Showing papers in "International Journal of Engine Research in 2017"
TL;DR: The laminar flame speed plays an important role in spark-ignition engines, as well as in many other combustion applications, such as in designing burners and predicting explosions as discussed by the authors.
Abstract: The laminar flame speed plays an important role in spark-ignition engines, as well as in many other combustion applications, such as in designing burners and predicting explosions. For this reason,...
76 citations
TL;DR: In this article, the authors assess the impact of turbulence and cavitation models on the prediction of diesel injector nozzle flow and conclude that accurate turbulence representation is crucial for cavitation in nozzle flows.
Abstract: The aim of this article is to assess the impact of turbulence and cavitation models on the prediction of diesel injector nozzle flow. Two nozzles are examined, an enlarged one, operating at incipient cavitation, and an industrial injector tip, operating at developed cavitation. The turbulence model employed includes the re-normalization group k–e, realizable k–e and k–ω shear stress transport Reynolds-averaged Navier–Stokes models; linear pressure–strain Reynolds stress model and the wall adapting local eddy viscosity large eddy simulation model. The results indicate that all Reynolds-averaged Navier–Stokes and the Reynolds stress turbulence models have failed to predict cavitation inception due to their limitation to resolve adequately the low pressure existing inside vortex cores, which is responsible for cavitation development in this particular flow configuration. Moreover, Reynolds-averaged Navier–Stokes models failed to predict unsteady cavitation phenomena in the industrial injector. However, the wall adapting local eddy viscosity large eddy simulation model was able to predict incipient and developed cavitation, while also capturing the shear layer instability, vortex shedding and cavitating vortex formation. Furthermore, the performance of two cavitation methodologies is discussed within the large eddy simulation framework. In particular, a barotropic model and a mixture model based on the asymptotic Rayleigh–Plesset equation of bubble dynamics have been tested. The results indicate that although the solved equations and phase change formulation are different in these models, the predicted cavitation and flow field were very similar at incipient cavitation conditions. At developed cavitation conditions, standard cavitation models may predict unrealistically high liquid tension, so modifications may be essential. It is also concluded that accurate turbulence representation is crucial for cavitation in nozzle flows.
74 citations
TL;DR: In this article, laser-induced fluorescence and particle image velocimetry technique was employed to quantitatively access the gas entrainment of diesel spray emerging from nozzle with orifice diameter down to 80'µm under injection pressure up to 300'MPa, together with OH* chemiluminescence imaging and two-color pyrometry techniques to resolve the combustion and soot formation processes.
Abstract: Increasing the injection pressure and downsizing the nozzle orifice diameter have been major measures for diesel engines to facilitate fuel–ambient gas mixture formation and combustion processes. The objective of this investigation is to carry out a quantitative analysis on the effects of micro-hole nozzle and ultra-high injection pressure on the mixing and combustion characteristics of diesel spray flame. Hence, laser-induced fluorescence and particle image velocimetry technique was employed to quantitatively access the gas entrainment of diesel spray emerging from nozzle with orifice diameter down to 80 µm under injection pressure up to 300 MPa, together with OH* chemiluminescence imaging and two-color pyrometry techniques to resolve the combustion and soot formation processes. Additionally, numerical simulation on the multi-phase flow inside injector nozzle was conducted to obtain information on internal flow dynamics. Experimental results show that over 80% of the ambient gas entrained into a spray pl...
66 citations
TL;DR: In this article, the authors investigate the turbulent multiphase flow inside a nine-hole common rail Diesel injector during a full injection cycle of ISO 4113 diesel fuel into air by implicit large-eddy simulation (LES).
Abstract: We investigate the turbulent multiphase flow inside a nine-hole common rail Diesel injector during a full injection cycle of ISO 4113 diesel fuel into air by implicit large-eddy simulation (LES). T...
51 citations
TL;DR: In this article, low-temperature compression ignition combustion can result in nearly smokeless combustion, as indicated by a smoke meter or other forms of soot measurement that rely on absorbance due to elemental...
Abstract: Low-temperature compression ignition combustion can result in nearly smokeless combustion, as indicated by a smoke meter or other forms of soot measurement that rely on absorbance due to elemental ...
