Chapter 2: This chapter focuses on the analysis of the spray structure at the SOI and Quasi- Steady stages of injection, considering each fluid as an incompressible continuum with constant density and viscosity in the absence of a cavitation model. Qualitative and quantitative experimental data from backlit imaging was used to validate the numerical results. This enables the validated CFD models to be used for further analysis of the spraydynamics and to clarify the impact of simultaneous physics on the fragmentation processes of the emerging liquid jet. The ability of Eulerian/VOF/LES-based CFD to reproduce the experimentally captured jet structure and penetration velocity and spray angle is demonstrated, showing that the selection of the boundary conditions, turbulence models and the quality of the mesh model can have a significant effect on the results. The influence of first and second order temporal discretization schemes and convection schemes on the computed morphology of the spray is been discussed and compared to experimental data. These results show that with a sufficiently fine mesh, and simulation conditions matching the experiments; the second order time derivative scheme and the Normalised Variable advection scheme give favourable comparisons with experimental measurements. The CFD methodology and key findings from Chapter 2 are used to provide the basis and support for the more comprehensive, complex and time-consuming simulations of in- and near-nozzle flow phenomena, as described in the subsequent chapters.
In the present days, use of fuel is picked its way of increase and price is also going to increase undoubtedly. So the use of present sources of petroleum becomes a serious issue. To provide the dieselfuel for diesel engines approximately not more than 40 years. Limited energy sources leads to the warning of potential lack of energy in the future. Approximately 1/3 of the petroleum fuels are consumed in the IC engines and exhaust gases emitted from these engines are one of the main reasons for the environmental pollution. In the last years, many studies on the IC engines aiming to reduce exhaust emissions have been carried out by changing operating parameters such as valve timing, injection timing, and atomization rate. At the same time, depletion of fossil fuels and environmental considerations has led to investigations on the renewable fuels such as ethanol, hydrogen, and biodiesel. Biodiesel derived from biological sources, among them lipid materials such as fats and oils have received increasing attention. The increasing demand of petroleum in developing countries like China, Russia and India has increased oil prices. Besides, the combustion of petroleum based fuels causes environmental problems, which threaten wild and human life, impacts on the environment and human health. In addition, the combustion products causes global warming one of the most important today’s world problem. The global warming is caused of emissions like carbon monoxide (CO), carbon dioxide (CO2), sulphur dioxide (SO2) and nitrogen oxides (NOx). In power system of using petroleum fuels, these components are emitted through the combustion process. Concerning environmental damage the transport sector has a clear responsibility. Its part in global warming potential has increased from year by year and now bigger than those of the domestic and industrial sector, while it highly constitutes the total emissions of this pollution type.
compression speed and strong impulse acting on the stopping device. On one side contains the base surface of the chamber, this chamber is composed of pyrex glass to enable observation of the spray and flame development. When the piston motion induces air inside the chamber, a swirl connecting port was used to produce a swirl flow inside the chamber. The port inclination angle can control the swirl velocity where velocity at 2/3-location from chamber centre is defined as swirl velocity[15, 16]. However, to obtain a quiescence gas flow of the duration fuel, the injection must be straight port. For the fuel injection system, an electronically controlled single-shot common rail injection system is employed to inject the fuel (biodiesel) into a combustion chamber. The time and amount of injected fuel is controlled by a fuel injection controller as shown in Figure 1.
ABSTRACT: In this paper fuel property such as viscosity, specific gravity, calorific value, flash point of Neem oil Bio-diesel and its blends with diesel oil in the ratio of 20:80(B20), 40:60(B40), and 60:40(B60), 80:20(B80) respectively were studied. It was also found that the properties of blend of B20 were very close to diesel oil. In addition to this an attempt has also made to study the fuel properties of Neem oil methyl ester blends with domestic kerosene oil and diesel oil in the ratio of 20:75:5(B20K5), 40:50:10(B40K10), 60:25:15(B60K15), and 80:0:20(B80K20),(Methyl ester : Conventional diesel : Kerosene).
