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Advanced ventilation techniques for modern long-range passenger aircraft to promote future energy management systems

Periodic Reporting for period 2 - ADVENT (Advanced ventilation techniques for modern long-range passenger aircraft to promote future energy management systems)

Reporting period: 2019-03-01 to 2020-08-31

• Motivation:
In case of civil aviation, the environmental control system (ECS) consumes large amounts of energy, especially during long-range flights. Here, novel ventilation concepts offer the potential for energy savings by reconsidering the fresh air fraction. Besides energy saving benefits, the improvement of the thermal passenger comfort and air quality are also possible using new concepts. Further, novel ventilation systems provide the opportunity to redesign the cabin structure including the ducting system in order to simplify construction and manufacturing processes by using pre-assembled modules, which suits the approach of a modular aircraft design.
• Boundary Conditions
To evaluate alternative ventilation concepts regarding passenger comfort several criteria are studied in detail. Here, the main focus lies on enhanced heat removal efficiency as well as optimized local ventilation and air exchange efficiencies to improve the air quality and thus the passenger well-being. Considering the environmental aspect, alternative concepts with the possibility to save bleed air associated with reduced cooling demands promise energy savings. Here, several components of the ECS benefit from these new concepts resulting in smaller and lighter components. Additionally, a redesign of the ducting system promises weight savings and thus a lower fuel consumption.
• Testing and evaluation of new concepts
To identify and verify corresponding concepts, parametric studies will be conducted experimentally and numerically. Hereto, a test rig, representing a full-scale long-range cabin mock-up, was designed and setup. Special attention is given to the possibility to precisely define the thermal and fluid dynamical boundary conditions in experimental as well as numerical studies. For the pre-selection of promising concepts, numerical simulations are conducted with a validated model and corresponding tool chain.
The top-level objectives are threefold:
1. Identification and benchmarking of novel ventilation concepts for modern long-range cabins using numerical simulations.
2. Deployment, set-up and testing of a ground-based, full-scale test facility (mock-up) for experimental simulations and studies of future long-range cabin ventilation concepts under realistic thermodynamically boundary conditions.
3. Provision of an experimental reference database of comfort-relevant parameters for different ventilation systems.
To achieve the top-level objectives, among others, the following tasks were performed.
Objective one:
- Promising novel concepts were pre-selected using numerical simulations. Here, thermal comfort and energy saving potential serve as an evaluation criterion. The most reasonable concepts will be implemented in the new long-range cabin mock-up.
Objective two:
- Planning, design and erection of the new mock-up based on the previously defined specifications and requirements.
- Startup of the new test facility including test of the air supply, volume flow measurement and temperature-control system.
- Integration of the first novel ventilation concept. Hereto, new air outlets were designed and installed.
- Installation of thermal manikins as well as the latest measurement techniques (e.g. local probes, infrared thermography, tracer-gas measurement system, etc.). Further, several control units are implemented to monitor and control the boundary conditions. In this regard, temperature-controlled sidewalls are used to simulate thermodynamically realistic boundary conditions. Hence, the mock-up is ready for the first validation tests.
Objective three:
- To simulate different flight phases experimentally, first successful tests of the mantle cooling/heating system are conducted. As a result, dynamic changes of the thermodynamic boundary conditions in a range covering relevant temperatures and time scales are possible.
- A test matrix was defined to validate the new ventilation concepts. Here, scenarios for static measurements with varied mass flow is included. Subsequently, the preparation process for the dynamic measurements begins.
In the following, the dissemination activities are summarized:
- One patent was applied
- Project website was released
- Two publications were presented at the AEC 2020 (content: results of numerical simulations and feature of the new test rig)
- Presentation for postponed Roomvent 2020 is scheduled
- Abstract submitted for upcoming Ventilation Conference 2021
Unfortunately, in the preparation of the experimental investigations some time delays occurred due to the Corona pandemic in 2020.
The progress beyond the state of the art comprises a) detailed specification documents which are the basis for the planning and design process of the new mock-up. The latter covers a modern long-range cabin layout and provides thermodynamically realistic boundary conditions for static and dynamic investigation of different flight phases. Hereto, temperature-controlled fuselage elements were successfully installed and tested. To our best knowledge, this new mock-up will be the largest dual-aisle cabin mock-up allowing the investigation of ventilation concepts regarding their energy efficiency, thermal comfort and capability of integration under precise boundary conditions. Further, novel ventilation concepts can be integrated with a high degree of flexibility due to the modular design of the test rig. b) Three new ventilation concepts revealed their potential for optimizing thermal comfort and energy efficiency in numerical simulations. Here, a CFD model including a tool chain was implanted in order to calculate comfort relevant indices. These new concepts are prepared to be applied for patents and will be investigated experimentally in the new cabin mock-up. The first concept, a ceiling-based ventilation system, is already installed. First validation tests comprising static measurements with a varied incoming mass flow are conducted to analyze the performance of the concept.
The expected results until the end of the project comprise the identification and experimental validation of a ventilation concept with benefits in terms of passenger comfort and energy efficiency. The capability to integrate the new system in the aircraft itself serves as an additional evaluation parameter, addressing the approach of a modular aircraft design. Further, the deployment of a ground-based test rig for experimental simulations of modern long-range cabins will be highly relevant for the European aircraft industry. The flexible integration of novel ventilation concepts and simultaneously providing thermodynamically realistic boundary conditions are the main features. Finally, an experimental and numerical database will be compiled comprising velocity, temperature and CO2 distributions as well as ventilation efficiencies for different ventilation concepts.
Potential impacts of the project so far are the identification of ventilation concepts which promise heat removal efficiencies more than 50% higher than provided by state-of-the-art mixing ventilation while at the same time improving thermal passenger comfort. It should be noted that a concomitant weight reduction of the support system was not estimated yet. Nevertheless, these first results clearly highlight the potential of energy reduction associated with fuel savings and thus with decreased amounts of CO2 exhaust.