Experimental study of the valve-bend interaction in an aircraft ECS system

Abstract

Papers presented to the 11th International Conference on Heat Transfer, Fluid Mechanics and Thermodynamics, South Africa, 20-23 July 2015.Aircraft ventilation systems are crucial in maintaining a good air quality during flight. The aim is delivering both fresh and recirculated air to the cabin and cockpit of the plane. Typical components in a ventilation system are heat units, fans, filters and valves. The latter are usually electronically controlled butterfly valves which regulate the flow rate in the system. These devices have a significant impact and the flow field after the valve affects the working of every component downstream in the network. In this paper the flow fields before and after a butterfly valve are studied using hotwire and stereoscopic PIV measurements. Two configurations are tested: one configuration consisting of a single valve (single valve configuration) and one configuration consisting of a valve closely coupled after a 90° bend (valve + bend configuration). The velocity is measured in both a horizontal and vertical measurement plane to study the spatial structure of the flow. Both PIV and hotwire measurements show good agreement. In both configurations, the flow field is highly 3 dimensional. The bend has a large impact on the flow field after the valve. The central wake is significantly increased in length and the turbulence intensities increase from around 50% for the single valve configuration to more than 75% for the valve + bend configuration. This significant impact shows the importance of the interaction of different components in a ventilation network on the general characteristics such as pressure drop or noise propagation.