Title: | Investigation of the Flow Field and the Pressure Recovery in a Gas Turbine Exhaust Diffuser at Design, Part-Load and Over-Load Condition | Authors: | Bauer, Maximilian Hummel, Simon Schatz, Markus Kegalj, Martin Vogt, Damian |
Language: | eng | Issue Date: | 2020 | Publisher: | American Society of Mechanical Engineers | Document Type: | Conference Object | Source: | Proc. ASME Turbo Expo 2020, GT2020-14310 | Published in (Book): | Proceedings of the ASME Power Conference - 2020 | Publisher Place: | New York | Conference: | ASME Turbo Expo: Turbine Technical Conference and Exposition 2020 | Abstract: | The performance of axial diffusers installed downstream of heavy duty gas turbines is mainly affected by the turbine load. Thereby the outflow varies in Mach number, total pressure distribution, swirl and its tip leakage flow in particular. To investigate the performance of a diffuser at different load conditions, a generic diffuser geometry has been designed at ITSM which is representative for current heavy duty gas turbine diffusers. Results are presented for three different operating conditions, each with and without tip flow respectively. Part-load, design-load and over-load operating conditions are defined and varied at the diffuser inlet in terms of Mach number, total pressure distribution and swirl. Each operating point is investigated experimentally and numerically and assessed based on its flow field as well as the pressure recovery. The diffuser performance shows a strong dependency on the inlet swirl and total pressure profile. A superimposed tip flow only influences the flow field significantly when the casing flow is weakened due to casing separation. In those cases pressure recovery increases with additional tip flow. There is a reliable prediction of the CFD simulations at designload. At part-load, CFD overpredicts the strut separation, resulting in an underpredicted overall pressure recovery. At over-load, CFD underpredicts the separation extension in the annular diffuser but overpredicts the hub wake. This leads to a better flow control in CFD with the result of an overpredicted overall pressure recovery. |
Organization Units (connected with the publication): | Strömungsmaschinen in der Energietechnik |
Appears in Collections: | 3 - Publication references (without fulltext) |
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