Bissoy.com
Doctors Medicines MCQs Q&A

A converging-diverging nozzle is operated at a pressure difference which is not the design value for isentropic flow. As a consequence a normal shock is formed in the diverging portion. In this situation the Mach number at the throat is

A converging-diverging nozzle is operated at a pressure difference which is not the design value for isentropic flow. As a consequence a normal shock is formed in the diverging portion. In this situation the Mach number at the throat is Correct Answer Exactly 1

Normal shock:

  •  When within the distance of a mean free path, the flow passes from a supersonic to a subsonic state, the velocity decreases suddenly and the pressure rises sharply. if there is an abrupt reduction of velocity in the downstream in course of a supersonic flow in a passage or around a body a shock is said to have occurred. 
  • Normal shocks are substantially perpendicular to the flow and oblique shocks are inclined at any angle.
  • Pressure ratio pb ⁄pr at the first critical point which represents flow that is subsonic in both the convergent and divergent sections but is choked with a Mach number of 1.0 in the throat (Chocked means flow maximum and fixed).

[ alt="F1 Satya Madhu 10.07.20 D1" src="//storage.googleapis.com/tb-img/production/20/07/F1_Satya_Madhu_10.07.20_D1.png" style="width: 253px; height: 136px;">

Normal Shock Condition

At throat Mach number is always unity, irrespective of back pressure. Therefore, option 3) is correct.

Related Questions

When a converging-diverging nozzle is operated at off-design conditions, a normal shock forms in the diverging portion. The nozzle can be assumed to be perfectly insulate from the surroundings. Then across the shock
At an Electronic Data processing unit, five out of the eight program sets P,Q,R,S,T,U,V and W are to be operated daily. On any one day, except for the first day of a month, only three of the program sets must be the ones that were operated on the previous day. The program operating must also satisfy the following conditions: 1. If program P is to be operated on a day, V can’t be operated on that day. 2. If Q is to be operated on a day, T must be one of the programs to be operated after Q. 3. If R is to be operated on a day, V must be one of the programs to be operated after R. 4. The last program to be operated on any day must be either S or U. If the program sets R and W are to be operated on the first day, which of the following could be the other program on that day?
Across the normal shockwave: 1) Stagnation pressure decreases whereas stagnation temperature remains constant 2) Mach number before the shockwave is always greater than one and after the shockwave, the Mach number need not be less than one 3) Across the shockwave there is a rise in pressure and temperature 4) The product of Mach number downstream of normal shockwave and upstream of normal shockwaves always one Which of the above statements are correct?
When the pressure drop across a converging-diverging nozzle is different from the design value for isentropic flow, which of the following is possible?
Statement (I) : Mass flow through the convergent nozzle is maximum when the exit Mach number is 1. Statement (II) : The divergent section is added to convergent nozzle to increase the exit Mach number and not to increase the mass flow rate
Statement (I) : When a bluff body moves at supersonic speed in still air, an attached shock wave is produced at its nose causing the flow to be subsonic behind the shock plane. Statement (II) : A normal shock always transforms supersonic flow into subsonic flow causing increase in pressure, temperature and entropy.
In a convergent divergent nozzle, the velocity at throat of nozzle is given by Where p­1 = initial entry pressure, v1 = initial entry specific volume and n = isentropic index of expansion.
In order that no shock wave develops when the flow is taking place through a converging-diverging tube, Mach number at exit should be:
The discharge of steam in a convergent-divergent nozzle __________ after the throat (i.e. in the divergent portion of the nozzle)
When the back pressure of a nozzle is below the designed value of pressure at exit of nozzle, the nozzle is said to be