Title page for ETD etd-09302008-202855


Type of Document Dissertation
Author Knost, Daniel G
Author's Email Address dknost@vt.edu
URN etd-09302008-202855
Title Parametric Investigation of the Combustor-Turbine Interface Leakage Geometry
Degree PhD
Department Mechanical Engineering
Advisory Committee
Advisor Name Title
Thole, Karen A. Committee Chair
Ball, Kenneth S. Committee Co-Chair
Duggleby, Andrew T. Committee Member
Ng, Fai Committee Member
Stremler, Mark A. Committee Member
Keywords
  • secondary flows
  • endwall cooling
  • gas turbine
  • optimization
Date of Defense 2008-09-19
Availability unrestricted
Abstract
Engine development has been in the direction of increased turbine inlet

temperatures to improve efficiency and power output. Secondary flows develop

as a result of a near-wall pressure gradient in the stagnating flow approaching

the inlet nozzle guide vane as well as a strong cross-passage gradient within the

passage. These flow structures enhance heat transfer and convect hot core flow

gases onto component surfaces. In modern engines it has become critical to cool

component surfaces to extend part life.

Bypass leakage flow emerging from the slot between the combustor and

turbine endwalls can be utilized for cooling purposes if properly designed. This

study examines a three-dimensional slot geometry, scalloped to manipulated

leakage flow distribution. Statistical techniques are used to decouple the effects

of four geometric parameters and quantify the relative influence of each on

endwall cooling levels and near-wall total pressure losses. The slot geometry is

also optimized for robustness across a range of inlet conditions.

Average upstream distance to the slot is shown to dominate overall cooling

levels with nominal slot width gaining influence at higher leakage flow rates.

Scalloping amplitude is most influential to near-wall total pressure loss as formation

of the horseshoe vortex and cross flow within the passage are affected.

Scalloping phase alters local cooling levels as leakage injection is shifted laterally

across the endwall.

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