MCQOPTIONS
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MCQOPTIONS
This section includes 15 Mcqs, each offering curated multiple-choice questions to sharpen your Thermal Engineering knowledge and support exam preparation. Choose a topic below to get started.
| 1. |
Nozzle angle of a simple impulse turbine is 25 . Determine the blade speed ratio if the turbine works at maximum efficiency. The Turbine blades are to be assumed frictionless. |
| A. | 0.4532 |
| B. | 0.2136 |
| C. | 0.5465 |
| D. | 0.6987 |
| Answer» B. 0.2136 | |
| 2. |
Steam is issued from the nozzles at 600 m/s in a simple impulse turbine. The nozzle angle is 25 and the mean blade velocity is 350 m/s. The blade velocity coefficient is 0.88. Determine the blade speed ratio. |
| A. | 0.325 |
| B. | 0.583 |
| C. | 0.654 |
| D. | 0.785 |
| Answer» C. 0.654 | |
| 3. |
A simple impulse turbine has a mean blade speed of 250 m/s. The nozzle angle is 20 and the steam velocity from the nozzle is 600 m/s. The turbine uses 3000 kg/h of steam. The blade outlet angle is 25 . Determine the amount of energy converted to heat by blade friction if the blade friction factor is 0.86. |
| A. | 65.32 kJ |
| B. | 30.50 kJ |
| C. | 45.32 kJ |
| D. | 78.32 kJ |
| Answer» C. 45.32 kJ | |
| 4. |
If for a certain simple impulse turbine, the blade inlet and outlet angles are 35 and 30 respectively and the relative velocity of steam to moving blade at entrance and exit are 350 m/s and 320 m/s respectively, determine the axial thrust on the bearings. The turbine has a steam flow rate of 20 kg/s. |
| A. | 850 N |
| B. | 815 N |
| C. | 750 N |
| D. | 456 N |
| Answer» C. 750 N | |
| 5. |
If the blade and nozzle efficiencies are 75% and 85% respectively, determine the stage efficiency. |
| A. | 75.65% |
| B. | 45.32% |
| C. | 63.75% |
| D. | 55.32% |
| Answer» D. 55.32% | |
| 6. |
Steam is issued from the nozzle at a velocity of 1000 m/s. The mean blade velocity is 450 m/s and the nozzle angle is 25 . The inlet and outlet angles of blades are equal. The mass of the steam flowing through the turbine per hour is 1000 kg. Calculate the blade efficiency if the blade velocity coefficient is 0.85. |
| A. | 88% |
| B. | 95% |
| C. | 50% |
| D. | 76% |
| Answer» E. | |
| 7. |
Velocity of the steam leaving the nozzle is 1200 m/s. The nozzle angle is 20 and the mean blade velocity is 500 m/s. The inlet and outlet angles of blades are equal. The mass of the steam flowing through the turbine per second is 0.4 kg. Considering the blades to be frictionless determine the Power Developed. |
| A. | 251.30 kW |
| B. | 150.21 kW |
| C. | 123.65 kW |
| D. | 321.56 kW |
| Answer» B. 150.21 kW | |
| 8. |
Steam issues from the nozzle with a velocity of 1000 m/s in a De Laval turbine. The nozzle angle is 20 , mean blade velocity is 350 m/s. The inlet and outlet angles of the blades are equal. The mass of the steam flowing through the turbine per second is 0.3 kg. Calculate the tangential force on the blades. Take blade velocity coefficient as 0.8. |
| A. | 451 N |
| B. | 256 N |
| C. | 318 N |
| D. | 196 N |
| Answer» D. 196 N | |
| 9. |
Which of the following statements regarding velocity compounded impulse turbine is FASLE? |
| A. | Maximum stage efficiency decreases with the with the increase in number of moving blades rows |
| B. | It has low efficiency and high steam consumption |
| C. | Optimum value of blade speed ratio for maximum efficiency increases with the with the increase in number of moving blades rows |
| D. | It requires comparatively small number of stages |
| Answer» D. It requires comparatively small number of stages | |
| 10. |
What is the optimum blade speed ratio for maximum blade efficiency in a multi-stage turbine? (n denotes the number of moving blade rows in series) |
| A. | ( frac{cos u2061 }{2*n} ) |
| B. | ( frac{cos u2061 }{2*n} ) |
| C. | ( frac{2*cos u2061 }{n} ) |
| D. | ( frac{2*cos }{n} ) |
| Answer» B. ( frac{cos u2061 }{2*n} ) | |
| 11. |
What is the maximum possible value of blade efficiency? |
| A. | sin u2061 <sup>2</sup> |
| B. | cos u2061 <sup>2</sup> |
| C. | sin u2061 <sup>2</sup> |
| D. | cos u2061 <sup>2</sup> |
| Answer» C. sin u2061 <sup>2</sup> | |
| 12. |
Blade speed ratio is the _____ |
| A. | ratio of blade speed to steam speed at entrance of the moving blade |
| B. | ratio of steam speed at entrance of the moving blade to blade speed |
| C. | ratio of blade speed to steam speed at exit of the moving blade |
| D. | ratio of steam speed at exit of the moving blade to blade speed |
| Answer» B. ratio of steam speed at entrance of the moving blade to blade speed | |
| 13. |
The ratio of relative velocity of steam to the moving blade at exit to the relative velocity of steam to the moving at entrance is called _____ |
| A. | reduction co-efficient |
| B. | blade velocity co-efficient |
| C. | friction loss |
| D. | factor of reduction |
| Answer» C. friction loss | |
| 14. |
Which of the following expressions represent the correct formula for calculating the blade efficiency? |
| A. | ( frac{(C_{w1}+C_{w2})*C_bl}{C_1^2} ) |
| B. | ( frac{2(C_{w1}+C_{w2})*C_bl)}{C_2^2} ) |
| C. | ( frac{2(C_{w1}+C_{w2})*C_bl)}{C_1^2} ) |
| D. | ( frac{2(C_{w1}+C_{w2})}{C_1} ) |
| Answer» D. ( frac{2(C_{w1}+C_{w2})}{C_1} ) | |
| 15. |
Which of the following statements regarding impulse turbine is correct? |
| A. | Only velocity of flow performs work on the blade |
| B. | Only velocity of Whirl performs work on the blade |
| C. | Axial component of velocity is called velocity of whirl |
| D. | Relative velocity of steam to moving blade at the inlet is always less than the relative velocity at outlet |
| Answer» C. Axial component of velocity is called velocity of whirl | |