneeds for comfortable driving, automobiles’ aerodynamic noise has became the focusof aerodynamic research. Usually we use wind tunnel test to provide auto companiessome valuable references to develop new cars of perfect aerodynamic property, withlow aerodynamic noise. And this suggest we must have a very low wind tunnelbackground noise. In wind tunnel test, the overloud wind tunnel background noise hassome significant influence not only in acoustic and pulse pressure measurements butalso aerodynamic force measurement which corelated to Renolds number..Besideswind tunnel noise can affect the surroundings and the health of the researchers.Traditionally we can decrease wind tunnel noise by adding some noise-eliminationmaterial or acoustical damper. But too much noise-reduction parts may not onlyincrease block-ratio, but reduce wind tunnel efficiency, what’s worse they haveself-noise. So researching the wind tunnel parts to achieve a good acoustic atmosphereon the conditional that no extra funds and cost can be added, has a very profoundmeaning on the background noise reduction and wind tunnel efficiency.Based on the above analysis, the following works have been completed in thispaper:1. The background noise measurement tests were carried out in HD-2wind tunnel,the aerodynamic noise and A-weighted noise were obtained at different measuredpoint. The analysis of the main noise sources in the wind tunnel and sections wheresome noise reduction design can be taken can provide some experimental referencefor thewind tunnel background noise suppression design.2. In this paper, a numercial computational model of driving section with fanwhich is main noise source is established. And some simulation by LES and Lighthillmethod about the influence of the flow field and acoustic performance caused bydifferent angle-mounted vanes were presented here.Besides, we also considered todrill some holes on the vanes to reduce noise.3. The corner section is an important component of the wind tunnel.In the fourcorners,the energy loss could account for40%~60%of the wind tunnel total loss, sogenerally speaking some deflectors are usually installed in the corner to improve theflow quality around the corner. In this paper we analysed three kind of deflectors:straight line-arc, double-arc, wing-SA070.61. And we achieved some resultsconcerning about their acoustic performance. 4. The flow field quality and the test area noise of wind tunnel are closely relatedto the contraction segment wall shape. The flow field of several contraction curves iscalculated using the numerical calculation method, and some design criteria are alsoachieved. Using parametric methods, a new kind of contraction curve had been putforward.5. According to the computational results concerning about wind tunnel structureparts, we established a virtual model and caculated it’s background noise and velocitydistribution. The numercial results suggest that partial optimization on the structure ofwind tunnel can help to lower its background noise. These results also provide somereference to the succeed transformation of old wind tunnel and construction of newwind tunnels.