42 citations
TL;DR: In this article, the authors investigated the load limits of reactivity controlled compression ignition combustion, a dual-fuel concept which combines port fuel injection of low-reactivity fuels with direct injection.
Abstract: This work investigates the load limits of reactivity controlled compression ignition combustion, a dual-fuel concept which combines port fuel injection of low-reactivity fuels with direct injection...
39 citations
TL;DR: In this paper, an equilibrium wall function model is employed in engine simulations to predict heat transfer in an internal combustion engine and the performance and phasing of internal combustion engines, and the results show that the model is accurate.
Abstract: Heat transfer affects the performance and phasing of internal combustion engines. Correlations and equilibrium wall-function models are typically employed in engine simulations to predict heat tran...
36 citations
TL;DR: In this paper, the authors estimate that 30% of the fuel consumed during typical heavy-duty vehicle operation occurs at elevated speeds with low-to moderate loads below 6.5 bar brake mean effective pressure.
Abstract: Approximately 30% of the fuel consumed during typical heavy-duty vehicle operation occurs at elevated speeds with low-to-moderate loads below 6.5 bar brake mean effective pressure. The fuel economy...
35 citations
TL;DR: In this article, the authors present experimental tests where lubricant oil was added to the engine in order to highlight its contribution to particle emissions from both gasoline and compressed natural gas spark-iggered engines.
Abstract: This work presents experimental tests where lubricant oil was added to the engine in order to highlight its contribution to particle emissions from both gasoline and compressed natural gas spark-ig...
35 citations
TL;DR: Soot onset in n-dodecane sprays is investigated both experimentally, by means of high-speed imaging data from the Sandia spray combustion vessel, and numerically, using the conditional moment closu... as discussed by the authors.
Abstract: Soot onset in n-dodecane sprays is investigated both experimentally, by means of high-speed imaging data from the Sandia spray combustion vessel, and numerically, using the conditional moment closu...
31 citations
TL;DR: In this article, numerical simulations of an n-dodecane spray flame (known as Spray A) with multiple injections (0.5 ms injection/ 0.5µm dwell/0.1µms injection) were carried out using the transpor...
Abstract: In this study, numerical simulations of an n-dodecane spray flame—known as Spray A—with multiple injections (0.5 ms injection/0.5 ms dwell/0.5 ms injection) have been carried out using the transpor...
TL;DR: Forthcoming directives from European Commission will force homologation in altitude to approach standards to actual driving conditions in order to reduce the gap between regulated and real-life driving conditions.
Abstract: Forthcoming directives from European Commission will force homologation in altitude to approach standards to actual driving conditions in order to reduce the gap between regulated and real-life emi...
TL;DR: In this paper, the range of application for direct injection in spark ignition engines has been extended to include a wide range of applications, such as renewable energy, energy security, and continuous drive for improving fuel economy.
Abstract: Ever tighter restrictions on pollutant emissions, energy security and a continuous drive for improving fuel economy have extended the range of application for direct injection in spark ignition eng...
TL;DR: In this article, the authors employ a mixed lubrication model to investigate the performance of the textured surface and obtain the hydrodynamic support of textured surfaces using the Jakobsson-Floberg-Olsson model.
Abstract: This article employs a mixed lubrication model to investigate the performance of the textured surface. The Jakobsson–Floberg–Olsson model is used to obtain the hydrodynamic support of the textured ...
TL;DR: In this article, the nanostructure of diesel particulates has been shown to impact its oxidation rate and burnout trajectory, and this nanostructures can evolve during the oxidation process, furthering its further evolution.
Abstract: The nanostructure of diesel particulates has been shown to impact its oxidation rate and burnout trajectory. Additionally, this nanostructure can evolve during the oxidation process, furthering its...
TL;DR: Cylinder deactivation can be implemented at low loads in diesel engines to improve efficiency and aftertreatment thermal management through reductions in pumping work and airflow, respectively as mentioned in this paper. But it is not suitable for turbocharged engines.
Abstract: Cylinder deactivation can be implemented at low loads in diesel engines to improve efficiency and aftertreatment thermal management through reductions in pumping work and airflow, respectively. The...
