Search Results

The authors carried out a basic and systematic investigation on diesel combustion processes using three different experimental apparatuses. This paper summarized the experimental results obtained from the three devices. Among the data contained in this paper are; (1) The structure and shape of diesel spray, the air movement around diesel spray and the spatial and temporal distributions of the size of droplets in diesel spray injected into the high pressure and room temperature charge. (2) The shape of diesel spray injected into the high pressure and high tempertaure charge. (3) The characteraistics of flame, and illumination delay, and ignition delay in the high pressure and high temperature charge.

The deformation of injector components cannot be disregarded as the pressure of the system increases. Deformation directly affects the characteristics of needle movement and injection quantity. In this study, structural deformation of the nozzle, the needle and the control plunger under different pressures is calculated by a simulation model. The value of the deformation of injector components is calculated and the maximum deformation location is also determined. Furthermore, the calculated results indicates that the deformation of the control plunger increases the control chamber volume and the cross-section area between the needle and the needle seat. A MATLAB model is established to The influence of structural deformation on needle movement characteristics and injection quantity is investigate by a numerical model. The results show that the characteristic points of needle movement are delayed and injection quantity increases due to the deformation.

In order to clarify certain aspects of the combustion process in differentially cooled engines, a special engine was built in which the surface temperatures of the piston crown, cylinder liner and cylinder head bottom could be varied independently. A computer programme to calculate the swirl and turbulence intensity in the combustion chamber was developed. Investigations showed that in order to improve the mixing process, the liner temperature should be kept low while the piston temperature may be increased only if the cylinder head temperature is kept low, and vice versa. A low coefficient of regression in the plotted results indicated that the flow parameters Investigated were not the determining parameters but only one among many others which need further investigation. The present investigation however Indicates that the high piston temperature found desirable earlier should preferably be combined with low cylinder head and liner temperatures.

In this contribution, the mechanical torque transmission between the Electric Motor (EM) and the Internal Combustion Engine (ICE) of a P0 architecture hybrid power unit is analysed. In particular, the system is made up of a brand new, single-cylinder 480cc engine developed on the basis of the Ducati 959 Panigale V90 2-cylinders engine. The thermal engine is assisted by a custom electric motor (30 kW), powered by a Li-Ion battery pack. The Ducati 959 Panigale engine is chosen because of its high power-to-weight ratio, and for taking advantage of its V90 2-cylinders layout. In fact, the proposed hybridization process considers to remove the vertical engine head and to replace it by the electric motor directly engaged to the crankshaft using the original valvetrain transmission chain, thus achieving a very compact package. This solution could be suitable for many V-type engines and it aims to obtain a small hybrid power unit for possible motorcycle/small vehicle applications.

Biodiesel derived from non-edible vegetable oils/tree borne oils hold potential for meeting India's future energy needs by part substitution of Diesel Fuel. This paper investigates performance of 5% blend of commercially available biodiesel (B5) in diesel as fuel for heavy duty vehicles. The test fuel was evaluated on buses with different aspiration technologies viz. naturally aspirated and turbo charged, and the same was compared with neat commercial diesel under different operating conditions like driving cycle, road load simulation (RLS) and wide open throttle (WOT) on chassis dynamometer for power, fuel economy, smoke and soot particle number concentration. Fuel economy was observed to be comparable with B5 in naturally aspirated bus while better fuel economy was observed in case of Turbo charged bus with B5. However, there was a marginal drop in the WOT power (vehicle) with B5 fuel in naturally aspirated bus while the drop was higher with Turbo charged bus.

Downsizing of engines is becoming more popular as manufacturers toil for increased fuel economy. Due to the downsizing of engines, Brake Mean Effective Pressure (BMEP) tends to increase, which in turn increases the heat release from engine. This necessitates the need for optimizing cooling system in order to get higher engine output and lower emissions to comply with stringent emission norms. In earlier engines, thermo-siphon principle was used with water as the coolant. This has been replaced in modern engines with pressurized cooling system with coolants like ethylene glycol mix. Along with the conventional objective of increased material durability with the optimized engine cooling system, it has been found that there is an improvement in the engine output due to increased charging efficiency. This paper describes the effect of engine coolant temperature on performance, emission and efficiency of a three-cylinder naturally aspirated spark ignited engine.

Primarily, Acoustic performance of muffler are evaluated by insertion loss (IL) and backpressure/restriction. Where Insertion loss is mainly depends upon proper selection of muffler volume, which is proportional to Engine Swept volume, along with internal design configuration, which drives the acoustic principle. Same time, meeting the vehicle level pass by noise (PBN) value as per regulatory norms and system level backpressure as per engine specification sheet are the key evaluating criteria of any good exhaust system. Here, a new Reactive/Reflective type muffler of tiny size have been designed for heavy commercial vehicle application, which is unique in shape and innovative to meet desire performance. In this design, mainly sudden expansion, sudden contraction, flow through perforation and bell-mouth flow phenomenon are used.

