Multidimensional Modeling of Natural Gas Jet and Mixture Formation in Direct Injection Spark Ignition Engines—Development and Validation of a Virtual Injector Model

2011 ◽  
Vol 133 (4) ◽  
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 few years, the integration of CFD tools in the internal combustion (IC) engine design process has continually increased, allowing time and cost savings as the need for experimental prototypes has diminished. Numerical analyses of IC engine flows are rather complex from both the conceptual and operational sides. In fact, these flows involve a variety of unsteady phenomena and the right balance between numerical solution accuracy and computational cost should always be 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 gas efflux from the injector and the mixture formation processes include turbulent and compressible flow features, such as rarefaction waves and shock formation, which are difficult to accurately capture with numerical simulations, particularly when the combustion chamber geometry is complex and the piston and intake/exhaust valve grids are moving. In this paper, a three-dimensional moving grid model of the combustion engine chamber, originally developed by the authors to include simulation of the actual needle lift, has been enhanced by increasing the accuracy in the proximity of the sonic section 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 then validated by comparing the numerical results to Schlieren experimental images for gas injection into a constant-volume bomb. 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 the case of a pancake-shaped test chamber and the real engine chamber. Finally, the fluid properties calculated 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 virtually unchanged there. The virtual injector model outcomes were shown to be in very good agreement with the results of the enhanced complete injector model, substantiating the reliability of the proposed novel approach.

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.

Effect of Chemical Hythane Composition on Pressure in Combustion Chamber of Engine

2019 ◽  
pp. 36-42
Author(s):  
A. P. Shaikin ◽  
I. R. Galiev
Keyword(s):  
Natural Gas ◽  
Combustion Chamber ◽  
Power Plants ◽  
Engine Speed ◽  
Combustion Engine ◽  
Fuel Mixture ◽  
Maximum Pressure ◽  
Chamber Volume ◽  
Excess Air ◽  
Scientific Papers

The article analyzes the influence of chemical composition of hythane (a mixture of natural gas with hydrogen) on pressure in an engine combustion chamber. A review of the literature has showed the relevance of using hythane in transport energy industry, and also revealed a number of scientific papers devoted to studying the effect of hythane on environmental and traction-dynamic characteristics of the engine. We have studied a single-cylinder spark-ignited internal combustion engine. In the experiments, the varying factors are: engine speed (600 and 900 min-1), excess air ratio and hydrogen concentration in natural gas which are 29, 47 and 58% (volume).The article shows that at idling engine speed maximum pressure in combustion chamber depends on excess air ratio and proportion hydrogen in the air-fuel mixture – the poorer air-fuel mixture and greater addition of hydrogen is, the more intense pressure increases. The positive effect of hydrogen on pressure is explained by the fact that addition of hydrogen contributes to increase in heat of combustion fuel and rate propagation of the flame. As a result, during combustion, more heat is released, and the fuel itself burns in a smaller volume. Thus, the addition of hydrogen can ensure stable combustion of a lean air-fuel mixture without loss of engine power. Moreover, the article shows that, despite the change in engine speed, addition of hydrogen, excess air ratio, type of fuel (natural gas and gasoline), there is a power-law dependence of the maximum pressure in engine cylinder on combustion chamber volume. Processing and analysis of the results of the foreign and domestic researchers have showed that patterns we discovered are applicable to engines of different designs, operating at different speeds and using different hydrocarbon fuels. The results research presented allow us to reduce the time and material costs when creating new power plants using hythane and meeting modern requirements for power, economy and toxicity.

