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2017-09-16
Journal Article
2017-01-9182
Sheng Li, Cunfu Chen, Xingjun Hu, Jiexun Cao
Abstract The magnitude of door closing force is important in vehicle NVH characters, and in most case, it is not fully studied by computer aided engineering (CAE) in an early developing stage. The research took a heavy-duty truck as the study object and used Computational Fluid Dynamic (CFD) method with dynamic mesh to analyze the flow field of the cabin during door closing process. The change trend of pressure with time was obtained, and the influence of different factors was studied. The experiments were conducted to verify the results. Results show that the velocity of closing door and the size of relief holes have a significant influence on cabin interior pressure, and greater velocity leads to larger the pressure in cabin. The initial angle of the door affects interior pressure less comparing with the velocity of closing door. The interior pressure could be reduced effectively with the method of decreasing the velocity of closing door and increasing the size of relief holes.
2017-09-04
Technical Paper
2017-24-0043
Thomas Kammermann, Jann Koch, Yuri M. Wright, Patrik Soltic, Konstantinos Boulouchos
The interaction of turbulent premixed methane combustion with the surrounding flow field can be studied using optically accessible test rigs such as a rapid compression expansion machine (RCEM). The high flexibility offered by such a machine allows its operation at various thermochemical conditions at ignition. However, limitations inherent to such test rigs due to the absence of an intake stroke do not allow turbulence production as found in IC-engines. Hence, means to introduce turbulence have to be implemented and the relevant turbulence quantities have to be identified in order to enable comparability with engine relevant conditions. A dedicated high-pressure direct injection of air at the beginning of the compression phase is considered as a measure to generate adjustable turbulence intensities at ignition timing and during the early flame propagation.
2017-09-04
Technical Paper
2017-24-0041
Daniele Piazzullo, Michela Costa, Luigi Allocca, Alessandro Montanaro, Vittorio ROCCO
In gasoline direct injection (GDI) engines, dynamics of the possible spray-wall interaction are key factors affecting the air-fuel mixture distribution and equivalence ratio at spark timing, hence influencing the development of combustion and the pollutants formation at the exhaust. Gasoline droplets impact may rebound with consequent secondary atomization or deposit in the liquid phase over walls as a wallfilm. This last slowly evaporate with respect to free droplets, leading to local enrichment of the mixture, hence to increased unburned hydrocarbons and particulate matter emissions. In this scenario, complex phenomena characterize the turbulent multi-phase system where heat transfer involves the gaseous mixture (made of air and gasoline vapour), the liquid phase (droplets not yet evaporated and wallfilm) and the solid wall, especially in the so-called wall-guided mixture formation mode.
2017-09-04
Technical Paper
2017-24-0027
Nearchos Stylianidis, Ulugbek Azimov, Nobuyuki Kawahara, Eiji Tomita
A chemical kinetics and computational fluid-dynamics (CFD) analysis were performed to evaluate the combustion of syngas derived from biomass and coke-oven solid feedstock in a micro-pilot ignited supercharged dual-fuel engine under lean conditions. For this analysis, a new reduced syngas chemical kinetics mechanism was constructed and validated by comparing the ignition delay and laminar flame speed data with those obtained from experiments and other detail chemical kinetics analysis available in the literature. The reaction sensitivity analysis was conducted for ignition delay at elevated pressures in order to identify important chemical reactions that govern the combustion process. We found that HO2+OH=H2O+O2 and H2O2+H=H2+HO2 reactions showed very high sensitivity during high-pressure ignition delay times and had considerable uncertainty.
2017-09-04
Technical Paper
2017-24-0026
Davide Paredi, Tommaso Lucchini, Gianluca D'Errico, Angelo Onorati, Stefano Golini, Nicola Rapetto
The scope of the work presented in this paper was to apply the latest open source CFD achievements to design a state of art, direct-injection (DI), heavy-duty, natural gas-fueled engine. Within this context, an initial steady-state analysis of the in-cylinder flow was performed by simulating three different intake ducts geometries, each one with seven different valve lift values, chosen according to an estabilished methodology proposed by AVL. The discharge coefficient (Cd) and the Tumble Ratio (TR) were calculated in each case, and an optimal intake ports geometry configuration was assessed in terms of a compromise between the desired intensity of tumble in the chamber and the satisfaction of an adequate value of Cd. Subsequently, full-cycle, cold-flow simulations were performed for three different engine operating points, in order to evaluate the in-cylinder development of TR and turbulent kinetic energy (TKE) under transient conditions.
