Session: 14-07 Modelling Methods for IAS

Paper Number: 126718

126718 - Partitioned Coupled Heat Transfer Fluid-Structure Interaction for Transient and Steady State Analysis of Aero Engines Applications 

Fluid-Structure interaction has a significant impact on heat transfer in aero engines. Thermal interaction of solid and gas appears e.g. for secondary flow cavities in compressors and turbines. Coupled multiphysics simulations including three systems CFD, structure analysis and gas network can significantly improve quality and efficiency of conjugate heat transfer analysis, and be very useful for supporting the matching of thermal models with measurements. Thermal matching activities are known to be very complex with high time and resource consumption. To match analytical thermal models with engine test measurements, strong engineering judgement and experience are required, and generally require an extensive iterative process to reach the desired quality.

 

A method for fluid-structure coupling for special purpose demands of aero engine heat transfer is presented. It is based on a partitioned approach designed to guarantee for standard processes, methods and tools (like mapping methods and solvers) for industrial applications and implemented as central coupling control software (CoSMiX) flexible in embedding respective modules on demand.

 

Fluid temperatures show much faster reaction than material temperatures and time scales differ significantly for the respective domains. Typically a thermal flight mission analysis of solid material can be several hours long and is fully simulated to optimally represent the transient behavior. An efficient approach to take the interaction with fluids into account is to embed stationary CFD analyses for only a special amount of representative operational points. This enables much fewer steps than necessary for a monolithic coupling like CHT and therefore to save computational effort.

The presented multi fidelity approach includes strong system coupling of 1D, 2D and 3D models.

Thermal analysis of aero engines is often based on 2D rotationally symmetric finite element models. Therefore, not only mapping on non-matching grid interfaces of 3D models but also mapping from 3D to 2D models and back is implemented including averaging methods in time and space.

The multiphysics method includes the coupling of the advective system representing the secondary air system with mapping of interface data and global convergence control respectively.

 

The coupling method has been used to support a real engine high pressure compressor matching campaign. The flow structure in the high pressure compressor drum is known to be very complex, unsteady, and highly driven by natural convection. The effort to match standard 2D thermal models using flow network and correlation-based heat transfer with measurements is typically very large, and may even beimpossible to capture all effects during the flight mission. The usage of a coupled model enables to significantly reduce the matching effort, by gaining a much better understanding of the physical phenomena and the thermal behavior of the component. A comparison of non-matched coupled/non-coupled model with measurements will be presented at high and low power conditions. The consequences on the matched thermal model are explained and quantified.

Presenting Author: Francois Cottier MTU Aero Engines AG

Presenting Author Biography: Francois Cottier has graduated as an engineer at the ENSIMEV, the national engineering school of the university of Valenciennes. He has 20 years experience in the aero propulsion industry at MTU Aero Engines in Munich, Germany. As specialist in thermal analysis of jet engine components, he has been responsible for turbine airfoils thermal design in several marketed jet engines, and lead various research pro-jects for the development of modern technologies in jet engines. As a specialist of numerical simulation of flow and heat transfer, he has been responsible for the integration of modern 3D simulation methods in the development processes of jet engines like computational fluid dynamics. Today he is participating to the development of future technologies and innovative concepts for aeronautical purposes.

Authors:

Ute Israel MTU Aero Engines AG
Francois Cottier MTU Aero Engines AG
Jochen Gier MTU Aero Engines AG