scholarly journals Free Stream Behavior of Hydrogen Released from a Fluidic Oscillating Nozzle

Fluids ◽  
2021 ◽  
Vol 6 (7) ◽  
pp. 245
Author(s):  
Anja Fink ◽  
Oliver Nett ◽  
Simon Schmidt ◽  
Oliver Krüger ◽  
Thomas Ebert ◽  
...  
Keyword(s):  
Free Stream ◽  
Combustion Engine ◽  
Direct Injection ◽  
Combustion Process ◽  
Vertical Direction ◽  
Spray Angle ◽  
Transport Sector ◽  
Flow Measurements ◽  
Injection Process ◽  
Bottom Dead Center

The H2 internal combustion engine (ICE) is a key technology for complete decarbonization of the transport sector. To match or exceed the power density of conventional combustion engines, H2 direct injection (DI) is essential. Therefore, new injector concepts that meet the requirements of a H2 operation have to be developed. The macroscopic free stream behavior of H2 released from an innovative fluidic oscillating nozzle is investigated and compared with that of a conventional multi-hole nozzle. This work consists of H2 flow measurements and injection tests in a constant volume chamber using the Schlieren method and is accompanied by a LES simulation. The results show that an oscillating H2 free stream has a higher penetration velocity than the individual jets of a multi-hole nozzle. This behavior can be used to inject H2 far into the combustion chamber in the vertical direction while the piston is still near bottom dead center. As soon as the oscillation of the H2 free stream starts, the spray angle increases and therefore H2 is also distributed in the horizontal direction. In this phase of the injection process, spray angles comparable to those of a multi-hole nozzle are achieved. This behavior has a positive effect on H2 homogenization, which is desirable for the combustion process.

Effects of Intake Port Optimization on Soot Emission from Diesel Engine

2014 ◽  
Vol 535 ◽  
pp. 333-339
Author(s):  
Yue Chen ◽  
Lin Lv ◽  
Jie Shen
Keyword(s):  
Standard Deviation ◽  
Soot Formation ◽  
Combustion Engine ◽  
Double Helix ◽  
Direct Injection ◽  
Combustion Process ◽  
Flow Coefficient ◽  
Swirl Ratio ◽  
Characteristic Parameters ◽  
Double Tangent

All future engine developments must consider the primary task of achieving the required emission levels. An important step towards the development of combustion engines is the optimization of the flow in the intake ports. The charging movement in the combustion chamber, which is generated by the intake flow, considerably influences the quality of the combustion engine. In this paper, steady CFD analysis were applied to different structures of double-tangent-port. The swirl ratio can be improved while flow coefficient remains unchanged if port eccentricity is 34.4 mm. By defining three characteristic parameters, the speed non-uniformity index, standard deviation and mixture concentration standard deviation and equivalent ratio range, quantitatively describing the combustion process in cylinder, and then compared with transient CFD three-dimensional contours, we can see that characteristic parameters can be more accurate and comprehensive in analyzing the influence of inlet structure of soot formation. Effects of different intake ports on fuel-air mixing in a turbocharged diesel direct injection engine during intake and compression strokes are analyzed. It turns out that the optimized double-tangent-port has the highest uniformity of velocity, in the meanwhile, air/fuel mixing is relatively uniform. On the other hand, mixed-port and double-helix-port can cause uneven flow field which is bad for combustion, even though the swirl ratio can increase largely. Finally, the simulation results show that soot emissions of the optimized double-tangent-port have significantly lower levels, at 2200 r/min under full load.

scholarly journals Numerical study for the spray characteristics of diesel engine powered by biodiesel fuels under different injection pressures

2021 ◽  
Author(s):  
Mohamed F. Al-Dawody ◽  
◽  
Khaled A. Al-Farhany ◽  
Naseer H. Hamza ◽  
Dhafer A. Hamzah ◽  
...  
Keyword(s):  
Diesel Engine ◽  
Methyl Ester ◽  
Combustion Engine ◽  
Numerical Study ◽  
Combustion Process ◽  
Simulation Software ◽  
Spray Angle ◽  
Large Momentum ◽  
Biodiesel Fuels ◽  
Injection Pressures

Great attention is directed towards the study of the spray phenomena theoretically and experimentally due to its dramatic effect on the combustion process that occurred in an internal combustion engine, in particular, the diesel engine. The spray macroscopic characteristic of diesel engines fueled with two different biodiesel fuels in addition to nominal diesel under various injection pressures has been investigated numerically in this work. The selected biofuels are Rapeseed methyl ester (RME), Waste cooking oil methyl ester (WCOME). The Russian simulation software Diesel-RK is used in this work. Four different injection pressures are used which are 200, 500, 800 and 1000 bar respectively. It is found that RME has higher spray penetration with a narrow spray angle due to high viscosity and large momentum compared to diesel fuel. The results reported that biodiesels have greater Sauter mean diameter (SMD) compared to pure diesel because of their higher viscosity and surface tension. Promising reduction in SMD comes with WCOME as the injection pressure increases. Cylinder pressure along with heat release is reduced in the case of biodiesel due to the reduction in heating values. The lowest ability to produce smoke is recorded for WCOME where 93% reduction is achieved followed by a 57% reduction for RME as compared to diesel. The obtained results are compared with the results of other researcher and the convergence between them is observed.

