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在一定容量以上的大流量增压器,由于结构强度的需要,其涡轮排气道都布置在涡轮和压气机之间。因为轴向尺寸很短,世界各国都把排气道设计成具有长方形截面的简单通道。气流在排气道中转向90°后向上或侧面排出(见图1)。显然这类排气道的排气损失是很大的。六十年代以后,有的国家在排气道进口处加一短的轴向扩压器,有的加大排气道轴向尺寸或排气口面积,也有将涡轮由单级改为双级,使排气损失有所减小。看来,在轴向尺寸受限制的条件下,这些想法的发展前途是不大的。本文在排气道进口处采用轴-径向扩压器和扩压器四周的导流蜗壳的思路来改进这类排气道。并对BBC公司生产的VTR400的原排气道和我们的两种改进方案进行一系列的对比试验研究。试验结果表明,由于减小了排气道中的损失,根据VTR400原来参数,两种改进方案可使涡轮效率分别提高4.6％和6.1％,涡轮功率分别提高68.5马力和88.1马力。这种改进方案有较好的实用价值。
In a certain capacity of large flow supercharger, due to the needs of structural strength, the turbine exhaust duct are arranged between the turbine and the compressor. Because of the short axial dimension, all countries in the world design the exhaust duct as a simple passage with a rectangular cross section. The airflow is deflected upward or laterally at 90 ° in the exhaust duct (see Figure 1). Obviously, the exhaust loss of such exhaust duct is very large. Since the 1960s, some countries have added a short axial diffuser at the exhaust inlet and some have increased the axial dimension or exhaust area of the exhaust duct. Some have also changed the turbine from a single stage to a double stage , So exhaust loss is reduced. It seems that the development of these ideas is not promising given the limited axial dimensions. This article at the exhaust inlet at the use of shaft - radial diffuser and diffuser around the scroll volute idea to improve such exhaust. A series of comparative experiments were conducted on the original exhaust passage of VTR400 manufactured by BBC Company and our two improved schemes. The experimental results show that the turbine efficiency can be increased by 4.6% and 6.1%, respectively, and the turbine power can be increased by 68.5 and 88.1 hp, respectively, due to the reduced loss in the exhaust passage according to the original parameters of the VTR400. This improvement program has good practical value.