Investigating the effect of spark advance, compression ratio and charge pressure on performance of an ultraboosted gasoline engine

Nowadays, one of the most demanded items in the automotive industry is to get more powerful engines with high performance but with less fuel consumption and cost. As an output of this demand automotive manufacturers are concentrated on the software tools to be able to predict and simulate possible failure modes, reactions and different correlation of engine parameters with a high performance results. A big advantage of these software tools is to get a chance to run a simulation several times by changing the hundreds of engine parameters. It is not only costs save but also time save for manufacturers which allows getting more results with a short time rather than a real time dynamometer tests. Simulation programs are the biggest assistants for that purpose, which allow changing hundreds of engine parameters for different engine operating conditions. To protect human health and achieve air quality standards, emission standards are getting tighter day by day overall the world, which is limiting specific amount of air pollutants that are released from fixed or mobile specific sources. Thus, suppliers also consider towing the rules for the restrictions. NOx, HC and CO pollutants are most critical ones that are produced by the internal combustion engines. By using the simulation programs this is also achieved to estimate the rate of pollutants that will be released from the system with entered input to the models. In same way it is possible to modify engine model based on these emission outputs by adjusting affecting parameters many times. This is a big advantage of simulation programs rather than usage of real engine setups and waste of time. There are many parameters that may have impact on the internal combustion engine performance. Key factors could be listed as; compression ratio, spark advance, knocking limit, boost pressure and so on. The purpose of this study is to investigate the effect of these parameters on the engine performance by defining the optimum operating condition of a selected gasoline engine. As a start point, engine to be run for five different compression ratios by sweeping from 8:1 to 12:1 based on swept spark advance. Spark advance has been swept from 0 to 50 deg CA, but for some of the compression ratios it was not possible to continue until 50 deg CA due to knocking. During this simulation it was important to monitor knocking limits as it will not be possible to continue analysis after a while due to engine knock by increased temperature and pressure with the incremental compression ratios. These datas were checked for 3 different engine speeds; 2000 rpm, 4000 rpm and 6000 rpm. Based on the analysis results one of the conditions with maximum power and minimum fuel will be selected as optimum operating condition. Right after this selection, boost pressure will be the main factor to force to improve the engine operating conditions. Boost pressure impact to be investigated on the engine outputs by changing when compared to the baseline. In the meantime, as air is increased inside the cylinders, the more fuel will be required to provide appropriate air fuel ratio. So in the second trial there will be change on not only boost pressure where pressure is increased inside the manifold, but also injected fuel amount to be adjusted. Ultra-boost provides better combustion by having more compressed air inside the cylinders which means higher temperature and pressure during combustion process. Thus, challenging point for the ultra-charging is knocking probability again. It will be tracked to understand how charge pressure impacts the spark advance limits with engine knocking limits. The outcomes from this thesis may contribute to have a perspective for improvement of the engine performance by using simulation programs and possible impacts of come critical parameters to engine performance.