Knowledge of the NO:NO 2 ratio emitted from a diesel engine is particularly important for ensuring the highest performance of SCR NO x aftertreatment systems. As real driving emissions from vehicles increase in importance, the need to understand the NO:NO 2 ratio emitted from a diesel engine during transient operation similarly increases. Previous work by the authors identified significant differences in NO:NO 2 ratio throughout the exhaust period of a single engine cycle, with proportionally more NO 2 being emitted during the blowdown period compared to the rest of the exhaust stroke. At the time it was not known what caused this effect. In this study, crank-angle resolved NO and NO 2 measurements using fast response CLD (for NO) and a new fast LIF instrument (for NO 2 ) have been taken from a single cylinder high-speed light duty diesel engine at three different speed and load points including a point with and without EGR. In addition, crank-angle resolved unburned hydrocarbon (UHC) measurements have been taken simultaneously using a fast FID. The NO x emitted per cycle and the peak cylinder pressure of that cycle have showed high correlation coefficients (R 2 < 0.97 at all test points) in this work. In addition, a variation of the NO:NO 2 ratio through the engine’s exhaust stroke is also observed indicative of in-cylinder stratification of NO and NO 2 . A new link between the NO:NO 2 ratio and the UHC emissions from an individual engine cycle is observed — the results show that where there are higher levels of UHC emissions in the first part of the exhaust stroke (blowdown), perhaps caused by injector dribble or release from crevices, the proportion of NO 2 emitted from that cycle is increased. This effect is observed and analysed across all test points and with and without EGR. The performance of the new fast LIF analyser has also been evaluated, in comparison with the previous state-of-the-art and standard “slow” emissions measurement apparatus showing a reduction in the noise of the measurement by an order of magnitude.

The effects of fuel blend properties on spray and injector performance has been investigated for several operating conditions in a side-mount injector for Gasoline Direct Injection (GDI) using two certification fuel blends, Euro 5 and Euro 6. Several X-ray diagnostic techniques were conducted to characterize the injector and spray morphology. Detailed internal geometry of the GDI injector was measured with a feature-resolution of 1.8 micrometers, through the use of hard X-ray tomography. The geometry characterization of this six-hole GDI, side mount injector, quantifies relevant hole and counterbore dimensions and reveals the intricate details within the flow passages, including surface roughness and micron-sized features. Internal valve motion was measured with a temporal resolution of 20 microseconds and a spatial resolution of 2.0 micrometers, for three injection pressures and several injector energizing strategies. The needle motion for both fuels exhibit similar lift profiles for common energizing commands. A combination of X-ray radiography and Ultra-Small-Angle X-ray Scattering (USAXS) was used to characterize the fuel mass distribution and the droplet sizing, respectively. Tomographic spray radiography revealed the near-nozzle distribution of fuel mass for each of the fuels, and the asymmetry produced by the angled nozzles. Under evaporative conditions, the two fuels show minor differences in peak fuel mass distribution during steady injection, though both exhibit fluctuations in injection during the early, transient phase. US-AXS measurements of the path-specific surface area of the spray indicated lower peak values for the more evaporative conditions in the near nozzle region. These spray measurements portray the specific behavior of real fuel blends under a variety of conditions, illustrating the need to examine multi-component fuels to better understand relevant cases. Furthermore, this work furnishes the realistic boundary values for simulations to appropriately predict the sprays which were experimentally measured, and influenced by those realistic conditions.

