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Surface Heat Exchangers For Aero Engines 2

Periodic Reporting for period 5 - SHEFAE 2 (Surface Heat Exchangers For Aero Engines 2)

Reporting period: 2020-02-01 to 2021-01-31

The project aim is to develop and demonstrate lighter and more efficient integrated heat exchanger systems for the turbofan engine. Currently in turbofan engines, heat exchangers are used to cool the oil that is supplied to the bearing chambers and generators. They contribute to achieving the best engine performance by maintaining oil and fuel temperatures within defined limits. In the future, core temperatures of turbofans will be higher leading to extensive use of heat exchangers in order to get the very lowest levels of fuel burn to reduce the environmental impact of aviation. Therefore development of compact, lightweight and low cost heat exchanger systems is required. In this context, research and development activities are foreseen, to assess, develop, design and manufacture:

High Length to depth ratio Surface Air Cooled Oil Coolers (SACOC);
Utilisation of engine structural components for thermal cooling;
Robust mounting systems to integrate the high length to depth Surface Air Cooled Oil Cooler (SACOC) on the turbofan engine;
High efficiency Fuel Oil Heat Exchanger (FOHE);
High reliability Modulating Oil Bypass Valve (MOBV) that is integrated within the Fuel Oil Heat Exchanger.

The heat exchanger systems will be tested on the rig to validate their performance and structural capabilities. The integration of the high length to depth ratio Surface Air Cooled Oil Coolers on the engine will require a robust mounting system to tolerate the induced stresses due to thermal and vibrational loads. Advanced manufacturing capability will be developed for the designs of the high length to depth ratio Surface Air Cooled Oil Coolers and the Fuel Oil Heat Exchanger with the integrated Modulating Oil Bypass Valve.
At the outset of the first period the requirements for the project and the components were established and the necessary functional and geometrical specifications were established. This led to the formation of numerous concept designs for the Surface Air Cooled Oil Cooler (SACOC) and it's mounting system, in addition the specifications informed the early concept studies for the Fan Outlet Guide Vane Coolers (FOGVCs). By the end of the first period Preliminary Design Reviews (PDRs) were held for the SACOC and Mounting System to down-select the concept to go forward to the detailed design phase. In addition to concept down-select there has been production of prototype components and some testing carried out to validate the computational modelling used to predict the performance of the coolers. Through the second period the concepts were further refined, a single concept for the SACOC was selected and developed to final design, as well as the mounting system. Some geometrical changes to the engine installation location led to a redesign in the mounting system, increasing the complexity by reducing the available space. A Critical Design Review (CDR) was conducted towards the end of period 2, following this further work has been conducted into the reaction of the cooler and mountings under loading. In Period 3, further analysis of the SACOC and Mounting system has been completed and the designs of the SACOC and mounting system have been finalised. Manufacture of the SACOC was launched in Period 3. Preliminary Design Reviews of both the FOHE and MOBV were completed in Period 3. Test standard SACOCs were manufactured in period 4 with testing planned to be complete in period 5.

Concepts have been generated and analysed for the FOGVCs and down-selected to a proposed component to manufacture to determine the feasibility of such a design, the validation testing will also validate some of the CFD modelling that has been conducted. In Period 3, a prototype FOGVC has been manufactured and instrumented ahead of wind tunnel testing planned in Period 4.

Specifications have been communicated in period 2 for the Fuel Oil Heat Exchanger (FOHE) and Modulating Oil Bypass Valve (MOBV) which will be studies as part of enhancements to the overall oil system. Some prototype parts have been manufactured in period 2 following communication of the specifications, with subsequent testing conducted to understand the current and potential capabilities of the components. Preliminary Design Reviews of both the FOHE and MOBV were completed in Period 3.This was followed by completion of the Critical Design Reviews for both units in period 4.
The activity to date has focused on determining the current state of the art as well as defining the requirements for future technologies which will improve upon the current standard and work towards a reduction in fuel burn leading to environmental benefits. The concepts produced and down-selected have been progressed to test standard hardware for all of the products under consideration.
Example CFD output
Concept overview of Heat Exchanger
Logo used for SHEFAE2 project