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Technical Paper

Study of Discharge under Swirl Flow and Combustion Conditions

2018-10-30
2018-32-0006
The combustion at a high EGR ratio is one of the effective means for improving the fuel efficiency of a gasoline engine. However, there is a problem that the combustion speed decreases. So it is necessary to intensify the in-cylinder flow to ensure the combustion speed. The spark discharge generated by the ignition coil is strongly influenced by the in-cylinder flow. It forms an arcuate discharge path along the flow, and possibly it blows off and re-discharges occurs under a strong gas flow. The behavior of spark discharge strongly affects the ignition, and consequently affects the stability of combustion. However, the phenomena in a combustion chamber is very complicated because of various environmental conditions, and the discharge and combustion phenomena under a strong gas flow are remains unclear. In this research, in order to study these phenomena, discharge and combustion experiments under flow using a constant volume container were performed.
Technical Paper

CFD analysis of a port fuel injection IC engine to study air-fuel mixture preparation and its impact on hydrocarbon emission and mixture homogeneity in combustion chamber

2018-10-30
2018-32-0005
At part load conditions, effective utilization of fuel is critical for drivability of an IC engine driven automobile, with minimum emissions and fuel consumption. It becomes cardinal to study the mixture preparation in engines to understand the Injection strategy that helps in achieving the prime objectives of lower emission and reliable operation. To add to the complexity of the problem being studied, the injection phenomenon is rapid, turbulent, multi-phase, two-way coupled (where the continuous phase affects the droplets and vice versa) and involves turbulence length scales and time scales, few orders of magnitude lower compared to the characteristic length in the turbulence integral scale. A methodology is developed in Star-CD and ES-ICE to simulate the mixture preparation in Port Fuel Injection (PFI) engines.
Technical Paper

Study on Realization of Dual Combustion Cycle by Lean Mixture and Direct Fuel Injection

2018-10-30
2018-32-0011
The purpose of this study is to realize dual-combustion cycle for gasoline engines. For the purpose, lean combustion and direct fuel injection were applied to small diesel engine. The lean gasoline-air mixture was provided and was ignited by small amount of pilot diesel fuel injection (the constant volume combustion). Then, diesel fuel was injected by main injection and was burned with the remained oxygen after the lean combustion (diffusion combustion). The equivalent ratio 0.3, 0.4 and 0.5 of mixture were used to avoid the spontaneous compression auto-ignition. The total equivalence ratio with supplied gasoline and diesel fuel was adjusted to 1.0. The base pilot injection timing was selected as the ignition of pre-mixture took place at T.D.C. and pilot injection timings were changed 2 degree before and behind of T.D.C. The main fuel injection timing were 50, 75 and 100 % of the duration between pilot injection timing and T.D.C.
Technical Paper

Lubricating oil droplets in cylinder on abnormal combustion in supercharged SI engine

2018-10-30
2018-32-0008
The super charged spark ignition engine has a problem of abnormal combustion at low speed and high load operating condition. This paper focuses on the sauce and mechanism of the abnormal combustion, namely, the behaviour of lubricating oil droplets in cylinder, ring crevice, piston crown and ring gap.The experimental approach and the numerical analysis have been carried out.
Technical Paper

Mixture Formation and Combustion Evaluation of a Motorcycle Engine Concept Equipped with One Fuel Injector for Each Intake Valve

2018-10-30
2018-32-0009
In light of a more stringent emission legislation and in anticipation of possible future measures to further reduce the real environmental impact of motorcycles, it is necessary to develop engine concepts which are efficient and low on emissions in a wide range of operating points. This poses an important challenge on the development of high performance motorcycles engines as their focus on full load behaviour conflicts sharply with the emission and efficiency demands of the remaining engine load map. The focus of this paper is to evaluate the potential of a port fuel injection (PFI) concept consisting of one individual fuel injector for each intake valve to solve this trade-off. Previous research shows a positive effect of such a setup on mixture formation due to better targeting and atomization, reducing HC emissions and cyclic variations.
Technical Paper