A CFD Study on Heavy Duty DI Diesel Engine to Achieve Ultra-Low Emissions

2010 ◽  
Author(s):  
M. Yilmaz ◽  
H. Koten ◽  
M. Zafer Gul
Keyword(s):  
Diesel Engine ◽  
Cfd Simulation ◽  
Combustion Engine ◽  
Direct Injection ◽  
Spray Angle ◽  
Combustion Model ◽  
Multiphase Model ◽  
Heavy Duty ◽  
Start Of Injection ◽  
Main Injection

Nowadays, automotive industries focused on clean diesel combustion in their combustion processes are investigated for their potential to achieve near zero particulate and NOx (Nitrogen oxides) emissions. Their main disadvantages are increased level of unburned hydrocarbons (HC) and carbon monoxide (CO) emissions, combustion control at high load, power output and limited operating range. The simulation of the air flow, spray and combustion in an internal combustion engine were prepared for a single cylinder of a nine-liter, six cylinder diesel engine. Many times the geometry is complex because moving pistons and valves are involved, which makes it difficult to generate structured mesh. In-cylinder spray-air motion interaction, a Lagrangian multiphase model has been applied in a heavy-duty CI engine under direct injection conditions. A comprehensive model for atomization of liquid sprays under high injection pressures has been employed. Three dimensional CFD calculations of the intake, compression and power strokes have been carried out with different spray angle, spray profile and start of injection. A new combustion model ECFM-3Z (Extended Coherent Flame Model) developed at IFP is used for combustion modeling. Finally, a calculation on an engine configuration with compression, spray injection and combustion in a direct injection Diesel engine is presented. In this study, exhaust emissions, and particularly the emission of NOx, CO and soot derived from premixed combustion are investigated, and the relationship between combustion and emission characteristics are showed. The calculated CFD simulation in different combustion cases was compared. The cases were prepared by changing the parameters: start of injection, spray angle and spray profile. Modeling of combustion proposed in the present study can be outlined as follows. NOx concentration is decreased by combustion of a over lean-mixture modeled by the pre-injection. Most of pre-mixture is combusted by main-injection, and therefore the amount of pre-injection and main-injection come into prominence. The results are greatly in agreement qualitatively with the previous experimental and computational studies in the literature.

Three-Dimensional Simulation of Gaseous Fuel Injection Through a Hybrid Approach

2010 ◽  
Vol 132 (7) ◽  
Author(s):  
L. Andreassi ◽  
A. L. Facci ◽  
S. Ubertini
Keyword(s):  
Fuel Injection ◽  
Combustion Engine ◽  
Direct Injection ◽  
Hybrid Approach ◽  
Three Dimensional ◽  
Air Entrainment ◽  
Gaseous Fuel ◽  
Injection System ◽  
Injection Process ◽  
Dimensional Simulation

Direct injection of gaseous fuel has emerged to be a high potential strategy to tackle both environmental and fuel economy requirements. However, since the electronic gaseous injection technology is rather new for automotive applications, limited experience exists on the optimum configuration of the injection system and the combustion chamber. To facilitate the development of these applications computer models are being developed to simulate gaseous injection, air entrainment, and the ensuing combustion. This paper introduces a new method for modeling the injection process of gaseous fuels in multidimensional simulations. The proposed model allows holding down grid requirements, thus, making it compatible with the three-dimensional simulation of an internal combustion engine.

scholarly journals Numerical Analysis of GDI Flash Boiling Sprays Using Different Fuels

Energies ◽  
2021 ◽  
Vol 14 (18) ◽  
pp. 5925
Author(s):  
Raul Payri ◽  
Pedro Marti-Aldaravi ◽  
Rami Abboud ◽  
Abian Bautista
Keyword(s):  
Alternative Fuels ◽  
Fuel Injection ◽  
Ambient Pressure ◽  
Direct Injection ◽  
Saturation Pressure ◽  
Combustion Process ◽  
Gasoline Direct Injection ◽  
Injection Process ◽  
Engine Combustion ◽  
Flash Boiling

