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一般汽车用大功率发动机,多采用轴流式风扇。但从声学角度看,轴流式风扇的噪声太大了。而且由于冷却水箱宽而薄,只用一个轴流式风扇,汽车的安装空间又过于狭窄,所以还会产生冷却风量不足的问题。本研究课题就在于确定径流式和横流式风扇在这种情况下是否能有更好的适应性,其衡量标志是:效率、同样安装空间下的噪声、安装的方便性。研究结果表明,相对于轴流式风扇而言,采用径流式风扇的冷却系,其噪声可降低7dB;而且最有利的是,装用自由排风风扇的水箱可布置在进风侧。采用承压侧布置水箱的冷却系有较高的效率,但噪声也较大。装用横流式风扇时,只能在进风侧布置水箱。如使用一般结构的横流式风扇,就噪声和效率而言,相对于轴流式风扇并无改进。本文对进风侧水箱布置、径流式风扇冷却系的设计进行了综合论证,所有的重要结构特点和环境条件都同时考虑了。冷却系还存在一些问题,这就是在某一转速下发生的噪声过高和水箱所产生的空气涡流问题。如采用横流式风扇,则在选定设计参数之前,先要优化其风扇叶片和导风罩。
General high-power automotive engines, the use of axial fans. But from an acoustic point of view, the axial fan noise is too high. And because the cooling tank wide and thin, only one axial fan, the installation space for the car is too narrow, so there will be insufficient cooling air flow problems. The subject of this research is to determine whether radial and cross-flow fans are better adaptable in this situation. The measures are: efficiency, noise in the same installation space, and ease of installation. The results show that a radial cooling system with radial fan can reduce noise by 7dB compared to axial fans, and most advantageously, a free-exhaust fan tank can be arranged on the inlet side. The use of pressure-side layout of the tank cooling system has a higher efficiency, but also larger noise. Installed with cross-flow fan, can only be arranged on the inlet side of the water tank. With a cross-flow fan of general construction, there is no improvement with respect to the axial flow fan in terms of noise and efficiency. In this paper, the layout of the inlet side of the water tank, radial fan cooling system, a comprehensive demonstration of the design, all the important structural features and environmental conditions are also considered. There are some problems with the cooling system, which is the noise that occurs at a certain speed and the air turbulence problems created by the water tank. If a cross-flow fan is used, its fan blades and draft shield should be optimized prior to selecting the design parameters.