Effect of injection timing on mixture preparation in a small gasoline direct-injection engine

2018-10-30
2018-32-0014
Gasoline direct-injection (GDI) engine has evolved as a solution to meet current demands of automotive industry. Benefits of a GDI engine includes higher fuel economy, good response, and lower cold start emissions. But it suffers from problems like combustion instabilities, misfires, and fuel wall impingement. This study focusses on implementing the gasoline direct-injection technology in a small bore engine where problems mentioned above are more predominant. Effects of fuel injection on in-cylinder flow, turbulence, mixture distribution and wall impingement are analyzed. Results showed that air motion inside the engine cylinder is influenced by direct-injection of fuel, with considerable variation in turbulent kinetic energy at the time of injection. Due to charge cooling effect, the mixture density was increased by about 10.8 % and trapped mass by about 9.5 %.
Technical Paper

Artificial neural network based predictive emission and fuel economy simulation of motorcycles

2018-10-30
2018-32-0030
As the number of different engine and vehicle concepts for powered-two wheelers is very high and will even rise with hybridization, the simulation of emissions and fuel consumption is indispensable for further development towards more environmental friendly mobility. In this work, an adaptive artificial neural network based predictive model for emission and fuel consumption simulation of motorcycles is presented. The model is developed in Matlab and Simulink and is integrated to a longitudinal vehicle dynamic simulation whereby it is possible to simulate various and not yet measured test cycles. Subsequently it is possible to predict real drive emissions and on-road fuel consumption by a minimum of previous measurement effort. The modelling approach is adaptive in terms of usability for different engine and exhaust gas treatment systems as the model does not require specific knowledge about technical vehicle parameters, which can be unknown due to manufacturers’ concealment.
Technical Paper

Devolopment of a Riding Simulator for Motorcycles.

2018-10-30
2018-32-0031
We developed the motorcycles based on RIDEOLOGY (Ride + Ideology) concept. In the past, the “Ride” was studied by a sensory evaluation with actual driving. However, the recent progress in numerical analysis, there have been developed driving simulators. It allows more qualitative measurement in a sensory evaluation. Therefore, we also developed a riding simulator specialized for motorcycles. In order to develop such riding simulator, there are some technical issues for motorcycles. First, we need to reproduce roll motion of motocycles. Compared to four-wheeled vehicles, motorcycles have a larger operating roll angle and higher center of rotation. Second, we need to reproduce vehicle control by rider’s changing body position. A rider controls vehicle’s lean by shifting his center of gravity. Therefore, it is necessary to construct a measurement system of rider’s body position. Third, we need to improve senses of speed and immersion.
Technical Paper

Development of Coaxial Thin Film Temperature Sensor with Improved Measurement Accuracy Based on Principle of Thermoelectromotive Force

2018-10-30
2018-32-0032
In recent years, improvement of fuel consumption and thermal efficiency is strongly required in the internal combustion engine to promote environmental. It is important to clarify the mechanism and reduce of cooling loss, however it is very difficult to measure cooling loss (heat transfer coefficient) from the working gas to combustion chamber wall. Measuring experimentally heat flux from chamber surface to coolant is one of evaluation methods of the cooling losses in the combustion chamber and has been widely used for R&D process in IC engines. Although this method has capability to measure detail of cooling process instantaneously and accurately including local phenomena, but it is necessary to improve the S/N ratio and responsiveness and durability.
Technical Paper

Static Stress and Thermal Analysis of Connecting Rod using FE-Analysis

2018-10-30
2018-32-0034
In series of automobile engine components, a connecting rod is used to convert linear motion of the piston to reciprocating motion of the crankshaft. In this paper, the static and thermal stress analysis of connecting rod made up of 42CrMo4 is conducted, using finite element method. After measuring the dimension of connecting rod, the model is developed in Solidworks software and imported to Solidworks Simulation software. Static stress analysis is done by fixing the crank end and load is applied at the piston end of connecting rod. Maximum stress point and section prone to failure is found out by this analysis. Also, the thermal analysis of the connecting rod is performed.The purpose of this study is to show the performance of connecting rod under different loading condition with considerable reduction in weight.
Technical Paper

