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Experimental And Numerical Study Of A Gas Turbine Exhaust Diffuser Applying Different Hub Extension Geometries

Rasouli Ghazi Kalayeh, Keyvan and Schäfer, Philipp and Finzel, Conrad and Hofmann, Willy (2015) Experimental And Numerical Study Of A Gas Turbine Exhaust Diffuser Applying Different Hub Extension Geometries. In: 11th European Turbomachinery Conference. EUROPEAN TURBOMACHINERY CONFERENCE, 23.-27.03.2015, Madrid, Spanien.

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Exhaust diffusers are utilized to recover the residual kinetic energy of the last turbine stage. The investigated diffuser consists of an annular duct and an attached Carnot diffuser. The baseline diffuser of the investigated gas turbine features a blunt end at hub, which leads to an extensive separated flow region in the Carnot diffuser. In order to reduce the separation size and the implicated losses, four different hub extension geometries and the baseline are examined numerically and experimentally for two operating conditions. The wind tunnel tests are compared to the numerical results, which are obtained by using the CFD code TRACE. Three competing performance parameters are used for analysis: pressure recovery, total pressure loss and flow uniformity factor. The investigated hub extensions lead to a reduction of the separation zones downstream of the hubs end. This results in a better diffuser performance in terms of pressure recovery and pressure loss of all extensions compared to the baseline. As expected, the ellipsoidal extension gives the highest pressure recovery for an infinite Carnot diffuser length. At the given length of the Carnot in this case, the Hollow Cylinder lead to the best compromise for all performance parameters. In sum, the choice of the geometry depends on the available length of the Carnot diffuser and its related costs.

Item URL in elib:https://elib.dlr.de/103181/
Document Type:Conference or Workshop Item (Speech)
Title:Experimental And Numerical Study Of A Gas Turbine Exhaust Diffuser Applying Different Hub Extension Geometries
AuthorsInstitution or Email of AuthorsAuthor's ORCID iD
Rasouli Ghazi Kalayeh, KeyvanAT-TURUNSPECIFIED
Finzel, ConradAlstom, Baden, SchweizUNSPECIFIED
Hofmann, WillyAlstom, Baden, SchweizUNSPECIFIED
Date:March 2015
Journal or Publication Title:11th European Turbomachinery Conference
Refereed publication:Yes
Open Access:No
Gold Open Access:No
In ISI Web of Science:No
Keywords:turbine diffuser hub extensions
Event Location:Madrid, Spanien
Event Type:international Conference
Event Dates:23.-27.03.2015
HGF - Research field:Energy
HGF - Program:Efficient Energy Conversion and Use (old)
HGF - Program Themes:Power Plants (old)
DLR - Research area:Energy
DLR - Program:E VG - Combustion and Gas Turbine Technologies
DLR - Research theme (Project):E - Gas Turbine (old)
Location: Göttingen
Institutes and Institutions:Institute of Propulsion Technology
Deposited By: Weggler, Dr.-Ing. Philipp
Deposited On:10 Mar 2016 10:07
Last Modified:10 Mar 2016 10:07

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