Experimental Research On Influencing Factors Of Performance Of Turbocharged Direct Injection Gasoline Engine

The increasing number of fossil fuel vehicles has exacerbated fossil energy shortages and environmental pollution.In this context,energy saving and emission reduction have become very important goals in the development of engine technology.Advanced technologies such as turbocharging,in-cylinder direct injection and variable intake and exhaust are used in gasoline engines.However,due to their complexity and coupling,the impact of these technologies on the performance of supercharged direct injection gasoline engines still needs in-depth study.This paper conducts experiments on two similar supercharged direct injection gasoline engines referred to as prototypes A and B,respectively,and comparatively analyzes the factors that cause the difference in power,economy,combustion,and emissions of the two prototypes;Based on prototype A,the effects of alcohol fuel addition,ignition timing and fuel injection pressure on the combustion and emissions of supercharged direct injection gasoline engine were further studied.The main conclusions of this article are as follows:The results of the comparative analysis of the performance of the two prototypes show that: compression ratio,intake and exhaust parameters,fuel type are important factors that affect the performance of the supercharged direct injection gasoline engine.Under the premise that the two engines have the same displacement,the larger compression ratio and more advanced dual variable valve timing(VVT)of the prototype B can increase the amount of fresh air,enhance the airflow movement in the cylinder,and shorten the stagnation period and burning duration,the heat release is advanced and more concentrated.High-grade gasoline can reduce the possibility of knocking and make the combustion more stable;In terms of economy,the fuel consumption of prototype B is lower and the area of low fuel consumption is larger;compared with the prototype A,the CO emission of the prototype B is reduced,but the THC and NOx emissions are increased.After adding 10% ethanol and 15% n-butanol respectively,the combustion process of Prototype A is improved,the lag period and the combustion duration are shortened,and the concentrated heat release is advanced;Although the fuel consumption rate has increased,the effective thermal efficiency has also increased.Since ethanol and butanol have higher latent heat of vaporization than gasoline,the addition of ethanol and butanol reduces the engine’s NOx emissions.By advancing the ignition moment,the maximum burst pressure and heat release rate in the cylinder increase,the combustion reaction rate accelerates,the lag period and combustion duration are shortened,and the combustion cycle variation is reduced.Fuel injection pressure has little effect on engine power;However,at low loads,fuel consumption increases with the increase in fuel injection pressure,and does not change significantly at medium and large loads.In summary,a suitably high compression ratio and advanced intake and exhaust technology can improve the power of the engine,improve the combustion characteristics,and improve the economy;Coupled with the earlier ignition advance angle,the appropriate amount of alcohol addition,and the proper injection pressure,the performance of the supercharged direct injection gasoline engine can be better optimized.