Study of double-wall effusion cooling scheme for gas turbine blade applications

Ngetich, GC

Abstract:: Porous multi-wall cooling schemes such as double-wall cooling combined with effusion cooling offer a practical approximation to transpiration cooling which in turn present a potential for high cooling effectiveness. Most of the existing double-wall effusion cooling studies have been on flat plate geometries. There are varying external static pressure and secondary flow features in flow over an aerofoil which have an influence on overall cooling performance. Thus, there is need to study dou...
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APA Style

Ngetich, G. C. (2019). Study of double-wall effusion cooling scheme for gas turbine blade applications [PhD thesis]. University of Oxford.

MLA Style

Ngetich, GC. Study of Double-Wall Effusion Cooling Scheme for Gas Turbine Blade Applications. 2019. University of Oxford, PhD thesis.

Chicago Style

Ngetich, GC. 2019. “Study of Double-Wall Effusion Cooling Scheme for Gas Turbine Blade Applications.” PhD thesis, University of Oxford.
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Authors

+ Ngetich, GC More by this author

Division:: MPLS
Department:: Engineering Science
Department:: University of Oxford
Role:: Author

Contributors

+ Ireland, PT

Department:: University of Oxford
Role:: Supervisor

+ The Rhodes Trust More from this funder

Funding agency for:: Ngetich, GC

+ Rolls-Royce Plc More from this funder

+ Engineering and Physical Science Research Council More from this funder

DOI:: 10.5287/ora-j0y5japxd
Type of award:: DPhil
Level of award:: Doctoral
Awarding institution:: University of Oxford

Language:: English
Keywords:: Turbine cooling

Heat transfer

Turbomachinery

aerodynamics

double-wall cooling

Gas turbine

Simplified numerical analysis model

Film cooling effectiveness
Subjects:: Gas-turbines--Cooling
UUID:: uuid:2c3ea9ed-d725-4d83-9c44-40e619c5f360
Deposit date:: 2020-02-27
ARK identifier:: ark:/29072/ora_2c3ea9edd7254d839c4440e619c5f360

Related item:: A Three-Dimensional Conjugate Approach for Analyzing a Double-Walled Effusion-Cooled Turbine Blade
Description:: A double-wall cooling scheme combined with effusion cooling offers a practical approximation to transpiration cooling which in turn presents the potential for very high cooling effectiveness. The use of the conventional conjugate computational fluid dynamics (CFD) for the double-wall blade can be computationally expensive and this approach is therefore less than ideal in cases where only the preliminary results are required. This paper presents a computationally efficient numerical approach for analyzing a double-wall effusion cooled gas turbine blade. An existing correlation from the literature was modified and used to represent the two-dimensional distribution of film cooling effectiveness. The internal heat transfer coefficient was calculated from a validated conjugate analysis of a wall element representing an element of the aerofoil wall and the conduction through the blade solved using a finite element code in ANSYS. The numerical procedure developed has permitted a rapid evaluation of the critical parameters including film cooling effectiveness, blade temperature distribution (and hence metal effectiveness), as well as coolant mass flow consumption. Good agreement was found between the results from this study and that from literature. This paper shows that a straightforward numerical approach that combines an existing correlation for film cooling from the literature with a conjugate analysis of a small wall element can be used to quickly predict the blade temperature distribution and other crucial blade performance parameters.
Related item:: Study of Film Cooling Effectiveness on a Double-Walled Effusion-Cooled Turbine Blade in a High-Speed Flow Using Pressure Sensitive Paint
Description:: A detailed analysis of film cooling performance on a double-walled effusion-cooled blade is essential for both the coolant consumption optimization and assessment of the film to offer the desired levels of the turbine blade protection. Yet there are hardly any film effectiveness studies on double-wall full-coverage film cooled turbine blades.This paper presents a detailed film cooling effectiveness study over the full surface of a double-walled effusion-cooled high-pressure turbine rotor blade using Pressure Sensitive Paint (PSP). PSP permitted a non-intrusive and conduction-errors-free means of obtaining clean and distinct local distribution of film effectiveness on the blade surface making it possible to extract valuable film cooling effectiveness performance data on the whole blade surface.Three large-scale circular pedestal double-wall blade designs with varying pedestal height, pedestal diameter and cooling hole diameter were tested in a high-speed stationary single-blade linear cascade running at engine-representative Mach and Reynolds numbers. All the blades were tested within a range of representative modern engine coolant mass flow, ṁc to mainstream, ṁg ratios; 1.6% < ṁc/ṁ∞ < 5.5%.High porosity blade exhibited a better flow distribution and was found to consistently perform the best.

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Copyright holder:: Ngetich, GC

Licence:: Terms and Conditions of Use for Oxford University Research Archive

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Study of double-wall effusion cooling scheme for gas turbine blade applications

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Study of double-wall effusion cooling scheme for gas turbine blade applications

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