A Study of Cycle-to-Cycle Flow Variations in a Small Spark-Ignition Engine at Low Throttle Opening

2018-10-30
2018-32-0035
Cycle-to-cycle flow variations significantly influence the combustion variations from one cycle to the next, particularly at low operating loads in small spark-ignition engines. Hence in the present work, cycle-to-cycle flow variations are analyzed at low throttle opening in a small spark-ignition engine using particle image velocimetry (PIV) technique. Experiments are conducted in an optically accessible single-cylinder port-fuel-injection engine (volume: 110 cm3) at 1200 rpm with throttle opening of 25%. Images are captured at different crank angle positions during both intake and compression strokes over a tumble measurement plane bisecting the intake and exhaust valves, and processed using cross-correlation method to obtain the instantaneous velocity fields considering 200 image pairs at each crank angle position considered.
Technical Paper

Analysis of Cooling and Warm-up Performance of Oil-cooled Engine with Fin-shaped Oil Jacket

2018-10-30
2018-32-0036
The oil-cooled engine has been developed in order to achieve a better warm-up performance. The oil-cooled engine has the oil jacket which pass around the exhaust port and the cylinder bore. The fins are installed inside the oil jacket to enhance the cooling performance. The result of a bench test shows that the fins enhance the cooling performance with slight loss of the warm-up performance. The aim of this study is to clarify effects of the fins. This study conducts two simulations to clarify effects of the fins. One is a cooling simulation, which is conducted to clarify the reason why the fins enhance the cooling performance. The other is a warm-up simulation, which is conducted to clarify the reason why the fins maintain the warm-up performance. The cooling simulation is conducted with a steady flow simulation. It simulates a full-load operation of the bench test, and it compares the converged temperature between the engines with/without the fins.
Technical Paper

Application of the newly developed KLSA model into optimizing the compression ratio of a turbocharged SI engine with cooled EGR

2018-10-30
2018-32-0037
Owing to the stochastic nature of engine knock, determination of the knock limited spark angle (KLSA) is very difficult in engine cycle simulation. Therefore, the state-of-the-art knock modeling is mostly limited to either merely prediction of knock onset (i.e. auto-ignition of end gas) or combining a simple unburned mass fraction model representative of knock intensity. In this study, a newly developed KLSA modeling method, which takes both predictions of knock onset and intensity into account, is firstly introduced. Multiple variables such as the excess air ratio (lambda), exhaust gas recirculation (EGR) ratio, cylinder pressure and the end gas temperature are included in the knock onset model. Based on the auto-ignition theory of hot spots in the end gas, both the energy density and heat release rate in hot spots are taken into consideration in the knock intensity (KI) model.
Technical Paper

Study of leak in small engines

2018-10-30
2018-32-0038
Complete engine leak testing is generally followed to conform quality of manufacturing and assembly of different parts which otherwise create failures related to overall performance, fluid leak, gas leak and emissions etc. Light weighting of engines and downsizing is a generally accepted and followed theme towards the future emission norms which influences the part design complexity. Objective of the study is to investigate the significant parameters related to leak in cylinder head system and countermeasures to reduce the same when designing the small compact engines. In this study a systematic approach has been followed for arriving the leak rate specifications to qualify the products. In the design and manufacturing of small engines, features like compact combustion chamber with constraints of clamping bolts layout, gasket design, compact crank case layout and lower wall thickness of major casting parts are used to achieve weight and cost targets.
Technical Paper

On the effect of the injector position on fuel-air mixture preparation in a two-stroke GDI engine

2018-10-30
2018-32-0040
Modern injection systems are characterized by low cost, light weight and diversified components based on a mature technology. In addition, the constant growth of computational resources allows an in-depth understanding and control of the injection process. In this scenario, increasing interest is presently being paid to understand if an application of such technologies to small two stroke engines could lead to a return to popularity in place of the more widespread use of the four stroke engine. Indeed, the possibility of achieving a drastic reduction of both specific fuel consumption and pollutant emissions would completely reverse the future prospect of the two stroke engine. The authors in previous studies developed a low pressure direct injection (LPDI) system for a 300 cm3 two stroke engine that was ensuring a performance consistent with a standard four stroke engine of similar size.
Technical Paper