For turbocharged diesel engine systems, emission reduction is the most significant challenge that manufacturers should overcome. In response to the emission reduction challenge most turbocharged diesel engine systems have adopted complex exhaust aftertreatment systems. Due to the current stringent emission regulation, exhaust aftertreatment system nowadays needs to discover new methods to increase its efficiency of pollution conversion. Increasing the inlet temperature of aftertreatment systems can help reduce the light-off time. Whilst most methods to do this involve increases in fuel consumption (retarded injection, engine throttling), insulating the turbocharger turbine to reduce heat loss does not have this drawback. This paper presents a simulation and experimental study the performance of a turbocharger with inner insulated turbine housing, compared with the standard turbocharger (same turbine wheel without inner insulation). Both turbochargers were tested on an engine gas stand test rig with a 2.2L prototype engine acting as an exhaust gas generator. In a steady state condition, the insulated turbocharger can achieve 5 to 14K higher turbine outlet temperature depending on the engine speed and load conditions. Three types of transient tests were implemented to investigate turbocharger turbine heat transfer performance. The test plan was designed to the engine warm up, step load transient, WLTC cycle and simplified RDE cycle. In the engine warm up test result, the temperature drops between the turbine inlet and outlet was reduced by 4K with the insulated turbine housing. In the results of step load transient test, the turbine with insulated turbine housing was observed to get only 4K temperature benefit but with 2kRPM higher turbocharger speed under the same turbocharger inlet and outlet boundary conditions. In the WLTC cycle test result, turbocharger average speed was increased by 0.8kRPM due to the increased enthalpy of the turbine with insulation, the turbine outlet temperature has an average 1.7K improvement. The experimental results were used to parameterise a simple, 1D, lumped capacitance model which could predict similar aerodynamic behaviour of the two turbines (turbine housing insulated and non-insulated). However, current model has less accuracy in highly transient process as the heat transfer coefficients are unchangeable in each process. The turbine outlet temperature got at most 10K error for the turbine with non-insulated housing and 13K error for the insulated one. The model was shown to over-estimate the benefits of the inner insulation for 1K in turbine outlet temperature.

Vehicle type approval drive cycles have become a mainstay for benchmarking performance of engines in the development cycle. However, they are typically long and costly to test, with questions of repeatability and real-world relevance. With the move to Real Driving Emission (RDE) style testing, complete foreknowledge of the cycle is no longer guaranteed. This paper presents a methodology for identifying key behaviours (or information rich regions) from the current worldwide harmonised light-duty test cycle (WLTC) type approval test using a moving 2-minute window approach. Three techniques for pattern recognition are presented and applied to data collected from a modern Gasoline Turbocharged Direct Injection (GTDI) engine, run through the WLTC. The techniques examine different points in the process, with the first examining response data, and working backwards to the original vehicle speed cycle specification. The first two techniques, Intensity Ratio (IR) for cumulative responses and Energy Residency (ER) for engine inputs, are newly developed in this paper. The final technique, Dynamic Time Warping (DTW) is a new application of an existing tool to the subject of vehicle drive cycles. The techniques are examined in isolation and discussed, before being brought together to identify commonly agreed information rich sub-cycle candidates that best represent the parent cycle. The techniques make use of a combination of time windowing, signal derivative and peak analysis methods. The two-minute window is chosen based on the length of an existing sub-cycle that was identified as part of earlier work, and this method is also described and validated in this paper. One sub-cycle identified by the approach represents a duration reduction of 93% to a containable 2-minute transient. This segment accounts for 15% of the overall WLTC fuel used. A discussion of the techniques and their applications is presented to motivate future work in this area.

The effects of orifice diameter on several aspects of diesel fuel jet flame structure were investigated in a constant-volume combustion vessel under heavy-duty, direct-injection (DI) diesel engine conditions using Phillips research grade #2 diesel fuel and orifice diameters ranging from 45 μm to 180 μm. The overall flame structure was visualized with time-averaged OH chemiluminescence and soot luminosity images acquired during the quasi-steady portion of the diesel combustion event that occurs after the transient premixed burn is completed and the flame length is established. The lift-off length, defined as the farthest upstream location of high-temperature combustion, and the flame length were determined from the OH chemiluminescence images. In addition, relative changes in the amount of soot formed for various conditions were determined from the soot incandescence images. Combined with previous investigations of liquid-phase fuel penetration and spray development, the results show that air entrainment upstream of the lift-off length (relative to the amount of fuel injected) is very sensitive to orifice diameter. As orifice diameter decreases, the relative air entrainment upstream of the lift-off length increases significantly. The increased relative air entrainment results in a reduced overall average equivalence ratio in the fuel jet at the lift-off length and reduced soot luminosity downstream of the lift-off length. The reduced soot luminosity indicates that the amount of soot formed relative to the amount of fuel injected decreases with orifice diameter. The flame lengths determined from the images agree well with gas jet theory for momentum-driven, non-premixed turbulent flames.

