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Improvements in the diesel fuel injection systems can provide efficient combustion in internal combustion engine. However, the detail relationship between the diesel injector nozzle cavitation parameters are still remain unclear. The main goal of this research is to verify the flow characteristics inside the fuel injector nozzle by using CFD. A computational fluid dynamics cavitation models of diesel injector nozzles is presented and tested. Then, the experimental data are used to validate the models. The researcher used the same shape configeration and boundary condition. The injection event is inherently transient, as the injection pressure varies with the needle lift position. In order to capture this transient aspect within a steady-state formulation, this study performed simulations for different lift positions for the base nozzle. The results is done for the flow distribution for needle lift positions at 0.275 mm, 0.2 mm, 0.15 mm, and 0.1 mm. The corresponding velocity vector is plotted in order to explain the transient cavitation behavior. The velocity vectors for needle lift=0.275 mm indicate that the flow entering the orifice encounters a sharp bend (i.e., large velocity and pressure gradients) at the top of the orifice inlet causing cavitation in this region, However, with needle lift position at 0.15 mm, the flow entrance into the orifice is relatively smooth.

Separation of the boundary layer over an airfoil causes a significant increase in the adverse pressure gradients and the losses of energy resulting in the reduction of the lift force and the increment of drag force. Therefore, delaying and eliminating flow separation is necessary to improve its aerodynamic characteristics. In this study, an injection of flow was introduced at the upper surface/suction side of the aerofoil to control the boundary layer separation effectively. Flow around the NACA0012 airfoil was examined, with the position of flow injection jet at 90° relative to the tangential surface of the airfoil at 20%, 50% and 80% of its chord length. The flow injection velocity was varied from 0%, 10%, 30% and 50% of the free stream velocity, which corresponds to 0, 2.5 x 10-4, 2.25 x 10-3 and 6.25 x 10-3 of the momentum coefficient. The results showed that the most suitable condition was at 10% of the blowing amplitude (2.5 x 10-4 of the momentum coefficient) of flow injection at the trailing edge, which was around 80% of the chord length at the upper surface/suction side. This configuration can successfully increase the lift force and decrease the drag force of the aerofoil at the angle equal to or larger than a stall angle of 16° compared to the baseline aerofoil.

This review paper focuses on the mixture motion into combustion chamber of internal combustion engine. The shape and orientation of the intake port is an important aspect as it defines how the air or fuel/air is delivered to the cylinder and therefore the motion of the fuel/air in the cylinder. Fluid motion into and within the cylinder is known as charge motion and is important due to the influencing turbulence in the cylinder which generally results in faster combustion, which increases combustion efficiency, reduces fuel consumption, reduces knock and pre-ignition in spark ignition engines. The velocity at which the charge enters the cylinder, directing fuel/air towards the spark plug or fuel injector for ignition, the transfer of heat which influences evaporation of the fuel, improving mixing of the fuel/air mixture, and can increase volumetric efficiency, although at the expense of turbulence A main combustion chamber that permits efficient combustion throughout the entire rotational speed range comprising a straight groove extending diametrically from an edge portion of the top surface of a piston and a pair of grooves branching right and left from the straight groove in such a curved manner as to return toward the edge of the surface.

Evaporative cooling mist spray is a cost effective solution for many cooling applications. Selection of misting spray nozzle play a major role in order to provide the suitable spraying condition in regards to the application. One of the most widely use mist spray application is evaporative cooling of outdoor open area. This study was carried out to characterized the spray formation, size of droplet, velocity of the droplet and the angle of the spray formation from a commercial mist spray nozzle namely 1/8 SF-CE SM nozzle with 1 mm and 2 mm diameter hole. Water was supplied with different pressure of 1, 2 and 4 bar. High speed video camera and still digital camera using short burst of flash were used to produce the video and image for analysis. The results show that increase in water pressure affect the spray angle, increase droplet speed and decrease droplet size of the mist spray.

Direct imaging technique is always used to obtain correlation of flame height or any other parameter of the visible portions of the flame. This is one of the important methods used in the combustion community to determine the characteristic of flame. Recently, the imaging technique has been developed and enhanced to provide more accurate data. However the utilization of the technology, such as the used of laserbased technique and acquiring sensor, increased the complexity of the process and also increased the amount of cost practically. This paper presents the results of an acoustic excitation towards a Liquid petroleum gaseous flame by using the direct visualizing technique. The direct visualizing technique is used to acquire the flame image and the images will be analyzed by using image analysis software. Results show the flame length at the flame core decreases when the amount of acoustic gradually increases. The effect of excitation towards the flame core is being investigated due to its significant influence toward the overall flame characteristic.

