Patent ID: 8262018

Claim:
A ram-air duct for supplying ambient air in an aircraft, comprising: a ram-air inlet duct including an inlet, a ram-air outlet duct including an outlet and arranged downstream of the ram-air inlet duct and in fluid communication with the ram-air inlet duct, a first movable element located at the inlet of the ram-air inlet duct and adapted to set an inlet parameter of the inlet, wherein a smaller inlet parameter corresponds to a smaller flow cross-section of the inlet and a larger inlet parameter corresponds to a larger flow cross-section of the inlet, and wherein the inlet parameter is adjustable within a control range from a minimal inlet parameter up to a maximal inlet parameter, a second movable element located at the outlet of the ram-air outlet duct and adapted to set an outlet parameter of the outlet, wherein a smaller outlet parameter corresponds to a smaller flow cross-section of the outlet and a larger outlet parameter corresponds to a larger flow cross-section of the outlet, and wherein the outlet parameter is adjustable within a control range from a minimal outlet parameter up to a second, maximal outlet parameter, and a control unit operatively coupled to actuators for moving the first and second movable elements, the control unit programmed to implement a control function linking together the outlet parameter and the inlet parameter, the control function designed such that an outlet parameter corresponding to a value of the control function is assigned to each inlet parameter, the control unit actuating the actuators to move the first and second movable elements according to the control function when the control unit implements the control function, wherein a substantially linear function is defined in such a way that connects together with a constant, linear gradient the end values of the inlet parameter and of the outlet parameter at the minimal ends of the respective control ranges and the end values of the inlet parameter and of the outlet parameter at the maximal ends of the respective control ranges, thereby providing an outlet parameter corresponding to a value of the linear function for each inlet parameter, and wherein the control function implemented by the control unit defines a gradient at the minimal inlet parameter that is less than the constant, linear gradient of the linear function and that is greater than or equal to zero.