The effects of compression ratio and combustion initiation location on knock emergence by using multiple pressure sensing devices

Knock research is an essential study because knock limits spark-ignition (SI) engine power output, durability, noise, fuel consumption, and emission performance. The thermal efficiency of can be improved by increasing the compression ratio, but at same time it leads to possibility end gas autoignition inside chamber. objective this work was show effect three different ratios (CRs) 8.5, 9.5, 10.5 on mechanism knock. In order achieve four equispaced spark plugs were fitted around circumference a special metal liner initiate flame fronts from those firing with approaches (e.g. timing, number, location). addition, six pressure sensors installed various locations precisely record event monitoring oscillations, combustion characteristics, intensity. In-cylinder heat release rate (HRR) analyses applied distinguish knocking for CRs. results showed that greater number produced more stable even delayed timing (ST) than single plug, also increased HRR propensity higher CRs due increase in temperature cylinder. maximum amplitude oscillation (MAPO) method used determine intensity, observed lowest CR 8.5 gave MAPO values compared operating conditions. However, instigated 9.5 because, plug numbers, during event, which coupled unburned mixture. Additionally, Fast Fourier transform (FFT) wavelet methods implemented observe frequencies induced It found sparking provoked vibration modes ranges