Jet oscillation applied for aircraft cabin ventilation using active flow control actuators

摘要

Maintaining a healthy cabin environment during flight relies on continual extraction of fresh air from the engine. To meet passengers' expectation for more comfortable cabin which requires improved air supply and address the ever critical energy and emissions concerns, novel air delivery methods inside the cabin are desired and, therefore, of practical significance.This study explores the effectiveness of jet oscillation using active flow control to improve air delivery inside a cabin. The pulsed jet and synthetic jet are selected among the various control techniques to provide the control excitations on the air supply condition based on a detailed review of current practices of cabin ventilation.CFD simulation is employed as the major method of studying cabin airflow while hotwire measurement and flow visualization are made to validate the modelling of the synthetic jet.The fresh air jet entering the cabin is seen to oscillate about its injection angle when the supply flow rate experiences a series of sudden changes. Such oscillatory motion enhances air exchange and improves the ventilation performance. Lower temperature and CO2 level are achieved under the pulsed supply conditions compared with the conventional steady supply conditions.Longer period of oscillation is maintained with proper modulation of the pulsed supply signal. The improvement of ventilation performance indicators reach up to 10% when the supply signal turns periodic.A compact speaker driven actuator is designed to form the synthetic jet for redirecting the cabin ventilation jet, which provides a more direct way of inducing air oscillation inside the cabin. Due to the constraint of the cabin ceiling, a single synthetic jet acting as a pulling effect is not able to fully deflect the attached ventilation jet.A secondary synthetic jet oriented perpendicular to the ventilation jet can be added to push the attached jet off the ceiling and causes the formation of a merged jet at a downstream distance with a deflected jet direction.This study represents a pioneering work on the exploration of applying active flow control in an indoor environment and has demonstrated the effectiveness of the control efforts on improving the air delivery efficiency.