Home » Mechanical Engineering » IC Engines and Nuclear Power Plants

Effect of supercharging on knocking tendency in a petrol (SI) engine with fixed fuel octane and fixed compression ratio. Fill the blank: Supercharging will ______ the knocking tendency under these constraints. Choose the correct effect.

Difficulty: Easy

Increase
Decrease
Not affect
Eliminate

Correct Answer: Increase

Explanation:

Concept/Approach
Supercharging raises the inlet density and pressure, leading to higher end-gas temperature and pressure during compression. For a fixed octane rating and fixed geometric compression ratio, this promotes auto-ignition.

Mechanism
Higher charge density → higher charge temperature after compression → reduced knock margin → increased knocking tendency.

Final Answer
Increase.

← Previous Question Next Question→

More Questions from IC Engines and Nuclear Power Plants

Hit-and-miss governing in I.C. engines: evaluate the truth of the statement. Statement: “In hit-and-miss governing, the fuel supply is cut off completely during one or more cycles.” Choose whether this is correct.
Definition of volumetric efficiency for reciprocating engines: choose the correct ratio. Identify the ratio defined as “volume of charge admitted at NTP divided by the swept volume of the piston.”
Typical pressure at the end of compression in diesel (CI) engines: choose the nearest value. Select the approximate end-of-compression pressure in a conventional automotive diesel engine.
Energy released per fission of a U-235 nucleus: select the approximate value in MeV. Choose the closest standard textbook value for fission of one atom of Uranium-235.
Spark timing in a four-stroke petrol (SI) engine: identify the usual ignition timing. Choose the standard practice for when the charge is ignited relative to top/bottom dead centre (TDC/BDC).
Predominant naturally occurring isotope of uranium: choose the correct nuclide. Select the isotope that is most abundant in natural uranium.
Four-stroke cycle temperature profile: identify when the minimum cylinder temperature occurs. Choose the stroke position at which the in-cylinder temperature is at its minimum during a cycle.
High-speed compression engines: identify the thermodynamic cycle of operation In internal-combustion engine theory, high-speed compression-ignition (diesel) engines are modeled to operate on which idealized cycle for analysis and design understanding? Choose the correct option.
Nuclear fission basics: average neutrons from U-235 fission On average, how many fast neutrons are produced per fission of U-235 in a thermal reactor context? Choose the correct option.
Moderator used in nuclear power plants: identify a common choice Which of the following is commonly used as a neutron moderator in power reactors? Choose the correct option.

Discussion & Comments

No comments yet. Be the first to comment!

Join Discussion