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Technical Paper

The Effect of Fuel Injection Pressure on Spray and Combustion Characteristics in a Gasoline Direct-Injection Engine

2014-10-13
2014-01-2604
A single-cylinder gasoline direct-injection engine was used for fuel spray and combustion visualizations with optical access to the combustion chamber. Experiments were conducted to investigate the effect of fuel injection pressure on spray and combustion characteristics inside the engine cylinder. A multi-hole high-pressure production injector was used with fuel pressures of 5 and 10 MPa. A Mie scattering technique was used to image the liquid phase of the fuel dispersion. The obtained spray images were then used to study the macroscopic spray characteristics such as spray structure, spray tip penetration and spray angle. Combustion visualization tests were performed to evaluate the effect of fuel injection pressure on combustion characteristics. In-cylinder pressure signals were recorded for the combustion analyses and synchronized with the high-speed combustion imaging recording.
Technical Paper

POD-Based Analysis of In-Cylinder Flow Data from Molecular Tagging Velocimetry in a Spark-Ignition Engine

2018-09-10
2018-01-1770
The fluid motion inside the engine cylinder is transient, three-dimensional and highly turbulent. It is also well known that cycle-to-cycle flow variations have a considerable influence on cycle-to-cycle combustion variations. Laser-based diagnostic techniques, for example, particle image velocimetry (PIV) or molecular tagging velocimetry, can be used to measure two or three components of the velocity field simultaneously at multiple locations over a plane. The use of proper orthogonal decomposition (POD) allows quantification of cycle-to-cycle flow variations, as demonstrated using PIV data [1]. In the present work, POD is used to explore the cycle-to-cycle flow variations utilizing molecular tagging velocimetry data. The instantaneous velocity fields were obtained over a swirl measurement plane when engine was operated at 1500 rpm and 2500 rpm.
Technical Paper

In-cylinder Combustion Visualization of a Direct-injection Spark-ignition Engine with Different Operating Conditions and Fuels

2012-09-10
2012-01-1644
A direct-injection and spark-ignition single-cylinder engine with optical access to the cylinder was used for the combustion visualization study. Gasoline and ethanol-gasoline blended fuels were used in this investigation. Experiments were conducted to investigate the effects of fuel injection pressure, injection timing and the number of injections on the in-cylinder combustion process. Two types of direct fuel injectors were used; (i) high-pressure production injector with fuel pressures of 5 and 10 MPa, and (ii) low-pressure production-intent injector with fuel pressure of 3 MPa. Experiments were performed at 1500 rpm engine speed with partial load. In-cylinder pressure signals were recorded for the combustion analyses and synchronized with the high-speed combustion imaging recording. Visualization results show that the flame growth is faster with the increment of fuel injection pressure.
Journal Article

High-Speed Flow and Combustion Visualization to Study the Effects of Charge Motion Control on Fuel Spray Development and Combustion Inside a Direct-Injection Spark-Ignition Engine

2011-04-12
2011-01-1213
An experimental study is performed to investigate the effects of charge motion control on in-cylinder fuel-air mixture preparation and combustion inside a direct-injection spark-ignition engine with optical access to the cylinder. High-pressure production injector is used with fuel pressures of 5 and 10 MPa. Three different geometries of charge motion control (CMC) device are considered; two are expected to enhance the swirl motion inside the engine cylinder whereas the third one is expected to enhance the tumble motion. Experiments are performed at 1500 rpm engine speed with the variation in fuel injection timing, fuel pressure and the number of injections. It is found that swirl-type CMC devices significantly enhance the fuel-air mixing inside the engine cylinder with slower spray tip penetration than that of the baseline case without CMC device. Combustion images show that the flame growth is faster with CMC device compared to the similar case without CMC device.
Technical Paper

Effect of Fuel Injection Timing on the Mixture Preparation in a Small Gasoline Direct-Injection Engine

2018-10-30
2018-32-0014
Gasoline direct-injection (GDI) engines have evolved as a solution to meet the current demands of the automotive industry. Benefits of a GDI engine include good fuel economy, good transient response, and low cold start emissions. However, they suffer from problems, like combustion instability, misfire, and impingement of fuel on in-cylinder surfaces. Therefore, to highlight the influence of fuel injection timing on in-cylinder flow, turbulence, mixture distribution and wall impingement, a computational study is conducted on a small-bore GDI engine. Results showed that air motion inside the engine cylinder is influenced by direct-injection of fuel, with considerable variation in turbulent kinetic energy at the time of injection. Due to charge cooling effect, mixture density and trapped mass were increased by about 10.8% and 9.5%, respectively.
Technical Paper