TL;DR: The prediction of cycle-to-cycle variability in spark ignition engines is extremely challenging for two key reasons: (1) high-fidelity methods such as large eddy simulation are required to ac...
Abstract: Numerical prediction of cycle-to-cycle variability in spark ignition engines is extremely challenging for two key reasons: (1) high-fidelity methods such as large eddy simulation are required to ac...
TL;DR: In this article, a direct dual fuel stratification strategy is proposed to improve heat release control over low-temperature combustion by combining reactivity stratification in the premixed charge with a diffusion-limited injection.
Abstract: Low-temperature combustion offers an attractive combination of high thermal efficiency and low NOx and soot formation at moderate engine load. However, the kinetically-controlled nature of low-temperature combustion yields little authority over the rate of heat release, resulting in a tradeoff between load, noise, and thermal efficiency. While several single-fuel strategies have achieved full-load operation through the use of equivalence ratio stratification, they uniformly require retarded combustion phasing to maintain reasonable noise levels, which comes at the expense of thermal efficiency and combustion stability. Previous work has shown that control over heat release can be greatly improved by combining reactivity stratification in the premixed charge with a diffusion-limited injection that occurs after low-temperature heat release, in a strategy called direct dual fuel stratification. While the previous work has shown how the heat release control offered by direct dual fuel stratification differs f...
TL;DR: In this article, the downsizing, coupled with turbocharging and variable valve actuation systems, are very common solutions to reduce the brake-specific fuel consumption at low-median fuel consumption.
Abstract: Referring to spark-ignition engines, the downsizing, coupled to turbocharging and variable valve actuation systems are very common solutions to reduce the brake-specific fuel consumption at low-med...
TL;DR: In this paper, a numerical analysis of the frictional behavior of mixed-hydrodynamic interaction in a textured piston compression ring-cylinder liner during the warm-up process is presented.
Abstract: Road vehicles account for a substantial portion of energy consumed by transportation. A large amount of this energy is lost to overcome friction within vehicle engines, in which the piston compression rings are a major source of such parasitic losses. The internal losses of engines increase several times in the case of unfavorable warm-up conditions. Recent developments in surface modification showed promising results in improving the frictional behavior of piston rings. Analyses are often idealized, such as isothermal conditions and unrealistic engine operating conditions. This study presents a numerical investigation of the frictional behavior of mixed-hydrodynamic interaction in a textured piston compression ring–cylinder liner during the warm-up process. The transient Reynolds equation is solved with a mass-conserving cavitation algorithm, realistic oil rheology, and practical engine operating conditions. Several multigrade and monograde oils are considered to draw comprehensive conclusions. The resul...
TL;DR: A potential combustion-related challenge with turbulen... as discussed by the authors is a potential combustion related challenge with turbo-jet ignition engines, which is a combustion technology that can offer higher thermal efficiency compared to the homogeneous spark ignition engines.
Abstract: Turbulent jet ignition is a combustion technology that can offer higher thermal efficiency compared to the homogeneous spark ignition engines. A potential combustion-related challenge with turbulen...
TL;DR: In this paper, the authors compared the fundamental thermodynamic underpinnings (i.e., working fluid properties and heat release profile) of various combustion strategies with engine measurements and compared the measured and modeled efficiencies.
Abstract: This work compares the fundamental thermodynamic underpinnings (i.e. working fluid properties and heat release profile) of various combustion strategies with engine measurements. The approach employs a model that separately tracks the impacts on efficiency due to differences in rate of heat addition, volume change, mass addition, and molecular weight change for a given combination of working fluid, heat release profile, and engine geometry. Comparative analysis between the measured and modeled efficiencies illustrates fundamental sources of efficiency reductions or opportunities inherent to various combustion regimes. Engine operating regimes chosen for analysis include stoichiometric spark-ignited combustion and lean compression-ignited combustion including homogeneous charge compression ignition, spark-assisted homogeneous charge compression ignition, and conventional diesel combustion. Within each combustion regime, the effects of engine load, combustion duration, combustion phasing, compression ratio,...
