1st, 2nd.....6th order of Noise 2

[par1]

1. What is the 1st, 2nd , 3rd ,4th, 5th & 6th order of Noise Calculation?
2. what is the physical meaning of it & also what is the significance of each one?
3. how one can measure it?

 

[GregLocock]

1) it is the ratio of the frequency of a particular harmonic to the rotating frequency of the system. So 2nd order of an engine running at 6000 rpm is 200 Hz

2) Varies, read an engine noise book.

3) with a microphone or accelerometer and an FFT analyser

Cheers

Greg Locock

 

[vanstoja]

To refine Greg Locock's input a bit, sequential rotational orders are the harmonic frequencies of the rotational speed of a machine's rotor. Integer rotational orders are 1X,2X,3X..etc where X is fundamental rotational speed. Knowing rotational speed enables calculation of any other integer order of rotational speed. Amplitudes of rotational orders higher than the first harmonic (fundamental) are not readily calculable and need to be cursurored in a noise analyzer display to get a readout of actual amplitudes which could possibly be amplified by coincidence with some resonant response at or near the same frequency.