Design Features of Optically Accessible Engines for Flow and Combustion Studies - A Review

2018-09-10
2018-01-1775
For long time, the measurement of spatially and temporally varying quantities like in-cylinder flow, mixing, and burning in an internal combustion engine remained impossible due to the lack of access to the engine cylinder. Hence, for quite some time, in-cylinder pressure remained the only quantity that could be temporally measured during an engine cycle, and the variations of quantities like temperature, heat release deduced from it. However, to guide modern engine developments for improved fuel economy and reduced emissions, understanding the intricacies of in-cylinder processes are essential. The advent of optical engine in conjunction with laser-based diagnostic techniques enabled measurement of various in-cylinder processes and study their influences on the combustion process. This paper highlights some key design features of optically accessible engines for flow and combustion studies.
Technical Paper

Combustion and Gaseous Emissions Characteristics of a Six-Cylinder Diesel Engine Operating within Wide Range of Natural Gas Substitutions at Different Operating Conditions for Generator Application

2014-04-01
2014-01-1312
The aim of this work is to study the combustion and gaseous emissions characteristics of a diesel engine dual-fueled with natural gas at different operating conditions (light to full load) for generator application. The electromechanical system was composed of a commercially available 18 liter, 6-cylinder diesel engine, coupled with the generator rated at 600 kWe at full-load. The flow of natural gas was electronically controlled using a throttle valve, and was inducted in the intake manifold before being introduced into the combustion chambers. Gaseous emissions of carbon monoxide (CO), hydrocarbons (HC) and nitrogen oxides (NOx) were measured under both diesel and dual fuel operations at different loads. This work also presents the effects of diesel oxidation catalyst to reduce HC and CO emissions under dual fuel operation. At each operating load, gas percentage was increased with corresponding decrease in diesel pilot while maintaining the same power output.
Technical Paper

Assessing the Effect of Compression Ratio on the Performance, Combustion and Emission Characteristics of a Spark-Ignition Engine, and Optimum Spark Advance at Different Operating Conditions

2018-09-10
2018-01-1668
Nowadays, emission regulations and the requirement to reduce greenhouse gas emissions have escalated engine development efforts. In the present work, the effect of compression ratio on the performance, combustion and emission characteristics of a spark-ignition engine is evaluated at different operating conditions. A single-cylinder, water-cooled, spark-ignition engine (modified from a compression-ignition version) was used, with combustion chamber geometry consisted of flat cylinder head and a hemispherical bowl in the piston. Results showed that the brake thermal efficiency was increased from 9.8% to 12.9% when compression ratio was increased from 6.7:1 to 9.4:1 at low operating load of 5 N-m. Carbon monoxide emission was decreased when compression ratio was increased at all operating loads. However, as expected, nitric oxide emission was increased with the increase in compression ratio, with lower difference at low loads compared to medium and high loads.
Technical Paper

A Study of Fuel Impingement Analysis on In-Cylinder Surfaces in a Direct-Injection Spark-Ignition Engine with Gasoline and Ethanol-Gasoline Blended Fuels

2010-10-25
2010-01-2153
An experimental study is performed to investigate the fuel impingement on cylinder walls and piston top inside a direct-injection spark-ignition engine with optical access to the cylinder. Three different fuels, namely, E85, E50 and gasoline are used in this work. E85 represents a blend of 85 percent ethanol and 15 percent gasoline by volume. Experiments are performed at different load conditions with the engine speeds of 1500 and 2000 rpm. Two types of fuel injectors are used; (i) High-pressure production injector with fuel pressures of 5 and 10 MPa, and (ii) Low-pressure production-intent injector with fuel pressure of 3 MPa. In addition, the effects of split injection are also presented and compared with the similar cases of single injection by maintaining the same amount of fuel for the stoichiometric condition. Novel image processing algorithms are developed to analyze the fuel impingement quantitatively on cylinder walls and piston top inside the engine cylinder.
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