Numerical assessment of RANS and LES modelling in particle separation devices
Creators: name:  J. MUELA 
name:   A. AMANI 
name:   E. SCHILLACI 
name:   J. RIGOLA 
name:   C. OLIET 
Publisher: name: Proceedings of  the 9th European Conference for Aerospace Sciences. Lille, France, 27 June - 1 July, 2022
Year: 2022
Subjects: FLIGHT PHYSICS
COMPUTATIONAL FLUID DYNAMICS

description: One of the most important challenges to be faced by the aerospace industry nowadays and the upcoming years is the reduction of gas emissions. The final aim is the design of All Electric Aircrafts (AEA) with zero emission. Nonetheless, fully electric flights are still a long way in the future, since there are lot and very challenging aspects to be faced before they become a reality [1]. Meanwhile, the bridge between current aircrafts and AEA are the More Electrical Aircrafts (MEA). The main idea of MEA is the substitution of all non-propulsive systems by systems fully electric-powered [2]. One of these systems is the Environmental Control System (ECS). This system is the one devoted to maintain both temperature and pressure air in the comfort range within the cabin. Conventionally, the inlet air required for feeding the compressors of the ECS is obtained by bleeding air from the latter stages of the compressors of the engine aircraft, which guarantees the supply of a clean air without Foreign Object Debris (FOD). Nonetheless, this bleeding induces an additional fuel burn and lead to the ingestion of potential harmful neurotoxic substances [3]. Aiming to avoid the issues of this air-bleeding, MEA are designed to use a new Electrical Environmental Control System (EECS), which is directly feed with air coming from the ambient atmosphere. The problem is that this air may content FOD, which can dramatically reduce the service life of the compressor, if not directly damage it. Therefore, a protection system against this FOD must be employed before the compressor of the EECS in order to minimize this risk. Inertial Particle Separator (IPS) devices are very well-suited candidates to be part of a reliable FOD protection systems for EECS [4]. These IPS devices have to be designed looking for guarantee the required FOD protection as well as the minimum pressure loss. Computational Fluid Dynamics (CFD) can be a really powerful tool for the design and optimization of IPS devices. In CFD, performing Direct Numerical Simulations (DNS) of turbulent flows, where all the temporal and length scales of the flow must be solved, is restricted to relatively simple academical cases due to nowadays computational resources. Therefore, for design and optimization of IPS devices, turbulence modelling technique must be employed. The two most common turbulence modelling techniques are Reynolds-Average Navier-Stokes (RANS) and Large Eddy Simulation (LES). LES offers higher accuracy than RANS at expense of higher computational cost, but RANS introduce a higher degree of modelling. The flow pattern found in IPS devices can be really complex, and its resolution can highly affect the calculated flow-particle interactions. Therefore, it is of interest to study and assess the capabilities and limitations of both modelling techniques in the simulation of IPS devices. The present work presents a detailed comparison between LES and RANS modelling in a canonical configuration for an IPS device. This comparison will allow to study and assess both the capacities and lacks of these modelling techniques for design and optimization purposes of IPS devices. References [1] Wheeler, Pat. Technology for the more and all electric aircraft of the future. IEEE International Conference on Automatica (ICA-ACCA), 2016. [2] Sarlioglu, B., and Morris, C. T. More electric aircraft: Review, challenges, and opportunities for commercial transport aircraft. IEEE Transactions on Transportation Electrification, 1(1), 54-64 (2015). [3] Mike Sinnett. 787 No-Bleed Systems: Saving Fuel and enhancing operational efficiencies. AERO Qtr 4, 2007. [4] Filippone, A. and Bojdo, N. Turboshaft engine air particle separation. Progress in Aerospace Sciences, 46(5), pp. 224-245, 2010.