Machine-translated by Google. Questions are authored in English.
Top

Discussion

Which statement best describes why sound cannot propagate upstream in a supersonic flow?

  • A.The flow carries disturbances downstream faster than they can travel
  • B.Sound waves are absorbed by the compressed gas
  • C.The temperature is too low for sound to propagate
  • D.Viscosity damps the waves before they travel far

Answer: A

A pressure disturbance moves relative to the gas at the speed of sound, but the gas itself is moving faster than that, so the net motion of every disturbance is downstream. This is why a supersonic flow cannot be influenced by anything happening behind it, and why choked nozzles behave as they do.

No comment is present. Be the first to comment.
Loading…

Post your comment

Please log in or register to post a comment.