Fire Safety Engineering is an application of science to improve the safety from the destructive effect of the fire. Paper is one of sources creating fire, however, research on flame spread towards paper is still not enough to describe about the phenomenon. Inspiration from this, the behavior of downward flame spread over paper/bagasse is experimentally investigated. Composition of 0%, 30%, 50%, 70% and 100% bagasse is determined for this research. Flame spread behavior for each composition is analyzed from the observation. Results show for each composition, the flame spreads with “U” shape at the beginning of combustion until the whole specimen. The result also shows that the flame spread rate decreases as bagasse composition increases. The highest flame spread is 0.8133 mm/s for pure paper and the lowest one is 0.4814 mm/s for pure bagasse. It infers that the flame spread shape and rate is influenced by the bagasse composition and density, respectively.Â

Small engines, with capacity not exceeding 150 cc, can be divided into two types: two-stroke and four-stroke engines. The exhaust pipe has significant influences on the performance of the engine. Thus, it is necessary to study factors that affect the exhaust in order to improve the performance of the engine. For this early stage, it would be appropriate to conduct the research by using simulations since they only require minimal resources and can be conducted in a short period. The objective of this study is to conduct the simulation for determining the required velocity and pressure in the exhaust pipe. The comparison is done between parameter values from different configuration of exhaust pipes; the most appropriate configuration is then proposed. Three types of exhaust pipe is proposed using computer software and simulations are carried out using ANSYS Workbench 15.0. Results show that the velocity and pressure fluctuate according to the diameter and length of the exhaust pipe. Model 3 exhaust pipe configurations have been selected as the most suitable exhaust pipe for obtaining the maximum pressure and velocity.

Biodiesel is a domestically produced, renewable fuel that can be manufactured from vegetable oils, animal fats, or recycled restaurant grease for use in diesel engines. The objective of this research is investigation the effects of the variant injection pressure on ignition delay and emission for different biodiesel using rapid compression machine. Rapid Compression Machine (RCM) is used to simulate a single compression stroke of an internal combustion engine as a real engine. Four types of biodiesel which are waste cooking oil, crude palm oil, algae and jatropha were tested at injection pressure of 80 MPa, 90 MPa and 130 MPa under constant ambient temperature at 950 K. Increased in injection pressure resulted shorter ignition delay proven by WCO5 which decreased from 1.3 ms at 80 MPa to 0.7 ms at 130 MPa. Meanwhile, emission for CO2 increased due to better fuel atomization for fuel-air mixture formation lead to completed combustion.

Fuel-air mixing is important process in diesel combustion. It significantly affects the combustion and emission of diesel engine. Biomass fuel has high viscosity and high distillation temperature and may negatively affect the fuel-air mixing process. Thus, study on the spray development and atomization of this type of fuel is important. This study investigates the atomization characteristics and droplet dynamic behaviors of diesel engine spray fuelled by rapeseed oil (RO) and comparison to diesel fuel (GO). Optical observation of RO spray was carried out using shadowgraph photography technique. Single nano-spark photography technique was used to study the characteristics of the spray while dual nano-spark shadowgraph technique was used to study the spray droplet behavior. Using in-house image processing algorithm, the images were processed and the boundary condition of each spray was also studied. The results show that RO has very poor atomization due to the high viscosity nature of the fuel when compared to GO. This is in agreement with the results from spray droplet dynamic behavior studies that shows due to the high viscosity, the RO spray droplets are large in size and travel downward, with very little influence of entrainment effect due to its large kinematic energy.

Rapeseed oil (RO) spray has very slow atomization due to its high viscosity nature. Although high injection pressure, high ambient temperature and combination of nozzle can promote faster atomization of rapeseed oil spray, another factor that was not discussed is the effect air movement that could positively influence RO spray development. To study the effect of air movement, in particular to generate the swirl (air movement inside the chamber), a swirler was used. Images were captured using a nano-spark shadowgraph photography technique and also high speed video imaging. Macrostructures of diesel sprays such as spray tip penetration length, spray shape, spraycone angle were obtained. Microstructures, such as droplet distribution and size were also studied. Result shows that IDI nozzle rapeseed oil spray has a narrow spray cone angle. The average droplet size is around 20~25µm. The large size of rapeseed oil droplet require assistant to improve atomization and results shows rapid air movement in chamber successfully improve atomization