Numerical Simulation of DI Diesel Engine’s Combustion Chamber Using Several Turbulence Models During Intake and Compression Strokes

2005 ◽  
Author(s):  
Seyed Ali Jazayeri ◽  
Masoud Mirzaei ◽  
Javad Kheyrollahi ◽  
Abdollah Shadaram
Keyword(s):  
Flow Field ◽  
Combustion Chamber ◽  
Three Dimensional ◽  
Flow Characteristics ◽  
Engine Performance ◽  
Turbulence Models ◽  
Computational Domain ◽  
Compression Process ◽  
Ic Engine ◽  
Performance And Emission

Atomization of the fuel that is injected to the combustion chamber depends on flow field characteristics during the compression process. Mixture formation, mixture preparation rate and delay period are some of the dominant factors in DI diesel engine performance and emission level. This paper presents a new CFD approach simulation of flow field during intake and compression of a four strokes IC engine. In this model a dynamic mesh is used to simulate the moving boundaries of engine parts, such as piston and valves. Computational domain, which is a precise model of one cylinder, is meshed to 300,000–500,000 cells. In our solution three different two-equation turbulence models are used. The capability of each model is highlighted and the results are compared with relevant works. The focus of these turbulence models and three-dimensional simulation of engine flow are to validate the reliability of flow characteristics. The results accurately demonstrate the three-dimensional characteristics of air motion in the swirl chamber and development of vortices.

The Simulation and Optimization on Flow Field in Intake Port of Engine Based on RE and CFD

2014 ◽  
Vol 1079-1080 ◽  
pp. 926-929
Author(s):  
Dan Han ◽  
Qian Wang ◽  
Bing Huan Li ◽  
Guo Jun Zhang ◽  
Shuo Wang
Keyword(s):  
Flow Field ◽  
Laser Scanning ◽  
Gas Flow ◽  
Gasoline Engine ◽  
Three Dimensional ◽  
Flow Characteristics ◽  
Turbulence Models ◽  
Intake Port ◽  
Three Dimensional Model ◽  
Simulation And Optimization

Intake port is an important part of the gasoline engine, its structure will influence the gas flow characteristics which directly affects the performance of the engine [1]. In this paper, three-dimensional CFD calculation and structural optimization were used to research the performance of gasoline engine. Firstly, the method of laser scanning and UG software were used to reverse modeling engine exhaust port and get the three-dimensional model. Secondly, after setting boundary conditions and turbulence models, the air flowing through the intake ports were simulated by FLUENT software respectively. Finally, based on numerical methods, the pressure field, velocity field were shown. The results of the simulation of flow field characteristics analysis show that the simulation and experimental results are in good agreement.

scholarly journals Numerical and experimental study on turbulence statistics in a large fan-stirred combustion vessel

2021 ◽  
Vol 62 (5) ◽  
Author(s):  
M. E. Morsy ◽  
J. Yang
Keyword(s):  
Isotropic Turbulence ◽  
Burning Velocity ◽  
Three Dimensional ◽  
Flow Characteristics ◽  
Turbulence Models ◽  
Initial Pressure ◽  
Dynamics Modeling ◽  
Turbulence Statistics ◽  
Experimental Conditions ◽  
Measured Velocity

Abstract Particle image velocimetry (PIV) has become a popular non-intrusive tool for measuring various types of flows. However, when measuring three-dimensional flows with two-dimensional (2D) PIV, there are some uncertainties in the measured velocity field due to out-of-plane motion, which might alter turbulence statistics and distort the overall flow characteristics. In the present study, three different turbulence models are employed and compared. Mean and fluctuating fields obtained by three-dimensional computational fluid dynamics modeling are compared to experimental data. Turbulence statistics such as integral length scale, Taylor microscale, Kolmogorov scale, turbulence kinetic energy, dissipation rate, and velocity correlations are calculated at different experimental conditions (i.e., pressure, temperature, fan speed, etc.). A reasonably isotropic and homogeneous turbulence with large turbulence intensities is achieved in the central region extending to almost 45 mm radius. This radius decreases with increasing the initial pressure. The influence of the third dimension velocity component on the measured characteristics is negligible. This is a result of the axisymmetric features of the flow pattern in the current vessel. The results prove that the present vessel can be conveniently adopted for several turbulent combustion studies including mainly the determination of turbulent burning velocity for gaseous premixed flames in nearly homogeneous isotropic turbulence. Graphic abstract

An Accurate Performance Prediction of Solid Fuel Ramjets Using Coupled Intake-Combustor-Nozzle Simulation

