FLUID FLOW CONTROL SYSTEM

摘要

Pressurised air bled from a turbine engine (14) is fed to an aircraft cabin (18) by way of a duct (12) the rate of flow along which is controlled by a butterfly valve (28) actuated by a pneumatic actuator (36). The actuator (36) operates in response to a control signal (54) derived at (42) from the inlet to the duct (12) and modified by a control signal (52) obtained by blending high and low air pressure signals (46, 48) derived from larger and smaller venturis (22, 26) and representing air flow. The degree of blending is set at (140) by an operator in dependence on the number of passengers in the cabin so that the amount of air supplied will not be more than is necessary even if there are few passengers.