The influence of fuel aromatic content and type on the exhaust emissions from a heavy-duty diesel engine were investigated by blending predetermined amounts of aromatic compounds with a known chemical structure into a low-aromatic base fuel. Seven test fuels were blended with constant cetane numbers and densities, but with mono-, di-, and tri-aromatic contents ranging from 10 to 30%, 0 to 10%, and 0 to 8%, respectively. The engine experiments were run using the AVL eight-mode steady-state simulation of the EPA transient test procedure. The results show that fuel total aromatic content or type did not significantly affect the engine’s PM emissions. NO x emissions, however, increased by 4.3% as the fuel mono-aromatic content increased from 10 to 30%.

A continuously variable transmission (CVT) allows a powertrain controller the freedom to develop a required output power at a range of engine torque and speed conditions. This flexibility can be used to maximise fuel efficiency. Due to low frictional and pumping losses a gasoline engine’s fuel efficiency is maximised at low speed, high torque conditions. However due to the reduced torque margin available, controlling a gasoline engine in this region compromises transient vehicle response. Dilution torque control, using EGR or lean burn, has the potential to maintain the economy gains available using a CVT powertrain whilst improving a vehicle’s driveability. This paper introduces preliminary work that has been undertaken to investigate the potential of charge dilution to control steady state engine torque. A test rig has been developed based around an engine fitted with variable cam phasing and an external EGR system. The paper contains a discussion of initial results of a lean dilution test program used to demonstrate the principle.

Acceleration of a 4-cylinder, 7-litre, turbocharged diesel engine has been investigated by the means of experimental and analytical procedure. The engine acceleration on a test stand has been tested using standard dynamometer which has been controlled by a computer. All measurements have been performed at the maximum fuel rack position, however the courses of engine load have been varied. Engine speed, dynamometer load, in-cylinder pressure and boost pressure-time history, have been measured during acceleration in order to acquire the data for validation of engine acceleration model. A non-linear, transient, multi-cylinder, turbocharged, diesel engine simulation has been developed for predictions of instantaneous engine and turbocharger speed and torque. The foundation of the model is a thermodynamic, steady state diesel engine simulation. The transient extension of the original model represents the diesel engine as a non-linear, dynamic system. The predictions of engine simulation model agree fairly well with experimental results and may be used for case studies of engine acceleration. As an example the model has been used to study the influence of manifold-pressure compensator (LDA-system) on the acceleration of turbocharged diesel engine. The original LDA-system has been modified and the comparison of the results predicted by the application of original and modified LDA system has been done.

The automotive catalytic converters, which are employed to reduce engine exhaust emissions, operate in transient conditions under all modes of operation. The fluctuation in air-fuel ratio is a major contributor to these transients. The consideration of these transients is essential in accurate modeling of catalyst operation during actual driving conditions. In this work, a numerical investigation is carried out to comprehend the dynamic response of three-way catalytic converters subjected to changes in air-fuel ratio. The mathematical model considers the coupling effect of heat and mass transfer with the catalyst reactions as exhaust gases flow through the catalyst. The converter dynamic response is studied by considering a converter operating under steady conditions, which is suddenly subjected to air-fuel ratio variations. Two types of imposed fluctuations (sinusoidal and step changes) are considered. The catalyst response is predicted by using a detailed chemical mechanism. The paper elucidates the effect of air-fuel modulations on the catalyst HC, CO, and NO conversion efficiencies.