The objective of the study is to investigate the effect of current pulsation frequency on the weld bead microstructure, segregation and hardness of Hastelloy C-2000 weldments. Bead on Plate (BoP) welds were made by using Pulsed Current Gas Tungsten Arc Welding method (PCGTAW) at eleven different frequencies. The weld bead width and depth of penetration was measured with the help of Dinolite macro analyzer. The microstructure of weldments are further examined through optical microscope and Scanning Electron Microscopy (SEM) to identify the type of grain, grain coarsening and extent of the Heat Affected Zone (HAZ). The grain structure turn into finer and equiaxed in all cases and there was an optimum frequency range over which the significant grain refinement was observed. Microsegregation of alloying elements were computed with the aid of Energy Dispersive X-ray Spectroscopy (EDS). Vickers Hardness Tester was used to measure the hardness of the weld samples at ambient conditions.

Previous research has shown that elevating fuel injection pressure results in better air-fuel mixture formation, allowing for a further increase in maximum exhaust gas recirculation (EGR) rate while consequently reducing NOx emissions. The aim of this paper is to find out whether there is an optimum injection pressure for lowest soot-NOx emissions at a given boost pressure in high-speed diesel engines. Experiments are carried out on a single-cylinder research engine with a prototype common-rail system, capable of more than 200 MPa injection pressure. The effect of injection pressure on soot-NOx formation is investigated for a variety of boost conditions, representing the conditions of single to multi-stage turbocharger systems. Analysis of the data is performed at the application relevant soot to NOx ratio of approximately 1:10. It is observed that above a critical injection pressure, soot-NOx emissions are not reduced any further.

Fossil fuels are the dominant source of energy today with the problem of their supply depletion becoming a global issue. Since stable energy supplies are necessary in order to sustain the activities of mankind, conservation of petroleum fuel and finding an appropriate substitute are critical. Additionally, solutions to global environmental pollution problems are simultaneously needed, such as the Kyoto protocol for global warming. The aim of this study is to investigate whether the combustion state of bunker oil can be improved by the mixing of DME (dimethyl ether), which is considered as a possible alternative fuel. The kinematic viscosity of DME blended fuel, as well as the engine performance characteristics of single cylinder direct injection diesel engine, was measured experimentally. In the kinematic viscosity measurement, a pressure cell type viscosity measurement system was established in order to apply the volatile DME blended fuel.

In Brazil there is a significant number of medium and high voltage power cables falling on vehicles causing catastrophic accidents leading to serious injuries and deceases. It is advised that the car works as a shield so passengers inside the vehicle should not open doors and windows, but to the knowledge of the authors no work has presented a quantified study showing details like electromagnetic field intensity and 3D plots to really illustrate this situation. This work uses numerical simulation to replicate a scenario of a high power cable in direct contact with a vehicle and numerous positions of human body models inside and outside of the vehicle. Electromagnetic field is calculated showing the shielding effectiveness of the vehicle chassis. Also, current density are calculated to show the path of the current including the human body models. Safety guidelines are presented based on electromagnetic field strength and several scenarios are simulated and quantified.

Variable nozzle turbine (VNT) adjusts the openings of its nozzles to insure the required flow at throat area, which broadens the operating range of the turbine, and improves the matching relationship between the turbocharger and the engine. But the changes of nozzle openings have significant influence on the flow field structure of downstream radial turbine. To evaluate this effect, the leakage flow through nozzle clearance in various nozzle openings were simulated by unsteady computational fluid dynamic (CFD). Meanwhile, the interaction between nozzle clearance leakage flow and nozzle wake were investigated to reveal its effects on aerodynamic losses and forced responses for downstream rotor. The results showed that the changes of nozzle openings not only affect the interaction between nozzle leakage flows and wake significantly, but also affect aerodynamic performance of the rotor and the blade forced response.

This paper studied the flame initiation and early development in a spark ignition engine by using the Schlieren technique and a high speed camera. Some effects of different engine operating conditions and different spark energy are discussed. It was discovered that at any engine operating condition there exists a minimum flame propagation velocity during the early stage, and that its value as well as the corresponding time and flame radius can be used as a criterion to determine whether the early flame propagation is easy or not. To study the effects of different spark energy a special spark ignition system was designed which was controlled by a microcomputer for producing different spark energy levels. Both experimental and theoretical results show that the augmentation of breakdown energy in spark duration makes the original flame size increase effectively, which results in speeding up the flame kernel formation and early development.