Transient Behavior of Glow Plugs in Direct-Injection Natural Gas Engines

2012 ◽  
Vol 134 (9) ◽  
Author(s):  
Stewart Xu Cheng ◽  
James S. Wallace
Keyword(s):  
Heat Transfer ◽  
Natural Gas ◽  
Direct Injection ◽  
High Surface ◽  
Cold Start ◽  
Transfer Model ◽  
Ignition Process ◽  
Computational Domain ◽  
Glow Plug ◽  
Natural Gas Engines

Glow plugs are a possible ignition source for direct injected natural gas engines. This ignition assistance application is much different than the cold start assist function for which most glow plugs have been designed. In the cold start application, the glow plug is simply heating the air in the cylinder. In the cycle-by-cycle ignition assist application, the glow plug needs to achieve high surface temperatures at specific times in the engine cycle to provide a localized source of ignition. Whereas a simple lumped heat capacitance model is a satisfactory representation of the glow plug for the air heating situation, a much more complex situation exists for hot surface ignition. Simple measurements and theoretical analysis show that the thickness of the heat penetration layer is small within the time scale of the ignition preparation period (1–2 ms). The experiments and analysis were used to develop a discretized representation of the glow plug domain. A simplified heat transfer model, incorporating both convection and radiation losses, was developed for the discretized representation to compute heat transfer to and from the surrounding gas. A scheme for coupling the glow plug model to the surrounding gas computational domain in the KIVA-3V engine simulation code was also developed. The glow plug model successfully simulates the natural gas ignition process for a direct-injection natural gas engine. As well, it can provide detailed information on the local glow plug surface temperature distribution, which can aid in the design of more reliable glow plugs.

scholarly journals Analysis of creation and combustion process of hydrogen-air mixtures by optical method in isochoric chamber

2017 ◽  
Vol 170 (3) ◽  
pp. 121-125
Author(s):  
Marek BRZEŻAŃSKI ◽  
Tadeusz PAPUGA ◽  
Łukasz RODAK
Keyword(s):  
Combustion Chamber ◽  
Flame Front ◽  
Dose Distribution ◽  
Optical Method ◽  
Direct Injection ◽  
Combustion Process ◽  
Variable Composition ◽  
Mixture Formation ◽  
Before And After

The article considers the analysis of combustion process of hydrogen-air mixture of variable composition. Direct injection of hydrogen into the isochoric combustion chamber was applied and the mixture formation took place during the combustion process. The influence of the dose distribution of the fuel supplied before and after ignition on the formation of the flame front and the course of the pressure in the isochoric combustion chamber was discussed. The filming process and registration of pressure in the isochoric chamber during research of combustion process was applied.

Effect of IC Engine Operating Conditions on Combustion and Emission Characteristics

1993 ◽  
Vol 115 (4) ◽  
pp. 694-701 ◽  
Author(s):  
Jiang Lu ◽  
Ashwani K. Gupta ◽  
Eugene L. Keating
Keyword(s):  
Internal Combustion Engine ◽  
Combustion Chamber ◽  
Internal Combustion Engines ◽  
Combustion Engine ◽  
Internal Combustion ◽  
Operating Conditions ◽  
Emission Characteristics ◽  
Ic Engine ◽  
Pollutants Emission ◽  
Good Agreement

Numerical simulation of flow, combustion, heat release rate, and pollutants emission characteristics have been obtained using a single cylinder internal combustion engine operating with propane as the fuel. The data show that for good agreement with experimental results on the peak pressure and the rate of pressure rise as a function of crank angle, spark ignition energy and local cylinder pressure must be properly modeled. The results obtained for NO and CO showed features which are qualitatively in good agreement and are similar to those reported in the literature for the chosen combustion chamber geometry. The results have shown that both the combustion chamber geometry and engine operating parameters affects the flame growth within the combustion chamber which subsequently affects the pollutants emission levels. The code employed the time marching procedure and solves the governing partial differential equations of multicomponent chemically reacting fluid flow by finite difference method. The numerical results provide a cost effective means of developing advanced internal combustion engine chamber geometry design that provides high efficiency and low pollution levels. It is expected that increased computational tools will be used in the future for enhancing our understanding of the detailed combustion process in internal combustion engines and all other energy conversion systems. Such detailed information is critical for the development of advanced methods for energy conservation and environmental pollution control.