In result of the permanent endeavor to reduce fuel consumption of vehicle engines, nowadays the implementation of downsizing concepts is being enforced. Thereby the desired nominal engine power can be produced by an engine with lower displacement operating with correspondingly higher charging pressure. Mechanical supercharging as well as turbocharging can be considered as a suitable supercharging method. This paper reports on experimental and simulation results regarding the stationary and transient operation of a four-stroke cycle SI passenger car engine supercharged by a new type of screw-type supercharger. In this manner the load control of the SI engine is performed by a supercharger internal slide valve system. Thus not only the throttling losses will be reduced noticeably, but also expansion work can be regained by this supercharger under certain operating conditions. The results obtained will be compared with those of the turbocharged reference engine.

Increase of the mean effective pressure in an automotive Diesel engine is generally the consequence of the turbocharging and subsequent charge cooling of the working medium. A problem of poor performance during the engine speed and load change is attributed to the nature of energy exchange between the engine and the turbocharger. Filling of the intake and exhaust manifolds, consequent increase of the pressure and acceleration of the rotating components of the turbocharger require a certain period of time. Dynamic performance of the turbocharger can be substantially improved by the assistance of an electric motor attached directly to the turbo shaft. A new concept of asynchronous electric motor with a very thin rotor was applied to support the turbocharger during the transient regimes of the engine. Experimental work for matching an electrically assisted turbocharger to an engine is rather expensive; it was therefore decided to determine general characteristic of the electric motor separately by experiments, whereas transient response of the turbocharged and intercooled Diesel engine was simulated by a zero-dimensional filling and emptying computer simulation method. A lot of experimentally obtained data and empirical formulae for the compressor, gas turbine, flow coefficients of the engine valves, intercooler, high pressure fuel pump with the pneumatic control device (LDA), combustion parameters etc. were applied to overcome deficiency introduced by the zero-dimensional simulation model. As the result a reliable and accurate program compatible with the experimental results in steady and transient engine operation was developed and is presented in the work. Faster transient response of the engine was obtained by applying an electric motor to assist the turbocharger; a few versions were introduced in the simulation program and were also analysed in the work.

Turbocharged engines are the standard architecture for designing efficient spark ignition and compression ignition reciprocating internal combustion engines (ICE). Turbochargers characterization and modeling are basic tasks for the analysis and prediction of the whole engine system performance and this information is needed in quite early stages of the engine design. Turbocharger characteristics (efficiency, pressure ratio, mass flow rates...) traditionally rely in maps of pseudo non-dimensional variables called reduced variables. These maps must be used by reciprocating ICE designer and modeler not only for benchmarking of the turbocharger, but for a multiplicity of purposes, i.e: assessing engine back-pressure, boost pressure, load transient response, after-treatment inlet temperature, intercooler inlet temperature, low pressure EGR temperature, ... Maps of reduced variables are measured in gas-stands with steady flow but non-standardized fluids conditioning; neither temperatures nor flows. In concrete: turbine inlet gas temperature; lubrication-oil flow and temperature; water-cooling flow and turbo-machinery external heat transfer are non-standardized variables which have a big impact in assessing said multiplicity of purposes. Moreover, adiabatic efficiency, heat losses and friction losses are important data, hidden in the maps of reduced variables, which depend on the testing conditions as much as on the auxiliary fluids temperature and flow rate. In this work it is proposed a methodology to standardize turbochargers testing based in measuring the maps twice: in close to adiabatic and in diathermal conditions. Along the paper it is discussed with special detail the impact of the procedure followed to achieve said quasi-adiabatic conditions in both the energy balance of the turbocharger and the testing complexity. As a conclusion, the paper proposes a methodology which combines quasi-adiabatic tests (cold and hot gas flow) with diathermal tests (hot gas flow) in order to extract from a turbocharger gas-stand all information needed by engine designers interested in controlling or 1D-modelling the ICE. The methodology is completed with a guide for calibrating said control-oriented turbocharger models in order to separate aerodynamic efficiency (adiabatic) from heat transfer losses and from friction losses in the analysis of the turbocharger performance. The outsourced calibration of the turbocharger model allows avoiding uncertainties in the global ICE model calibration, what is very interesting for turbochargers benchmarking at early ICE-turbo matching stages or for global system analysis at early control design stages.

