Conjugate Heat Transfer Analysis of an Engine Internal Cavity

Abstract

The analysis of heat transfer in engine cavities or blade internal cooling systems is one of the most challenging work for aircraft engines designers for two main reasons. Firstly, the efficiency of such systems has a direct influence on both life and performance of these engines. Secondly, the available tools to predict heat transfer in both solid parts and surrounding cooling gases, i.e. Navier Stokes and conduction codes, are often used independently. An interaction model between the fluid and solid media is generally required and remains a difficult issue in engine configurations. A coupling procedure between a Navier-Stokes code and a conduction solver is therefore the only way to achieve heat transfer predictions in all flow situations. The objective of this work is to present such a procedure, which has been developed at Snecma and based on a Finite Volume Navier-Stokes code and a commercial Finite Element solver. The first application showed in the paper demontrates, with an uncoupled calculation that the Navier-Stokes code MSD, from ONERA, is able to predict heat transfer with an acceptable accuracy. The discretization used in the solid to predict heat conduction is briefly presented. Then the steady state coupling procedure is exposed and validated with an analytical solution. Finally, a conjugate heat transfer computation in a rotor/rotor cavity of a real engine, with rotating solid disks, is described in detail.

The Application of Discontinuous Galerkin Methods in Conjugate Heat Transfer Simulations of Gas Turbines

“…According to our mesh independent study, the fluid and solid domains are partitioned into 8470 and 6160 elements respectively, as shown in Figure 6. The computational temperature distributions at three different axial locations in Figure 7 appear as parabolic profiles in the fluid region and logarithmic profiles in the solid region, and also show good agreement with the analytical results in [2]. …”

“…The second case is the conjugate heat transfer of a Poiseuille pipe flow, of which the analytical solution was derived by Montenay et al [2]. The geometry of the case is sketched in Figure 5 …”

“…In 1999, Martin et al [1] developed a sequential conjugate strategy, by which a code for gas flow field computation and another one for solving heat conduction in solid blade was combined through an inner iteration process. This method taking advantage of available single-filed solvers had then been promptly adopted by some investigations [2][3][4][5][6], most of which used mature parabolic or elliptic equation solvers based on finite element (FE) methods in the solid domain. Meanwhile, partially aiming at enhancing the stability of the algorithm, the direct or full conjugate strategy [7][8][9][10][11] that integrates the governing equations in both fluid and solid domains using a single code also began to be developed and applied.…”

Coupled Fluid-Structure Transient Thermal Analysis of a Gas Turbine Internal Air System With Multiple Cavities

“…Among the advantages it may offer are a lower level of human intervention and time required to set up the models, and more importantly, automatic generation of the boundary conditions for the downstream components. However, this comes at a price of a considerably higher computational effort required to run a simulation through an engine transient flight cycle leading to long analysis times.Many studies in recent years sought to improve the predictive capabilities of thermo-mechanical analysis codes by coupling FE solvers to detailed CFD models of individual components to more accurately evaluate wall temperature distribution in turbine cavities, see, for example, [3,4,5,6,7]. While these studies were able to obtain only a general agreement with the experimental data, they did demonstrate many of the fundamental features outlined in earlier investigations.…”

Coupled Fluid-Structure Transient Thermal Analysis of a Gas Turbine Internal Air System With Multiple Cavities

“…Many studies in recent years sought to improve the predictive capabilities of thermo-mechanical analysis codes by coupling FE solvers to detailed CFD models of individual components to more accurately evaluate wall temperature distribution in turbine cavities, see, for example, [3,4,5,6,7]. While these studies were able to obtain only a general agreement with the experimental data, they did demonstrate many of the fundamental features outlined in earlier investigations.…”