TFC project deals with a combined process of gas turbine and high temperature fuel cell (here Solid Oxide Fuel Cell). In this process, the waste heat generated by the electrochemical processes in the fuel cell has been recovered and fed back into the gas turbine cycle, reducing the amount of heat introduced into the process by combustion in the combustion chamber to raise the air temperature to the turbine inlet temperature. The remaining fuel from the anode side of the fuel cell, which has a low heating value due to the presence of the non-combustible gas components, is further converted by advanced burner technology, and the thermal energy is used to raise the air temperature.

FTD contributes in this project mainly in three areas:

1. Design of a high-temperature heat exchanger to preheat the air to a cathode input temperature suitable for the fuel cell (from approx. 600 °C to 700 °C)
2. Heat transfer analysis for relevant components whose thermal management is of great importance. Enhancement of convective heat transfer by surface design. As a focus, heat transfer and combustion processes in porous medium are investigated
3. Development of the burner concept for combustion of low calorific fuels with the help of the following three measures
   • Micro-mixing plus strong preheating of the air and gas side
   • Combustion in porous medium
   • Catalytic combustion (metal monolith catalyst)

Start date: 2020

Responsible researcher: Tianxiao Xie

The objective of this household project is to gather knowledge about the thermal behaviour of hybrid-electric components by means of a market- and research-relevant application for the year +2035. Representative models of the electric motor, the battery and the power electronics are generated as heat sources and combined with available heat sinks (e.g. air, fuel, etc.) in a reasonable way. This is done, among other things, by integrating special heat exchangers and peripheral devices (pumps, fans, etc.).

The modelling of this interaction of heat sources and sinks allows the formulation of potentials and limits and can be used for subsequent optimisation at component and system level.

Research activities can be represented by the following points:

• Performance analyses of conventional, hybrid and all-electric aircrafts (battery-electric) using Gasturb
• Modelling of an equivalent circuit model (ECM) for Lithium-Ion batteries using Matlab/Simulink
• Thermal battery modelling for a representative flight mission including recuperation using Simscape
• Thermal Management System design for battery applications with different heat sinks & cooling cycles
• User-defined creation of Simscape components
• Loss modelling and evaluation of electric motors (PMSM, IM) for (hybrid)-electric aviation
• Modelling of a representative motor model considering losses and heat transfer using Simscape
• Analysis of different hybrid-electric drivetrain configurations considering the current state of research as well as predicted developments up to +2035 for the identification of efficient drivetrain topologies

Start date: 2019

Responsible researcher: Paul König

As part of the joint project "Flexible wall structures for acoustic liners", the suitability of new materials for the production of acoustically damping wall elements (liners) is to be examined. These are installed in the engine inlet and in the bypass duct in order to reduce the noise emissions from the fan and nozzle, for example. Future engines tend to increase the size of the fan and thus reduce the speed. Compared to the status quo, the consequences are lower frequencies with a broader bandwidth character. New liner concepts must therefore be adapted in order to continue to meet the changed acoustic conditions.

This should be done by selecting suitable structures and materials (e.g. resin systems with inherent damping). This results in both a broadening of the effective frequency range and improved overall damping compared to conventional liners, and thus a reduction in noise emissions from engines.

The design, development and production of the new liner is to be based on the example of two different damper concepts. The first concept has been used successfully in aviation for years in its classic form and is known as the Helmholz resonator liner (HR liner). The actual operating principle is a mixture of a classic Helmholtz resonator and a λ/4 resonator with additional damping when the flow passes through the cover layer. With this liner concept, the use of plastics as the cell chamber wall is intended to achieve not only the self-damping of the new material, but also an additional effect through flexible cell chamber walls. It is to be expected that with a suitable design, the effective frequency range can be broadened.

As a second concept, a type of membrane resonator not previously used in aviation is to be investigated. The membrane resonator liner also promises broadband damping behavior, but its acoustic properties and material parameters must first be examined in detail in order to implement a suitable design for a planned application in the engine.

Of great importance for the success of the project and the potential use of the new noise-absorbing plastic structures is the consideration of the requirements from engine integration, the expected environmental and operating conditions and an initial analysis of possible manufacturing processes.

The consideration of the many individual aspects for the design of the test specimens to be examined, which are measured in terms of flow acoustics and evaluated in comparison to conventional liners as part of the project, ensures the connection to the overall system "eco-efficient aircraft engine" and shows potential and possible weak points in detail at an early stage of the plastic structures. The joint project bundles the expertise of the Chair of Aircraft Engine Design in the area of ​​overall engine integration and thus enables the comprehensive investigation of this innovative liner concept.

Start date: 2021

Responsible researcher: Michael Pohl

ETHAN project deals with the design, management and system testing of highly integrated electro-thermal systems. In this project, FTD is involved in the construction of a thermal network for the purpose of thermal management of the hybrid-electric propulsion system. In this thermal management system, the thermal behavior of those components whose temperatures need to be constantly monitored should be modeled and the interaction of them should be studied at the system level. The choice of cooling concepts, which will eventually influence the architecture of the entire thermal management system, will be carefully studied in this project. All possible failure situations during flight and the resulting behavior of the thermal management system will be examined for a safe and reliable mission.

Start date: 2022

Responsible researcher: Tianxiao Xie

The overall goal of ETHAN (Elecktrische und Thermische Netzwerke für Hybrid-Elektrische Antriebssysteme) is to develop a new, coupled electrical and thermal system architectures for hybrid-electric aircraft to achieve the goals of environment friendly aviation formulated in the European strategy document "Flight Path 2050".

Mainly involved in thermal network modelling and optimization of the electric component cooling system design. Technical objectives include a complete description of all thermally relevant network components, i.e. the components of the cooling system and in particular those of the electric drive system. Thermal networks for different system configurations are to be developed using the component models and subsequently steady-state and transient operating conditions are to be analyzed. Optimization strategies will be used to find the best possible designs according to the requirements.

Start date: 2022

Responsible researcher: Karunakar Reddy Konda

Heat exchangers are critical in aerospace applications and in mission-critical aviation. Development of heat exchangers for hybrid electric applications are an emerging field. My research involves the development of a multi-scale, structurally loaded heat exchanger model for the ETHAN project (Elecktrische und Thermische Netzwerke für Hybrid-Elektrische Antriebssysteme). The overall goal of ETHAN is to develop a new, coupled electrical and thermal system architectures for hybrid-electric aircraft to achieve the goals of environment friendly aviation formulated in the European strategy document "Flight Path 2050".

The technical objectives of my research include the thermomechanical modelling of the transient operating states of the heat exchanger model, the mechanical or structural design including operation and maintenance considerations, and manufacturing considerations involving cost estimates.  The above will be coupled with results from heat transfer and pressure drop analysis to determine the overall functional heat exchanger model. My work also serves to understand the basic failure modes of the heat exchanger in accordance with ARP4754 safety standards and CS23 certification standards. Finally, optimization strategies will be used to find the best possible designs according to the requirements and problem specifications.

Start date: 2022

Responsible researcher: Akilan Mathiazhagan