Modeling the fuel injection process in modern gasoline direct injection engines plays a principal role in characterizing the in–cylinder mixture formation and subsequent combustion process. Flash boiling, which usually occurs when the fuel is injected into an ambient pressure below the saturation pressure of the liquid, is characterized by fast breakup and evaporation rates but could lead to undesired behaviors such as spray collapse, which significantly effects the mixture preparation. Four mono–component fuels have been used in this study with the aim of achieving various flashing behaviors utilizing the Spray G injector from the Engine Combustion Network (ECN). The numerical framework was based on a Lagrangian approach and was first validated for the baseline G1 condition. The model was compared with experimental vapor and liquid penetrations, axial gas velocity, droplet sizes and spray morphology and was then extended to the flash boiling condition for iso–octane, n–heptane, n–hexane, and n–pentane. A good agreement was achieved for most of the fuels in terms of spray development and shape, although the computed spray morphology of pentane was not able to capture the spray collapse. Overall, the adopted methodology is promising and can be used for engine combustion modeling with conventional and alternative fuels.

scholarly journals CFD 3D Analysis of Charge Motion and Combustion in a Spark-Ignition Internal Combustion Engine under Close-to-Idle Condition

2020 ◽  
Vol 197 ◽  
pp. 06011
Author(s):  
Roberto Bozza ◽  
Vincenzo De Bellis ◽  
Stefano Fantoni ◽  
Donato Colangelo
Keyword(s):  
Combustion Engine ◽  
Early Stage ◽  
Local Level ◽  
Combustion Process ◽  
Spark Ignition ◽  
Operating Conditions ◽  
Transport Sector ◽  
3D Analysis ◽  
Charge Motion ◽  
Throttle Valve

The increasingly stringent limitations on noxious missions of transport sector highly affect the development of new engines. The operating conditions of the engine at low-load and idle play a relevant role along the regulatory homologation cycles, contributing to overall emissions. In this work, the effectiveness of some solutions to improve the behaviour under close-to-idle operation of a Spark-Ignition motorcycle engine are compared by 3D CFD analyses. Specifically, the effects of two designs of the intake port and of the opening direction of the throttle valve, either clockwise or counterclockwise, are investigated. Multi-cycle simulations are carried out, under motored and fired conditions, for a single close-to-idle operating point. The various designs are compared in terms of capability to generate a stable tumble vortex during the intake phase and to produce an adequate turbulence level at the beginning of the combustion process. The analyses revealed that a clockwise throttle opening can produce enhanced turbulence levels at the end of the compression stroke, especially in a close-to-spark region (increase of about 5% and 27 % at the TDC at a global and local level, respectively, compared to the base configuration). Additional limited improvements are obtained with the high tumbling design, where, however, a penalty on the maximum power output could emerge. The flow and turbulence motion differences among the tested geometries reflect on combustion development in its early stage, and on its degree of completeness at the exhaust valve opening. A clockwise opening of the throttle valve leads to an increase of the mass fraction burned of 5 percent points, compared to the base configuration.

scholarly journals Diagnosing of misfire events in compression-ignition engines with the help of vibroacoustic methods in the aspect of OBD system application in diesel locomotives

2008 ◽  
Vol 132 (1) ◽  
pp. 3-16
Author(s):  
Jerzy MERKISZ ◽  
Marek WALIGÓRSKI
Keyword(s):  
Internal Combustion Engines ◽  
Combustion Engine ◽  
High Reliability ◽  
Direct Injection ◽  
Combustion Process ◽  
Vibration Signal ◽  
Internal Combustion ◽  
Compression Ignition ◽  
Compression Ignition Engine ◽  
Railway Traction

The article concerns the possibilities of use of the method being able to assess of the combustion process and its lack in internal combustion engines of railway traction vehicles, that bases on the use of vibration signal parameters. The paper includes the results of research conducted on the engine test bench with a single cylinder research and compression-ignition engine with direct injection, and tests for the engine of a diesel locomotive in the exploitation condition. Possibility of the vibration signal estimators application to the assessment of a combustion process lack in an internal combustion engine and a high reliability of combustion process diagnostics basing on the above method have been proved.

