Study on the Aerodynamic Performance of Gas Turbine Exhaust Diffuser Coupled with Last Stage Turbine

YAN Chenxi; WANG Jiajun; YAO Jiaxu; SU Pengfei; KONG Xianglin; FANG Yu; LI Zhigang; LI Jun

doi:10.7652/xjtuxb202508013

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Study on the Aerodynamic Performance of Gas Turbine Exhaust Diffuser Coupled with Last Stage Turbine

更新时间：2025-07-30

- Study on the Aerodynamic Performance of Gas Turbine Exhaust Diffuser Coupled with Last Stage Turbine
- Journal of Xi’an Jiaotong University Vol. 59, Issue 8, Pages: 134-146(2025)
- 作者机构：
  
  1.西安交通大学叶轮机械研究所， 710049，西安
  2.东方电气集团东方汽轮机有限公司， 618000，四川德阳
  3.清洁高效透平动力装备全国重点实验室， 618000，四川德阳
- 作者简介：
- 基金信息：
- DOI：10.7652/xjtuxb202508013
  CLC： TK474.7
- Received：20 February 2025，
  
  Online First：11 April 2025，
  
  Published：10 August 2025
- 稿件说明：
移动端阅览
YAN Chenxi, WANG Jiajun, YAO Jiaxu, et al. Study on the Aerodynamic Performance of Gas Turbine Exhaust Diffuser Coupled with Last Stage Turbine[J]. Journal of Xi’an Jiaotong University, 2025, 59(8): 134-146.
DOI：

YAN Chenxi, WANG Jiajun, YAO Jiaxu, et al. Study on the Aerodynamic Performance of Gas Turbine Exhaust Diffuser Coupled with Last Stage Turbine[J]. Journal of Xi’an Jiaotong University, 2025, 59(8): 134-146. DOI： 10.7652/xjtuxb202508013.

摘要

为探究透平末级出口流动对燃气轮机排气扩压器性能的影响，获取由透平末级、排气扩压器和收集器组成的完整系统的气动性能，建立了耦合透平末级的燃气轮机排气扩压器气动性能高保真分析模型。采用数值求解三维Reynolds-Averaged Navier-Stokes方程和SST

k-ω

湍流模型的方法，对比研究了不同流量下，排气扩压器的流场结构和静压恢复系数。结果表明：随着进口流量的降低，排气扩压器内流动分离导致的总压损失增加，排气扩压器静压恢复系数下降。收集器内主要存在两股旋流，与弯扭段相邻的拐角处涡旋和回流增加了压力损失，降低了静压恢复系数。设计流量下，排气扩压器非弯扭段静压恢复系数为0.645，110%设计流量下静压恢复系数增加了10.2%；小设计流量导致排气扩压器总压损失增加，扩压能力降低，50%设计流量下扩压器的静压恢复系数为－0.059。设计流量大于70%时，透平末级动叶叶顶间隙泄漏射流能够抑制排气扩压器机匣的分离流动，从而降低总压损失。该研究为考虑透平末级出口流动作用下的燃气轮机排气扩压器气动性能研究提供了一定的参考。

Abstract

To investigate the impact of the flow at the last stage outlet on the performance of the gas turbine exhaust diffuser and to obtain the aerodynamic performance of a complete system composed of the last stage turbine

exhaust diffuser

and collector

this paper establishes a high-fidelity analysis model for the aerodynamic performance of the gas turbine exhaust diffuser coupled with the last stage turbine. Using numerical methods to solve the three-dimensional Reynolds-averaged Navier-Stokes equations along with the SST

k-ω

turbulence model

this paper compares the flow field structure and static pressure recovery coefficient of the exhaust diffuser under different flow rates. The results indicate that as the inlet flow rate decreases

the total pressure loss due to flow separation within the exhaust diffuser increases

leading to a reduction in the static pressure recovery coefficient. Two main vortices exist within the collecto

r; the vortices and backflow near the bend increase pressure loss and reduce the static pressure recovery coefficient. At the design flow rate

the static pressure recovery coefficient of the non-bend section of the exhaust diffuser is 0.645

while at 110% of the design flow rate

this coefficient increases by 10.2%. A lower design flow rate results in increased total pressure loss and reduced diffusing capability

with the static pressure recovery coefficient at 50% of the design flow rate being －0.059. When the design flow rate exceeds 70%

the leakage jet from the blade tip of the last stage turbine can suppress the separation flow in the diffuser casing and reduce total pressure loss. This paper provides a reference for studying the aerodynamic performance of gas turbine exhaust diffusers considering the effects of the flow at the last stage outlet.

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references

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