1.Volute casing in a centrifugal blower is employed to:
2.The design efficiency of the pump increases with
a.increasing specific speed b.decreasing specific speed
c.not effected specific speed d.decresing specific speed and increasing density
3.Power required to drive a centrifugal compressor is proportional to:
a.speed b.cube of the speed c.square of the speed
d.does not change with speed
4.The cavitation in a hydraulic machine is namely due to
a.low velocity b.low pressure c.high velocity d.high pressure
5.Francis turbine part load conditions are obtained by:
a.adjusting guide vanes b.adjusting the impeller vanes
c.adjusting the impeller speed d.adjusting impeller and guide vanes
2.The design efficiency of the pump increases with
a.increasing specific speed b.decreasing specific speed
c.not effected specific speed d.decresing specific speed and increasing density
3.Power required to drive a centrifugal compressor is proportional to:
a.speed b.cube of the speed c.square of the speed
d.does not change with speed
4.The cavitation in a hydraulic machine is namely due to
a.low velocity b.low pressure c.high velocity d.high pressure
5.Francis turbine part load conditions are obtained by:
a.adjusting guide vanes b.adjusting the impeller vanes
c.adjusting the impeller speed d.adjusting impeller and guide vanes
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1.Volute casing in a centrifugal blower is employed to:
Change kinetic energy to pressure energy. As volute similar to diffuser, it decrease the velocity, while increasing static pressure. Also will give results in equal pressure, hence no radial thrust on the shaft.
2. c.not effected specific speed
Increasing specific speed in low flow rate will increase design efficiency, however in highg flow rate increasing specific speed will decrease efficiency. Also density not affected efficiency. As sepcific speed already indicates maximum value of efficiency for certain process.
3. b.cube of the speed
Power coefficient,
P' = P/ρN^3D^5 = constant,
P1/ρ1N1^3D1^5 = P2/ρ2N2^3D2^5, ρ2 = ρ1 and D1 = D2
P1/N1^3 = P2/N2^3
P2 = (N2^3/N1^3)P1
4. b.low pressure
Cavitation is indication that liquid already evaporated. Less pressure means liquid easier to evaporate at lower temperature.
5. a.adjusting guide vanes.
The cross sectional area between the adjustable vanes being varied for flow control at part load.
Refer to turbomachinary hand book for more explanation.
Change kinetic energy to pressure energy. As volute similar to diffuser, it decrease the velocity, while increasing static pressure. Also will give results in equal pressure, hence no radial thrust on the shaft.
2. c.not effected specific speed
Increasing specific speed in low flow rate will increase design efficiency, however in highg flow rate increasing specific speed will decrease efficiency. Also density not affected efficiency. As sepcific speed already indicates maximum value of efficiency for certain process.
3. b.cube of the speed
Power coefficient,
P' = P/ρN^3D^5 = constant,
P1/ρ1N1^3D1^5 = P2/ρ2N2^3D2^5, ρ2 = ρ1 and D1 = D2
P1/N1^3 = P2/N2^3
P2 = (N2^3/N1^3)P1
4. b.low pressure
Cavitation is indication that liquid already evaporated. Less pressure means liquid easier to evaporate at lower temperature.
5. a.adjusting guide vanes.
The cross sectional area between the adjustable vanes being varied for flow control at part load.
Refer to turbomachinary hand book for more explanation.
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