droplets, but the liquid jet breakup process depends on various conditions. Two different lengths can be identified breakup processes: the intact core length and the break up length. The break up length is defined as the distance from the nozzle exit to the point where droplets are formed on the liquid jet surface, whereas the intact core length refers to the distance from the nozzle exit to the point where the liquid jet breaks up into droplets at the jet centerline. The droplets are injected at certain locations near the injector within the computational domain. The size of these droplets and the spray angle can be estimated from aerodynamics theories of liquid jet beak up.  The droplet velocity can be estimated as a fraction of the injection velocity. The droplets may be injected at the end of the intact core length and on a circle having a radius equal to that of the injector. Droplets may be injected at the end of the intact core length and random axial and radial locations from the injector axis. The injected liquid does not break-up instantly
Experimental research on the dynamics o f the Rolamite-type mechanism with vibrating elements was done in three directions: research on the dynamic processes running in the RTM roller-band system; research on the processes offriction-control between the elements o f the RTM; and research on the dynamic processes running in the Rolamite vibromotors. The increase o f the supply-voltage amplitude, the decrease o f the force-load magnitude o f the flexible band, and the decrease o f the angle o f the wrapping o f the roller by the flexible band cause an increase in the amplitude o f the roller vibrations. An RTM with rotating vibrating rollers, compared with the vibrating rollers o f the other type, has a better bearing capacity and is much more sensitive. The highest synchronicity o f rotation o f the rotors is provided by a Rolamite vibromotor with two rotors and a piezoelectric converter o f vibrations that simultaneously rotates both rotors. This is compared with the Rolamite vibromotor with two rotors and a piezoelectric converter o f vibrations, which rotates only one rotor.
Atomization is important in combustion, since most of the combustion systems (such as internal combustion engines and industrial furnaces) work on liquid fuels that cannot be used before being atomized. And it is essential in increasing combustion efficiency in such systems because of the high liquid surface to mass ratio generated after atomization, which in turn leads to higher rates of evaporation and mixing, and then combustion . Atomization is defined as the conversion of liquid from its bulky form into a spray of droplets and other physical dispersions of small particles in a gaseous environment. This could take place due to the kinetic energy of the liquid being atomized, or by being in contact with high- velocity gaseous substance, or as a result of an external force. Despite how the sheet is produced, its instability is increased by the surrounding aerodynamic disturbances, causing it to spread out from the nozzle with a decrease in its thickness and perforations that take place and develop toward each other creating threads and ligaments. The collapse of these ligaments with each other leads to the formation of variable size droplets. The size of these droplets is determined by the liquid sheet initial thickness, velocity gradient between the liquid and the surrounding gas, and liquid physical properties (mainly viscosity and surface tension). However, disintegrating the liquids into small drops is not the only objective of the atomization process, but it is important to ensure a
Figure 4.13 presents the variation of each injector’s spray penetration in the turbo and non-turbocharged cases. In the naturally aspirated case, as discussed previously in Fig. 4.10, INJ-0 and INJ-180 face upwind flow towards the injection points and hence their penetrations are similar. On the other hand, the penetration of INJ-270 is greatly reduced from the other sprays due to the complexity of the flow and the existence of a vortex near the wall. In the case of turbocharging, the difference is not as large compared to the naturally aspirated case; however, the penetrations of INJ-90 and INJ-270 are reduced since both of them are exposed to a complicated flow. The effect of the vortices on vaporization is consistent with the discussion by Jagus et al. . Also note that the spray penetration at 300 MPa injection pressure is lower than 100 and 200 MPa in the experiment and the computation. Fast atomization induced by higher injection pressure results in droplet vaporization and hence reduces the penetration.
emissions trend at 20% blend of biodiesel is as H20 > P20, may be due to the low cetane number of biodiesel , which lead to ignition lag and causes to accumulate large amount of un burned mixture of air and bio-fuel. This accumulated charge after reaching the self ignition condition will burn at a time causes better combustion than diesel. As a result, the adiabatic flame temperature or maximum temperature inside cylinder is more in case of biodiesels than diesel. Hence, this catalyzes reactions for oxidation of nitrogen and hence NOX emissions are more for biodiesels. For other blends, trend is similar to that for 20% blend. As load increases, NOX emission increases. However, emissions are less when compared with 20% blend.