2020 ◽  
Vol 36 (6) ◽  
pp. 933-941
Author(s):  
A. M. Tahsini
Keyword(s):  
Combustion Chamber ◽  
Solid Fuel ◽  
Solid Phase ◽  
Three Dimensional ◽  
Flow Fields ◽  
Reacting Flow ◽  
Computational Domain ◽  
Regression Rate ◽  
Fuel Flow ◽  
Accurate Performance

ABSTRACTThe performance of the solid fuel ramjet is accurately predicted using full part simulation of this propulsion system, where the flow fields of the intake, combustion chamber, and the nozzle are numerically studied all together. The conjugate heat transfer is considered between the solid phase and the gas phase to directly compute the regression rate of the fuel. The finite volume solver of the compressible turbulent reacting flow is utilized to study the axisymmetric three dimensional flow fields, and two blocks are used to discretize the computational domain. It is shown that the combustion chamber's pressure is changed due to the fuel flow rate's increment which must be taken into account in predictions. The results demonstrate that omitting the pressure dependence of the regression rate and also the effect of the combustor's inlet profile on the regression rate, which specially exists when simulating the combustion chamber individually, under-predicts the solid fuel burning rate when the regression rate augmentation technique is applied to improve the performance of the solid fuel ramjets. It is also illustrated that using the inlet swirl to increase the regression rate of the solid fuel augments considerably the thrust level of the considered SFRJ, while the predictions without considering all parts of the ramjet is not accurate.

scholarly journals Numerical Investigation of Fluid Flow and In-Cylinder Air Flow Characteristics for Higher Viscosity Fuel Applications

Processes ◽  
2020 ◽  
Vol 8 (4) ◽  
pp. 439 ◽  
Author(s):  
Mohd Fadzli Hamid ◽  
Mohamad Yusof Idroas ◽  
Shukriwani Sa’ad ◽  
Teoh Yew Heng ◽  
Sharzali Che Mat ◽  
...  
Keyword(s):  
Guide Vane ◽  
Flow Characteristics ◽  
Engine Performance ◽  
Intake Manifold ◽  
3D Analysis ◽  
Ansys Fluent ◽  
Ic Engine ◽  
Cold Flow ◽  
Ci Engine ◽  
Combustion Processes

Generally, the compression ignition (CI) engine that runs with emulsified biofuel (EB) or higher viscosity fuel experiences inferior performance and a higher emission compared to petro diesel engines. The modification is necessary to standard engine level in order to realize its application. This paper proposes a guide vane design (GVD), which needs to be installed in the intake manifold, is incorporated with shallow depth re-entrance combustion chamber (SCC) pistons. This will organize and develop proper in-cylinder airflow to promote better diffusion, evaporation and combustion processes. The model of GVD and SCC piston was designed using SolidWorks 2017; while ANSYS Fluent version 15 was utilized to run a 3D analysis of the cold flow IC engine. In this research, seven designs of GVD with the number of vanes varied from two to eight vanes (V2–V8) are used. The four-vane model (V4) has shown an excellent turbulent flow as well as swirl, tumble and cross tumble ratios in the fuel-injected region compared to other designs. This is indispensable to break up heavier fuel molecules of EB to mix with the air that will eventually improve engine performance.

The Effect of Upstream Flow Conditions to Laminar Mixing in a Miniature Combustion Chamber

2003 ◽  
Author(s):  
Peter L. Woodfield ◽  
Kazuya Tatsumi ◽  
Kazuyoshi Nakabe ◽  
Kenjiro Suzuki
Keyword(s):  
Combustion Chamber ◽  
Three Dimensional ◽  
Flow Characteristics ◽  
Baffle Plate ◽  
Micro Gas Turbine ◽  
Laminar Mixing ◽  
Fuel Jet ◽  
Single Jet ◽  
Inlet Conditions ◽  
Volume Method

A three-dimensional unstructured finite-volume method is used to investigate laminar flow characteristics of a miniature chamber with a possible application to micro gas turbine combustor design. The chamber is cylindrical in shape and 20mm in diameter with the fuel stream entering via a single jet in the center of one end of the can. Oxidizer jets are generated by a circular baffle plate having six holes surrounding the fuel jet. Attention is given to the effect of the inlet conditions on the flow structure and mixing pattern inside the chamber. Computations are carried out with the calculation domain inlet being positioned at two different locations; (1) at the immediate entrance to the combustion chamber (2) one combustor diameter upstream of the baffle plate. Numerous inlet conditions are considered including ‘top-hat’, fully-developed, swirling, an annular backward facing step and some asymmetrically skewed profiles. The baffle plate is shown to have a significant smoothing effect on the inlet conditions for a Reynolds number of 100.

