Investigation of in-nozzle flow characteristics of fuel injectors of IC engines (original) (raw)
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International Journal of Engine Research
The internal details of fuel injectors have a profound impact on the emissions from gasoline direct injection engines. However, the impact of injector design features is not currently understood, due to the difficulty in observing and modeling internal injector flows. Gasoline direct injection flows involve moving geometry, flash boiling, and high levels of turbulent two-phase mixing. In order to better simulate these injectors, five different modeling approaches have been employed to study the engine combustion network Spray G injector. These simulation results have been compared to experimental measurements obtained, among other techniques, with X-ray diagnostics, allowing the predictions to be evaluated and critiqued. The ability of the models to predict mass flow rate through the injector is confirmed, but other features of the predictions vary in their accuracy. The prediction of plume width and fuel mass distribution varies widely, with volume-of-fluid tending to overly concen...
Combustion Analysis of CI Engine under the Influence of two different Injecting Nozzles
The combustion process taking place inside the engine cannot be directly visualized for the analysis purpose but the same can be possible by performing the experiment and listing the data into graphical form and by the curves of graphs we can conclude the main core of the experiment. Generally combustion is divided into three major parts pressure-crank angle study, pressure-volume study & fuel-line pressure. This paper includes the study of combustion of CI engine when it is experimented by two different types of nozzles. The study gives a brief idea of the amount of pressure and volume attained inside the combustion chamber of CI engine.
A mathematical model for the prediction of the injected mass diagram of a S.I. engine gas injector
2013
A mathematical model of gaseous fuel solenoid injector for spark ignition engine has been realized and validated through experimental data. The gas injector was studied with particular reference to the complex needle motion during the opening and closing phases, which strongly affects the amount of fuel injected. As is known, in fact, when the injector nozzle is widely open, the mass flow depends only on the fluid pressure and temperature upstream the injector: this allows one to control the injected fuel mass acting on the “injection time” (the period during which the injector solenoid is energized). This makes the correlation between the injected fuel mass and the injection time linear, except for the lower injection times, where we experimentally observed strong nonlinearities. These nonlinearities arise by the injector outflow area variation caused by the needle bounces due to impacts during the opening and closing transients [1] and may seriously compromise the mixture quality control, thus increasing both fuel consumption and pollutant emissions, above all because the S.I. catalytic conversion system has a very low efficiency for non-stoichiometric mixtures. Moreover, in recent works [2; 3] we tested the simultaneous combustion of a gaseous fuel ( compressed natural gas, CNG, or liquefied petroleum gas, LPG) and gasoline in a spark ignition engine obtaining great improvement both in engine efficiency and pollutant emissions with respect to pure gasoline operation mode; this third operating mode of bi-fuel engines, called “double fuel” combustion, requires small amounts of gaseous fuel, hence forcing the injectors to work in the non-monotonic zone of the injected mass diagram, where the control on air-fuel ratio is poor. Starting from these considerations we investigated the fuel injector dynamics with the aim to improve its performance in the low injection times range. The first part of this paper deals with the realization of a mathematical model for the prediction of both the needle motion and the injected mass for choked flow condition, while the second part presents the model calibration and validation, performed by means of experimental data obtained on the engine test bed of the Internal Combustion Engine Laboratory of the University of Palermo.
In-nozzle flow spray characteristics in gasoline multi-hole injectors
City, University of London, 2020
In-nozzle flow spray characteristics in gasoline multi-hole injectors. (Unpublished Doctoral thesis, City, University of London) This is the accepted version of the paper. This version of the publication may differ from the final published version.
Experimental and Numerical Study of an Air Assisted Fuel Injector for a D.I.S.I. Engine
SAE Technical Paper Series, 2007
The transient behaviour of the fuel spray from an air assisted fuel injector has been investigated both numerically and experimentally in a Constant Volume Chamber (CVC) and an optical engine. This two phase injector is difficult to analyse numerically and experimentally because of the strong coupling between the gas and liquid phases. The gas driven atomization of liquid fuel involves liquid film formation, separation and break up and also liquid droplet coalescence, break up, splashing, bouncing, evaporation and collision. Furthermore, the liquid phase is the dominant phase in many regions within the injector.
