The Impact of Swirl Ratio and Injection Pressure on Fuel-Air Mixing in a Light-Duty Diesel Engine

2012 ◽  
Author(s):  
Dipankar Sahoo ◽  
Benjamin R. Petersen ◽  
Paul C. Miles
Keyword(s):  
Diesel Engine ◽  
Heat Release ◽  
Mixture Distribution ◽  
Injection Pressure ◽  
Operating Mode ◽  
Swirl Ratio ◽  
Rich Mixture ◽  
Light Duty ◽  
Start Of Injection ◽  
The Impact

Toluene fuel-tracer laser-induced fluorescence is employed to quantitatively measure the equivalence ratio distributions in the cylinder of a light-duty diesel engine operating in a low-temperature, high-EGR, and early-injection operating mode. Measurements are made in a non-combusting environment at crank angles capturing the mixture preparation period: from the start-of-injection through the onset of high-temperature heat release. Three horizontal planes are considered: within the clearance volume, the bowl rim region, and the lower bowl. Swirl ratio and injection pressure are varied independently, and the impact of these parameters on the mixture distribution is correlated to the heat release rate and the engine-out emissions. As the swirl ratio or injection pressure is increased, the amount of over-lean mixture in the upper central region of the combustion chamber, in the bowl rim region and above, also increases. Unexpectedly, increased injection pressure results in a greater quantity of over-rich mixture within the squish volume.

Effect of Swirl Ratio and Injection Pressure on Autoignition, Combustion and Emissions in a High Speed Direct Injection Diesel Engine Fuelled With Biodiesel (B-20)

2009 ◽  
Author(s):  
Vinay Nagaraju ◽  
Mufaddel Dahodwala ◽  
Kaushik Acharya ◽  
Walter Bryzik ◽  
Naeim A. Henein
Keyword(s):  
Diesel Engine ◽  
High Speed ◽  
Direct Injection ◽  
Injection Pressure ◽  
Combustible Mixture ◽  
Injection System ◽  
Ignition Process ◽  
Swirl Ratio ◽  
Mixture Formation ◽  
Physical And Chemical

Biodiesel has different physical and chemical properties than ultra low sulfur diesel fuel (ULSD). The low volatility of biodiesel is expected to affect the physical processes, mainly fuel evaporation and combustible mixture formation. The higher cetane number of biodiesel is expected to affect the rates of the chemical reactions. The combination of these two fuel properties has an impact on the auto ignition process, subsequently combustion and engine out emissions. Applying different swirl ratios and injection pressures affect both the physical and chemical processes. The focus of this paper is to investigate the effect of varying the swirl ratio and injection pressure in a single-cylinder research diesel engine using a blend of biodiesel and ULSD fuel. The engine is a High Speed Direct Injection (HSDI) equipped with a common rail injection system, EGR system and a swirl control mechanism. The engine is operated under simulated turbocharged conditions with 3 bar Indicated Mean Effective Pressure (IMEP) at 1500 rpm, using 100% ULSD and a blend of 20% biodiesel and 80% ULSD fuel. The biodiesel is developed from soy bean oil. A detailed analysis of the apparent rate of heat release (ARHR) is made to determine the role of the biodiesel component of B-20 in the combustible mixture formation, autoignition process, premixed, mixing controlled and diffusion controlled combustion fractions. The results explain the factors that cause an increase or a drop in NOx emissions reported in the literature when using biodiesel.

A Study on the Calculation of Heat Release Rate to Compensate the Error Due to Single Zone Assumption in Diesel Engine

2005 ◽  
Author(s):  
Seung Hyup Ryu ◽  
Ki Doo Kim ◽  
Wook Hyeon Yoon ◽  
Ji Soo Ha
Keyword(s):  
Diesel Engine ◽  
Heat Release ◽  
Computational Analysis ◽  
Combustion Process ◽  
Operating Conditions ◽  
Zone Model ◽  
Specific Heats ◽  
Start Of Injection ◽  
Release Analysis ◽  
Improved Model

Accurate heat release analysis based on the cylinder pressure trace is important for evaluating combustion process of diesel engines. However, traditional single-zone heat release models (SZM) have significant limitations due mainly to their simplified assumptions of uniform charge and homogeneity while neglecting local temperature distribution inside cylinder during combustion process. In this study, a heat release analysis based on single-zone model has been evaluated by comparison with computational analysis result using Fire-code, which is based on multi-dimensional model (MDM). The limitations of the single-zone assumption have been estimated. To overcome these limitations, an improved model that includes the effects of spatial non-uniformity has been applied. From this improved single-zone heat release model (Improved-SZM), two effective values of specific heats ratios, denoted by γV and γH in this study, have been introduced. These values are formulated as the function of charge temperature changing rate and overall equivalence ratio by matching the results of the single-zone analysis to those of computational analysis using Fire-code about medium speed marine diesel engine. Also, it is applied that each equation of γV and γH has respectively different slopes according to several meaningful regions such as the start of injection, the end of injection, the maximum cylinder temperature, and the exhaust valve open. This calculation method based on improved single-zone model gives a good agreement with Fire-code results over the whole range of operating conditions.

