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Investigation of Trailing Edge Cooling Concepts in a High Pressure Turbine Cascade: Aerodynamic Experiments and Loss Analysis

Rehder, Hans-Jürgen (2012) Investigation of Trailing Edge Cooling Concepts in a High Pressure Turbine Cascade: Aerodynamic Experiments and Loss Analysis. Journal of Turbomachinery, 134 (5). American Society of Mechanical Engineers (ASME). doi: 10.1115/GT2009-59303.

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As part of a European research project, the aerodynamic and thermodynamic performance of a high pressure turbine cascade with different trailing edge cooling configurations was investigated in the wind tunnel for linear cascades at DLR in Göttingen. A transonic rotor profile with a relative thick trailing edge was chosen for the experiments. Three trailing edge cooling configurations were applied, first central trailing edge ejection, second a trailing edge shape with a pressure side cut-back and slot equipped with a diffuser rib array, and third pressure side film cooling through a row of cylindrical holes. For comparison aerodynamic investigations on a reference cascade with solid blades (no cooling holes or slots) were performed. The experiments covered the subsonic, transonic and supersonic exit Mach number range of the cascade while varying cooling mass flow ratios up to 2 %. This paper analyzes the effect of coolant ejection on the airfoil losses. Emphasis was given on separating the different loss contributions due to shocks, pressure and suction side boundary layer, trailing edge and mixing of the coolant flow. Employed measurement techniques are schlieren visualization, blade surface pressure measurements and traverses by pneumatic probes in the cascade exit flow field and around the trailing edge. The results show that central trailing edge ejection significantly reduces the mixing losses and therefore decreases the overall loss. Higher loss levels are obtained when applying the configurations with pressure side blowing. In particular the cut-back geometry reveals strong mixing losses due to the low momentum coolant fluid which is decelerated by the diffuser rib array inside the slot. The influence of coolant flow rate on the trailing edge loss is tremendous, too. Shock and boundary layer losses are major contributions to the overall loss but are less affected by the coolant. Finally a parameter variation changing the temperature ratio of coolant to main flow was performed, resulting in increasing losses with decreasing coolant temperature.

Item URL in elib:https://elib.dlr.de/76951/
Document Type:Article
Title:Investigation of Trailing Edge Cooling Concepts in a High Pressure Turbine Cascade: Aerodynamic Experiments and Loss Analysis
AuthorsInstitution or Email of AuthorsAuthor's ORCID iDORCID Put Code
Date:September 2012
Journal or Publication Title:Journal of Turbomachinery
Refereed publication:Yes
Open Access:No
Gold Open Access:No
In ISI Web of Science:Yes
EditorsEmailEditor's ORCID iDORCID Put Code
Wisler, DavidEditor, ASME Journal of TurbomachineryUNSPECIFIEDUNSPECIFIED
Publisher:American Society of Mechanical Engineers (ASME)
Keywords:high pressure turbine cascade, trailing edge cooling concepts, aerodynamic experiments, airfoil loss analysis
HGF - Research field:Aeronautics, Space and Transport
HGF - Program:Aeronautics
HGF - Program Themes:Propulsion Systems (old)
DLR - Research area:Aeronautics
DLR - Program:L ER - Engine Research
DLR - Research theme (Project):L - Turbine Technologies (old)
Location: Göttingen
Institutes and Institutions:Institute of Propulsion Technology > Turbine
Deposited By: Rehder, Dipl.-Ing. Hans-Jürgen
Deposited On:09 Aug 2012 11:00
Last Modified:14 Jun 2023 16:45

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