61. The isentropic heat drop in the nozzle of an impulse steam turbine with a nozzle efficiency 0.9, blade velocity ratio 0.5 and mean blade velocity 150 m/s in kJ/kg is
    

1. 1. 50
      

   
   
   

   2. 40
      

   
   
   

   3. 60
      

   
   
   

   4. 75

   
   
   

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1. View Hint View Answer Discuss in Forum

   Blade velocity ratio =	u	= 0.5
   	v1

   
   or u = 0.5 v₁
   where u = mean blade velocity, and
   v₁ = Absolute velocity of steam at inlet
   

   =	150	= 300 m /s
   	0.5

   
   

   K.E. at inlet =	1	× m × v12 =	m	(300)2 J
   	2		2

   
   Nozzle efficiency = 0.9
   

   ∴ Isentropic heat drop in nozzle =	(300)2	= 50 kJ/kg
   	2 × 0.9

   
   

   Correct Option: A

   Blade velocity ratio =	u	= 0.5
   	v1

   
   or u = 0.5 v₁
   where u = mean blade velocity, and
   v₁ = Absolute velocity of steam at inlet
   

   =	150	= 300 m /s
   	0.5

   
   

   K.E. at inlet =	1	× m × v12 =	m	(300)2 J
   	2		2

   
   Nozzle efficiency = 0.9
   

   ∴ Isentropic heat drop in nozzle =	(300)2	= 50 kJ/kg
   	2 × 0.9

   
   

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62. List-I	List-ll
    A. Steam nozzle	1. Mach number
    B. Compressible	2. Reaction turbine
    C. Surface tension	3. Biot number
    D. Heat conduction	4. Nusselt number
    	5. Super saturation
    	6. Weber number

1. 1. A-5, B-1, C-6, D-3

   
   
   

   2. A-1, B-1, C-6, D-4

   
   
   

   3. A-5, B-2, C-6, D-1

   
   
   

   4. A-6, B-1, C-2, D-3

   
   
   

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1. View Hint View Answer Discuss in Forum

   A-5, B-1, C-6, D-3

   Correct Option: A

   A-5, B-1, C-6, D-3

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63. In adiabatic flow with friction, the stagnation temperature along a streamline.... (increase/ remain constant)
    

1. 1. Remain constant

   
   
   

   2. increase

   
   
   

   3. decrease

   
   
   

   4. None of these

   
   
   

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1. View Hint View Answer Discuss in Forum

   Remain constant

   Correct Option: A

   Remain constant

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64. Subsonic and supersonic diffusers have the following geometry.
    

1. 1. Divergent and convergent respectively
      

   
   
   

   2. Both divergent
      

   
   
   

   3. Both convergent
      

   
   
   

   4. Convergent and divergent respectively

   
   
   

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1. View Hint View Answer Discuss in Forum

   Convergent and divergent respectively

   Correct Option: D

   Convergent and divergent respectively

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65. When initially dry and saturated steam flows through a nozzle, the ratio of actual discharge to calculated discharge is
    

1. 1. Equal to 1.0
      

   
   
   

   2. Greater than 1.0
      

   
   
   

   3. Less than 1.0
      

   
   
   

   4. Independent of inlet conditions

   
   
   

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1. View Hint View Answer Discuss in Forum

   Greater than 1.0
   

   Correct Option: B

   Greater than 1.0
   

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