The control of combustion is a key topic for diesel engine development in terms of performance and pollutant emissions. The combustion process is piloted through the proper injection strategy, which depends on the features of the injection system. Mechanical-hydraulic models of high-pressure injection systems often support the accurate tuning of the injection strategy. The higher is the accuracy in the modeling of the electro-injector behavior, the deeper is the role of the simulation. Under such a viewpoint, the validation of the models is undoubtedly fundamental. One of the most crucial information characterizing the injector relies on the measurement of the needle displacement. Needle displacement affects rate, timing and quantity of injected fuel; it also influences the flow features within the nozzle, which are then reflected by the primary atomization process. Needle is considered hardly-accessible due to the injector architecture itself, making difficult the measurement of displacement. Nevertheless, the problem has been handled in different ways and three measurement techniques have been proposed. On one side, there is the measurement based on eddy-current transducers; on the other side, there are two alternative procedures, based on the use of optical sensors. However, in all cases, the needle is traced indirectly, since the position of the control plunger of the needle is observed. The current contribution presents a novel experimental technique for the measurement of needle displacement. The method is based on the direct visualization of the needle, allowing for the detailed definition of its law of motion through digital imaging, when the injector is characterized on a test-rig under transient conditions. The paper describes the details of the diagnostic scheme, the experimental facility and the digital imaging set-up. The main features and the capabilities of the method are discussed, in comparison with the other available techniques.

Fully variable valve technology of diesel engine can change the movement parameters of valve flexibly, and then the performance of engine can be improved. But the actual valve movement can’t track the optimal valve profile due to the nonlinear characteristics of hydraulic system in transient work conditions, which make the engine performance be deteriorated. To solve the problem, the paper introduced the idea of dynamic programming (DP) into the control of FVVA system. Firstly, the paper presented a new electro-hydraulic FVVA system. To verify the FVVA system, the GT-suite models of FVVA system and engine were built. Secondly, for the purpose of achieving optimal performance, based on the NSGA-II genetic algorithm, we got the database of the optimal valve profile movement parameters using modeFRONTIER platform. In database, there are multiple feasible solutions for one work condition. To achieve the optimal engine performance in every cycle, according to the real-time valve movement profile, the controller will choose different solutions with DP method in one cycle based on the database obtained before. The DP controller can make the engine performance to be optimal according to the real-time valve profile in transient conditions. In steady conditions, optimal valve profiles can be reached by a PID controller. Thirdly, the DP controller and PID controller were designed with Simulink separately. The DP controller will adjust valve control parameters in one cycle and the PID controller will adjust the parameters cycle by cycle. At last, the DP-PID controller was compared with the single PID controller which adjust control parameters once in one cycle. The simulation results show that the performance of engine with DP-PID controller is improved compared to the PID controller especially in transient conditions. The average brake power can be improved by 3.3% to 4.7% compared to single PID controller.

In-cylinder flow fields make significant impacts on the fuel atomization, fuel mixture formation, and combustion process in spark ignition direct injection (SIDI) engines. In recent years, model-based simulation approaches are preferred in regard to investigating the transient in-cylinder flow field characteristics. Most commonly, the simulation models are validated using single representative flow field at a typical crank angle measured by particle image velocimetry (PIV). However, it provides only limited knowledge about the flow field which is highly three-dimensional and of transient nature. In this study, crank angle-resolved PIV measurements are conducted on three distinct planes inside the cylinder to capture the transient process of flow field characteristics which vary with the crank angle. These three planes consist of one tumble plane through the spark plug tip, one tumble plane along two intake ports, and one swirl plane at 30 mm below the cylinder head. Large eddy simulation (LES) is employed for the numerical computations using the CONVERGE codes. On the basis of large datasets for both temporal and spatial domains, a multi-index systematic validation approach is conducted. Crank angle-resolved calculations of global indices and local indices are implemented using the flow fields velocity data obtained from both PIV and LES on select planes. Global indices reveal the trends in similarities of different crank angle degrees and locations, while local indices give the detail comparison results. In summary, with the systematic multi-index validation approach, the crucial crank angle degrees and locations for model verification will be detected. Furthermore, the corresponding critical flow features are analyzed. Practical guideline of flow field validation is proposed.