2017-09-04
Technical Paper
2017-24-0029
Tommaso Lucchini, Gianluca D'Errico, Tarcisio Cerri, Angelo Onorati, Gilles Hardy
Heavy-duty engines have to be carefully designed and optimized in a wide portion of their operating map to satisfy the emissions and fuel consumptions requirements for the different applications they are used for. Within this context, computational fluid dynamics is a useful tool to support combustion system design, making possible to test effects of injection strategies and combustion chamber design. Within this context, the predictive capability of the combustion model play a big role since it has to ensure accurate predictions in terms of cylinder pressure trace and the main pollutant emissions in a reduced amount of time. For this reason, both detailed chemistry and turbulence chemistry interaction need to be included. In this work, the authors intend to apply combustion models based on tabulated kinetics for the prediction of Diesel combustion in Heavy Duty Engines. Three different approaches were considered: well-mixed model, presumed PDF and flamelet progress variable.
2017-09-04
Technical Paper
2017-24-0034
Michele Battistoni, Carlo N. Grimaldi, Valentino Cruccolini, Gabriele Discepoli, Matteo De Cesare
Water injection in highly boosted GDI engines has become an attractive area over the last few years as a way of increasing efficiency, enhancing performance and reducing emissions. The technology and its effects are not new, but current gasoline engine trends for passenger vehicles have several motivations for adopting this technology today. Water injection enables higher compression ratios, optimal spark timing and elimination of fuel enrichment at high load, and possibly replacement of EGR. Physically, water reduces charge temperature by evaporation, dilutes combustion, and varies the specific heat ratio of the working fluid, with complex effects. Several of these mutually intertwined aspects are investigated in this paper through CFD simulations, focusing on a turbo-charged GDI engine with port water injection. Different strategies for water injection timing, pressure and spray targeting are investigated.
2017-09-04
Technical Paper
2017-24-0038
Golnoush Ghiasi, Irufan Ahmed, Yuri M. Wright, Jann Koch, Nedunchezhian Swaminathan
Engines with reduced emissions and improved efficiency are of high interest for road transport. However, achieving these two goals is challenging and various concepts such as PFI/DI/HCCI/PCCI are explored by engine manufacturers. Three dimensional computational fluid dynamics is becoming an integral part in analysing engine in cylinder processes, since it provides access to in-cylinder flow and thermo-chemical processes which gives a closer understanding to the tumble and swirling motions in order to construct clean engines. The combustion modelling, its accuracy and robustness play a vital role in this. Flamelet based methods are quite attractive for SI engine application. In this study, an unstrained flamelet model is used to simulate premixed combustion inside a GPFI single-cylinder, four-stroke SI engine.
2017-09-04
Technical Paper
2017-24-0036
S Krishna Addepalli, Om Prakash Saw, J M Mallikarjuna
Mixture distribution in the combustion chamber of gasoline direct injection (GDI) engines significantly affects the combustion, performance and emission characteristics. The mixture distribution in the engine cylinder in turn depends on many parameters viz., fuel injector hole diameter and orientation, fuel injection pressure, start of fuel injection, in-cylinder fluid dynamics etc. In these engines, the mixture distribution is broadly classified as homogeneous and stratified. However, with the currently available engine parameters it is difficult to objectively classify the type of mixture distribution. In this study, an attempt is made to objectively classify the mixture distribution in GDI engines using a parameter called the “stratification index”. The analysis is carried out on a four-stroke wall-guided GDI engine using computational fluid dynamics (CFD).
2017-09-04
Technical Paper
2017-24-0033
Priyanka Dnyaneshwar Jadhav, J M Mallikarjuna
Future stringent emission norms are impelling researchers to look for new emission control techniques. Today, gasoline direct injection (GDI) engines are becoming more popular because of high potential to reduce emissions over a wide operating load range, unlike conventional port fuel injection (PFI) spark ignition (SI) engines. Also, turbocharged GDI engines allow engine downsizing with certain restriction on compression ratio due to knocking tendency, thereby limiting the fuel economy. However, use of exhaust gas recirculation (EGR) delays combustion and lowers the knocking tendency which will aid in improving the fuel economy. The present computational fluid dynamic (CFD) investigation is aimed to evaluate the effect of EGR rate on the performance and emission characteristics of a two-liter turbocharged four stroke GDI engine. The compression ratio of 9.3 and the engine speed of 1000 rev/min., are selected for the analysis.
