Turbomachinery Design and Theory 1st. Edition by Rama S.R. Gorla, Aijaz A. Khan | 9780824709808 | 0824709802

Mechanical Engineering Design

Turbomachinery Design and Theory

118 SOLVED PROBLEMS

Question: 4.DE.17

In a centrifugal compressor air enters at a stagnation temperature of 288 K and stagnation pressure of 1.01 bar. The impeller has 17 radial vanes and no inlet guide vanes. The following data apply: Mass flow rate: 2.5 kg/s Impeller tip speed: 475 m/s Mechanical efficiency: 96% Absolute air ...

Verified Answer:

1. Mechanical efficiency is

η_m = \frac{\te...

Question: 4.DE.16

The following design data apply to a double-sided centrifugal compressor: Impeller eye root diameter: 18 cm Impeller eye tip diameter: 31.75 cm Mass flow: 18:5 kg/s Impeller speed: 15500 rpm Inlet stagnation pressure: 1.0 bar Inlet stagnation temperature: 288 K Axial velocity at inlet (constant): ...

Verified Answer:

At eye root,

C_a

= 150 m/s ∴ [latex...

Question: 4.DE.15

The impeller of a centrifugal compressor rotates at 15,500 rpm, inlet stagnation temperature of air is 290 K, and stagnation pressure at inlet is 101 kPa. The isentropic efficiency of impeller is 0.88, diameter of the impellar is 0.56 m, axial depth of the vaneless space is 38 mm, and width of ...

Verified Answer:

1. Impeller tip speed

U_2 = \frac{\pi D_2N}...

Question: 4.DE.14

A centrifugal compressor compresses air at ambient temperature and pressure of 288 K and 1 bar respectively. The impeller tip speed is 364 m/s, the radial velocity at the exit from the impeller is 28 m/s, and the slip factor is 0.89. Calculate the Mach number of the flow at the impeller tip. If ...

Verified Answer:

The absolute Mach number of the air at the impelle...

Question: 1.1

A radial flow hydraulic turbine produces 32 kW under a head of 16mand running at 100 rpm. A geometrically similar model producing 42 kW and a head of 6mis to be tested under geometrically similar conditions. If model efficiency is assumed to be 92%, find the diameter ratio between the model and ...

Verified Answer:

Assuming constant fluid density, equating head, fl...

Question: 7.12

The following particulars relate to a small inward flow radial gas turbine. Rotor inlet tip diameter 92 mm Rotor outlet tip diameter 64 mm Rotor outlet hub diameter 26 mm Ratio C3/C0 0.447 Ratio U2/C0 (ideal) 0.707 Blade rotational speed 30,500 rpm Density at impeller exit 1.75 kg/m³ Determine (1) ...

Verified Answer:

(1) Dimensionless specific speed is

N_s = 0...

Question: 7.DE.11

A small inward radial flow gas turbine operates at its design point with a total-to-total efficiency of 0.90. The stagnation pressure and temperature of the gas at nozzle inlet are 310 kPa and 1145 K respectively. The flow leaving the turbine is diffused to a pressure of 100 kPa and the velocity ...

Verified Answer:

The overall efficiency of turbine from nozzle inle...

Question: 7.DE.10

The following particulars relate to a single-stage turbine of free vortex design: Inlet temperature, T01 1100 K Inlet pressure, p01 4 bar Mass flow 20 kg/s Axial velocity at nozzle exit 250 m/s Blade speed at mean diameter 300 m/s Nozzle angle at mean diameter 25° Ratio of tip to root radius 1.4 ...

Verified Answer:

For no loss up to throat

\frac{p^*} {p_{01}...

Question: 7.9

single-stage axial flow gas turbine has the following data Mean blade speed 340 m/s Nozzle exit angle 15° Axial velocity (constant) 105 m/s Turbine inlet temperature 900°C Turbine outlet temperature 670°C Degree of reaction 50% Calculate the enthalpy drop per stage and number of stages required. ...

Verified Answer:

At 50%,

α_2 = β_3

α_3 = β_2[...

Question: 7.DE.8

A single-stage axial flow gas turbine with equal stage inlet and outlet velocities has the following design data based on the mean diameter: Mass flow 20 kg/s Inlet temperature, T01 1150 K Inlet pressure 4 bar Axial flow velocity constant through the stage 255 m/s Blade speed, U 345 m/s Nozzle ...

Verified Answer:

(1) From the velocity triangles

C_{w2} = Ca...