blowdown

Deverbal from blow down.

blowdown (countable and uncountable, plural blowdowns)

1. (chemical engineering) The removal of liquid and solid hydrocarbons from a refinery vessel by the use of pressure.
2. (industrial engineering) Cooling fluid discharged from a plant at the end of its cycle.
3. (forestry) Uprooting, overtopping, or bole breakage of trees by the wind; windthrow and windsnap.
4. (aviation) The action of aerodynamic forces to tend to cause a deflected control surface to return to its neutral position, or prevent the surface from deflecting past a certain point.

   At higher airspeeds, the 737's maximum rudder deflection is limited by blowdown, helping to prevent flight-control inputs from overstressing the aircraft's vertical stabilizer.

   • 2002 March 13, National Transportation Safety Board, “Accident Sequence Study”, in Aircraft Accident Brief: EgyptAir Flight 990, Boeing 767-366ER, SU-GAP, 60 Miles South of Nantucket, Massachusetts, October 31, 1999‎, archived from the original on 11 May 2022, page 38:

     According to Boeing, these movements were consistent with the effects of blowdown on those surfaces as documented during flight tests. However, the outboard aileron split recorded by the FDR after about 0150:27, which is discussed later in this section, was not consistent with the flight test data.

5. (manufacturing, informal) An instance of blowing down with compressed air.

   Give these parts a blowdown with your air hose before you put them in the ultrasonic cleaning tank.

• blowdown limit