This paper presents an application of the mean value combustion model to simulate large bore turbocharged diesel engines, coupled with large electric AC synchronous generators, to mimic power generation within a training simulator for a ship board electrical power system. A mean value engine model has been developed to simulate the most prevalent phenomena occurring in diesel direct injection internal combustion engines. The combustion process is modeled as a mean value system where characteristics of combustion are averaged over the entire cycle. Detailed models of the air intake, fuel delivery, and internal/external cooling systems have been developed using concepts from fluid dynamics and thermodynamics. The engine model has been created in MATLAB ® Simulink ® to simulate actual hardware signals sent to the power management controller to facilitate the development of the power system trainer. The model has been structured so that it is highly adaptable and is capable of simulating a wide variety of engine bore sizes and cylinder numbers which has significantly increased the utility of the work presented herein.

Continued interest in kinetically-modulated combustion regimes, such as HCCI and PCCI, poses a significant challenge in controlling the ignition timing due to the lack of direct control of combustion phasing hardware available in traditional SI and CI engines. Chemical kinetic mechanisms, validated based on fundamental data from experiments like rapid compression machines and shock tubes, offer reasonably accurate predictions of ignition timing; however utilizing these requires high computational cost making them impractical for use in engine control schemes. Empirically-derived correlations offer faster control, but are generally not valid beyond the narrow range of conditions over which they were derived. This study discusses initial work in the development of an ignition correlation based on a detailed chemical kinetic mechanism for three component gasoline surrogate, composed of n-heptane, iso-octane and toluene, or toluene reference fuel (TRF). Simulations are conducted over a wide range of conditions including temperature, pressure, equivalence ratio and dilution for a range of tri-component blends in order to produce ignition delay time and investigate trends in ignition as pressure, equivalence ratio, temperature and fuel reactivity are varied. A modified, Arrhenius-based power law formulation will be used in a future study to fit the computed ignition delay times.

A two-degree freedom air fuel ratio controller (Model based feed forward transient plus closed loop Proportional-Integral-Derivative (PID) steady state controllers) developed for controlling the air fuel ratio of the charge in a small displacement (125 CC) SI engine is presented. The feed forward controller’s airflow and injector models were developed after conducting extensive experiments on the engine modified for the Port Fuel Injection (PFI) operation. A dynamic air fuel ratio model obtained (air fuel ratio changes measured using an UEGO sensor) by injecting the Pseudo Random Binary Signal (PRBS) signal in addition to base line fuel injection pulse, was used for designing the PID controller. Optimal PID gain values were identified using Nelfer-Mead optimization technique. The control algorithms were implemented and optimized using SIMULINK blocks that are run under dSPACE on the MicroAuto box hardware. The optimized control algorithms were ported on the specially designed, in-house built, low cost engine management system (EMS) developed around an 8-bit microcontroller. The spark timing was also controlled simultaneously for knock free operation. The two-degree freedom air fuel ratio controller could maintain the air fuel ratio under steady and transient conditions closely. High thermal efficiency and low HC & NOx emissions were achieved using the developed EMS. At higher speed elevated NOx emission was observed, due to the use of leaner mixture. The improvements are expected to be higher if a suitable smaller injector is used.

Pipeline natural gas composition is monitored and controlled in order to deliver high quality, relatively consistent gas quality in terms of heating value and detonation characteristics to end users. The consistency of this fuel means gas-fired engines designed for electrical power generation (EPG) applications can be highly optimized. As new sources of high quality natural gas are found, the demand for these engines is growing. At the same time there is also an increasing need for EPG engines that can handle fuels that have wide swings in composition over a relatively short period of time. The application presented in this paper is an engine paired with an anaerobic digester that accepts an unpredictable and varying feedstock. As is typical in biogas applications, there are exhaust stream contaminants that preclude the use of an oxygen or NO x sensor for emissions feedback control. The difficulty with such a scenario is the ability to hold a given exhaust gas emission level as the fuel composition varies. One challenge is the design of the combustion system hardware. This design effort includes the proper selection of compression ratio, valve events, ignition timing, turbomachinery, etc. Often times simulation tools, such as a crank-angle resolved engine model, are used in the development of such systems in order to predict performance and reduce development time and hardware testing. The second challenge is the control system and how to implement a robust control capable of optimizing engine performance while maintaining emissions compliance. Currently there are limited options for an OEM control system capable of dealing with fuels that have wide swings in composition. Often times the solution for the engine packager is to adopt an aftermarket control system and apply this in place of the control system delivered on the engine. The disadvantage to this approach is that the aftermarket controller is not calibrated and so the packager is faced with the task of developing an entire engine calibration at a customer site. The controller must function well enough that it will run reliably during plant start-up and then eventually prove capable of holding emissions under typical operating conditions. This paper will describe the novel use of a crank-angle resolved four-stroke engine cycle model to develop an initial set of calibration values for an aftermarket control system. The paper will describe the plant operation, implementation of the aftermarket controller, the model-based calibration methodology and the commissioning of the engine.