Multidimensional Modeling of Natural Gas Jet and Mixture Formation in DI SI Engines: Development and Validation of a Virtual Injector Model

2009 ◽  
Author(s):  
Mirko Baratta ◽  
Andrea E. Catania ◽  
Francesco C. Pesce
Keyword(s):  
Natural Gas ◽  
Combustion Chamber ◽  
Combustion Engine ◽  
Direct Injection ◽  
Test Chamber ◽  
Computational Cost ◽  
Computational Domain ◽  
Rarefaction Waves ◽  
Mixture Formation ◽  
Ic Engine

During the last years, the integration of computational CFD tools in the internal combustion (IC) engine design process has continuously been increased, allowing to save time and cost as the need of experimental prototypes has diminished. Numerical analyses of IC engine flows are rather complex from both the conceptual and operational sides. In fact, such flows involve a variety of unsteady phenomena, and the right balance between numerical solution accuracy and computational cost should be always reached. The present paper is focused on computational modeling of natural gas (NG) direct injection (DI) processes from a poppet-valve injector into a bowl-shaped combustion chamber. At high injection pressures, the efflux of gas from the injector and the mixture formation processes include compressible and turbulent flow features, such as rarefaction waves and shock formation, which are difficult to be accurately captured by the numerical simulation, particularly when combustion chamber geometry is complex and piston and intake/exhaust valve grids are moving. A three-dimensional moving grid model of the combustion engine chamber, originally developed by the authors, was enhanced by increasing the accuracy in the sonic section proximity of the critical valve seat nozzle, in order to precisely capture the expansion dynamics the methane undergoes inside the injector and immediately downstream from it. The enhanced numerical model was validated by comparing numerical results to Schlieren experimental images for nitrogen injection into a constant-volume bomb. Then, numerical studies were carried out in order to characterize the fuel jet properties and the evolution of mixture-formation for a centrally-mounted injector configuration in both cases of a pancake test chamber and the real-shaped engine chamber. Finally, the fluid properties computed by the model in the throat-section of the critical nozzle were taken as reference data for developing a new effective ‘virtual injector’ model, which allows the designer to remove the whole computational domain upstream from the sonic section of the nozzle, keeping the flow properties practically unchanged. The outcomes of such a virtual injector model were shown to be in very good agreement with the results of the enhanced complete injector model, confirming the reliability of the proposed novel approach.

scholarly journals Comparative Study on CFD Turbulence Models for the Flow Field in Air Cooled Radiator

Processes ◽  
2020 ◽  
Vol 8 (12) ◽  
pp. 1687
Author(s):  
Chao Yu ◽  
Xiangyao Xue ◽  
Kui Shi ◽  
Mingzhen Shao ◽  
Yang Liu
Keyword(s):  
Flow Field ◽  
Transient Flow ◽  
Three Dimensional ◽  
Turbulence Models ◽  
Compartment Model ◽  
Navier Stokes ◽  
Engine Compartment ◽  
Detached Eddy Simulation ◽  
Eddy Simulation ◽  
Relevant Calculation

This paper compares the performances of three Computational Fluid Dynamics (CFD) turbulence models, Reynolds Average Navier-Stokes (RANS), Detached Eddy Simulation (DES), and Large Eddy Simulation (LES), for simulating the flow field of a wheel loader engine compartment. The distributions of pressure fields, velocity fields, and vortex structures in a hybrid-grided engine compartment model are analyzed. The result reveals that the LES and DES can capture the detachment and breakage of the trailing edge more abundantly and meticulously than RANS. Additionally, by comparing the relevant calculation time, the feasibility of the DES model is proved to simulate the three-dimensional unsteady flow of engine compartment efficiently and accurately. This paper aims to provide a guiding idea for simulating the transient flow field in the engine compartment, which could serve as a theoretical basis for optimizing and improving the layout of the components of the engine compartment.

