Solve Problem 1.114 by using the values of \(n\) and \(N\) as \(200 \mathrm{rpm}\) and 6 instead of \(100 \mathrm{rpm}\) and 4 , respectively.

Data From Problem 1.114:-

In a centrifugal fan (Fig. 1.118(a)), the air at any point is subjected to an impulse each time a blade passes the point, as shown in Fig. 1.118(b). The frequency of these impulses is determined by the speed of rotation of the impeller \(n\) and the number of blades, \(N\), in the impeller. For \(n=100 \mathrm{rpm}\) and \(N=4\), determine the first three harmonics of the pressure fluctuation shown in Fig. 1.118(b).

Transcribed Image Text:

Impeller n A Pmax = 690 Pressure (kPa) 0 ST 2TT 3T t(s) (a) Centrifugal fan (b) Ideal pressure fluctuation at a point FIGURE 1.118 Pressure fluctuations of air in centrifugal fan.