Engine bleed air systems include components that deliver and control compressed engine bleed air from the main engine to downstream systems, including: cabin air conditioning, aircraft and hydraulic reservoir pressurisation, engine start, and wing and engine cowl ice removal. The design and integration of aircraft pneumatic bleed air valves is becoming ever more challenging due to the aggressive environment in which the valves must operate close to the aircraft engine. High temperatures, high pressures and non-homogenous air flow all contribute to the performance of pneumatic engine valves and their actuators.
Design optimisation of pneumatic valves and their associated actuation mechanisms is critical to keeping unscheduled costly delays to a minimum. Although they can be optimised in-situ, the associated costs are substantial and therefore, the ability to predict valve performance during the design phase would reduce these costs considerably.
Simple models based on flow coefficients relating mass flow to pressure drop across a valve are typically used to predict the behaviour of pneumatic valves. However, when internal valve phenomena are present, such as non-linear frictional effort and fluid flow effects near to the valve-closure position, these simple models fail.
In order to facilitate valve design optimisation, a complete description of the fundamental physical phenomena encountered within the engine environment is necessary.
The MOTIVE project will:
- commission a state-of-the-art friction test bench to measure the frictional effort produced by aircraft pneumatic actuation pistons and butterfly valves
- commission a state-of-the-art aerodynamic torque test bench for pneumatic butterfly valves
- develop a complete, analytical multi-physics based model to predict valve performance and controllability, based on thermal, mechanical and aerodynamic considerations.
The MOTIVE project will, for the first time, create an industry disruptive, virtual prototyping framework for optimising valve and actuator piston design which can be easily integrated into multi-physics modelling software such as MODELICA. This will maximise the functionality and predictively of the multi-physics modelling solution and enable the immediate exploitation of that model for optimisation of subsequent valve designs, reducing the incidents of engine bleed air valve malfunction.