Sign up now
to enroll in courses, follow best educators, interact with the community and track your progress.
Questions (15 - 21)
283 plays

In this lesson, questions (15 - 21) have been explained.

Harshit Aggarwal
Cleared UPSC ESE twice with Rank 63 and 90 in mechanical engg. Got 99 percentile in GATE. Cracked ONGC, BHEL,ISRO, SAIL, GAIL successfully

Unacademy user
  1. COURSE: Questions on Steam Turbine Lesson : Questions -(15-21

  2. About me Graduated from NIT Nagpur in 2008 A. Cleared Engineering Services Examination (ESE-UPSC) Exam Got the offer letter from most of the Maharatna and Navratna Companies Cleared GATE Exam Rate, Review, Recommend, Share <* Follow me on Unacademy at: aggarwal

  3. Question 15 A single-stage impulse turbine with a diameter of 120 cm runs at 3000 rpm. If the blade speed ratio is 0.42 then, the inlet velocity of steam will be (a) 79 m/s (b) 188m/s (c) 450 m/s (d) 900 m/s

  4. Solution 15 blade speed velocity of steam entry m/s inlet velocity steam = Blade speed ratio = at entry 1.2 50-450 m/s Tx1.2x50- 450 m/s V,60-60 Ans: c

  5. Question 16 Which one of the following is used to bring down the speed of an impulse steam turbine to practical limits? (a) A centrifugal governor (c) A large flywheel (b) Compounding of the turbine (d) A gear box Ans b

  6. Question 17 Why is compounding of steam turbines done? (a) To improve efficiency (c) To reduce exit losses (b) To reduce the speed of rotor (d) To increase the turbine output Ans : b

  7. Question 18 List I gives the various velocities in the velocity diagrams of a two-stage impulse turbine. List II gives the blade angles. Match the velocity from List I with the angle in List II and select the correct answer using the codes given below the lists: List I List II A. Relative velocity of steam at inlet 1. Nozzle angle B. Absolute velocity of steam at inlet 2. Moving blade leading edge C. Relative velocity of steam at outlet D. Absolute velocity of steam at angle tip of blade tip of blade tip of blade outlet tip of blade angle 3. Moving blade trailing edge 4. Fixed blade leading edge angle Codes: (a) 243() 21 43 (c 2 3 4(d) 1 234 Ans: c

  8. Question 19 Assertion (A): Impulse staging is commonly employed in high pressure part and reaction staging in intermediate low pressure parts of the steam turbine Reason (R): The tip leakage across moving blades is less in impulse staging as the pressure drop is small and there can be large pressure drop across fixed blades and nozzles (a) Both A and R are individually true and R is the correct explanation of A (b) Both A and R are individually true but R is not the correct explanation of A (c) A is true but R is false (d) A is false but R is true Ans a

  9. Question 20 Running speeds of steam turbine can be brought down to practical limits by which of the following method(s):? 1. By using heavy flywheel 3. By compounding (a) 3 alone 2. By using a quick response governor 4. By reducing fuel feed to the furnace. (c) 1, 2 and 4 (b) 1, 2, 3 and 4 (d) 2 and 8 Ans d

  10. Question 21 Which one of the following is the feature of pressure compounding (Rateau staging)? (a) Low efficiency at low rotational speeds (b) High efficiency with low fluid velocities (c) High efficiency with high fluid velocities (d) Low efficiency at high rotational speeds Ans b