In-cylinder pressure measurements and indicating diagrams have proven to be a valuable research tool for the analysis of combustion in spark-ignition or compression-ignition engines. With the use of thermodynamic models, the rate of heat release and mass fraction burned curves are calculated, and from the latter the CA50 parameter (crank angle fifty), which is the angle in which 50% of the total fuel has been burned. The empirical process of obtaining the optimum start of combustion typically leads to a value of CA50 from 8° to 10° after top dead center. This paper attempts to numerically investigate which properties have an influence on this optimum CA50. A simple thermodynamic model was implemented which used the Wiebe function for the rate heat release. The CA50 was then evaluated for combustion duration in the base configuration and in a theoretical adiabatic engine.

This paper investigated highly precise control of the air fuel ratio (AFR) of a gasoline engine in a transient state acceleration or deceleration at several starting engine speeds and several intake valve opening (IVO) timings. First, a two-input and one-output linearized engine model was developed for the design of the AFR control system. In order to compensate for the AFR deterioration caused by the actuation of the throttle valve during acceleration or deceleration, a feed-forward (FF) controller was developed based on the model. In order to add adaptability to the FF controller, a compensation using an error value from the AFR target value was equipped. The feedback (FB) system was designed using a backstepping method that is well known as an adaptive controller for a non-linear system.

To mitigate the global warming and to develop sustainable transportation, investigations on combustion properties of carbon neutral fuels i.e., electro-fuels and bio-fuels such as propanol and butanol are essential. In the past, there were very limited researches concerning the fuel-lean combustion of those fuels, which is however a promising method for reducing the NOx emissions. Moreover, the literature chemical kinetic mechanisms have not been widely validated against the fuel-lean combustion data. Ignition delay time (IDT) is one key parameter and is widely used for validation of chemical kinetic mechanisms. The measurements of IDTs of diluted 1-propanol (nC3H7OH, CH3CH2CH2OH) and 1-butanol (nC4H9OH, CH3CH2CH2CH2OH) mixtures (with 90% bath gas (Ar+N2)) were therefore conducted in a rapid compression machine (RCM), at temperatures between 800 and 1000 K, pressures of 20 and 40 bar, under lean combustion conditions with equivalence ratios (ф) of 0.25, 0.5 and 0.9.

Percussive breaking is basically a process in which short duration blows with high force intensity are applied in rapid succession, resulting in rock, concrete or pavement fragmentation. The machine for such a task is the hydraulic breaker which turns the hydraulic energy supplied by a positive displacement pump into mechanical energy as percussions of a piston against a chisel. This work presents the results of experimental tests carried out on a hydraulic breaker to determine its blow impact energy. Then, using these data, theoretical considerations are formulated in order to understand the phenomenon of the tool loading especially at the instant of the impact of the piston against the chisel, leading to the energy release.

With the degradation of lithium-ion batteries, the battery safety performance changes, which further influences the safe working window. In this paper, the pouch ternary lithium-ion battery whose rated capacity is 4.2 Ah is used as the research object to investigate the impact of the high-temperature calendar and cyclic aging on tolerance performance. The overcharge-to-thermal-runaway test is performed on the fresh cell and aged cell (90% SOH). The inflection point of voltage for aged cells appears earlier than that of the fresh cell, while the voltage corresponding to the inflection point is the same for them, which means that the voltage at which lithium plating occurs is the same. However, the voltage plateau and the crest voltage before thermal runaway of aged cell are significantly higher than that of the fresh cell. Besides, ohmic heat, reversible heat, and side reaction heat make contribution to the thermal runaway triggering.

This paper deals with the performance, emission and combustion features of a single cylinder four stroke compression ignition engine with fuel injection timing at advancement and retardment. The current experiment was conducted on a single cylinder four stroke diesel engine fuelled with microalgae methyl ester blended with pure diesel in the proportions of 30% and 70% respectively and it was designated as B30 (30% Microalgae methyl ester + 70% Pure diesel). The present test was carried out at three different fuel injection timings such as 190 R CA (Retarded crank angle), 230 S CA (Standard crank angle) and 270 A CA (Advanced crank angle) BTDC.

As authors reported in SAE Trans. 800968, entitled “Investigation on the Characteristics of Diesel Fuel Spray”, the flame never proceeds into the initial-part of the spray during injection. The length of the initial part-lies within 10 to 15 mm regardless of the conditions of the injection systems and of the ambient conditions. The ignition delay does not decrease but becomes constant when the ambient temperature or the pressure exceed a discrete value. The authors would like to propose a new concept of “Spray Formation Delay” during which the field is generated where the physical and chemical delay can exist. The spray formation delay is one of the major factors which control the above mentioned limitation of ignition delay. The characteristics of the spray formation delay are investigated and clarified.