An Open Cycle Simulation of DI Diesel Engine Flow Field Effect on Spray Processes

Author(s):  
Kohei Fukuda ◽  
Abbas Ghasemi ◽  
Ronald Barron ◽  
Ram Balachandar

The article takes a gander at inevitable results of logical leisure with whirl enhancing modifications on a right away Injection diesel engine. 4 holes at a diversion over every chamber with estimations of the outlet start from 2, 2.five, 3 and 3.5 mm are through within the chamber with affordable tendency concerning the chamber center factor Numerical guesses are the first-class change to provide clean enduring of the fluid circulate wonder in a DI Diesel Engine. outcomes discover that the unessential beginning of two.five mm (2nd) bypass on an unequalled begin and excessive weight. Spin development just motor vitality massiveness increment with the changing starting widths. The chamber with 2.five mm establishing make a most vital execution improvement while the chambers with excessive broadness than second hole bypass on a to a few diploma chop down execution. whilst the development in partition transversely over develops the move discipline characteristics like spin, the execution decays beyond 2.five mm. considering the execution attitude an ensuing hole gives improved ingesting and finally most outrageous load for the proportional gas implanted. alternate ultimate holes have to a few diploma more fiery debris launch. in view that numerical results exhibited that ensuing hole offers a transcendent. Of all of the splendid numerical modifications the resultant chamber gives stepped forward presentation and lessens the fee and dreary experimentation tests.


Author(s):  
B. Jayashankara ◽  
V. Ganesan

This paper presents the computational fluid dynamics (CFD) modeling to study the effect of intake port bend angle on the flow field inside the cylinder of a direct injection (DI) diesel engine under motoring conditions. The flow characteristics of the engine are investigated under transient conditions. A single cylinder DI diesel engine with two direct intake ports whose outlet is tangential to the wall of the cylinder and two exhaust ports has been taken up for the study. Effect of intake port bend angle (20°, 30°, and 40°) on the flow field inside the cylinder has been investigated at an engine speed of 1000 rpm. The pre-processor GAMBIT is used for model preparation and commercial computational fluid dynamics code STAR-CD has been used for solution of governing equations and post processing the results. CFD results during both intake and compression strokes have been compared with experimental results of Payri et-al [7, 8]. The predicted swirl ratio, radial velocity and turbulent intensity variations at different crank angles and at different locations are discussed. Distribution of velocity and turbulence intensity inside the cylinder is also discussed. It is observed that the intake ports with 20° bend angle produce maximum swirl and also results in a slight decrease in volumetric efficiency compared to intake ports with 30° and 40° bend angles and there is no appreciable variation in turbulent intensity. Hence, for the better performance of a DI diesel engine, it is concluded that the intake ports with 20° bend angle is most appropriate and CFD is an effective design tool to develop more efficient DI diesel engines.


2003 ◽  
Author(s):  
Wook Choi ◽  
Byung-Chul Choi ◽  
Hyung-Koo Park ◽  
Kyung-Jei Joo ◽  
Je-Hyung Lee

Author(s):  
J. David Rathnaraj ◽  
B. Jefferson Raja Bose ◽  
Michael N. Kumar

Knowledge of the flow phenomena inside the cylinder is necessary for optimum design of the intake port and the piston cavity configurations. Recent trends in direct injection diesel engines have increased the need for clear understanding of the flow field, especially the swirl characteristics. The swirl flow is an essential parameter which affects the air fuel mixing, combustion efficiency and therefore the engine performance. The purpose of this study is to investigate the combustion, emission, spray and flow field phenomena of a D I diesel engine and to come up with a geometrical shape for a port and valve or valves that produce the optimum swirl ratio. The percentage opening of a helical port for the DI diesel engine is simulated and studied using Computational Fluid Dynamics with experimental validation. Steady flow rig experiments are most widely used to evaluate the swirl ratio of an intake port design. The three dimensional developing flow patterns are needed throughout the compression and combustion stroke to understand the various experimental results. Flow is simulated by solving governing equations, viz., conservation of mass and momentum using the simple-algorithm. Turbulence has been modeled by standard kφ–φ∈ model with standard wall treatment. The predictive accuracy of the calculation method is compared with detailed mass flow rate and paddle rpm measurements. The results are in good agreement with experimental results and clearly predict the under predictability of the paddle swirl meter in lower lifts. Emission standards, which demand large reduction in NOx and PM emission, require a more comprehensive study of all elements that contribute to emission formulation. The combustion chamber is subject of research and development in an effort to achieve optimized combustion system. The intake port fluid dynamics contribute to the fuel air mixing which in turn is the most important parameter for the control of fuel burning rate for diesel engines. The intake port fluid dynamics also significantly affects ignition delay, the magnitude and timing of the diffusion burn, the magnitude of the premixed burn and emission of nitrous oxide and soot. According to the Modulated Kinetics (MK) concept, which improves the emission performance of diesel engines, a D I Diesel engine requires higher intake swirl in the part-load region. The computations are used to optimize the swirl flow characteristics of an intake port system over a wide range of operating conditions. In this study, the numerical simulation of the helical intake port and variable swirl intake port for two-valve DI Diesel engines are discussed with experimental validation. The improvement of swirl generation capacity of the port design according to the stringent emission norms are also studied.


2008 ◽  
Vol 2 (3) ◽  
pp. 354-365 ◽  
Author(s):  
Jinou Song ◽  
Chunde Yao ◽  
Yike Liu ◽  
Zejun Jiang

2021 ◽  
Vol 220 ◽  
pp. 106901
Author(s):  
Ahmad O. Hasan ◽  
Ahmed I. Osman ◽  
Ala'a H. Al-Muhtaseb ◽  
Hani Al-Rawashdeh ◽  
Ahmad Abu-jrai ◽  
...  

Energies ◽  
2021 ◽  
Vol 14 (14) ◽  
pp. 4136
Author(s):  
Clemens Gößnitzer ◽  
Shawn Givler

Cycle-to-cycle variations (CCV) in spark-ignited (SI) engines impose performance limitations and in the extreme limit can lead to very strong, potentially damaging cycles. Thus, CCV force sub-optimal engine operating conditions. A deeper understanding of CCV is key to enabling control strategies, improving engine design and reducing the negative impact of CCV on engine operation. This paper presents a new simulation strategy which allows investigation of the impact of individual physical quantities (e.g., flow field or turbulence quantities) on CCV separately. As a first step, multi-cycle unsteady Reynolds-averaged Navier–Stokes (uRANS) computational fluid dynamics (CFD) simulations of a spark-ignited natural gas engine are performed. For each cycle, simulation results just prior to each spark timing are taken. Next, simulation results from different cycles are combined: one quantity, e.g., the flow field, is extracted from a snapshot of one given cycle, and all other quantities are taken from a snapshot from a different cycle. Such a combination yields a new snapshot. With the combined snapshot, the simulation is continued until the end of combustion. The results obtained with combined snapshots show that the velocity field seems to have the highest impact on CCV. Turbulence intensity, quantified by the turbulent kinetic energy and turbulent kinetic energy dissipation rate, has a similar value for all snapshots. Thus, their impact on CCV is small compared to the flow field. This novel methodology is very flexible and allows investigation of the sources of CCV which have been difficult to investigate in the past.


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