Experimental Investigation of the Flow Field of a Ceiling Fan

Volume 3 ◽  
2004 ◽  
Author(s):  
Ankur Jain ◽  
Rochan Raj Upadhyay ◽  
Samarth Chandra ◽  
Manish Saini ◽  
Sunil Kale
Keyword(s):  
Experimental Investigation ◽  
Energy Consumption ◽  
Flow Field ◽  
Three Dimensional ◽  
Flow Characteristics ◽  
Tip Vortex ◽  
Optimal Designs ◽  
Tropical Regions ◽  
Fundamental Understanding ◽  
Blade Tip

A ceiling fan is the predominating comfort provider in tropical regions worldwide. It consists of an assembly of an electric motor with 3–4 blades suspended from the ceiling of a room. Despite its simplicity and widespread use, the flow induced by a ceiling fan in a closed room has not been investigated, and sub-optimal designs are in wide use. There is vast potential for energy conservation and improved comfort by developing optimized fan designs. This work develops a fundamental understanding of the flow characteristics of a ceiling operating inside a closed room. Using smoke from thick incense sticks, the flow field created by the ceiling fan is visualized. In most regions, the flow is periodic and three-dimensional. Vortices are seen to be attached to the blade tip and hub, which reduces downward flow and increases energy consumption. Only the middle 75% of blade actually pushes the air downwards, and the comfort region is limited to a cylinder directly under the blades; velocities in this region were measured with a vane anemometer. Winglets and spikes attached to the blade tip disrupted the tip vortex, and increased downflow by about 13% without any increase in power consumption.

Time Accurate Euler Simulation of Interaction of Nozzle Wake and Secondary Flow With Rotor Blade in an Axial Turbine Stage Using Nonreflecting Boundary Conditions

1995 ◽  
Author(s):  
S. Fan ◽  
B. Lakshminarayana
Keyword(s):  
Flow Field ◽  
Boundary Conditions ◽  
Unsteady Flow ◽  
Secondary Flow ◽  
Rotor Blade ◽  
Three Dimensional ◽  
Computational Domain ◽  
Turbine Stage ◽  
Axial Turbine ◽  
Unsteady Pressure

The objective of this paper is to investigate the three dimensional unsteady flow interactions in a turbomachine stage. A three-dimensional time accurate Euler code has been developed using an explicit four-stage Runge-Kutta scheme. Three-dimensional unsteady non-reflecting boundary conditions are formulated at the inlet and at the outlet of the computational domain to remove the spurious numerical reflections. The three-dimensional code is first validated for 2-D and 3-D cascades with harmonic vortical inlet distortions. The effectiveness of non reflecting boundary conditions is demonstrated. The unsteady Euler solver is then used to simulate the propagation of nozzle wake and secondary flow through rotor and the resulting unsteady pressure field in an axial turbine stage. The three dimensional and time dependent propagation of nozzle wakes in the rotor blade row and the effects of nozzle secondary flow on the rotor unsteady surface pressure and passage flow field are studied. It was found that the unsteady flow field in the rotor is highly three-dimensional and the nozzle secondary flow has significant contribution to the unsteady pressure on the blade surfaces. Even though the steady flow at the midspan is nearly two-dimensional, the unsteady flow is 3-D and the unsteady pressure distribution can not by predicted by a 2-D analysis.

scholarly journals Assessment of Machine-Learned Turbulence Models Trained for Improved Wake-Mixing in Low-Pressure Turbine Flows

Energies ◽  
2021 ◽  
Vol 14 (24) ◽  
pp. 8327
Author(s):  
Roberto Pacciani ◽  
Michele Marconcini ◽  
Francesco Bertini ◽  
Simone Rosa Taddei ◽  
Ennio Spano ◽  
...  
Keyword(s):  
Boundary Layers ◽  
Three Dimensional ◽  
Turbulence Models ◽  
Reynolds Numbers ◽  
Computational Domain ◽  
Trailing Edge ◽  
Low Pressure Turbine ◽  
Wide Range ◽  
Turbulence Closures ◽  
The Impact

This paper presents an assessment of machine-learned turbulence closures, trained for improving wake-mixing prediction, in the context of LPT flows. To this end, a three-dimensional cascade of industrial relevance, representative of modern LPT bladings, was analyzed, using a state-of-the-art RANS approach, over a wide range of Reynolds numbers. To ensure that the wake originates from correctly reproduced blade boundary-layers, preliminary analyses were carried out to check for the impact of transition closures, and the best-performing numerical setup was identified. Two different machine-learned closures were considered. They were applied in a prescribed region downstream of the blade trailing edge, excluding the endwall boundary layers. A sensitivity analysis to the distance from the trailing edge at which they are activated is presented in order to assess their applicability to the whole wake affected portion of the computational domain and outside the training region. It is shown how the best-performing closure can provide results in very good agreement with the experimental data in terms of wake loss profiles, with substantial improvements relative to traditional turbulence models. The discussed analysis also provides guidelines for defining an automated zonal application of turbulence closures trained for wake-mixing predictions.

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