Adiabatic and conjugate simulations on the flow field in a gas turbine vane with pressure side film cooling and trailing edge cutback

Abstract

The present study concentrates on the numerical investigation of pressure side film cooling in a linear nozzle vane cascade typical of a high-pressure turbine in gas turbine engines. The cooling scheme features a pressure side cutback and two rows of cooling holes located upstream of the cutback. The main goal is to evaluate the applicability of a simple numerical method, i.e. the steady incompressible Reynolds-averaged Navier Stokes, in such a complex industrial application. The simulations are performed according to an adiabatic and conjugate approach. Two values of the coolant-to-mainstream mass flow ratio ( MFR = 1% and 2.8%) are simulated at exit Mach number of M2 is = 0.2. The computed flow/temperature fields in the cooled regions of the vane pressure side are presented and compared to available measurements of: holes and cutback exit velocity and discharge behavior; boundary layer along traverses at strategic axial locations, adiabatic film cooling effectiveness. In addition, distributions of overall film cooling effectiveness and heat transfer coefficients are reported for the conjugate cases. Both adiabatic and conjugate techniques provide reasonable predictions of three-dimensional aerodynamic and thermal features of the investigated cooled vane. The conjugate heat transfer is much more complicated than one-dimensional conduction within the vane material.

Assessment of binary PSP technique for film cooling effectiveness measurement on nozzle vane cascade with cutback trailing edge

“…9b and 10a) can be explained by considering that, as stated before, TLC measurements were performed on a model manufactured with a rapid prototyping machine while PSP measurements were run on a Plexiglas model. The unavoidable imperfections in the internal geometry and the high roughness of the internal surface of the first model caused a flow separation in the slot exit section at low injection rates, as documented in Ravelli and Barigozzi [26]. This separation was not present in the Plexiglas models, realized by a 4 axis NC machine assuring a precise geometry definition with very smooth internal surfaces.…”

“…To fully assess the binary PSP technique, the same methodology successfully tested on the flat plate case was applied to a more complex geometry like the cooling of the pressure side of a high pressure nozzle vane cascade equipped with a cutback trailing edge. This test case was chosen because the same geometry has been extensively tested, both experimentally [22][23][24] and numerically [25,26], at Bergamo University Laboratory so film cooling effectiveness distributions measured at variable MFR and downstream Mach number with the wide banded TLC technique are available for comparison [22]. These tests were considered by the authors very challenging.…”

Turbine vane endwall aerothermal and film cooling performance considering realistic swirling inflow conditions

“…By solving steady three-dimensional RANS equations, the computational results of the endwall heat transfer were found to have a good agreement with experimental data. 15 Ravelli and Barigozzi 16 studied the conjugate heat transfer characteristic with a vane pressure side cooling scheme. They reported that the heat transfer coefficient could be predicted reasonably by both adiabatic and conjugate approaches.…”