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Calculating Incidence Losses in the Turbine Cascade

机译：计算涡轮机级联的发病率损失

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The flow in turbine cascades with incidences is accompanied by a separated flow around the airfoils, which is difficult to calculate with acceptable accuracy. Therefore, in practice, empirical formulas are used to estimate losses from the incidence. The analysis of these formulas made it possible to identify the geometric and operating parameters of the cascade that have the greatest influence on the losses: the inlet metal angle, thickness of the leading edge of the profile, thickness of the profile, relative pitch, incidence, and exit flow velocity. It is unrealistic to obtain a reliable analytical expression for losses that takes into account the influence of all these parameters. Therefore, the path consisting in creating a program that uses the data of numerous experiments and finds an equation for calculating the losses in a group of cascades close to the specified one in terms of geometric parameters was chosen. Accordingly, a bank of experimental data on losses in a large number of cascades was formed and tested at different incidences and flow velocities. According to the test results, an increase in the flow velocity out of the cascade leads to a decrease in losses from a positive incidence. All cascades are clearly divided into three large groups according to the nature of losses. For the cascades of each group, the ranges of variation of the angles of the flow inlet and outlet and the thickness of the profile and its leading edge are determined. The set of these parameters determines the form of the approximating polynomial for each given cascade. To reflect the effect of the pitch and exit velocity and find the design equation, cascades with narrow deviations of the parameters from the given value are selected from the group, and the unknown polynomial coefficients are calculated using the least squares method. Calculations according to the developed program give smaller deviations from experiments than the known formulas.
机译：涡轮机级联的流动伴随着翼型围绕翼型的分离流动，这难以以可接受的精度计算。因此，在实践中，经验性公式用于估计发病率的损失。这些公式的分析使得可以识别对损失影响最大的级联的几何和操作参数：入口金属角度，轮廓的前缘的厚度，轮廓的厚度，曲线厚度，相对间距，入射和退出流速。获得考虑所有这些参数影响的可靠分析表达是不现实的。因此，选择了在创建使用众多实验数据的数据的程序中组成的路径，并找到用于计算在几何参数的一组级联级联级联级联级级级的方程。因此，在不同的血型和流速下形成并测试了一系列关于大量级联损耗的实验数据。根据测试结果，级联的流速的增加导致阳性入射损失的降低。根据损失的性质，所有瀑布都明确分为三个大型群体。对于每个组的级联，确定流动入口和出口角的变化范围以及轮廓的厚度及其前缘。这些参数的集合确定了每个给定级联的近似多项式的形式。为了反映间距和出口速度的效果并找到设计方程，从给定值中选择具有窄的参数偏差的级联，并且使用最小二乘法计算未知的多项式系数。根据开发的程序的计算与实验较小的偏差比已知式。

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