Technologies to achieve future emission legislations with two stroke motorcycles

2018-10-30
2018-32-0042
Increasingly stringent emission regulations force manufacturers of two wheelers to develop low emission motorcycle concepts. Especially for small two-stroke engines with symmetrical port timing structure, causing high HC-emissions due to scavenge losses, this is a challenging demand that can only be met with alternative mixture formation strategies and by intensifying the use of modern development tools. Changing from EU4 to EU5, emission legislation will not only have an impact on the improvement of internal combustion but will also drastically change the after-treatment system. Nowadays, small two-stroke engines make use of a simple carburetor for external mixture preparation. The cylinders are scavenged by air/fuel mixtures. Equipped with exhaust gas after-treatment systems, such as secondary air with two or three catalytic converters, the emission limits for EURO 4 homologation can be achieved with carbureted engines.
Technical Paper

Overview of different gas exchange concepts for two stroke engines

2018-10-30
2018-32-0041
The concept of a loop scavenged two-stroke engine, controlling the intake and exhaust port by the moving piston, is a proven way to realize a simple and cheap combustion engine. But without any additional control elements for the gas exchange this concept reaches quickly its limits for current emission regulations. In order to fulfil more stringent emission and fuel consumption limits with a two-stroke engine, one of the most important measures is to avoid scavenging losses of fuel and oil. Additionally, for a 3-way exhaust gas aftertreatment it is necessary to follow a lambda = 1 concept. Therefore using internal mixture preparation systems in combination with different concepts to control the gas exchange process, the two-stroke engine could become a choice for automotive applications, especially as a Range Extender in a Plugin Hybrid Electric Vehicle (PHEV).
Technical Paper

Influence of ethanol and 2-butanol blended fuels on combustion and emissions in a small displacement two stroke engine

2018-10-30
2018-32-0044
Small displacement two-stroke engines are cheap and low-maintenance propulsion systems and commonly used in scooters, recreation vehicles and handheld power-tools. The restriction of emission legislation and the increasing environmental awareness of end users as well as decreasing energy resources cause a rethinking in the development of propulsion systems and fuels in these fields. Despite recent improvements of electric powertrains, two stroke engines are the unchallenged propulsion system in high performance handheld power tools at the moment. The reasons are the extraordinary high power to weight ratio of two-stroke engines, the high energy density of liquid fuels and the reliability of the product with respect to extreme ambient conditions. Nevertheless, further improvements on emissions and fuel consumption of small displacement two-stroke engines have to be realized.
Technical Paper

Performance improvements to a production, Semi Direct fuel injected, 2-stroke engine for a racing application

2018-10-30
2018-32-0043
The following material presents an overview of using a production 2-stroke engine and transforming it into one for the racing application of Snocross. This paper will explore the changing of engine hardware, engine related hardware and software while staying within the project scope for schedule, tooling capabilities and rules of the governing body for Snocross racing. This conversion process is discussed in detail through analytical calculations, to the experimental validation with dynamometer, airflow bench and infield test data.
Technical Paper

Assessing Tire Performance from Vehicle Dynamic Transfer Functions

2018-10-30
2018-32-0048
The aim of this study is to develop techniques which can be used to assess tire performance for a motorcycle. This approach focusses on using vehicle level performance parameters and transfer functions to assess tire performance. Several vehicle level dynamic parameters and transfer functions like cornering speeds, lateral acceleration, roll angles and roll rates, roll transfer function, lateral acceleration factor respectively are used to understand the effect of tires on motorcycle dynamic behavior. Tire behavior is then studied by assessing maneuverability of the motorcycle in maneuvers like slalom and lane change. A subjective assessment is then performed to understand rider’s feedback and relate the same with objective findings. Interesting results on the relationship between subjective perception of the riders, tire force characteristics and objective measurements are presented.
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