Expert: Paul Soderman - 9/28/2008

Question
QUESTION:  Hello. i would like to know if a C-D nozzle at least ome meter long could be used as an aspirator. And suppose the nozzle is bent (especialy at the throat) through an angle between 45 & 90 degrees could it be possible to use as an aspirator. Please in your answer try to be precise. thanks for understanding.

ANSWER: I will try hard to be precise.  But since you haven't given me any flow conditions or boundary conditions I can say that a CD nozzle is a form of venturi, and a venturi can be made into an aspirator, and the answer is yes.  Precisely.

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QUESTION:  Thanks for that answer.So how does one turn a venturi into an aspirator?

Answer
By connecting one end of a tube into a small hole in the venturi and the other end to a vacuum chamber or volume you wish to suction.  The venturi of course is the throat of your CD nozzle.

The tube does not protrude into the venturi, but is flush with the inner wall surface.