汽车刮水器气动升力的风洞试验及数值研究

The experimental and numerical research on aerodynamic lift of automobile windshield wiper

  • 摘要: 目前国内外有关汽车刮水器气动升力的研究仅局限于静态转角的稳态数值计算,且尚无相关验证性的试验结果。对此设计和完成了刮水器静态转角的验证性风洞试验,采用多点测试方法测得了四种刮水器在不同风速和转角下的稳态气动升力,辅以稳态数值计算分析了刮水器气动升力产生与变化机理,同时以测试结果验证了相关数值计算方法真实可靠。此外提出了一种新型动网格策略—动网格域盒,结合动网格域盒与用户自定义函数UDF计算分析了刮水器动态转角的瞬态气动升力。研究结果表明,气动升力对刮水器稳定性的影响不容忽视,且在某一特定风速及转角下存在最大值;刮水器上行的气动升力明显小于稳态值,下行的气动升力明显大于稳态值。

     

    Abstract: Current researches on the aerodynamic lift of automobile windshield wiper are widely focused on the steady numerical calculation of static angle, and the research results of different papers are various, yet no test result can be found to support the simulations. A wind tunnel test is designed and executed to validate and verify the simulation method. Steady aerodynamic lifts of four kinds of wipers with different wind speeds and different rotate angles are measured using multi-point test method. The combination of wind tunnel test and steady numerical calculation helps understanding of lift generation and variation. Furthermore, a new dynamic mesh strategy called the domain-box of dynamic mesh is proposed, the transient aerodynamic lift is simulated and analyzed with User Definition Function method (UDF). The researching result shows that the maximum aerodynamic lift of all four wipers can counteract 68.6% of the precompression, the effect of aerodynamic lift on the stability of wiper cannot be ignored. The lift will achieve its maximum at a certain wind speed and angle, and the magnitude of lift depends on the wind speed of the windward side, the spiral vortex of the leeward and the angle between wind and wiper. Furthermore, the aerodynamic lift is lower than that of steady case when the wipers ascends, and higher when descends.

     

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