Controlling leakage flows over a rotor blade tip using air-curtain injection: Part II — Rotor casing film cooling

Qiang Zhao, Xing Yang, Zhao Liu, Zhenping Feng, Terrence W. Simon

Research output: Chapter in Book/Report/Conference proceedingConference contribution

Abstract

In modern gas turbine engines, the rotor casing region experiences high thermal loads due to complex flow structures and aerothermal effects. Thus, casing cooling is one of essential measures to ensure turbine service lifetime and performance. However, studies on heat transfer and cooling over the rotor casing with tip leakage flows are limited in the open literature during the past decades. The present work aims at controlling leakage flows over the blade tip and decreasing heat loads on the rotor casing. A novel approach proposed in a companion paper (GT2019-90232) is adopted in this paper as Part II by introducing an air-curtain injection from the rotor casing through a pair of inclined rows of discrete holes positioned in the range of 30% and 50% axial chord downstream of the blade leading edge in the casing. This air-curtain injection approach is applied to flat and recessed tips with and without tip injection to evaluate its sealing capability on tip leakage flows and film cooling effectiveness on the casing for two injection ratios of 0.7% and 1.0%. In this paper, Reynolds-averaged Navier- Stokes (RANS) simulations with Shear Stress Transport (SST) k-ω turbulence model and γ-Reθ transition model, which are validated with relevant experimental data, are performed to investigate tip leakage flows and film cooling effectiveness on the casing in a single-stage, high-pressure gas turbine engine. Results show that casing injection can reduce tip leakage mass flow effectively by changing the development and migration of tip leakage mass flows, especially when the recessed tip is applied. Adding tip injection would further reduces the tip leakage. The casing injection also provides an excellent cooling effect on the casing across rotor middle chord through trailing edge regions. In the presence of the recessed tip, coolant spreads out well on the rotor tip and the casing surfaces, resulting in better film cooling effectiveness on the casing over rotor tip leading edge. In addition, the tip injection could provide an extra cooling effect in some other regions of the casing.

Original languageEnglish (US)
Title of host publicationHeat Transfer
PublisherAmerican Society of Mechanical Engineers (ASME)
ISBN (Electronic)9780791858653
DOIs
StatePublished - 2019
EventASME Turbo Expo 2019: Turbomachinery Technical Conference and Exposition, GT 2019 - Phoenix, United States
Duration: Jun 17 2019Jun 21 2019

Publication series

NameProceedings of the ASME Turbo Expo
Volume5B-2019

Conference

ConferenceASME Turbo Expo 2019: Turbomachinery Technical Conference and Exposition, GT 2019
Country/TerritoryUnited States
CityPhoenix
Period6/17/196/21/19

Bibliographical note

Funding Information:
The authors would like to acknowledge the financial support from the Key Project of National Natural Science Foundation of China (Grant No. 51336007).

Publisher Copyright:
Copyright © 2019 ASME.

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