2017-09-04
Technical Paper
2017-24-0032
Gilles Decan, Stijn Broekaert, Tommaso Lucchini, Gianluca D'Errico, Jan Vierendeels, Sebastian Verhelst
The present work details a study of the heat flux through the walls of an internal combustion engine. The determination of this heat flux is an important aspect in engine optimization, as it influences the power, efficiency and the emissions of the engine. Therefore, a set of simulation tools in the OpenFOAM® software has been developed, that allows the calculation of the heat transfer through engine walls for ICEs. Normal practice in these types of engine simulations is to apply a wall function model to calculate the heat flux, rather than resolving the complete thermo-viscous boundary layer, and perform simulations of the closed engine cycle. When dealing with a complex engine, this methodology will reduce the overall computational cost. It however increases the need to rely on assumptions on both the initial flow field and the behavior in the near-wall region.
2017-09-04
Technical Paper
2017-24-0012
Andrea Piano, Giulio Boccardo, Federico Millo, Andrea Cavicchi, Lucio Postrioti, Francesco Concetto Pesce
Nowadays, injection rate shaping and multi-pilot events can help to improve fuel efficiency, combustion noise and pollutant emissions in diesel engine, providing high flexibility in the shape of the injection that allows combustion process control. Different strategies can be used in order to obtain the required flexibility in the rate, such as very close pilot injections with almost zero dwell time or boot shaped injections with optional pilot injections. Modern Common-Rail Fuel Injection Systems (FIS) should be able to provide these innovative patterns to control the combustion phases intensity for optimal tradeoff between fuel consumption and emission levels.
2017-09-04
Technical Paper
2017-24-0007
Joachim Beeckmann, Raik Hesse, Felix Bejot, Nan Xu, Heinz Pitsch
Especially for internal combustion engine simulations, various combustion model rely on the laminar burning velocity. With respect to computational time needed for CFD, the calculation of laminar burning velocities using a detailed chemical mechanism can be replaced by incorporation of approximation formulas, based on rate-ratio asymptotics, or by empirically obtained correlations, based on power law expressions. This study revisits the formulation of existing analytical approximation and correlation formulas. It investigates applicable temperature, pressure, and equivalence ratio ranges with special focus on engine combustion conditions. The review identifies individual missing model dependent parameters, e.g. incorporation of exhaust gas recirculation. Fuels chosen here are methane/air and hydrogen/air. In addition, this study focuses on the feasibility to calculate correctly burning velocities of hydrogen/methane/air mixtures.
2017-09-04
Technical Paper
2017-24-0167
Enrico Mattarelli, Carlo Rinaldini, Tommaso Savioli, Giuseppe Cantore, Alok Warey, Michael Potter, Venkatesh Gopalakrishnan, Sandro Balestrino
A CFD study on a 2-stroke (2-S) opposed piston high speed direct injection (HSDI) Diesel engine is reported in this work. The engine main features (bore, stroke, port timings, et cetera) were defined in a previous stage of the project, with the support of CFD-1D engine simulations and empirical hypotheses. The current analysis is focused on the assembly made up of scavenge ports, manifold and cylinder. The first step of the study consisted in the construction of a parametric mesh on a simplified geometry. Two geometric parameters and 3 different operating conditions were considered. A CFD-3D simulation by using a customized version of the KIVA-4 code was performed on a set of 243 different cases, sweeping all the most interesting combinations of geometric parameters and operating conditions. The post-processing of this huge amount of data allowed us to define the most effective geometric configuration, named baseline.
2017-09-04
Technical Paper
2017-24-0128
Lauretta Rubino, Jan Piotr Oles, Antonino La Rocca
Environmental authorities such as EPA, VCA have enforced stringent emissions legislation governing air pollutants released into the atmosphere. Of particular interest is the challenges introduced by the limit on particulate number (PN) counting (#/km) and real driving emissions (RDE) testing; with the Euro 6c emissions legislation being shortly introduced for the gasoline direct injection engines. Gasoline particulate filters (GPF) are considered to be the most immediate solution. While engine calibration and testing over the NEDC allows the limits to be met, real driving emission and cold start represent a challenge. The present work focuses on an experimental durability study on road under real word driving conditions. Two set of experiments were carried out. The first study analyzed a Gasoline Particulate Filter (GPF) (2,4 liter, diameter 5,2” round) installed in underfloor (UF) position driven for up to 200.000 km.