Today, Reynolds Averaged Navier Stokes (RANS) simulation approach remains the most widely used method in computational fluid dynamic studies of IC-Engines because it allows a good prediction of the mean flow properties at an affordable computational cost. The main limit of the RANS approach resides in the method used to predict turbulence that fails in the reproduction of anisotropic turbulence conditions. It can result in a lack of accuracy in reproducing the main physical processes, as spray evolution (mixture formation), heat transfer, and combustion, governing the IC-Engine physics. To fix this problem, the large Eddy Simulation (LES) approach can be considered. In LES the governing equations are filtered in space, rather than time-averaged as in RANS. It allows the direct solution of all the turbulent scales up to a cut-off length defined by the filter dimension. Therefore, in LES a more accurate description of the turbulence and of all the physical processes correlated to it has to be expected. However, even if the LES method allows an irrefutable improvement in turbulent flow solution accuracy, today its application to industrial IC-Engine design is still rare because of its high computational cost. During the last few years, significant advances in numerical methods, sub-grid scale models, and hardware performance have supported LES applications in many industrial fields. This paper is intended to work in the same direction by presenting a new LES methodology based on the coupling between LES and an adaptive mesh refinement (AMR) procedure. The main goal of this procedure is to guarantee a good resolution of the turbulent flow field adapting the filter size to the local turbulence length scale. The developed procedure allows a significant reduction of the total mesh size and, therefore, of the computational cost. The LES-AMR method was tested on an IC-Engine geometry for which experimental results were available.

An electronic fuel injection system for a 4-stroke, 16 cylinders, V-configuration, medium speed, large bore locomotive diesel engine has been developed and successfully retrofitted on a rebuilt diesel locomotive. The engine employs a Pump-Line-Nozzle (PLN) system of fuel injection into the cylinder. Original fuel injection system used is a mechanical fuel injection pump connected to a mechanical fuel injector through a high pressure fuel line. The fuel injection pump meters the fuel delivery using a single helix machined on its plunger. The fuel injection timings are however optimized only for the rated speed and load resulting in non-optimised operation at other engine operating points. An electronic fuel injection pump having a solenoid valve for both fuel metering and injection timing along with ECU has been developed for retrofitment on rebuilt diesel locomotives. Interfacing of the ECU to the engine test cell controller has been done by developing suitable hardware and software. ECU calibration has been done and various maps of the engine have been developed. The engine was tested on the engine test bed. High pressure injector, modified fuel headers, fuel connection systems, a new high capacity fuel pump and layout of the wire harness were installed. After thorough testing and debugging, the EFI kit has been retrofitted on a rebuilt diesel locomotive and tested on load box followed by brief field trials. A savings of 4% fuel consumption over the duty cycle has been obtained. In addition there is an appreciable reduction in the smoke emissions during steady-state as well as transient operations.