CFD Analysis of the Scavenging Process in Marine Two-Stroke Diesel Engines

2014 ◽  
Author(s):  
Fredrik H. Andersen ◽  
Johan Hult ◽  
Karl-Johan Nogenmyr ◽  
Stefan Mayer
Keyword(s):  
Diesel Engines ◽  
Axial Velocity ◽  
Fuel Injection ◽  
Vortex Breakdown ◽  
Combustion Engine ◽  
Combustion Process ◽  
Tangential Velocity ◽  
Engine Performance ◽  
Adverse Pressure Gradient ◽  
Bottom Dead Center

The scavenging process is an integral part of any two-stroke internal combustion engine regardless of being spark ignited (SI) or compression ignited (CI). The scavenging process is responsible for replacing the burned gas from the combustion process from the previous working stroke with fresh air/charge before the subsequent compression stroke. This implies that the scavenging process is integral to engine performance as it influence the initial condition for the combustion process, thus affecting the fuel economy, power output and emission of hazardous gases. Two-stroke diesel engines for marine propulsion normally operates by the uniflow scavenging method, where the scavenge air enters the cylinder via inlet ports located near the bottom dead center and exits through one or several exhaust valves located in the cylinder head. This arrangement concentrates the airflow in one direction through the cylinder thus giving the method its name. The inlet ports are angled with respect to the local radius which will introduce a tangential velocity component to the air flow. The air moves axially through the cylinder in a swirling motion that favors mixing of fuel and air as the injected fuel is transported with the swirling air in the combustion chamber during fuel injection. A known characteristic of swirling flows is an adverse pressure gradient in the center of the rotating flow which might lead to a local deficit in axial velocity and the formation of central recirculation zones, known as vortex breakdown. Optimal scavenging is achieved when the gas exchange is done by displacement, the local deficit in axial velocity will increase the mixing of burned gas and scavenge air thus decreasing the amount of pure displacement.

scholarly journals Effects of Injector Spray Angle on Performance of an Opposed-Piston Free-Piston Engine

Energies ◽  
2020 ◽  
Vol 13 (14) ◽  
pp. 3735
Author(s):  
Qinglin Zhang ◽  
Zhaoping Xu ◽  
Shuangshuang Liu ◽  
Liang Liu
Keyword(s):  
Combustion Engine ◽  
Fluid Dynamic ◽  
Combustion Process ◽  
Three Dimensional ◽  
Mixture Distribution ◽  
Combustion Efficiency ◽  
Spray Angle ◽  
Piston Engine ◽  
Free Piston ◽  
Free Piston Engine

A free-piston engine is a novel internal combustion engine which has the advantages of a variable compression ratio and multi-fuel adaptability. This paper focuses on numerical simulation for combustion process and spray angle optimization of an opposed-piston free-piston engine. The working principle and spray-guided central combustor structure of the engine are discussed. A three-dimensional computational fluid dynamic model with moving mesh is presented based on the tested piston motion of the prototype. Calculation conditions, spray models, and combustion models were set-up according to the same prototype. The effects of spray angle on fuel evaporation rate, mixture distribution, heat release rate, in-cylinder pressure, in-cylinder temperature, and emissions were simulated and analyzed in detail. The research results indicate that the performance of the engine was very sensitive to the spray angle. The combustion efficiency and the indicated thermal efficiencies of 97.5% and 39.7% were obtained as the spray angle reached 40°.

Study of Combustion Anomalies of H2-ICE With External Mixture Formation

2006 ◽  
Author(s):  
Stephen A. Ciatti ◽  
Thomas Wallner ◽  
Henry Ng ◽  
William F. Stockhausen ◽  
Brad Boyer
Keyword(s):  
Internal Combustion Engines ◽  
Large Scale ◽  
High Efficiency ◽  
Combustion Engine ◽  
Direct Injection ◽  
Combustion Process ◽  
Engine Performance ◽  
Internal Combustion ◽  
Hydrogen Combustion ◽  
Mixture Formation

Although hydrogen is considered one of the most promising future energy carriers, there are several challenges to achieving a “hydrogen economy,” including finding a practical, efficient, cost-effective end-use device. Using hydrogen as a fuel for internal combustion engines is seen as a bridging technology toward a large-scale hydrogen infrastructure. To facilitate high-efficiency, high-power-density use of hydrogen with near-zero emissions in an internal combustion engine, detailed analysis of the hydrogen combustion process is necessary. This paper presents thermodynamic results regarding engine performance and emissions behavior during investigations performed on a single-cylinder research engine fueled by pressurized gaseous hydrogen. Avoiding combustion anomalies is one of the necessary steps to further improve the hydrogen engine power output at high-load operation while, at the same time, reducing fuel consumption and emissions during part-load operation. The overall target of the investigations is an improved combustion concept especially designed for hydrogen-engine-powered vehicles. Future activities include performing optical imaging of hydrogen combustion by using an endoscope. We will also investigate supercharged external mixture formation, as well as hydrogen direct-injection operation.

Sign in / Sign up

Export Citation Format

Share Document