2017-09-04
Technical Paper
2017-24-0107
Alessandro Montanaro, Luigi Allocca, Vittorio Rocco, Michela Costa, Daniele Piazzullo
Enhancement of i.c. engine performances in terms of fuel economy and environment and human health preservation is an increasing key factor of the research in recent times. Mainly, that is due to the more and more stringent European and worldwide regulations tending to limit pollutant emissions to carbon monoxide, unburned hydrocarbons, nitrogen oxide, and particulate matter. Development of direct injection strategy (DI) in spark ignition (SI) engines partially fulfilled these tasks, as they run at higher compression ratios, with respect to port fuel injection (PFI), and operating with different injection strategies, so a greatest control over the air-to-fuel ratio is achieved. However, today the engines’ complexity and the number of sub-systems have increased, so the traditional techniques used for their optimization are often inadequate for the required challenges of high power output and low environmental impact.
2017-09-04
Technical Paper
2017-24-0103
Marlene Wentsch, Marco Chiodi, Michael Bargende
Main limiting factor in the application of 3D-CFD simulations within an engine development process is the very high time demand. The computing time of a 3D-CFD simulation is predominantly influenced by the number of cells within the computational mesh. An arbitrary cell coarsening, however, results in a distinct distortion of the simulation outcome. It is rather necessary to adapt the calculation models to the new mesh structure in order to ensure reliability and predictability of the 3D-CFD engine simulation. In the last decade, a fast response 3D-CFD tool was developed at FKFS in Stuttgart. It aims for a harmonized interaction between computational mesh, implemented calculation models and defined boundary conditions in order to enable fast running simulations for engine development tasks.
2017-09-04
Technical Paper
2017-24-0054
Francesco de Nola, Giovanni Giardiello, Alfredo Gimelli, Andrea Molteni, Massimiliano Muccillo, Roberto Picariello
In the last few years, the automotive industry had to face three main challenges: the compliance of more severe pollutant emission limits, better engine performance in terms of torque and drivability and the simultaneous demand for a significant reduction in fuel consumption as well. These conflicting goals have driven the evolution of automotive engines. In particular, the achievement of all these mandatory aims, together with the increasingly stringent requirements for carbon dioxide reduction, led to the development of highly complex engine architectures needed to perform advanced operating strategies. Thus, Variable Valve Actuation (VVA), Exhaust Gas Recirculation (EGR), Gasoline Direct Injection (GDI), turbocharging, powertrain hybridization and other solutions have gradually and widely equipped the modern internal combustion engines, enhancing the possibilities to achieve the required goals.
2017-09-04
Technical Paper
2017-24-0090
Robert E. Morgan, Morgan Heikal, Emily Pike-Wilson
Urban air quality remains a major concern, in particular NOx and particle emission from diesel powered vehicles. Electrification offers a medium to long term solution, but there remains a need to significantly reduce internal combustion engine emissions in the short and medium term and potentially in the long term for long range inter city transportation. Late injection low temperature combustion (LTC) has the potential to achieve ultra-low emissions levels in a compression ignition engine by increasing the lean pre-mixed burn fraction. However, significant quantities of diluent are normally required to achieve the required delay in ignition and pre-mixing. This results in high boost requirements and increased pumping work negating the benefit of the LTC combustion strategy and increasing fuel consumption. Test results from a single cylinder light duty research engine are presented using a novel ramped combustion chamber.
2017-07-10
Technical Paper
2017-28-1953
Tushar Narendra Puri lng, Lalitkumar Ramujagir Soni lng, Sourabh Deshpande
Abstract The infliction of rigorous emission norms across the world has made the automobile industry to focus and dwell upon researches to reduce the emissions from internal combustion engines, namely diesel engines. Variation in fuel injection timing has better influence on reduction of engine exhaust emissions. This papers deals with the variation of fuel injection timing along with fuel injection pressure numerically on a 4 stroke, single cylinder, and direct injection diesel engine running at full load condition using CONVERGE CFD tool. As the piston and bowl geometry considered in this work is symmetric, only 60 degree sector of the piston cylinder assembly is considered for numerical simulation over complete 360 degree model.