Application of Hyperbolic Tangent Approximation Model to Gasoline Direct Injection Engine Simulation

2017 ◽  
Author(s):  
Tomoyuki Hosaka ◽  
Taisuke Sugii ◽  
Eiji Ishii ◽  
Kazuhiro Oryoji ◽  
Yoshihiro Sukegawa
Keyword(s):  
Open Source ◽  
Internal Combustion Engines ◽  
Combustion Engine ◽  
Direct Injection ◽  
Internal Combustion ◽  
Experimental Results ◽  
Gasoline Direct Injection ◽  
Pollutant Emissions ◽  
Mixture Formation ◽  
Hyperbolic Tangent

The improved fuel economy and low pollutant emissions are highly demanded for internal combustion engines. Gasoline Direct Injection (GDI) engine is the one of promising devices for highly efficient engine. However, GDI engines generally tend to emit more Particulate Matter (PM) than Port Fuel Injection (PFI) engine because the fuel sprayed from the injector can easily attach to the wall, which is the major origin of PM. Therefore, the precise analysis of the fuel/air mixture formation and the prediction of emissions are required. From the view of industrial use, Computational Fluid Dynamics (CFD) becomes a necessary tool for the various analyses including the fuel/air mixture formation, spray attachment on the cylinder wall, the in-cylinder turbulence formation, the combustion and emission etc. In our previous study, the flow and spray simulation in internal combustion engine has been conducted using OpenFOAM®, the open-source CFD toolbox. Since the engine involves the dynamic motion such as valve and piston, the morphing and mapping approach was employed. Furthermore, by virtue of open-source code, we have developed the methodology of the hybrid simulation from the internal nozzle flow to the fuel/air mixture in order to take into account detailed breakup process nearby injector nozzle. We expand the above research to the combustion simulation. For the combustion model, the Hyperbolic Tangent Approximation (HTA) model is adopted. The HTA model has a simple form of equation and one can easily implement; moreover, the HTA model has the following features: 1. capability of both laminar and turbulent flow, 2. the clearness of analytical derivation based on the functional approximation of the reaction progress variable distribution in a one-dimensional laminar flame. In the current study, the premixed flame is studied on a gasoline combustion engine. The simulations for in-cylinder engine are conducted with different Air/Fuel (A/F) ratio conditions, and the results are compared with the experimental results. The in-cylinder pressure agrees well with experimental results and the validity of the current methodology is confirmed.

Numerical Simulation of Direct Injection Engine With Using Porous Medium

2012 ◽  
Author(s):  
Arash Mohammadi ◽  
Ali Jazayeri ◽  
Masoud Ziabasharhagh
Keyword(s):  
Porous Medium ◽  
Direct Injection ◽  
Combustion Process ◽  
Packed Bed ◽  
Published Data ◽  
Mixture Formation ◽  
Flammability Limits ◽  
Ic Engine ◽  
Engine Simulation ◽  
Wide Range

Porous media (PM) has interesting advantages in compared with free flame combustion due to the higher burning rates, the increased power range, the extension of the lean flammability limits, and the low emissions of pollutants. Future clean internal combustion (IC) engines should have had minimum emissions level (for both gaseous and particulate matter) under possible lowest fuel consumption permitted in a wide range of speed, loads and having good transient response. These parameters strongly depend on mixture formation and combustion processes which are difficult to be controlled in a conventional engine. This may be achieved by realization of homogeneous combustion process in engine. This paper deals with the simulation of direct injection IC engine equipped with a chemically inert PM, with cylindrical geometry to homogenize and stabilize the combustion of engine. A 3D numerical model for PM engine is presented in this study based on a modified version of the KIVA-3V code. Due to lack of any published data for PM engines, numerical results of thermal and combustion wave propagation in a porous medium are compared with experimental data of lean methane-air mixture under filtration in packed bed and very good agreement is seen. For PM engine simulation methane as a fuel is injected directly inside hot PM that is assumed, mounted in cylinder head. Lean mixture is formed and volumetric combustion occurs in PM and in-cylinder. Mixture formation, pressure and temperature distribution in both phases of PM and in-cylinder fluid with the production of pollutants CO and NO and also effects of injection time in the closed part of the cycle are studied.

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