TL;DR: In this article, the authors developed knock criteria for aviation diesel engines that have experienced a number of malfunctions during flight and ground operation, and evaluated the reliability of the knock criteria.
Abstract: The objective of this study was to develop knock criteria for aviation diesel engines that have experienced a number of malfunctions during flight and ground operation. Aviation diesel engines have...
TL;DR: In this paper, the results of computational studies investigating the ignition of high-pressure natural gas jets in a compression-ignition engine with glow plug ignition assist were presented, and the results showed that the acceleration of the gas jets was not affected by the glow plug.
Abstract: This article presents the results of computational studies investigating the ignition of high-pressure natural gas jets in a compression-ignition engine with glow plug ignition assist. The simulati...
TL;DR: In this paper, the chemical and physical properties of particulate matter emitted by a 2.0-L BMW lean-burn turbocharged gasoline direct injection engine operated by a two-stage turbocharged engine are analyzed.
Abstract: This study presents detailed characterization of the chemical and physical properties of particulate matter emitted by a 2.0-L BMW lean-burn turbocharged gasoline direct injection engine operated u...
TL;DR: In this paper, the effects of injector nozzle inclusion angle, injection pressure, boost ratio, and swirl ratio on gasoline compression ignition combustion were studied in a closed-cycle computational fluid dynamical system.
Abstract: In this work, we study the effects of injector nozzle inclusion angle, injection pressure, boost, and swirl ratio on gasoline compression ignition combustion. Closed-cycle computational fluid dynam...
TL;DR: In this paper, a quantitative analysis of late-cycle soot oxidation in diesel engines was performed using two-dimensional KL factor images obtained by the two-color method, and the spatially integrated KL factor was converted into the in-cylinder soot mass using a new formula of diesel soot emissivity.
Abstract: This study concerns a quantitative analysis of late-cycle soot oxidation in diesel engines that focuses on two-dimensional KL factor images obtained by the two-color method. The spatially integrated KL factor was converted into the in-cylinder soot mass using a new formula of diesel soot emissivity. This methodology was applied to two combustion systems: a heavy-duty optical engine which was tuned for a higher fuel–air mixing capability and a rapid compression and expansion machine which had a lower mixing performance. The in-cylinder soot mass history during the last stage of soot oxidation phase was converted into a normalized soot mass history and was used for comparison with simulated soot mass history. A model calculation of in-cylinder soot mass history which was based on oxidation of a primary soot particle was performed with the surface-specific soot oxidation rate as a parameter. A value of the surface-specific soot oxidation rate was specified from the curve fitting approach between the experime...
TL;DR: In this paper, numerically the free-piston engine generator is investigated numerically, which is a new alternative to traditional reciprocating engine, which moves without mechanical restriction of crankshaft system.
Abstract: Free-piston engine generator is a new alternative to traditional reciprocating engine, which moves without mechanical restriction of crankshaft system. This article investigated numerically the fri...
TL;DR: In this article, a single pulse fuel injection and high levels of exhaust gas recirculation was used to reduce oxides of nitrogen and particulate matter. But the results were limited.
Abstract: Advanced diesel combustion, accomplished via a single pulse fuel injection and high levels of exhaust gas recirculation, is shown to be a path to reduce oxides of nitrogen and particulate matter si...
TL;DR: In this paper, a soot sensor for on-board diagnostics to monitor a diesel particulate filter and detect the failure of the filter has been presented, which accumulates soot particles in exhaust gas on the sensing element.
Abstract: If emissions control systems and engine control devices experience a failure, the engine system may malfunction causing exhaust emissions to exceed the standard levels of the regulated emissions. Thus, the functional status of each of all primary control devices needs to be monitored for detecting possible failures, so that the proper action can be taken to warn the vehicle operator. This article reviews a soot sensor currently developed for on-board diagnostics to monitor a diesel particulate filter and detect the failure. Original equipment manufacturers have selected a resistive soot sensor for the on-board diagnostics application because of its commercial feasibility in terms of functionality and cost. The sensor accumulates soot particles in exhaust gas on the sensing element. Structure, design, and function of the cumulative sensor including the signal processing techniques are described. Since the sensor signal contains noises and fluctuations, the post-diesel particulate filter soot concentration ...