2017-06-28
Journal Article
2017-01-9180
Johannes Wurm, Eetu Hurtig, Esa Väisänen, Joonas Mähönen, Christoph Hochenauer
Abstract The presented paper focuses on the computation of heat transfer related to continuously variable transmissions (CVTs). High temperatures are critical for the highly loaded rubber belts and reduce their lifetime significantly. Hence, a sufficient cooling system is inevitable. A numerical tool which is capable of predicting surface heat transfer and maximum temperatures is of high importance for concept design studies. Computational Fluid Dynamics (CFD) is a suitable method to carry out this task. In this work, a time efficient and accurate simulation strategy is developed to model the complexity of a CVT. The validity of the technique used is underlined by field measurements. Tests have been carried out on a snowmobile CVT, where component temperatures, air temperatures in the CVT vicinity and engine data have been monitored. A corresponding CAD model has been created and the boundary conditions were set according to the testing conditions.
2017-06-05
Technical Paper
2017-01-1834
Dirk von Werne, Prasanna Chaduvula, Patrick Stahl, Michael Jordan, Jamison Huber, Korcan Kucukcoskun, Mircea Niculescu
Abstract Fan noise can form a significant part of the vehicle noise signature and needs hence to be optimized in view of exterior noise and operator exposure. Putting together unsteady CFD simulation with acoustic FEM modeling, tonal and broadband fan noise can be accurately predicted, accounting for the sound propagation through engine compartment and vehicle frame structure. This paper focuses on method development and validation in view of the practical vehicle design process. In a step by-step approach, the model has been validated against a dedicated test-set-up, so that good accuracy of operational fan noise prediction could be achieved. Main focus was on the acoustic transfer through the engine compartment. The equivalent acoustic transfer through radiators/heat exchangers is modeled based on separate detailed acoustic models. The updating process revealed the sensitivity of various components in the engine compartment.
2017-04-11
Journal Article
2017-01-9450
Ali Reza Taherkhani, Carl Gilkeson PhD, Philip Gaskell PhD, Rob Hewson PhD, Vassili Toropov PhD, Amin Rezaienia PhD, Harvey Thompson
Abstract This paper investigates the optimization of the aerodynamic design of a police car, BMW 5-series which is popular police force across the UK. A Bezier curve fitting approach is proposed as a tool to improve the existing design of the warning light cluster in order to reduce drag. A formal optimization technique based on Computational Fluid Dynamics (CFD) and moving least squares (MLS) is used to determine the control points for the approximated curve to cover the light-bar and streamline the shape of the roof. The results clearly show that improving the aerodynamic design of the roofs will offer an important opportunity for reducing the fuel consumption and emissions for police vehicles. The optimized police car has 30% less drag than the non-optimized counter-part.
2017-03-28
Technical Paper
2017-01-0686
Mohammed Jaasim Mubarak Ali, Francisco Hernandez Perez, S. Vedharaj, R. Vallinayagam, Robert Dibble, Hong Im
Abstract Pre-ignition in SI engine is a critical issue that needs addressing as it may lead to super knock event. It is widely accepted that pre-ignition event emanates from hot spot(s) that can be anywhere inside the combustion chamber. The location and timing of hotspot is expected to influence the knock intensity from a pre-ignition event. In this study, we study the effect of location and timing of hot spot inside the combustion chamber using numerical simulations. The simulation is performed using a three-dimensional computational fluid dynamics (CFD) code, CONVERGE™. We simulate 3-D engine geometry coupled with chemistry, turbulence and moving structures (valves, piston). G-equation model for flame tracking coupled with multi-zone model is utilized to capture auto-ignition (knock) and solve gas phase kinetics. A parametric study on the effect of hot spot timing and location inside the combustion chamber is performed.
2017-03-28
Technical Paper
2017-01-0713
Håkan Persson, Aristotelis Babajimopoulos, Arjan Helmantel, Fredrik Holst, Elin Stenmark
Abstract The demands for a future diesel engine in terms of emission compliance, CO2 emissions, performance and cost effectiveness set new requirements for the development process of the combustion system. This paper focuses on the development of the next generation Volvo Cars diesel combustion system, which should comply with Euro 6d including Real Driving Emissions (RDE), with emphasis on the novel methods applied throughout the process. The foundation of a high performing combustion system is formed by first determining the requirements for the system, after which the key factors that affect system performance are selected, such as the charge motion, combustion chamber geometry and injector nozzle geometry. Based on the requirements, a robust charge motion with desired flow characteristics is defined. A new automated CFD optimization process for combustion chamber geometry and spray target is developed.
