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Knocking in spark ignition engine can be reduced by
- a)Increasing the compression ratio
- b)Increasing the inlet air temperature
- c)Increasing the coolant water temperature
- d)Retarding the spark advance
Correct answer is option 'D'. Can you explain this answer?
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Knocking in spark ignition engine can be reduced bya)Increasing the co...
Factors affecting knocking in SI engine:
i) Compression ratio:- Higher compression ratio will result in higher temperature of the charge, tendency to knock will increase.
ii) Inlet air temperature:- The effect of inlet air temp is same as compression ratio. High inlet temp of the air fuel mixture will increase knocking.
iii) Advancing the spark:- Advancing the spark will result in more compression during sparking. The increase in temperature during the sparking will be higher. Hence tendency to knock will increase and so by retarding the spark, the tendency to knock will decrease.
iv) Coolant water temperature:- By increasing coolant water temperature, less heat will be carried from the engine which will increase the engine temperature. So the knocking will increase.
Most Upvoted Answer
Knocking in spark ignition engine can be reduced bya)Increasing the co...
Knocking in a spark ignition engine refers to the undesirable phenomenon of uncontrolled combustion of the fuel-air mixture in the combustion chamber. It is characterized by a knocking or pinging sound and can lead to engine damage if not addressed. To reduce knocking, the spark advance can be retarded.
Increasing the compression ratio:
- Increasing the compression ratio in a spark ignition engine can increase knocking tendencies. This is because a higher compression ratio leads to higher cylinder pressures and temperatures, which can cause the fuel-air mixture to ignite prematurely and result in knocking.
Increasing the inlet air temperature:
- Increasing the inlet air temperature can actually increase knocking tendencies. This is because a higher inlet air temperature leads to a higher charge density and a higher likelihood of auto-ignition, which can result in knocking.
Increasing the coolant water temperature:
- Increasing the coolant water temperature does not have a significant effect on knocking. The coolant water temperature primarily affects the engine's operating temperature and cooling system performance, but it does not directly impact knocking tendencies.
Retarding the spark advance:
- Retarding the spark advance is the most effective way to reduce knocking in a spark ignition engine. The spark advance refers to the timing of the spark plug firing in relation to the piston position. By retarding the spark advance, the ignition of the fuel-air mixture is delayed, allowing more time for the combustion process to occur and reducing the likelihood of uncontrolled combustion and knocking.
Retarding the spark advance allows the fuel-air mixture to burn more uniformly and smoothly, reducing the peak cylinder pressures and temperatures that can lead to knocking. It also helps to ensure that the combustion process is properly timed and controlled, resulting in improved engine performance and efficiency.
Overall, retarding the spark advance is the preferred method for reducing knocking in a spark ignition engine as it directly addresses the combustion process and allows for better control of the fuel-air mixture ignition.
Increasing the compression ratio:
- Increasing the compression ratio in a spark ignition engine can increase knocking tendencies. This is because a higher compression ratio leads to higher cylinder pressures and temperatures, which can cause the fuel-air mixture to ignite prematurely and result in knocking.
Increasing the inlet air temperature:
- Increasing the inlet air temperature can actually increase knocking tendencies. This is because a higher inlet air temperature leads to a higher charge density and a higher likelihood of auto-ignition, which can result in knocking.
Increasing the coolant water temperature:
- Increasing the coolant water temperature does not have a significant effect on knocking. The coolant water temperature primarily affects the engine's operating temperature and cooling system performance, but it does not directly impact knocking tendencies.
Retarding the spark advance:
- Retarding the spark advance is the most effective way to reduce knocking in a spark ignition engine. The spark advance refers to the timing of the spark plug firing in relation to the piston position. By retarding the spark advance, the ignition of the fuel-air mixture is delayed, allowing more time for the combustion process to occur and reducing the likelihood of uncontrolled combustion and knocking.
Retarding the spark advance allows the fuel-air mixture to burn more uniformly and smoothly, reducing the peak cylinder pressures and temperatures that can lead to knocking. It also helps to ensure that the combustion process is properly timed and controlled, resulting in improved engine performance and efficiency.
Overall, retarding the spark advance is the preferred method for reducing knocking in a spark ignition engine as it directly addresses the combustion process and allows for better control of the fuel-air mixture ignition.
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Knocking in spark ignition engine can be reduced bya)Increasing the compression ratiob)Increasing the inlet air temperaturec)Increasing the coolant water temperatured)Retarding the spark advanceCorrect answer is option 'D'. Can you explain this answer?
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