Question
Download Solution PDFWhich of the following factors contribute towards detonation in a SI engine?
Answer (Detailed Solution Below)
Detailed Solution
Download Solution PDFConcept:
Knocking or detonation is due to the auto-ignition of the end portion of the unburned charge in the combustion chamber.
Cause of detonation:
Compression ratio:
Increasing the compression ratio increases both the temperature and pressure. An increase in temperature reduces the delay period of the end charge. Hence tendency to knock increases. Therefore, in order to reduce the possibility of detonation, it is essential to keep the compression ratio as low as possible.
Lean fuel mixture:
A lean mixture burns slower than a rich mixture. This longer burning time causes higher combustion chamber temperature, which promotes the tendency for unburned fuel in front of the spark ignition flame to detonate.
Engine Overheating:
Even the excessive intake air temperature or overheating of the engines can cause pre-ignition because the mixture in the cylinder will be at a higher temperature and so closer to the ignition point.
Last updated on May 28, 2025
-> SSC JE ME Notification 2025 will be released on June 30.
-> The SSC JE Mechanical engineering application form will be available from June 30 to July 21.
-> SSC JE 2025 CBT 1 exam for Mechanical Engineering will be conducted from October 2 to 31.
-> SSC JE exam to recruit Junior Engineers in different disciplines under various departments of the Central Government.
-> The selection process of the candidates for the SSC Junior Engineer post consists of Paper I, Paper II, Document Verification, and Medical Examination.
-> Candidates who will get selected will get a salary range between Rs. 35,400/- to Rs. 1,12,400/-.
-> Candidates must refer to the SSC JE Previous Year Papers and SSC JE Civil Mock Test, SSC JE Electrical Mock Test, and SSC JE Mechanical Mock Test to understand the type of questions coming in the examination.