| Clean,economical and efficient has always been the goal pursued by the internal combustion engine industry.With the development of China’s economy,the output of automobiles has gradually increased,and the problem of urban traffic congestion has become more and more serious.Motorcycles can reduce the problem of traffic congestion to a large extent due to the less road resources occupied by driving and parking.At the same time,the vast rural areas of our country are widely distributed,the roads are inconvenient,and motorcycles are flexible and convenient,which is suitable for rural transportation.Due to the current energy crisis and environmental pollution issues,which have received widespread attention from all walks of the world,people have put forward higher requirements for the performance of motorcycle engines.This thesis takes the motorcycle engine of an enterprise as the research object.After the engine is expanded,the high-speed power is low compared with the same type of engine on the market,and the market competitiveness is weak.This article intends to use a combination of numerical simulation calculations and experiments,through the discussion of the engine intake and exhaust accessories,intake and exhaust system structure,valve phase and other factors,and at the same time analyze the engine air flow conditions to achieve improvement with purpose of the engine power and economy.Finally,a bench test was carried out on the improved airway and engine pair to verify the optimization plan.The main contents of this article are as follows:(1)First,the engine’s original GT model is established by measuring engine-related parameters,calculating engine performance,and benchmarking with bench data.The error is controlled within 5% to ensure that the model can be used for subsequent analysis.(2)The effects of engine air filters,intake and exhaust pipes,air distribution phases,compression ratios,and flow coefficients on engine performance are analyzed through simulation calculations.Summarizing the influence laws laid a foundation for further improvement of the engine.(3)The effects of engine air filters,intake and exhaust pipes,air distribution phases,compression ratios,and flow coefficients on engine performance are analyzed through simulation calculations.Summarizing the influence laws laid a foundation for further improvement of the engine.(4)Then the engine inlet is modeled in three dimensions,and the fluid field simulation software STARCCM+ is used to perform a flow field simulation analysis.Further structural optimization opinions are proposed for the analysis results to obtain the final inlet structure.(5)Finally,the airway steady flow test and engine bench test are carried out according to the improvement plan.The airway steady flow test results show that the improved airway overall flow coefficient is increased by 5%,and the tumble ratio is basically the same as the original machine.Bench test results show that the engine’s power performance and economy have been improved.The maximum power appears at 7500r/min,increased from 6kW to 6.59 kW,an increase of 9.8%;the maximum torque at 5500r/min increased from 9.1N·m to 9.3N·m,increased by 2.2%;the minimum fuel consumption rate was reduced from 256g/kW·h to 246g/kW·h at 4000r/min,a decrease of 4.3%,fulfilling the manufacturer’s expected requirements. |