Both, the continuous tightening of the exhaust emission standards and the global efforts for a significant lowering of CO2 output in public traffic display significant developments for future diesel engines. These engines will utilize not only the mandatory Diesel oxidation catalyst (DOC) and particulate trap (DPF), but also a DeNOx aftertreatment system as well — at least for heavier vehicles. The DOC as well as actually available sophisticated DeNOx aftertreatment technologies, i.e. LNT and SCR, depends on proper exhaust gas temperatures to achieve a high conversion rates. This aspect becomes continuously critical due to intensified measures for CO2 reduction, which will conclude in a drop of exhaust gas temperatures. Furthermore, this trend has to be taken into account regarding future electrification and hybridization scenarios. In order to ensure the high NOx conversion rates in the EAS intelligent temperature management strategies will be required, not only based on conventional calibration measures, but also a further upgrade of the engine hardware. Advanced split-cooling and similar thermal management technologies offer the merit to lower CO2 emissions on one hand and increase exhaust gas temperature at cold start and warm-up simultaneously on the other hand. Besides this, also variable valve train functionalities deliver a substantial potential of active thermal management. In the context of this paper various concepts for exhaust gas temperature management are investigated and compared. The final judgment will focus on the effectiveness concerning real exhaust temperature increase vs. corresponding fuel economy penalty. Further factors, like operational robustness, consequences on operational strategies and related software algorithms as well as cost are assessed. The utilized reference engine in this advanced program is represented by a refined I-4 research engine to achieve best combustion efficiency at minimal engine-out emissions. The detailed studies were performed with an injection strategy, featuring one pilot injection and one main injection event, and an active, advanced closed-loop combustion control. The engine used in this study allows fulfillment of Euro 6 and Tier 2 Bin 5 emissions standards, while offering high power densities above 80 kW/ltr. As a résumé, it can be stated, that with all accomplished variations a significant increase in temperature downstream low pressure turbine can be achieved. The PI and PoI quantities define dominant parameters for emission formation under cold and warm conditions. By using an exhaust cam-phaser CO-, HC- and NOx emissions can be significantly lowered, separating VVT functions from the other investigated strategies.

Engine Control Units (ECUs) are developed to manage the variable conditions in an operating engine, such as fuel injection, spark ignition, and valve timing, for achieving the goal of high performance, high efficiency and low emissions. Typically, an engine model is necessary for developing the engine control system. Most of the engine models for engine control are mean value engine model (MVEM) based on empirical volumetric efficiency to calculate the intake air flow rate. This kind of model is not able to simulate the changes of the valve, such as valve lift and valve timing. It can not be used for the engine with variable valve train (VVT). Therefore, a new method, able to inform the valve changing, is applied to adapt the new demand of engine models. The proposed engine model is similar to most current models except the charging system. The charging model is developed by using filling-and-emptying model to simulate the air exchange in the engine, including the intake and exhaust air dynamics. The flow through the valves is calculated according to the pressure drop between the cylinder and the manifold, the flow area of the valve opening and its flow coefficient. The other important feature of the proposed engine model is the capability of real time simulation. The model is verified by experimental volumetric efficiency and engine torque. Finally, a HIL (Hardware in the Loop) simulation is performed to confirm the real time simulation.

Phase-enhanced x-ray imaging has been used to examine the geometry and dynamics of four diesel injector nozzles. The technique uses a high-speed camera, which allows the dynamics of individual injection events to be observed in real time and compared. Moreover, data has been obtained for the nozzles from two different viewing angles, allowing for the full three-dimensional motions of the needle to be examined. This technique allows the needle motion to be determined in situ at the needle seat and requires no modifications to the injector hardware, unlike conventional techniques. Measurements of the nozzle geometry have allowed the average nozzle diameter, degree of convergence or divergence, and the degree of rounding at the nozzle inlet to be examined. Measurements of the needle lift have shown that the lift behavior of all four nozzles consists of a linear increase in needle lift with respect to time until the needle reaches full lift and a linear decrease as the needle closes. For all four nozzles, the needle position oscillates at full lift with a period of 170–180 μs. The full-lift position of the needle changes as the rail pressure increases, perhaps reflecting compression of the injector components. Significant lateral motions were seen in the two single-hole nozzles, with the needle motion perpendicular to the injector axis resembling a circular motion for one nozzle and linear oscillation for the other nozzle. The two VCO multihole nozzles show much less lateral motion, with no strong oscillations visible.