Increasingly restrictive limits on Oxides of Nitrogen - NOx levels and desire for low methane emissions from gas engines are driving the change from lean-burn to stoichiometric combustion strategies on heavy-duty on-highway natural gas engines in order to take advantage of inexpensive and effective three-way catalyst technology. The change to stoichiometric combustion has led to increased tendency for engine knock due to higher in-cylinder temperatures. To suppress engine knock, Exhaust Gas Recirculation (EGR) rates from 10 to 30% are used. While high EGR rates nominally improve Brake Thermal Efficiency (BTE) and reduce exhaust gas temperatures, they also slow down combustion. However, by deploying a controlled spark triggered homogeneous charge volumetric ignition, very short burn durations can be achieved without the destructive effects of engine knocking towards high efficiency gas engines. In the interest of achieving 45% BTE in spark ignited an on-highway class 8 truck engines fueled on natural gas and to meet EURO 6 and future California emissions standards of 0.02 gm/kw-hr NOx, Controlled Auto-Ignition (CAI) is herein demonstrated on a 15 liter truck engine. CAI is enabled by (a) having a combustion device capable of exceptionally good combustion stability in the presence of high EGR rates (COV of IMEP < 0.75 %), (b) cylinder pressure based combustion feedback, and (c) fast closed loop combustion control (using a Woodward RT-CDC control system). This system enables significant reduction in burn duration by controlling a two phase combustion event. The first phase is normal spark ignited propagating flame, which then triggers the second phase which is volumetric auto-ignition. The location and percentage of fuel that burns in the volumetric auto-ignition event is controlled relative to that which occurs via the conventional spark ignited flame propagation process by use of high speed combustion in the loop feedback control. Auto-ignition mass fraction burned (MFB) ratios of 25–50% have been achieved yielding higher heat release rates at the end of combustion than at the center of combustion with the result being a shortening of the combustion burn duration from a nominal 20–30 degrees to a near optimal 10–15 degrees even with EGR rates as high as 25%. A novel and patent pending burn duration control strategy is employed to stably maintain this knock-free combustion strategy even with compression ratio as high as 14:1. The benefits are significant increase in Brake Thermal Efficiency and substantial reduction in engine out methane emissions without sacrifice of transient responsiveness.

Natural gas is traditionally considered as a promising fuel in comparison to gasoline due to the potential of lower emissions and significant domestic reserves. These emissions can be further diminished by using noble gases, such as argon, instead of nitrogen as the working fluid in internal combustion engines. Furthermore, the use of argon as the working fluid can increase the thermodynamic efficiency due to its higher specific heat ratio. In comparison to pre-mixed operation, the direct injection of natural gas enables the engine to reach higher compression ratios while avoiding knock. Using argon as the working fluid increases the in-cylinder temperature at top dead center and enables the compression ignition of natural gas. In this numerical study, the combustion quality and ignition behavior of methane injected into a mixture of oxygen and argon has been investigated using a three-dimensional transient model of a constant volume combustion chamber. A dynamic structure large eddy simulation model has been utilized to capture the behavior of the non-premixed turbulent gaseous jet. A reduced mechanism consists of 22-species and 104-reactions were coupled with the CFD solver. The simulation results show that the methane jet ignites at engine-relevant conditions when nitrogen is replaced by argon as the working fluid. Ignition delay times are compared across a variety of operating conditions to show how mixing affects jet development and flame characteristics.

