If jet exhaust velocity
is greater than the local speed of sound, very high levels of broadband shock-associated noise and screech tones can be generated.
An NTR uses nuclear fission as an energy source instead of chemical combustion, and uses just hydrogen as a propellant, allowing it to achieve a very high exhaust velocity
and high thrust, Discovery News reported.
N] derives from the fact that it remains relatively constant for a variety of full-scale atmospheric conditions and varying ratio of exhaust velocity
to wind speed.
As a result, the noise intensity (Fahy, 2001) produced and the work down by the exhaust fan can be rated with the square of the exhaust velocity
generated to remove the cooking fumes.
While in the take-off and approach configuration (ejector aft), the hush kit forces exhaust through a uniquely designed nozzle into an ejector shroud that ultimately reduces exhaust velocity
, hence noise values.
The difference in minimum self-reentrainment dilution ratios can be attributed to the difference in exhaust velocity
and exhaust louver design in the two installations.