Patent ID: 7430865

Claim:
An auxiliary power unit configured to be coupled to a torque bearing element of a primary power unit, comprising: a fly wheel comprising a drive shaft and a plurality of blades; an injection nozzle for injecting a condensable fluid towards the plurality of blades; a clutch system configured to selectively couple the drive shaft to the torque bearing element; and a control system configured to control the clutch system to selectively couple the drive shaft to the torque bearing element, wherein the control system is configured to adjust a characteristic parameter of the condensable fluid to adjust a rotational speed of the drive shaft, wherein the control system comprises a first sensor for detecting a speed of the torque bearing element and a second sensor for detecting the speed of the drive shaft, wherein the control system is configured to adjust the characteristic parameter of the condensable fluid based on the detected speeds of the torque bearing element and the drive shaft.