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.

Two-Stroke Marine Diesel Engine Variable Injection Timing System Performance Evaluation and Optimum Setting for Minimum Fuel Consumption at Acceptable NOx Levels

2014 ◽  
Author(s):  
Dimitrios T. Hountalas ◽  
Spiridon Raptotasios ◽  
Antonis Antonopoulos ◽  
Stavros Daniolos ◽  
Iosif Dolaptzis ◽  
...  
Keyword(s):  
Diesel Engine ◽  
Fuel Consumption ◽  
Engine Performance ◽  
Operating Conditions ◽  
Specific Fuel Consumption ◽  
Injection Timing ◽  
Nox Emissions ◽  
Pressure Measurements ◽  
Cylinder Pressure ◽  
Start Of Injection

Currently the most promising solution for marine propulsion is the two-stroke low-speed diesel engine. Start of Injection (SOI) is of significant importance for these engines due to its effect on firing pressure and specific fuel consumption. Therefore these engines are usually equipped with Variable Injection Timing (VIT) systems for variation of SOI with load. Proper operation of these systems is essential for both safe engine operation and performance since they are also used to control peak firing pressure. However, it is rather difficult to evaluate the operation of VIT system and determine the required rack settings for a specific SOI angle without using experimental techniques, which are extremely expensive and time consuming. For this reason in the present work it is examined the use of on-board monitoring and diagnosis techniques to overcome this difficulty. The application is conducted on a commercial vessel equipped with a two-stroke engine from which cylinder pressure measurements were acquired. From the processing of measurements acquired at various operating conditions it is determined the relation between VIT rack position and start of injection angle. This is used to evaluate the VIT system condition and determine the required settings to achieve the desired SOI angle. After VIT system tuning, new measurements were acquired from the processing of which results were derived for various operating parameters, i.e. brake power, specific fuel consumption, heat release rate, start of combustion etc. From the comparative evaluation of results before and after VIT adjustment it is revealed an improvement of specific fuel consumption while firing pressure remains within limits. It is thus revealed that the proposed method has the potential to overcome the disadvantages of purely experimental trial and error methods and that its use can result to fuel saving with minimum effort and time. To evaluate the corresponding effect on NOx emissions, as required by Marpol Annex-VI regulation a theoretical investigation is conducted using a multi-zone combustion model. Shop-test and NOx-file data are used to evaluate its ability to predict engine performance and NOx emissions before conducting the investigation. Moreover, the results derived from the on-board cylinder pressure measurements, after VIT system tuning, are used to evaluate the model’s ability to predict the effect of SOI variation on engine performance. Then the simulation model is applied to estimate the impact of SOI advance on NOx emissions. As revealed NOx emissions remain within limits despite the SOI variation (increase).

CFD Modelling of the Effects of Injection Timing on the Combustion Process and Emissions in an HSDI Diesel Engine

2012 ◽  
Author(s):  
Raouf Mobasheri ◽  
Zhijun Peng
Keyword(s):  
Diesel Engine ◽  
High Speed ◽  
Cfd Simulation ◽  
Direct Injection ◽  
Combustion Process ◽  
Injection Timing ◽  
Cfd Modelling ◽  
Combustion Modeling ◽  
Pressure Trace ◽  
Hsdi Diesel Engine

High-Speed Direct Injection (HSDI) diesel engines are increasingly used in automotive applications due to superior fuel economy. An advanced CFD simulation has been carried out to analyze the effect of injection timing on combustion process and emission characteristics in a four valves 2.0L Ford diesel engine. The calculation was performed from intake valve closing (IVC) to exhaust valve opening (EVO) at constant speed of 1600 rpm. Since the work was concentrated on the spray injection, mixture formation and combustion process, only a 60° sector mesh was employed for the calculations. For combustion modeling, an improved version of the Coherent Flame Model (ECFM-3Z) has been applied accompanied with advanced models for emission modeling. The results of simulation were compared against experimental data. Good agreement of calculated and measured in-cylinder pressure trace and pollutant formation trends were observed for all investigated operating points. In addition, the results showed that the current CFD model can be applied as a beneficial tool for analyzing the parameters of the diesel combustion under HSDI operating condition.

scholarly journals Influence of the diesel pilot injector configuration on ethanol combustion and performance of a heavy-duty direct injection engine

2021 ◽  
pp. 146808742110012
Author(s):  
Nicola Giramondi ◽  
Anders Jäger ◽  
Daniel Norling ◽  
Anders Christiansen Erlandsson
Keyword(s):  
Direct Injection ◽  
Engine Performance ◽  
High Load ◽  
Operating Conditions ◽  
Injection System ◽  
Injection Timing ◽  
Diesel Combustion ◽  
Heavy Duty ◽  
Pure Ethanol ◽  
Ethanol Combustion

