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Multi-physics mOdelling of high Temperature engIne ValvEs

Periodic Reporting for period 1 - MOTIVE (Multi-physics mOdelling of high Temperature engIne ValvEs)

Reporting period: 2018-03-01 to 2019-08-31

Pneumatic bleed systems account for a significant proportion of scheduled interruptions during in service life to undertake needed airplanes’ maintenance. Design optimisation of pneumatic valves and their associated actuation mechanisms is therefore critical to keep unscheduled and costly delays to a minimum. Pneumatic valves and their actuation systems can be optimised in-situ; however, the associated costs are substantial. Being able to predict valve performance during the design phase would reduce these costs considerably.

In order to facilitate valve design optimisation, a complete description of the fundamental physical phenomena encountered within the engine environment is necessary. Thermal physics, mechanical physics, and fluid dynamics are the three main physical domains which are involved. The MOTIVE project aims to deliver high-fidelity, multi-physics models combining these three physical domains in order to develop a complete predictive model for valve and actuator performance.

The achievement of the overall project aim will be accomplished via two major technical objectives:
•Successful completion of a comprehensive experimental testing campaign involving materials characterisation, bespoke friction testing, and aerodynamic testing;
•Development of a multi-physics model capable of describing the thermal physics, mechanical physics, and fluid dynamics. The multi-physics models will be calibrated and validated against the experimental data.
The delivery of high-fidelity multi-physics models to be used as virtual test bench for valve and actuator performance is achieved through a framework of activities involving materials characterisation (WP2, WP6), bespoke friction and aerodynamic testing (WP3, WP4, WP5), and development of state-of-the-art multi-physics numerical and analytic models (WP7).

The project has spent most of its first eighteen months focussing on foundation work for the implementation of an extensive experimental programme, based on which the development and calibration of multi-physics models will be undertaken. An extensive material characterisation programme was also initiated, which provides the numerical models with a comprehensive and parametric database of properties for the materials used in pneumatic valve systems.

Activities in WP2 are undertaken by TWI and aims to develop a coefficient of friction database for selected material couples. Activities undertaken as part of WP2 until now include: definition of a test plan and procurement of material samples for testing; development and setup of a friction coefficient test bench to cover environmental temperatures between -50°C and 700°C and contact pressures in the range 0.1MPa to 1GPa; a comprehensive experimental test programme to determine static and kinetic coefficients of friction for the required operational environment and this is currently in progress.

WP3 and WP4, led by SCITEK and currently in progress, aim to commission specifically designed friction test benches to measure the friction contribution of real-scale components used in pneumatic valve configurations in bleed systems. Based on technical specifications agreed with the Topic Manager, the test benches mentioned above were designed, manufactured and commissioned. The test benches will offer the possibility to tests several configuration of seal systems and to output the friction generated by the same seals as function of a wide range of values of relevant parameters, such as velocity, operating pressure and environmental temperature (-50°C and 700°C). The experimental programme has now started and is currently ongoing.

WP5 activities cover the fluid dynamics domain of the pneumatic valve investigation and will provide the project with experimental results in terms of aerodynamic torque performance and its influence on the friction contribution of the pneumatic valve components. An experimental test bench will be designed and commissioned to test real-scale components and a testing programme will be undertaken to generate experimental data for the calibration of the models. To date, the specifications and requirements for the test bench have been defined and agreed, and the design process has already started and is currently in progress. Activities in WP5 are led and undertaken by ESI and Ventil.

Finally, WP7 includes all those activities aimed to the development of multi-physics numerical and analytical models of pneumatic components. Thermal physics, mechanical physics and fluid mechanics models will be developed and calibrated against the experimental results obtained from the friction tests, aerodynamic torque tests and from the diaphragm materials characterisation study undertaken in the other work packages. A comprehensive theoretical study, including a critical review of existing numerical friction models capable of incorporating various phenomena (e.g. hysteric dynamical behaviour during pre-sliding, friction lag or non-reversibility of friction force, Stribeck effect) was undertaken. The development of the numerical models was initiated and are currently being implemented.
The aerospace industry currently lacks a multi-physics predictive model for high temperature engine valve design optimisation. As matter of fact, current state-of-the-art multi-physics modelling frameworks have limited friction and aerodynamic modelling capabilities. MOTIVE aims to advance current design and analysis tools for pneumatic valves by developing and delivering a comprehensive analytical multi-physics based model to predict valve performance and controllability, based on thermal, mechanical and aerodynamic considerations.

Expected results until the end of the project can be listed as follows:

•Commission a state-of-the-art friction test bench to measure the friction produced by aircraft pneumatic actuation pistons and butterfly valves.
•Commission a state-of-the-art aerodynamic torque test bench for pneumatic butterfly valves.
•Comprehensive parametric database of coefficient of friction properties as a result of an axtensive material characterisation of material couples used in pneumatic valve components
•Generation of results from a detailed friction test experimental programme to quantify the frictional effort of valve materials and different valve designs.
•Generation of results from an axtensive aerodynamic flow testing of pneumatic valves in order to quantify their aerodynamic properties.
•Produce a complete model of valve and actuation system, involving thermal, mechanical and fluid physics, capable of predicting valve performance for a range of geometries, across a wide range of operational conditions.

MOTIVE is expected to contribute to the specific impacts of the Clean Sky 2 Large Passenger Aircraft IADP by achieving its ultimate goal of developing multi-physics models of high temperature aircraft pneumatic engine valves, which can be used to optimise valve design and material combinations. A successful delivery of the multi-physics models will enable the efficient use of numerical and analytic models as a virtual prototyping tool, contributing to:

• Maintaining the competitive advantage of the European aircraft manufacturing sector in the long-term
• Offer a more sustainable process for producing pneumatic components.
• Promote technologies that enhance the ability to customise bleed air extraction and minimise fuel burn, with positive impacts towards H2020 and ACARE targets.