APU进口门为什么无法完全关闭

willbebetter · 发表于 2015-1-23 16:00:14

求助，这段英文实在理解不了。。。求大神解释原理。。。为什么进口门关闭会产生压差造成APU转动？而开一点就会消除，什么原理？
f there is a pressure differential from the inlet of the
APU, and the outlet of the APU, then air will flow. If air
flows in sufficient quantities, the APU will rotate or
windmill’ during flight. Therefore, there is a need to
neutralize that pressure differential. When the door is
closed, the pressure on the back side of the APU is
higher than on the inlet side causing the differential to
be in the opposite direction. So, the APU inlet door is
left slightly open to neutralize the pressure differential
across the APU during flight to prevent ’windmilling’.