Development of a High-Order Method for the Prediction of Low-Pressure Turbine Losses using Quasi-Direct Numerical Simulations

Bolinches i Gisbert, Marc (2020). Development of a High-Order Method for the Prediction of Low-Pressure Turbine Losses using Quasi-Direct Numerical Simulations. Thesis (Doctoral), E.T.S. de Ingeniería Aeronáutica y del Espacio (UPM). https://doi.org/10.20868/UPM.thesis.66214.

Description

Title: Development of a High-Order Method for the Prediction of Low-Pressure Turbine Losses using Quasi-Direct Numerical Simulations
Author/s:
  • Bolinches i Gisbert, Marc
Contributor/s:
  • Corral García, Roque
Item Type: Thesis (Doctoral)
Date: 2020
Subjects:
Freetext Keywords: dinámica de fluidos computacional; large eddy simulation; aerodinámica de cascadas lineales; métodos de alto orden; flux reconstruction = computational fluid dynamics; large eddy simulation; linear cascade aerodynamics; high-order methods; flux reconstruction
Faculty: E.T.S. de Ingeniería Aeronáutica y del Espacio (UPM)
Department: Motopropulsión y Termofluidodinámica [hasta 2014]
Creative Commons Licenses: Recognition - No derivative works - Non commercial

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Abstract

In this thesis the implementation of a compact high-order Computational Fluid Dynamics (CFD) method and its validations is tackled. The chosen compact scheme is that of the Flux-Reconstruction (FR) method. This method is indeed a family of methods that can recover other schemes such as Discontinuous Galerkin method. These methods are particularly well suited for massively parallel hardware architectures since many operation per degree of freedom are performed which are independent of neighboring cells. The implementation of the CFD method has been made on utility Graphical Processor Units (GPU) in order for the software to take advantage of their parallel architecture. The GPUs used in this work are single precision hardware. This imposed further action in order to keep the precision of the solution. Particularly, action was needed in the implementation of our time-marching algorithm. This was mainly due to the fact that very small time-steps were imposed by stability conditions. The Kahan summation algorithm was used in order to prevent single-precision errors from appearing as the solution marched in time. The validation of the method was carried out against a very rich array of high-quality experimental data. This validation case consisted of a low velocity Low Pressure Turbine linear cascade designed by ITP Aero. The experiments were carried out at the Polytechnic University of Madrid. Pressure distribution were measured over the profile; velocity and root-mean-square (RMS) of velocity fluctuations were measured in the boundary layer; and total pressure, velocity and RMS of velocity and angle distributions were measured at the exit measurement station. All these data were compared against the numerical results with outstanding agreement for all the cases. Global quantities such as the cascade turning angle and cascade losses also agreed well with experimental data. More importantly, the Reynolds lapse rate, i.e., the variation of the cascade loss with Reynolds number, was captured by our simulations. This thorough comparison is expected to increase confidence in compact high-order schemes. ----------RESUMEN---------- Esta tesis aborda el desarrollo y la implementación de un método compacto de alto orden para mecánica de fluidos computacional. El esquema propuesto es el del método de reconstrucción de flujo (Flux-Reconstruction). Este método es, en realidad, una familia de métodos con la que se pueden recuperar otros esquemas populares tales como el Discontinuous Galerkin. Dado que estos métodos requieren de una gran cantidad de operaciones per grado de libertad, su implementación en ordenadores preparados para la computación en paralelo es especialmente eficiente. De hecho, la implementación hecha en esta tesis es en tarjetas gráficas (GPU). Las tarjetas gráficas utilizadas en este trabajo son de uso común, i.e., tarjetas no diseñadas para computación. Estas tarjetas tienen una arquitectura hecha para precisión simple y, por tanto, operaciones adicionales son necesarias para preservar la calidad de la solución. En particular, el esquema de integración en el tiempo se tuvo que modificar para evitar error de precisión. Esto es debido al extremadamente pequeño paso de tiempo que impone la estabilidad del esquema. El algoritmo de Kahan se implementó en nuestro método de integración para resolver este problema adicional. El método desarrollado se validó utilizando datos experimentales de alta calidad. Este caso de validación consiste en una cascada de turbina de baja presión y baja velocidad diseñado por ITP Aero. Los ensayos experimentales se realizaron en la Universidad Politécnica de Madrid. Durante los ensayos se midieron la presión sobre el perfil; la velocidad y sus variaciones sobre la capa límite; y las distribuciones de presión total, velocidad y sus variaciones, y ángulo en la estación de salida. El nivel de acuerdo entre todos los datos medidos experimentalmente y los numéricos es muy alto. En particular, el “Reynolds lapse rate” (variaciones de las pérdidas de la cascada con el número de Reynolds) es capturado con precisión. Este resultado es especialmente relevante y creemos que ayudará aumentar la confianza en este tipo de métodos.

More information

Item ID: 66214
DC Identifier: http://oa.upm.es/66214/
OAI Identifier: oai:oa.upm.es:66214
DOI: 10.20868/UPM.thesis.66214
Deposited by: Archivo Digital UPM 2
Deposited on: 28 Feb 2021 08:47
Last Modified: 28 Feb 2021 08:47
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