MCQOPTIONS
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MCQOPTIONS
This section includes 14 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. |
In a single stage reaction turbine, the mean blade velocity is observed to be 200 m/s and the nozzle angle is 20°. The absolute value of the steam leaving the nozzle is 350 m/s. The factor with which the relative velocity of steam changes wit respect to the moving is 2.1. If the moving blade inlet and outlet aangles are equal then calculate the degree of reaction of the turbine. |
| A. | 50% |
| B. | 66% |
| C. | 75% |
| D. | 84% |
| Answer» C. 75% | |
| 2. |
In a Parson’s reaction turbine, the outlet angle of blade is 25°. Calculate the work done per second by the blades if the blade mean blade speed is 60 m/s and the absolute velocity of the steam leaving the nozzle is 120 m/s. The mass flow rate of steam is 0.1 kg per second. |
| A. | 756 W |
| B. | 854 W |
| C. | 945.12 W |
| D. | 1065 W |
| Answer» D. 1065 W | |
| 3. |
In a reaction turbine, the fixed blades and the moving blades are of the same shape but reversed in direction. The mean blade speed is 30 m/s. The absolute velocity of the steam leaving the nozzle is 90 m/s and the absolute velocity of steam leaving the moving blade is 64 m/s. Determine the nozzle angle. |
| A. | 20° |
| B. | 25° |
| C. | 30° |
| D. | 35° |
| Answer» C. 30° | |
| 4. |
In a single stage Parson’s reaction turbine, the mean blade velocity is observed to be 60 m/s and the nozzle angle to be 20°. Determine the the entrance angle of moving blade if the absolute velocity of the steam leaving the nozzle is 120 m/s. |
| A. | 38° |
| B. | 56° |
| C. | 23° |
| D. | 28° |
| Answer» B. 56° | |
| 5. |
The following data refers to a particular stage of a Parson’s reaction turbine: Mean blade speed = 90 m/s Velocity of steam leaving the nozzle = 120 m/s Nozzle angle = 20° Mass flow rate of steam = 0.8 kg per secondCalculate the tangential force on the blade. |
| A. | 203.54 N |
| B. | 108.42 N |
| C. | 65.32 N |
| D. | 195.45 N |
| Answer» C. 65.32 N | |
| 6. |
The axial force on the blades in Parson’s reaction turbine is always zero. |
| A. | True |
| B. | False |
| Answer» B. False | |
| 7. |
The maximum value of efficiency for a Parson’s reaction turbine is _____ |
| A. | \(\frac{2(cos)^2}{1+(cos α)^2} \) |
| B. | \(\frac{2(cos α)^2}{1+(cos α)^2} \) |
| C. | \(\frac{1+(cos α)^2}{2(cos α)^2} \) |
| D. | \(\frac{2(cos α)^2}{1+(cos α)^2} \) |
| Answer» E. | |
| 8. |
What should be the ratio of blade speed to absolute velocity of steam leaving the nozzle for a Parson’s reaction turbine to work at maximum efficiency? |
| A. | cosα |
| B. | cosβ |
| C. | sinα |
| D. | sinβ |
| Answer» B. cosβ | |
| 9. |
Which of the following statements does NOT hold true for a Parson’s reaction turbine? |
| A. | α = Ф |
| B. | θ = β |
| C. | C1 = Cr2 |
| D. | Cr1 = Cr2 |
| Answer» E. | |
| 10. |
The degree of reaction of a Parson’s reaction turbine is _____ |
| A. | 0% |
| B. | 25% |
| C. | 50% |
| D. | 100% |
| Answer» D. 100% | |
| 11. |
Which of the following is the correct formula for calculating the degree of reaction of a reaction turbine? |
| A. | Rd=\(\frac{2C_{bl}(C_{w1}+C_{w2})}{C_{r2}^2-C_{r1}^2} \) |
| B. | Rd=\(\frac{C_{r2}^2-C_{r1}^2}{2C_{bl} (C_{w1}+C_{w2})} \) |
| C. | Rd=\(\frac{C_{bl}(C_{w1}+C_{w2})}{2(C_{r2}^2-C_{r1}^2)} \) |
| D. | Rd=\(\frac{2(C_{r2}^2-C_{r1}^2)}{C_{bl}(C_{w1}+C_{w2})} \) |
| Answer» C. Rd=\(\frac{C_{bl}(C_{w1}+C_{w2})}{2(C_{r2}^2-C_{r1}^2)} \) | |
| 12. |
Which of the following expressions for degree of reaction (Rd) of a reaction turbine stage is correct? |
| A. | Rd=\(\frac{Heat \, drop \, in \, moving \, blades}{Heat \, drop \, in \, the \, stage}\) |
| B. | Rd=\(\frac{Heat \, drop \, in \, the \, stage}{Heat \, drop \, in \, moving \, blades}\) |
| C. | Rd=\(\frac{Heat \, drop \, in \, fixed \, blades}{Heat \, drop \, in \, the \, stage}\) |
| D. | of a reaction turbine stage is correct?a) Rd=\(\frac{Heat \, drop \, in \, moving \, blades}{Heat \, drop \, in \, the \, stage}\) b) Rd=\(\frac{Heat \, drop \, in \, the \, stage}{Heat \, drop \, in \, moving \, blades}\) c) Rd=\(\frac{Heat \, drop \, in \, fixed \, blades}{Heat \, drop \, in \, the \, stage}\) d) Rd=\(\frac{Heat \, drop \, in \, the \, stage}{Heat \, drop \, in \, fixed \, blades}\) |
| Answer» B. Rd=\(\frac{Heat \, drop \, in \, the \, stage}{Heat \, drop \, in \, moving \, blades}\) | |
| 13. |
In case of reaction turbines, the magnitude of velocity of steam relative to moving blade increases as the steam progresses. |
| A. | True |
| B. | False |
| Answer» B. False | |
| 14. |
The magnitude of velocity of steam relative to moving blade in case of an impulse turbine _____ |
| A. | always remains constant as steam glides over the blades |
| B. | depending on friction present on the blades, increases or remains constant as the steam glides over the blades |
| C. | depending on friction present on the blades, decreases or remains constant as the steam glides over the blades |
| D. | depending on friction present on the blades, increases or decreases as the steam glides over the blades |
| Answer» D. depending on friction present on the blades, increases or decreases as the steam glides over the blades | |