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Performance Analysis of an Annular Diffuser Under the Influence of a Gas Turbine Stage Exit Flow.

机译：燃气轮机级出口流影响下的环形扩压器性能分析。

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摘要

In this investigation the performance of a gas turbine exhaust diffuser subject to the outlet flow conditions of a turbine stage is evaluated. Towards that goal, a fully three-dimensional computational analysis has been performed where several turbine stage-exhaust diffuser configurations have been studied: a turbine stage with a shrouded rotor coupled to a diffuser with increasing divergence angle in the diffuser, and a turbine stage with an unshrouded rotor was also considered for the exhaust diffuser performance analysis. The large load of this investigation was evaluated using a steady state numerical analysis utilizing the "mixing plane" algorithm between the rotating rotor and stationary stator and diffuser rows. Finally, an unsteady analysis is performed on a turbine stage with an unshrouded rotor coupled to an annular exhaust diffuser with an outer wall opening angle of 18°. It has been found that the over the tip leakage flow in the unshrouded rotor emerges as a swirling wall jet at the upper wall of the diffuser. When using the turbine with the shrouded rotor no wall jet was observed, making the flow at the entrance to the diffuser "quasi-uniform". The maximum opening angle of the diffuser upper wall achieved before the diffuser stalls was 12° with a static pressure recovery coefficient of Cp = 0.293. When the wall jet was observed, diffuser opening angles of 18° were possible with a static pressure recovery of Cp = 0.365. Consequently the wall jet energizes the diffuser upper wall boundary layer flow, allows for higher static pressure recovery levels and postpones diffuser stall.;By altering the speed of the rotor the effect of the swirl in the turbine exit plane on the performance of the diffuser was explored. In the case where the wall jet was absent the diffuser recovers more pressure when the inlet is swirl-free. In this case the performance of the diffuser is independent on whether the turbine exit flow has co or counter swirl. In the presence of the wall jet, higher static pressure recovery was achieved when the wall jet was in co-swirl and the core flow at a slightly counter-swirl direction. This observation was more pronounced when larger diffuser upper wall opening angles were considered.;In the unsteady analysis it was found that the wall jet axial velocity and swirl intensities pulsate with the relative position of the rotor to the stator. The wall jet is always co-swirling while the core flow is counter-swirling. Moreover, the wall jet does not penetrate the diffuser boundary layer as deeply as was observed in the steady state case and flow separation occurs at the upper endwall corner of the diffuser. Furthermore the performance of the diffuser shows a periodic variation that seems to depend on the relative position of the rotor to the stator. The averaged pressure recovery coefficient is Cp = 0.321 which is 11.0 % less than predicted in the steady state case.
机译：在这项研究中，评估了受涡轮级出口流量条件影响的燃气轮机排气扩压器的性能。为了实现该目标，已进行了三维三维计算分析，其中研究了几种涡轮级排气扩压器配置：涡轮级，其带罩转子连接至扩压器，扩压器中的发散角增大，而涡轮级具有对于排气扩散器的性能分析，还考虑使用无罩转子。使用稳态数值分析，利用旋转转子与固定定子和扩散器排之间的“混合平面”算法，对稳态下的数值分析进行了评估。最后，在涡轮级上进行非稳态分析，该涡轮级的非转子罩连接到环形排气扩压器，其外壁开度为18°。已经发现，在无遮盖的转子中的尖端泄漏流在扩散器的上壁处以涡旋壁射流的形式出现。将涡轮机与带罩转子一起使用时，未观察到壁喷流，从而使扩散器入口处的流量“准均匀”。扩散器失速之前扩散器上壁的最大打开角度为12°，静压恢复系数为Cp = 0.293。当观察到壁射流时，扩散器的打开角度为18°，静压恢复率为Cp = 0.365。因此，壁面射流激励了扩压器的上壁边界层流，允许更高的静压恢复水平并推迟了扩压器的失速。通过改变转子的速度，涡轮出口平面中的涡流对扩压器的性能产生了影响探索。在没有壁流的情况下，当入口无涡流时，扩散器会恢复更多压力。在这种情况下，扩散器的性能取决于涡轮机出口流是否具有同向或反向涡流。在壁射流的存在下，当壁射流处于同向旋流且岩心在稍微反旋向流动时，可获得更高的静压恢复。当考虑较大的扩压器上壁打开角度时，这种观察更加明显。在非稳态分析中，发现壁射流的轴向速度和旋流强度随着转子相对于定子的相对位置而脉动。壁流始终是共旋的，而核心流是逆旋的。而且，壁射流不像在稳态情况下所观察到的那样深地穿透扩散器边界层，并且在扩散器的上端壁拐角处发生流动分离。此外，扩散器的性能显示出周期性变化，该变化似乎取决于转子与定子的相对位置。平均压力恢复系数为Cp = 0.321，比稳态情况下的预测值低11.0％。

著录项

  • 作者

    Blanco, Rafael Rodriguez.;

  • 作者单位

    University of Kansas.;

  • 授予单位 University of Kansas.;
  • 学科 Engineering Aerospace.;Engineering Mechanical.
  • 学位 M.S.
  • 年度 2013
  • 页码 96 p.
  • 总页数 96
  • 原文格式 PDF
  • 正文语种 eng
  • 中图分类
  • 关键词

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