Session: 32-06 High Pressure Turbines 1

Paper Number: 125281

125281 - Investigation of Endwall Secondary Flows in a Low Aspect Ratio Transonic Turbine, Part II: Passage Oblique Shock 

With increasing exit Mach number to off-design conditions, increased losses in a turbine are incurred due to the increase in shock losses.  Specifically, the transonic regime is specifically of interest as it exhibits both a loss bucket behavior as well as the potential for unique trailing edge shedding modes at midspan.  As for the endwall secondary flows, there can be increased losses due to the increase in shock interactions with endwall secondary vortices.  In this second part of the two part series, the variation in exit isentropic Mach number varied up to 1.15 where the endwall secondary flow development is compared between numerical predictions and experimental results for a low aspect ratio turbine (AR = 0.66 and Zw = 1.0).  Experimental results are produced via testing in the SLU linear turbine cascade and include results of airfoil static pressures and downstream survey data.  Numerical analysis is completed using Cadence Fine/Turbo (RANS modeling with the SST k-omega turbulence closure model) and validated via the experimental data.  Numerical predictions include airfoil static pressure loading, passage secondary flow development, shock interactions within the passage, as well as downstream mixing loss characterization.  Results show the impact of the exit isentropic Mach number on the shock-vortex and shock-boundary layer interactions affecting the endwall secondary flow development.  With increased exit isentropic Mach number, the flow exhibits a transition in the passage shock behavior having a direct impact on the endwall secondary flow development and shock-induced vortices within the passage.  However, this work also shows the resulting shock-vortex interaction with the passage vortex lift-off line as a direct result of the change in the passage shock formation.  As a result, the downstream mixing losses are then compared at six downstream planes (0.2, 0.5, 0.8, 1.3, 2.0, and 3.0Cx) where numerically predicted entropy production is assessed showing the increased rate of production at higher exit isentropic Mach number.  The results of this part shows evidence and support for additional schematics presented which detail the endwall secondary flow development for varying passage shock structure within the transonic regime.

Presenting Author: Mary K. Jennerjohn Christianer Honeywell

Presenting Author Biography: Mary K. Jennerjohn Christianer is originally from Florissant, MO. She holds both a B.S. and Ph.D. in Aerospace Engineering from Saint Louis University. Her focus throughout her Ph.D. research included endwall secondary flow and mixing loss development downstream of a linear turbine cascade. Upon finishing her studies, Mrs. Christianer relocated to Phoenix, AZ, to begin her career in industry. Thus far, Mrs. Christianer has contributed to both the aerospace and automotive industry with her knowledge of aerodynamics and heat transfer. Overall, Mrs. Christianer has been involved in research including jet impingement cooling, elastic turbulence, shock-boundary layer interactions, battery electric vehicle cooling and aerodynamics, and turbine aerodynamics. While Mrs. Christianer's research has been diverse throughout her career, it has been predominantly focused on turbomachinery aerodynamics. Currently, Mrs. Christianer works at Honeywell as a Sr. advanced mechanical design engineer involved in turbine aerodynamics.

Authors:

Mary K. Jennerjohn Christianer Honeywell
Mark Mcquilling Saint Louis University
Craig W. Mckeever Honeywell