Towards the Large-Eddy Simulation of a full engine: Integration of a 360 azimuthal degrees fan, compressor and combustion chamber. Part I: Methodology and initialisation

Abstract

Optimising the design of aviation propulsion systems using computational fluid dynamics is essential to increase their efficiency and reduce pollutant as well as noise emissions. Nowadays, and within this optimisation and design phase, it is possible to perform meaningful unsteady computations of the various components of a gas-turbine engine. However, these simulations are often carried out independently of each other and only share averaged quantities at the interfaces minimising the impact and interactions between components. In contrast to the current state-of-the-art, this work presents a 360 azimuthal degrees large-eddy simulation with over 2100 million cells of the DGEN-380 demonstrator engine enclosing a fully integrated fan, compressor and annular combustion chamber at take-off conditions as a first step towards a high-fidelity simulation of the full engine. In order to carry such a challenging simulation and reduce the computational cost, the initial solution is interpolated from stand-alone sectoral simulations of each component. In terms of approach, the integrated mesh is generated in several steps to solve potential machine dependent memory limitations. It is then observed that the 360 degrees computation converges to an operating point with less than 0.5% difference in zero-dimensional values compared to the stand-alone simulations yielding an overall performance within 1% of the designed thermodynamic cycle. With the presented methodology, convergence and azimuthally decorrelated results are achieved for the integrated simulation after only 6 fan revolutions.

Predictive Analysis of Code Optimisations on Large-Scale Coupled CFD-Combustion Simulations using the CPX Mini-App

“…Currently, the components are designed and manufactured separately, which can lead to reduced engine performance due to optimizations made within individual elements being negated as a result of integration with other components. This is because without coupled simulations, there is information loss as unsteady interaction between components cannot be modelled [5]. Such coupled simulations have become furthermore important with the industry ambitions to reach virtual certification of full aero-engine designs [6], [7].…”

“…However, information is often lost as a result of this process, as bidirectional transfer of some information, particularly unsteady interactions such as turbulence intensity, are not possible. Therefore, it is desirable to run multiple components together in a single simulation such that interactions can be more accurately captured [5].…”

Effect of Compressor Unsteady Wakes on a Gas Turbine Combustor Flow

“…The use of a monolithic eddy-resolving simulation to predict and further understand the flow through a gas turbine is indeed possible, and has been recently proven by the impressive fully-annular compressor-combustor LES of Pérez Arroyo et al [8]. Nevertheless, such applications are still limited to small geometries, and the high computational requirements make them infeasible for regular industrial use.…”

Generation of Realistic Boundary Conditions at the Combustion Chamber/Turbine Interface Using Large-Eddy Simulation

“…Thus, to be able to accurately simulate the multicomponent coupling without reducing the number of blades or without additional simplifying assumptions, the best option is to perform a 360 • simulation of the complete turbomachine. Despite the constant progress in computing capabilities, very few examples of complete engine simulations are available in the literature (even fewer using LES) and in any case, these simulations remain very expensive [1][2][3][4]. As a re-Energies 2021, 14, 8206 2 of 23 sult, and for engine manufacturers, this solution is not feasible today during the design phases, and other options must be considered.…”