Damper and exhaust system that maintains constant air discharge velocity

An exhaust system that maintains a constant velocity discharge comprising

• an air exhaust duct having a charge opening and a discharge opening defining an air flow path for receiving exhaust air from a discharge system,
• opposing damper blades pivotally mounted within the air exhaust duct and within the flow path, each damper blade having an end that is supported in cantilevered fashion in the duct so that an opposing end is free to move within the duct,
• wherein each damper blade is parabolic in shape to minimize the turbulence over the blade and reduce vibration, and
• means for pivoting each blade within the duct to vary the discharge opening through the duct,
• a sensor for measuring air volume change along the air flow path within the duct, and
• a controller operatively connected to the sensor and each blade pivoting means for controlling pivotal movement of each parabolic damper blade in response to the measured change in the air volume along the air flow path so as to maintain a substantially constant velocity of air as it exits the discharge opening.