Thanks to its properties and production pathways, ethanol represents a valuable alternative to fossil fuels, with potential benefits in terms of CO2, NOx, and soot emission reduction. The resistance to autoignition of ethanol necessitates an ignition trigger in compression-ignition engines for heavy-duty applications, which in the current study is a diesel pilot injection. The simultaneous direct injection of pure ethanol as main fuel and diesel as pilot fuel through separate injectors is experimentally investigated in a heavy-duty single cylinder engine at a low and a high load point. The influence of the nozzle hole number and size of the diesel pilot injector on ethanol combustion and engine performance is evaluated based on an injection timing sweep using three diesel injector configurations. The tested configurations have the same geometric total nozzle area for one, two and four diesel sprays. The relative amount of ethanol injected is swept between 78 – 89% and 91 – 98% on an energy basis at low and high load, respectively. The results show that mixing-controlled combustion of ethanol is achieved with all tested diesel injector configurations and that the maximum combustion efficiency and variability levels are in line with conventional diesel combustion. The one-spray diesel injector is the most robust trigger for ethanol ignition, as it allows to limit combustion variability and to achieve higher combustion efficiencies compared to the other diesel injector configurations. However, the two- and four-spray diesel injectors lead to higher indicated efficiency levels. The observed difference in the ethanol ignition dynamics is evaluated and compared to conventional diesel combustion. The study broadens the knowledge on ethanol mixing-controlled combustion in heavy-duty engines at various operating conditions, providing the insight necessary for the optimization of the ethanol-diesel dual-injection system.

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.

Startup and Steady-State Performance of a New Renewable Hydroprocessed Depolymerized Cellulosic Diesel Fuel in Multiple Diesel Engines

2016 ◽  
Vol 138 (10) ◽  
Author(s):  
Eric Bermudez ◽  
Andrew McDaniel ◽  
Terrence Dickerson ◽  
Dianne Luning Prak ◽  
Len Hamilton ◽  
...  
Keyword(s):  
Steady State ◽  
Diesel Engine ◽  
Cetane Number ◽  
Operating Conditions ◽  
Engine Operation ◽  
Start Of Injection ◽  
Ignition Quality ◽  
Engine Testing ◽  
Engine Start ◽  
Distillate Fuel

A new hydroprocessed depolymerized cellulosic diesel (HDCD) fuel has been developed using a process which takes biomass feedstock (principally cellulosic wood) to produce a synthetic fuel that has nominally ½ cycloparaffins and ½ aromatic hydrocarbons in content. This HDCD fuel with a low cetane value (derived cetane number from the ignition quality tester, DCN = 27) was blended with naval distillate fuel (NATO symbol F-76) in various quantities and tested in order to determine how much HDCD could be blended before diesel engine operation becomes problematic. Blends of 20% HDCD (DCN = 45), 30%, 40% (DCN = 41), and 60% HDCD (DCN = 37) by volume were tested with conventional naval distillate fuel (DCN = 49). Engine start performance was evaluated with a conventional mechanically direct injected (DI) Yanmar engine and a Waukesha mechanical indirect injected (IDI) Cooperative Fuels Research (CFR) diesel engine and showed that engine start times increased steadily with increasing HDCD content. Longer start times with increasing HDCD content were the result of some engine cycles with poor combustion leading to a slower rate of engine acceleration toward rated speed. A repeating sequence of alternating cycles which combust followed by a noncombustion cycle was common during engine run-up. Additionally, steady-state engine testing was also performed using both engines. HDCD has a significantly higher bulk modulus than F76 due to its very high aromatic content, and the engines showed earlier start of injection (SOI) timing with increasing HDCD content for equivalent operating conditions. Additionally, due to the lower DCN, the higher HDCD blends showed moderately longer ignition delay (IGD) with moderately shorter overall burn durations. Thus, the midcombustion metric (CA50: 50% burn duration crank angle position) was only modestly affected with increasing HDCD content. Increasing HDCD content beyond 40% leads to significantly longer start times.

Impact of Intake Induced Swirl on Combustion and Emissions on a Single Cylinder Diesel Engine

2016 ◽  
Author(s):  
Eduardo Barrientos ◽  
Ivan Bortel ◽  
Michal Takats ◽  
Jiri Vavra
Keyword(s):  
Diesel Engine ◽  
Heat Release ◽  
Operating Conditions ◽  
Common Rail ◽  
Injection System ◽  
Nox Emissions ◽  
Cylinder Pressure ◽  
Swirl Ratio ◽  
Single Cylinder ◽  
Optimal Values