Nowadays, Computational Fluid Dynamic (CFD) codes are widely used in different industrial fields. Although hardware and numerical model improvements, the mesh generation remains one of the key points for a successful CFD simulation. Mesh quality is influenced by the adopted mesh generator tool and, after all, by the designer’s experience and it becomes very important when moving meshes are required. In fact, mesh skewness, aspect ratio, and non-orthogonality have to be controlled during the deforming process since their wrong evolution could produce an unphysical behavior of the computed flow field. Mesh motion could be performed by different strategies: dynamic smoothing operation and dynamic re-meshing operation, are, today, two of the mainly used approaches. All of them can be combined to guarantee the correct reproduction of motion profile and a good mesh quality level. In this context, the authors have implemented a moving mesh methodology in the Open Source CFD code OpenFOAM®. A multiple number of meshes is used to cover the whole simulation period, and the grid point motion is accommodated by an automatic mesh motion techinque with polyhedral cell support. The Laplace equation is chosen to govern mesh motion. This guarantees that an initial valid mesh remains valid for arbitrary boundary motion. Mesh to mesh interpolation is performed by using a cell based, distance weighted interpolation technique. The proposed approach was tested on a real IC-engine geometry. In particular, the mesh quality evolution during motion, the numerical results and the computational costs were evaluated.

Continued regulatory pressure necessitates the use of precisely designed turbochargers to create the design trapped equivalence ratio within large-bore stationary engines used in the natural gas transmission industry. The upgraded turbochargers scavenge the exhaust gases from the cylinder, and create the air manifold pressure and backpressure on the engine necessary to achieve a specific trapped mass. This combination serves to achieve the emissions reduction required by regulatory agencies. Many engine owner/operators request that an upgraded turbocharger be tested prior to installing the turbocharger on the engine. The purpose of the test is to prevent field hardware iterations that are oftentimes necessary for the turbocharger to meet the air specification on the particular engine. Reworking a turbocharger due to not meeting the airflow and pressure requirement for emissions purposes can be quite costly and in many cases easily discovered through test-cell performance testing. Confirming the as-built turbocharger design specification prior to transporting the turbocharger to the field can decrease downtime and installation costs. There are, however, technical challenges that must be overcome to compare test-cell data to field conditions. This paper discusses the corrections that must be made to the test-cell data in order to determine how the turbocharger will perform on the engine. As the litmus test of the new testing system, performance data is corrected to site conditions verifying the air specification as designed by the end user. The correction method utilized herein is the ASME Power Test Code 10 (PTC-10) version 1997. Performance test data and the compressor map are corrected with the PTC-10 method to field conditions verifying turbocharger site performance before installation. After installation, data collected from the turbocharger operating on engine is compared with test corrected data, authenticating the turbocharger testing system and correction methods.

High power density and thermal efficiency combined with very low NOx exhaust emissions are main challenges in today’s gas engine development programmes. Until recently open chamber combustion systems using traditional spark ignition were considered to be limited by knock and misfire in their potential to achieve the above mentioned goals. The main task of the work reported here was to achieve a stable, knock-free combustion using a knock-prone gas fuel of 70 methane number for a specific power density of 25 kW/L at 250 mg/m 3 N NOx emission according to the TA Luft. The combustion system development was carried out on a single cylinder engine (SCE), thus, a special aspect of the work was to ensure transferability of the single cylinder engine combustion system development results to the targeted V12 multi-cylinder engine. Prior to engine testing, intensive simulation work was undertaken to specify the most promising engine hardware configurations. The main emphasis was on the 3D CFD analysis of the in-cylinder charge motion and its interaction with carefully chosen combustion chamber geometry variants. The ultimate scope was to generate high local turbulence levels during combustion, enabling a short combustion duration with low variation coefficients. The experimental phase included engine tests for several combustion relevant parameters and the detailed combustion analysis with respect to flame propagation and knock centre location using the optical combustion diagnosis system AVL VISIOLUTION. This paper describes the overall work procedure as well as the analytical and experimental methods and tools employed in the combustion system development programme. It also gives information on engine test results, the value and contribution of combustion visualisation, as well as on the engine performance which could be finally reached.