Flow separation refers to a sort of detachment of the air flow from the aircraft and it creates vortices and eddies that can increase drag. The EU-funded VIPER (Valve high performances for flow control separation in aircraft) project aimed to minimise and delay flow separation through active electrical systems. This will maintain more favourable aerodynamic conditions over wing surfaces and support more electric aircraft with fewer hydraulic and pneumatic systems. Project partners designed, manufactured and successfully tested an innovative pulsed jet valve based on amplified piezoelectric actuators (APA). The main benefits of employing APA technology for such a valve are the controllability and fast response time of piezo-based valves. It is able to provide a pulsed sonic jet up to 500 Hz, with a mass flow around 34 g/s through a slot 1 mm wide and 80 mm long. They also designed an efficient switching power amplifier. Together, the amplifier the new actuator, offer the sonic jet an electrical consumption around 40 W as a result of energy recovery. The VIPER team achieved optimal results in jet performance for the valve's ejection speed and mass flow that are beyond the state of the art: air exit velocity (340 m/s); air linear mass flow (425 g/s/m); and actuation frequency range(0-500 Hz). Although many pulsed jets actuators have been designed and tested to date, the mass flow rate reached is the highest obtained in an actuator of this volume. VIPER's active flow control device will significantly decrease noise and emissions associated with air travel, providing important relief from the pressures faced by the public and the planet.
Aircraft, VIPER, valve, flow control separation, amplified piezoelectric actuators