可调式液力变矩器泵涡间隙对性能的影响研究

发布时间：2019-01-08 19:22

【摘要】：导叶可调式液力变矩器是大功率液力机械调速系统的关键部件,目前主要应用相似设计方法进行设计,即在基型变矩器的基础上进行相似放大或缩小。由于其应用领域较窄,有关其设计理论和方法研究很少,在设计新型变矩器时缺乏相应的设计理论和准则。如泵轮和涡轮之间的间隙大小对变矩器的性能和压力脉动等有影响,在现有的几种变矩器产品中,泵涡相对间隙(间隙与循环圆直径之比)的范围在0.2%~1.6%之间。本文使用Blade Gen对Y615型双涡轮可调式液力变矩器进行建模,使用Turbo Grid对各叶轮流道进行网格划分,使用CFX计算流体力学软件进行数值计算与结果后处理。并通过设置压力监测点的方法,研究了泵轮叶片及离心涡轮叶片前后边的压力脉动情况。然后通过改变离心涡轮进口边半径,改变泵涡间隙,分析改变泵涡间隙对液力变矩器性能及压力脉动的影响。在所有相邻叶轮对之间,泵轮和离心涡轮互相之间的干涉效应最显著。其他叶轮对之间的干涉效应基本可以忽略。泵轮叶片数较少(15片),而且叶片正面出流压力高,背面出流压力低,泵轮的出流压力在周向上成高低交错分布,对其下游的涡轮造成周期性冲击。液流进入涡轮流道时,会与涡轮叶片进口边发生冲击,出现高压区。当涡轮叶片与泵轮叶片接近时,两叶片之间间隙极小,形成阻塞效应。另外泵轮背面存在低速低压的湍流区。此湍流区会产生不规则流场,并且吸收外部传来的压力脉动。其内部也会产生与外部不同频率的压力脉动。设定泵涡间隙时,需要考虑最重要的因素就是涡轮前端高压区的尺寸。泵涡间隙会影响液力变矩器的性能参数,如效率曲线、泵轮力矩系数,也决定了压力脉动的大小。泵涡间隙越小,泵轮涡轮间的动静干涉效应就越强,压力脉动越大。而泵涡间隙较大,则能够使泵轮的出流在无叶片流道进行较充分的压力扩散,使离心涡轮的入流在周向上压力比较均匀,降低压力脉动效应,提高效率。但是较大的泵涡间隙会降低泵轮力矩系数。而且实际中无叶片流道过长也会产生回流等现象。因此泵涡间隙的选取需要综合考虑各方面因素。
[Abstract]:The guide vane adjustable hydraulic torque converter is the key component of the high power hydraulic mechanical speed regulation system. At present, the similar design method is mainly used, that is, the similar amplification or reduction is carried out on the basis of the basic torque converter. Because of its narrow application field and few researches on its design theory and method, there is no corresponding design theory and criterion in the design of new torque converter. For example, the size of the clearance between the pump wheel and the turbine has an effect on the performance and pressure fluctuation of the torque converter. The relative clearance of the pump vortex (the ratio of the clearance to the diameter of the circulating circle) is between 0.2% and 1.6% in several existing torque converter products. In this paper, Blade Gen is used to model Y615 double turbine adjustable torque converter, Turbo Grid is used to mesh each impeller runner, and CFX computational fluid dynamics software is used for numerical calculation and post-processing. The pressure pulsation in front and back of pump blades and centrifugal turbine blades is studied by setting pressure monitoring points. Then, by changing the inlet radius of centrifugal turbine and changing the vortex clearance of the pump, the influence of changing the vortex clearance on the performance and pressure pulsation of hydraulic torque converter is analyzed. The interference effect between pump wheel and centrifugal turbine is the most significant among all adjacent impeller pairs. The interference effect between other impeller pairs can be neglected. The number of vane of pump wheel is less (15 pieces), and the outlet pressure of the blade is high in front and low in back side. The outlet pressure of pump wheel is staggered in the direction of the circle, which causes periodic impact on the turbine downstream. When the liquid flow enters the turbine passage, it will impact the inlet edge of the turbine blade and appear high pressure area. When the turbine blade is close to the pump wheel blade, the gap between the two blades is very small, resulting in a blocking effect. In addition, there is a low-speed low-pressure turbulence region on the back of the pump wheel. This turbulent region produces irregular flow fields and absorbs pressure pulsations from outside. The internal pressure pulsation is also different from that of the external pressure pulsation. The most important factor to consider when setting the pump vortex clearance is the size of the high pressure area at the front end of the turbine. The vortex clearance will affect the performance parameters of hydraulic torque converter, such as the efficiency curve and the torque coefficient of pump wheel, which also determine the pressure pulsation. The smaller the vortex clearance, the stronger the static and static interference effect and the greater the pressure pulsation. However, if the vortex clearance is large, the flow of pump wheel can be diffused fully in the vane free flow channel, and the inlet pressure of centrifugal turbine will be more uniform in the circumferential direction, the pressure pulsation effect will be reduced, and the efficiency will be improved. But the larger vortex clearance will reduce the torque coefficient of the pump wheel. And in practice the vane passage too long will also produce reflux and other phenomena. Therefore, the selection of pump vortex clearance needs to consider various factors.
【学位授予单位】：哈尔滨工业大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TH137.332

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