Engine induced swirl improves mixing of fuel and air and at optimal values accelerates burn, improves the combustion stability and can decrease particulate matter (PM). However, swirl increases convective heat loss and cylinder charge loss and could increase nitrogen oxides (NOx) emissions. High intensity of swirl could impede flame development and increases emissions of total hydrocarbons (THC) and carbon monoxide (CO). Therefore, careful and smart selection of optimal swirl values is paramount in order to obtain beneficial impact on combustion and emissions performance. This study is conducted on a 0.5L single cylinder research engine with common rail (CR) diesel injection system, with parameters corresponding to modern engines of passenger cars. The engine has three separate ports in the cylinder head. The change of swirl ratio is defined by closing appropriate ports. There are three levels of swirl ratio under study — 1.7, 2.9 and 4.5, corresponding to low, medium and high swirl levels respectively. This study highlights the influence of intake induced swirl on combustion parameters and emissions. Assessed combustion parameters are, among others, heat release rate, cylinder pressure rise and indicated mean effective pressure. Assessed emissions are standard gaseous emissions and smoke, with emphasis on PM emissions. An engine speed of 1500 rpm was selected, which well represents common driving conditions of this engine size. Various common rail pressures are used at ambient inlet manifold pressure (without boost pressure) and at 1 bar boosted pressure mode. It is found that when the swirl level is increased, the faster heat release during the premixed combustion and during early diffusion-controlled combustion causes a quick increase in both in-cylinder pressure and temperature, thus promoting the formation of NOx. However, since swirl enhances mixing and potentially produces a leaning effect, PM formation is reduced in general. However, maximum peak temperature is lower for high swirl ratio and boosted modes due to the increase of heat transfer into cylinder walls. Furthermore, it is necessary to find optimal values of common rail pressures and swirl ratio. Too much mixing allows increase on PM, THC and CO emissions without decrease on NOx emissions in general. Common rail injection system provides enough energy to achieve good mixing during all the injection time in the cases of supercharged modes and high common rail pressure modes. Positive influence of swirl ratio is found at lower boost pressures, lower revolution levels and at lower engine loads. The results obtained here help providing a better understanding on the swirl effects on diesel engine combustion and exhaust emissions over a range of engine operating conditions, with the ultimate goal of finding optimal values of swirl operation.

Low-sooting combustion in a small-bore high-speed direct-injection diesel engine using narrow-angle injectors

2008 ◽  
Vol 222 (10) ◽  
pp. 1927-1937 ◽  
Author(s):  
T-G Fang ◽  
R E Coverdill ◽  
C-F F Lee ◽  
R A White
Keyword(s):  
Diesel Engine ◽  
High Speed ◽  
Direct Injection ◽  
Fuel Efficiency ◽  
Operating Conditions ◽  
Injection Timing ◽  
Exhaust Pipe ◽  
Injection Angle ◽  
Direct Injection Diesel Engine ◽  
Combustion Flame

An optically accessible high-speed direct-injection diesel engine was used to study the effects of injection angles on low-sooting combustion. A digital high-speed camera was employed to capture the entire cycle combustion and spray evolution processes under seven operating conditions including post-top-dead centre (TDC) injection and pre-TDC injection strategies. The nitrogen oxide (NO x) emissions were also measured in the exhaust pipe. In-cylinder pressure data and heat release rate calculations were conducted. All the cases show premixed combustion features. For post-TDC injection cases, a large amount of fuel deposition is seen for a narrower-injection-angle tip, i.e. the 70° tip, and ignition is observed near the injector tip in the centre of the bowl, while for a wider-injection-angle tip, namely a 110° tip, ignition occurs near the spray tip in the vicinity of the bowl wall. The combustion flame is near the bowl wall and at the central region of the bowl for the 70° tip. However, the flame is more distributed and centralized for the 110° tip. Longer spray penetration is found for the pre-TDC injection timing cases. Liquid fuel impinges on the bowl wall or on the piston top and a fuel film is formed. Ignition for all the pre-TDC injection cases occur in a distributed way in the piston bowl. Two different combustion modes are observed for the pre-TDC injection cases including a homogeneous bulky combustion flame at earlier crank angles and a heterogeneous film combustion mode with luminous sooting flame at later crank angles. In terms of soot emissions, NO x emissions, and fuel efficiency, results show that the late post-TDC injection strategy gives the best performance.

Control-Oriented Model Development and Experimental Validation for a Modern Diesel Engine

2020 ◽  
Author(s):  
Kuo Yang ◽  
Pingen Chen
Keyword(s):  
Diesel Engine ◽  
Diesel Engines ◽  
Model Development ◽  
Engine Performance ◽  
Operating Conditions ◽  
Least Square ◽  
Injection Timing ◽  
Model Based ◽  
Wide Range ◽  
Mean Square Errors

Abstract Modern Diesel engines have become highly complex multi-input multi-output systems. Controls of modern Diesel engines to meet various requirements such as high fuel efficiency and low NOx and particulate matter (PM) emissions, remain a great challenge for automotive control community. While model-based controls have demonstrated significant potentials in achieving high Diesel engine performance. Complete and high-fidelity control-oriented Diesel engine models are much needed as the foundations of model-based control system development. In this study, a semi-physical, mean-value control-oriented model of a turbocharged Diesel engine equipped with high-pressure exhaust gas recirculation (EGR) and variable geometry turbocharger (VGT) is developed and experimentally validated. The static calibration of Diesel engine model is achieved with the least-square optimization methodology using the experimental test data from a physical Diesel engine platform. The normalized root mean square errors (NRMSEs) of the calibration results are in the range of 0.1095 to 0.2582. The cross-validation results demonstrated that the model was capable of accurately capturing the engine torque output and NOx emissions with the control inputs of EGR, VGT and Start of Injection timing (SOI) in wide-range operating conditions.

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