Design and Analysis of Rocket Engine Injectors
The quality and homogeneity of an atomized fluid and therefore the stability and efficiency of hybrid engine are basically determined by the oxidizer injection system. The hybrid rocket engine uses gaseous oxygen as oxidizer. Evaporation and combustion of the atomized gaseous oxygen droplets needs to be completed inside the combustion chamber, which is less than one meter long. The pressure drop over the injector protects the feed and tank system against backflow of hot combustion gas. To respect this amount of requirements the most important equations and design of several injectors are explained. Different types of injectors are designed to use in solid, liquid and hybrid rocket engine. The injectors are experimentally analyzed using special test bench and wind tunnel. The flow over injectors are studied and determined.
Development of a fuel injector relative performance tester and cleaner
Proceeding of 2nd International Colloquium on Computational & Experimental Mechanics (ICCEM 2021)
Fuel injector is considered to be the heart of a vehicles fuel circulation system. They are very much important to the overall functionality and performance of any vehicle. The main principle behind the working of a fuel injector in a vehicle is spraying or dispersion of fuel into the engine. In todays technology each and every modernized vehicle consists of an ECM which is considered to be the central processing unit for the engine and it is the vehicles engine computer. This computerized control supervises the overall frequency of dispersion of fuel into the engine with specified time intervals. It also defines the timeline of the engine by calculating the efficiency and it stimulates the overall performance of the system. Certain symptoms indicate that the fuel injector is failing and losing its efficiency. Dispersion or spraying discharge of the fuel minimizes over the time. Clogging is one of the defects that happens in the injector. This clogging will in turn affect the engine performance directly or indirectly. Scale formation is also a defect in the inner bore of the nozzle of the fuel injector which occurs due to idleness. To overcome the above concerns a fuel injector relative performance tester and cleaner was developed. By utilizing this device a fuel injectors performance can be analyzed and the nozzle passage can be cleaned. This will in turn improve the performance of the engine.
Journal of Physics: Conference Series, 2007
The internal nozzle and near the nozzle exit flows of an enlarged transparent model of an outwards opening injector were investigated for different flow rates and needle lifts under steady state flow conditions. A high resolution CCD camera, high speed video camera and an LDV system were employed to visualize the nozzle flow and quantify the tangential velocity characteristics. The images of the internal flow between the valve seat and the square cross-section end of the needle guide revealed the presence of four separated jet flows and four pairs of counter-rotating vortices with each pair bounded in-between two adjacent jets. The counter-rotating vortices are highly unstable with a circumferential oscillatory motion which was transmitted to the spray outside the nozzle with almost the same frequency. The dominant circumferential frequencies at the nozzle exit were identified by FFT analysis of the tangential velocities. A linear relationship exists between the dominant frequencies and the flow Reynolds number based on injection velocity and needle lift. Magnified images of the flow just outside the nozzle exit showed formation of interconnecting streamwise strings on the liquid film as soon as it emerges from the annular exit passage. The interspacing between the strings was found to be linearly related to injection velocity and almost independent of the needle lift.
Failure in Fuel Injector Nozzles Used in Diesel Engines
Journal of Mechanics Engineering and Automation, 2015
This paper aims to conduct a study of the problems associated with the wear of the needles and fuel injection nozzles utilized in diesel engines. The wear found on the needles is mainly associated to impurities in the fuel oil and microcavitation occurred due to high pressure in the phase of the air compression for combustion of the combustible fluid. These pressures associated with the temperature and the fluid velocity results in the occurrence of vaporization, which releases shock waves that cause damage to the affected surface. The impurities solid particles from the fuel oil cause problems inside the nozzles as obstruction of the holes and wear on the needle tip and nozzle seat surface. These failures affect in the atomization of the fuel, since the deterioration of the internal passages of the nozzles interferes in the spray formation and in the end passage of the fluid. For the execution of this study it will be used digital microscopic analysis in specimens that suffered damage, in order to investigate the effects of fuel property, and the temperature conditions and pressure in the formation of the wear on the needles and injector nozzle.