Quasi-Dimensional Diesel Engine Combustion Modeling With Improved Diesel Spray Tip Penetration, Ignition Delay, and Heat Release Submodels

2017 ◽  
Vol 139 (11) ◽  
Author(s):  
Shuonan Xu ◽  
Hirotaka Yamakawa ◽  
Keiya Nishida ◽  
Zoran Filipi
Keyword(s):  
Diesel Engine ◽  
Heat Release ◽  
Diesel Engines ◽  
Ignition Delay ◽  
Air Entrainment ◽  
Oxygen Mixture ◽  
Diesel Spray ◽  
Spray Tip Penetration ◽  
Simulation Tools ◽  
The Impact

Increasingly stringent fuel economy and CO2 emission regulations provide a strong impetus for development of high-efficiency engine technologies. Diesel engines dominate the heavy duty market and significant segments of the global light duty market due to their intrinsically higher thermal efficiency compared to spark-ignited (SI) engine counterparts. Predictive simulation tools can significantly reduce the time and cost associated with optimization of engine injection strategies, and enable investigation over a broad operating space unconstrained by availability of prototype hardware. In comparison with 0D/1D and 3D simulations, Quasi-Dimensional (quasi-D) models offer a balance between predictiveness and computational effort, thus making them very suitable for enhancing the fidelity of engine system simulation tools. A most widely used approach for diesel engine applications is a multizone spray and combustion model pioneered by Hiroyasu and his group. It divides diesel spray into packets and tracks fuel evaporation, air entrainment, gas properties, and ignition delay (induction time) individually during the injection and combustion event. However, original submodels are not well suited for modern diesel engines, and the main objective of this work is to develop a multizonal simulation capable of capturing the impact of high-injection pressures and exhaust gas recirculation (EGR). In particular, a new spray tip penetration submodel is developed based on measurements obtained in a high-pressure, high-temperature constant volume combustion vessel for pressures as high as 1450 bar. Next, ignition delay correlation is modified to capture the effect of reduced oxygen concentration in engines with EGR, and an algorithm considering the chemical reaction rate of hydrocarbon–oxygen mixture improves prediction of the heat release rates. Spray and combustion predictions were validated with experiments on a single-cylinder diesel engine with common rail fuel injection, charge boosting, and EGR.

Effects of Different Biodiesel Blends on Heat Release and Its Related Parameters

2006 ◽  
Author(s):  
Girish Parvate-Patil ◽  
Manuel Vasquez ◽  
Malcolm Payne
Keyword(s):  
Diesel Engine ◽  
Heat Release ◽  
Fuel Injection ◽  
Load Condition ◽  
Engine Performance ◽  
Injection Pressure ◽  
Single Cylinder ◽  
Medium Speed ◽  
Performance And Emissions ◽  
Fuel Injection Pressure

This paper emphasizes on the effects of different biodiesels and diesel on; heat release, ignition delay, endothermic and exothermic reactions, NOx, fuel injection pressure due to the fuel’s modulus of elasticity and cylinder pressure. Two 100% biodiesel and its blends of 20% with of low sulfur #2 diesel, and #2 diesel are tested on a single cylinder diesel engine under full load condition. Engine performance and emissions data is obtained for 100% and 20% biodiesels blends and #2 diesel. Testes were conducted at Engine Systems Development Centre, Inc. (ESDC) to evaluate the effects of biodiesel and its blends on the performance and emissions of a single-cylinder medium-speed diesel engine. The main objective of this work was to gain initial information and experience about biodiesel for railway application based on which biodiesel and its blends could be recommended for further investigation on actual locomotives.

Optimization of Injector Spray Configurations for an HSDI Diesel Engine at High Load

2007 ◽  
Author(s):  
Michael J. Bergin ◽  
Rolf D. Reitz
Keyword(s):  
Diesel Engine ◽  
Large Diameter ◽  
Orientation Angle ◽  
Merit Function ◽  
High Load ◽  
Operating Conditions ◽  
Injection Timing ◽  
Swirl Ratio ◽  
Start Of Injection ◽  
Hsdi Diesel Engine

CFD simulations were conducted with the KIVA-3v code with improved spray and combustion sub-models. Combustion analysis was performed using micro-genetic optimizations for a 1.9L HSDI diesel engine at a high load operating conditions (∼15 bar imep). The study explored injector spray configurations, including the number of injector nozzle holes, the hole diameters, and their orientations. The engine swirl ratio and start-of-injection timing were also varied. The optimizations considered injector nozzles with 14, 12, 10 and 8 injector holes. Each configuration included consideration of a pair of injector holes. Variations in the orientation angle of the first hole were explored. For the second hole, both the orientation angle and the azimuthal spacing relative to the first hole were varied. The chosen parameters allowed the holes to be symmetrically spaced or coincident azimuthally. The performance of each simulation was based on a merit function which accounts for fuel economy, NOx and soot emissions. For the test conditions chosen, an 8-hole injector configuration was found to be the best. This is explained by the improved fuel spray penetration and mixing associated with a smaller number of large diameter nozzle holes. For all injector configurations, the optima selected groups of holes where the total angular spacing between holes was less than eight degrees. The optimum swirl ratio found was approximately that of the baseline engine design.

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