The balancing of the electric grid has become more challenging due to the expansion of fluctuating renewable energy sources for electric power generation. The importance of power plants driven by internal combustion engines will increase since they can react flexibly and quickly to changes in the energy demand. With regard to the emission of pollutants and CO 2 , gas fueled engines are favored for gensets. However, it is more challenging to meet the dynamic load requirements with a gas engine than with a conventional diesel engine because the load acceptance of the gas engine is limited by the occurrence of knocking combustion. Dual fuel engines are a good compromise between these two engine concepts; they can use gaseous fuel during steady state engine operation and increase the diesel share during transient modes to improve the dynamic behavior. The high number of degrees of freedom of dual fuel combustion concepts requires advanced operating strategies. The aim of this paper is to investigate and evaluate strategies to improve the transient behavior of a 20-cylinder large bore diesel-gas engine (displacement 6.24 dm 3 per cylinder) for a genset application. In the investigations, the latest turbocharging technology is applied in combination with a turbine waste gate. A wide range diesel injector that covers the whole diesel injection range of approximately 1 % to 100 % diesel fraction 1 of the rated power fuel mass provides the basis for the most flexible diesel injection. A 1D simulation tool was used to model and optimize the genset in transient operation. The combustion process was simulated with Vibe heat release rate models. The optimized transient engine operating strategies were validated on a highly dynamic single cylinder research engine test bed. The paper provides a comparison of different strategies that use these technologies to improve the dynamic behavior of the genset in island mode operation during a 50 % load step. Key to meeting the challenging requirements is an optimized diesel injection strategy or even a switch from gas operation mode to diesel operation mode during the load step. Based on the results of simulation and engine testing, potential ways to minimize engine speed drop and recovery time after the load demand increase are evaluated.

The following article details a method for the optimization and improved use of the internal combustion engine as main propulsion. The focus here is not on new propulsion systems or combustion processes, but on the characterization of the typical usage of existing systems in order to enable better utilization. As one major potential for improvement, the transient machinery operation is examined and discussed in this article. Higher fuel consumption and higher emissions occur compared with stationary engine operation in that operation mode. Experimental data from test bed (“Caterpillar MaK 6M20”) measurements are presented which explain the consequences of transient operation. Furthermore, appropriate analyzing methods to evaluate this operation mode are shown. Finally, a modelling approach is presented using the data for calibration and validation of an engine simulation model. The most significant part to predict real transient efficiency and emissions is the in-cylinder process and especially its combustion process. Therefore, the simulation model does not use engine maps but a mostly physically based engine model by using thermodynamic approaches and chemical reaction kinetics. The specific application of that simulation model for four-stroke medium-speed engines covers the behavior of transient operation during ship maneuverings since it is developed for integration into a ship engine simulator.

Pistons for heavy duty diesel applications endure high thermal loads and therefore result in reduced durability. Pistons for such heavy duty applications are generally designed with an internal oil gallery — called the piston cooling gallery (PCG) — where the intent is to reduce the piston crown temperatures through forced convection cooling and thereby ensure the durability of the piston. One of the key factors influencing the efficiency of such a heat-transfer process is the volume fraction of oil inside the piston cooling gallery — defined as the filling ratio (FR) — during engine operation. As a part of this study, a motoring engine measurement system was developed to measure the piston filling ratio of an inline-6 production heavy duty engine. In this system, multiple high precision pressure sensors were applied to the piston cooling gallery and a linkage was designed and fabricated to transfer the piston cooling gallery oil pressure signal out of the motoring engine. This pressure information was then correlated with the oil filling ratio through a series of calibration runs with known oil quantity in the piston cooling gallery. This proposed method can be used to measure the piston cooling gallery oil filling ratio for heavy duty engine pistons. A preliminary transient Computational Fluid Dynamics (CFD) analysis was performed to identify the filling ratio and transient pressures at the corresponding transducer locations in the piston cooling gallery for one of the motoring test operating speeds (1200 RPM). A mesh dependency study was performed for the CFD analysis and the results were compared against those from the motoring test.