1. In which of the following modes of analysis does the temperature, velocity or pressure at any normal cross-section of an axisymmetric nozzle remain to be the same?
a) One dimensional
b) Two dimensional
c) Three dimensional
d) N-dimensional, where N can be 1,2,3,…
Explanation: The simplest nozzle analysis is one-dimensional. In this case, for an axisymmetric nozzle, the flow properties across any normal cross-section will remain to be the same, or the flow properties are said to be uniform.
2. What is the average diameter of a solid particle in a nozzle flow above which there is a chance of occurrence of thermal lag?
a) 0.1 μm
b) 10 μm
c) 100 μm
d) 1 μm
Explanation: If the average diameter of the solid particles or the liquid droplets in a nozzle flow exceeds 0.1μm, it may lead to thermal and velocity lag. The thermal lag depends upon the convection and radiation means of losing energy and the velocity lag depends upon the drag experienced by the particles.
3. Which of the following does the nozzle boundary layer depend on?
I) Axial pressure gradient
II) Nozzle geometry
III) Surface roughness
a) I, II and III
b) Only II and III
c) Only I and III
d) Only III
Explanation: Nozzle boundary layer depends on all three factors. In addition to these, it also depends on the heat losses to the walls.
4. Dissociation of the reaction products __________ with the rise in the chamber temperature and _________ with the rise in chamber pressure of a chemical rocket engine.
a) increases, increases
b) decreases, increases
c) decreases, decreases
d) increases, decreases
Explanation: Higher chamber temperature results in higher dissociation of the reaction products. But the dissociation can be suppressed by an increase in the chamber pressure.
5. Which of the following is a highly refined form of kerosene used as rocket fuel?
a) RP-1
b) HMX
c) RDX
d) C-4
Explanation: RP-1 is a highly refined form of kerosene. It is short for Rocket Propellant-1 or Refined Petroleum-1. A part of RP-1 includes toxic and carcinogenic hydrazine
6. Which of the following fuels were used in the first stage of Titan I?
a) RP-1
b) RDX
c) HMX
d) LH2
Explanation: RP-1 fuel is used in the first stage of Titan 1. Other than that, it was also used in the first stages of Saturn V, Energeia, Saturn I and IB etc. It is a cheaper and less explosive alternative to LH2
7. The fuel which releases the most energy per unit mass of combustion is ____________
a) LH2
b) RP-1
c) Kerosene
d) Methane
Explanation: Compared to hydrocarbon fuels, liquid hydrogen delivers most energy per unit mass of combustion. Any hydrocarbon fuel, when subjected to combustion produces more pollution than LH2.
8. 1-methyl-1, 2-dicyclopropyl cyclopropane is also called as ____________
a) Syntin
b) Kerosene
c) RP-1
d) Jet fuel
Explanation: Syntin is a high-energy formulation briefly used in the upper stages of rockets developed by the Soviet Union. Its molecular formula is C10H16 and it is a mixture of 4 stereoisomers
9. ____________ is not a metallic additive in rocket propellants.
a) Beryllium
b) Aluminum
c) Nitroglycerine
d) Boron
Explanation: Nitroglycerine is a dense, colorless, explosive liquid. Its chemical formula is C3H5N3O9. It is neither metallic nor an additive.
10.Knocking in spark-ignition internal combustion engines is not the same as ____________
a) detonation
b) pinging
c) pinking
d) pre-ignition
Explanation: Knocking and pre-ignition are two separate events. Knocking happens when the combustion of some of the air-fuel mixture doesn’t occur because of the propagation of flame front due to spark-plug ignition, but when one or more air-fuel mixture pockets explode outside the normal combustion front. Pre-ignition refers to the case in which combustion happens even before the spark-plug fires