2017-03-28
Journal Article
2017-01-0748
Zhenkan Wang, Sara Lonn, Alexios Matamis, Oivind Andersson, Martin Tuner, Marcus Alden, Mattias Richter
Abstract In a previous study, in order to investigate the effect of charge stratification on combustion behavior such as combustion efficiency and combustion phasing which also largely affects the emissions, an experiment was conducted in a heavy-duty compression ignition (CI) metal engine. The engine behavior and emission characteristics were studied in the transition from HCCI mode to PPC mode by varying the start of injection (SOI) timing. To gain more detailed information of the mixing process, in-cylinder laser diagnostic measurements, namely fuel-tracer planar laser induced fluorescence (PLIF) imaging, were conducted in an optical version of the heavy-duty CI engine mentioned above. To the authors’ best knowledge, this is the first time to perform fuel-tracer PLIF measurements in an optical engine with a close to production bowl in piston combustion chamber, under transition conditions from HCCI to PPC mode.
2017-03-28
Technical Paper
2017-01-0751
Praveen Kumar, Yu Zhang, Michael Traver, David Cleary
Abstract In this study a detailed 1-D engine system model coupled with 3-D computational fluid dynamics (CFD) analysis was used to investigate the air system design requirements for a heavy duty diesel engine operating with low reactivity gasoline-like fuel (RON70) under partially premixed combustion (PPC) conditions. The production engine used as the baseline has a geometric compression ratio (CR) of 17.3 and the air system hardware consists of a 1-stage variable geometry turbine (VGT) with a high pressure exhaust gas recirculation (HP-EGR) loop. The analysis was conducted at six engine operating points selected from the heavy-duty supplemental emissions test (SET) cycle, i.e., A75, A100, B25, B50, B75, and C100.
2017-03-28
Technical Paper
2017-01-0756
Zhenkuo Wu, Christopher Rutland, Zhiyu Han
Abstract Natural gas is a promising alternative fuel for internal combustion engines due to its rich reserves and low price, as well as good physical and chemical properties. Its low carbon structure and high octane number are beneficial for CO2 reduction and knock mitigation, respectively. Diesel and natural gas dual fuel combustion is a viable pathway to utilize natural gas in diesel engines. To achieve high efficiency and low emission combustion in a practical diesel engine over a wide range of operating conditions, understanding the performance responses to engine system parameter variations is needed. The controllability of two combustion strategies, diesel pilot ignition (DPI) and single injection reactivity controlled compression ignition (RCCI), were evaluated using the multi-dimension CFD simulation in this paper.
2017-03-28
Journal Article
2017-01-0716
Randy Hessel, Zongyu Yue, Rolf Reitz, Mark Musculus, Jacqueline O'Connor
Abstract One way to develop an understanding of soot formation and oxidation processes that occur during direct injection and combustion in an internal combustion engine is to image the natural luminosity from soot over time. Imaging is possible when there is optical access to the combustion chamber. After the images are acquired, the next challenge is to properly interpret the luminous distributions that have been captured on the images. A major focus of this paper is to provide guidance on interpretation of experimental images of soot luminosity by explaining how radiation from soot is predicted to change as it is transmitted through the combustion chamber and to the imaging. The interpretations are only limited by the scope of the models that have been developed for this purpose. The end-goal of imaging radiation from soot is to estimate the amount of soot that is present.
2017-03-28
Journal Article
2017-01-0722
Pablo Olmeda, Jaime Martin, Antonio Garcia, David Villalta, Alok Warey, Vicent Domenech
Abstract Growing awareness about CO2 emissions and their environmental implications are leading to an increase in the importance of thermal efficiency as criteria to design internal combustion engines (ICE). Heat transfer to the combustion chamber walls contributes to a decrease in the indicated efficiency. A strategy explored in this study to mitigate this efficiency loss is to promote low swirl conditions in the combustion chamber by using low swirl ratios. A decrease in swirl ratio leads to a reduction in heat transfer, but unfortunately, it can also lead to worsening of combustion development and a decrease in the gross indicated efficiency. Moreover, pumping work plays also an important role due to the effect of reduced intake restriction to generate the swirl motion. Current research evaluates the effect of a dedicated injection strategy to enhance combustion process when low swirl is used.
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