Comparison Between Steady and Unsteady Double-Entry Turbine Performance Using the Quasi-Steady Assumption
Comparison Between Steady and Unsteady Double-Entry Turbine Performance Using the Quasi-Steady Assumption
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DOI：
10.1115/1.4000580
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发表时间：
2011-07-01
影响因子：
1.7
通讯作者：
Seiler, Martin
中科院分区：
文献类型：
--
作者：
Copeland, Colin D.;Martinez-Botas, Ricardo;Seiler, Martin
为了了解脉动流动对涡轮性能的影响，本文对一台周向分流的双进涡轮进行了实验性能评估。通过保持恒速但改变脉冲的频率，频率的影响被证明在涡轮的性能中起着重要的作用。测量了在较低频率下循环平均效率下降的趋势。主要目标之一是评估非稳定性能与准稳定假设的不同程度。为了对一台多进水轮机进行定常和非定常对比，进行了多种定常、等流量和不等流量条件的试验。然后将稳态数据作为三个无量纲参数的函数进行内插，以允许与瞬时非稳态运行进行逐点比较。平均而言，准稳态假设通常低估了通过涡轮的质量流量和效率损失，尽管这种差异随着频率的增加而减小。异相脉动产生了不稳定的运行轨道，这对应于显著的稳态、部分准入损失，这反映为准稳态效率的下降。然而，准稳态同相和异相预测之间的差异并没有在测量结果中得到复制，这表明在脉动流中不相等的入流损失并不像在定常流中那样显著。[DOI：10.1115/1.4000580]
The experimental performance evaluation of a circumferentially divided, double-entry turbocharger turbine is presented in this paper with the aim of understanding the influence of pulsating flow. By maintaining a constant speed but varying the frequency of the pulses, the influence of frequency was shown to play an important role in the performance of the turbine. A trend of decreasing cycle-averaged efficiency at lower frequencies was measured. One of the principal objectives was to assess the degree to which the unsteady performance differs from the quasi-steady assumption. In order to make the steady-unsteady comparison for a multiple entry turbine, a wide set of steady equal and unequal admission flow conditions were tested. The steady-state data was then interpolated as a function of three, nondimensional parameters in order to allow a point-by-point comparison with the instantaneous unsteady operation. As an average, the quasi-steady assumption generally underpredicted the mass flow and efficiency loss through the turbine, albeit the differences were reduced as the frequency increased. Out-of-phase pulsations produced unsteady operating orbits that corresponded to a significant steady-state, partial admission loss, and this was reflected as a drop in the quasi-steady efficiency. However, these differences between quasi-steady in-phase and out-of-phase predictions were not replicated in the measured results, suggesting that the unequal admission loss is not as significant in pulsating flow as it is in steady flow. [DOI: 10.1115/1.4000580]