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首页> 外文会议>ASME turbo expo >AN INNOVATIVE PASSIVE TIP-LEAKAGE CONTROL METHOD FOR AXIAL TURBINES: LINEAR CASCADE WIND TUNNEL RESULTS
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AN INNOVATIVE PASSIVE TIP-LEAKAGE CONTROL METHOD FOR AXIAL TURBINES: LINEAR CASCADE WIND TUNNEL RESULTS

机译：用于轴向涡轮机的创新被动尖漏控制方法：线性级联风洞效果

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Depending on the blade aspect ratio, tip-leakage losses can contribute up to one third of the total losses in an axial turbine blade row. In unshrouded turbine blade rows, the radial gaps allow working fluid to pass from the pressure to the suction sides. This tip-leakage flow does not contribute to the work output of the turbine stage. Therefore, any technique which tends to reduce tip-leakage losses has the objective to decrease the flow through the tip gaps. A frequently used method of reducing the tip-leakage flow is the modification of the blade tip geometry by so-called squealers or winglets. Since this method decreases the sensitivity of tip-leakage losses on tip gap width, it is called tip desensitization. This paper presents a new method for tip desensitization: the passive blade tip injection. A low speed cascade wind tunnel is used for experimental investigations. Geometry of the turbine cascade is the up-scale of the tip section of a gas turbine rotor row. Three different gap widths in the range from 0.85% to 2.50% chord length are used. Total pressure, static pressure and flow angles are obtained by traversing a pneumatic five-hole probe about 0.3 axial chord lengths downstream of the turbine cascade. For investigations of the tip injection effect, a single blade of the cascade is modified by an injection channel. Based on experimental results, it is shown that the passive tip injection method decreases tip-leakage losses. At small tip gaps, this reduction can be rather significant. Finally, the positive influence of blade tip injection on tip-leakage losses is described by an analytical model based on the discharge coefficient.
机译：根据叶片纵横比，尖端泄漏损耗可以贡献轴向涡轮叶片行中的总损耗的三分之一。在不受欢迎的涡轮机叶片行中，径向间隙允许工作流体从压力到吸入侧。这种尖端泄漏流线没有促进涡轮机级的工作输出。因此，倾向于减少尖端泄漏损耗的任何技术都具有降低流过尖端间隙的流动。经常使用的减小尖端泄漏流程的方法是通过所谓的耳器或小翼的叶片尖端几何修改。由于该方法降低了尖端间隙宽度对尖端泄漏损耗的灵敏度，因此称为TIP脱敏。本文提出了一种新的尖端脱敏方法：被动刀片尖端注入。低速级联风洞用于实验研究。涡轮机级联的几何形状是燃气轮机转子排的尖端部分的上方。使用三种不同的间隙宽度为0.85％至2.50％的弦长。通过穿过涡轮机级联下游的气动五孔探针约0.3轴向弦长而获得总压力，静压和流动角度。为了研究尖端注入效果，通过注射通道修改级联的单个叶片。基于实验结果，示出了被动尖端注射方法降低了尖端泄漏损耗。在小尖端间隙中，这种减少可能相当重要。最后，基于放电系数的分析模型描述了叶片尖端注射对尖端泄漏损耗的正影响。

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