Session: 

Paper Number: 151855

Thermodynamic Analysis of Ecs-Engine Coupled System for Commercial Aircraft 

Over the years, aircraft engines have undergone many architectural modifications to enhance their fuel efficiency. Prominent among them is the increase of bypass ratio through augmenting the engine diameter and/or reducing the core size. Given that the engine performance is sensitive to bleed air extraction, feasibility of efficient smaller engine cores relies on understanding the interactions between the engine and the bleed-consuming systems. Among these systems (e.g. engine start-up, anti-ice and pneumatic systems), the environmental control system (ECS) is the biggest consumer of bleed air, consuming on average up to 75% of the total engine non-propulsive power for a short-medium-range aircraft at cruise. The study presented in this paper focuses on engine-ECS interactions.

Common practices have the engine and ECS designed separately, which puts the engine bleed flow at the boundary between the two systems. From the point of view of engine design and performance simulation, the ECS bleed air flow is simply a sink, whose magnitudes and positions at different operating points are typically assigned based on regulations. Given the engine core sensibility to the bleed air extraction, as well as the evident importance of the bleed flow for the ECS operation, an integrated ECS-engine model would contribute to the understanding of system interactions and would grant access to the combined-system performance. This is all the more true in context of new system architecture exploration. For purposes of developing one such thermodynamic model of the combined ECS-engine system, generic turbofan-type engine and a simplified ECS architecture (consisting of an air cycle machine, a primary and a secondary heat exchanger, a condenser and a reheater) are chosen as use cases.

The paper begins with a brief literature review of the respective engine and ECS cycle sizing processes, followed by a review on the nature of interactions between the two systems when they are put together in operation. The subsequent 0D thermodynamic analysis performed in PROOSIS^TM software is presented in two parts:

1)     Co-simulation, where the engine cycle sizing is carried out for typical mission points like take-off, climb and cruise. Analogously, the separate ECS cycle sizing is carried out with cruise as the design point. The individually sized models are then co-simulated in off-design mode to evaluate the resulting performance; the calculations are done at different operating scenarios including extreme cases such as hot-day take-off, cold-day cruise or normal-day one-engine inoperative.

2)     Co-sizing, where the engine and ECS cycles are sized in unison from the outset, thus rendering transparent new optima for the boundary parameters on which the comprehensive system performance depends.

Subsequently, simulations of thus co-sized systems are carried out for the same operating cases as in the co-simulation group, and the differences in the resulting system behavior observed in the two respective case groups are discussed. The metrics chosen to evaluate the engine performance impacts are the thrust-specific fuel consumption, shaft power offtake, compressor bleed mass flow and its power consumption.

In conclusion, the present work develops the thermodynamic analysis of a directly coupled ECS-engine system, with the main objective of opening the engine design envelope to accommodate the requirements of the simplified ECS model rather than to design the engine with assumed values for engine bleed. The analysis is dedicated to the understanding of the interactions between these systems of interest, and to revealing performance tendencies when the two are designed as an integrated whole.

Presenting Author: Spurthy Subramanya Safran Tech

Presenting Author Biography: Subramanya Spurthy is a third year PhD student studying low level robust modelling of commercial aircraft environmental control system under the joint tutorship between ISAE-Supaéro and Safran Tech. Spurthy graduated from the master’s degree in Aerospace Engineering with Aerodynamics and Propulsion major at ISAE-Supaéro in 2021, following the bachelor’s degree in Aeronautical Engineering from Nitte Meenakshi Institute of Technology Bangalore in 2019. Her areas of professional interest are aircraft engine design, performance analysis, and turbomachinery. As a part of her PhD studies she had presented the paper on historical evolution of commercial aircraft environmental control system at Sci Tech 2024 and the paper on air management system for commercial aircraft environmental control system at Turbo Expo 2024.

Authors:

Spurthy Subramanya Safran Tech
Aleksandar Joksimovic Institut supérieur de l'aéronautique et de l'espace
Sarah Rebholz Safran Tech
Frederic Tong-Yette Safran Tech
Xavier Carbonneau Institut supérieur de l'aéronautique et de l'espace