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This paper reports on a comprehensive, crank-angle transient, three dimensional, computational fluid dynamics (CFD) model of the complete lubrication system of a multi-cylinder engine using the CFD software Simerics-Sys / PumpLinx. This work represents an advance in system-level modeling of the engine lubrication system over the current state of the art of one-dimensional models. The model was applied to a 16 cylinder, reciprocating internal combustion engine lubrication system. The computational domain includes the positive displacement gear pump, the pressure regulation valve, bearings, piston pins, piston cooling jets, the oil cooler, the oil filter etc… The motion of the regulation valve was predicted by strongly coupling a rigorous force balance on the valve to the flow.

A model is presented in which distinction is made between the contributions of the different mechanisms of heat transfer to an air bag fabric during deployment. An experimental setup, designed for simulation and recording of the thermal response of permeable and coated (impermeable) air bag fabrics, is described. Comparisons between the experimental results and numerical predictions show fair agreement. The preliminary results show that the model provides a framework in which the interplay between the three convective heat transfer coefficients (two surface and one volumetric) that affect the fabric temperature (and the heat loss from the upstream bag gas) can be examined. Currently the magnitude of these surface convective heat fluxes are being examined experimentally.

The effect of wall temperature on single surface flame quenching and flame structure of an atmospheric premixed methane-air flame was studied. The luminous region of a laminar flame was located at an angle of 45 degrees to a temperature- controlled surface. C2 laser-induced fluorescence was used as an indicator of flame position while Raman spectroscopy was used to determine gas temperature profiles near the surface. These measurements were conducted for wall positions (vertical distance from the surface) ranging from 50 mm to 1.0 mm and wall temperatures ranging from 150 °C to 600 °C. C2 laser-induced fluorescence measurements indicated flame position is affected by the presence of a surface and the surface temperature. Larger C2 fluorescence intensity values were observed for higher wall temperatures at all distances from the surface.

A study of fuel spray characteristics for diesel fuel from a multi-hole nozzle injector was performed yielding tip penetration length and spray cone angle for each of the spray plumes from a six hole injector. The main feature of the system used was that analysis of all the fuel plumes could occur at one time, as all the plumes were imaged on the same piece of film. Spray behavior was examined for two injection pressures (72 MPa and 122 MPa) and for ambient temperatures up to 523 K (250°C). The results in this paper show how the spray plumes behave as they leave each of the six holes of the injector. The characteristics of each hole differs during injection. The variations of spray cone angle and tip penetration length between holes are small, but significant. These variations in tip penetration and cone angle changed as the temperature of the chamber changed, but the overall characteristics of the spray plumes changed only slightly for the temperatures used in this paper.

Homogeneous Charge Compression Ignition (HCCI) combustion is known for its significant fuel economy benefit with near-zero NOx and particulate emissions. Stable HCCI combustion relies on a well-controlled temperature and composition of the cylinder charge at the intake valve closing that in turn requires a precise coordination of all engine inputs. In this paper, the HCCI combustion is realized by retaining hot residual from the previous combustion event using the recompression valve strategy. The recompression valve strategy closes the exhaust valves before the top dead center and opens the intake valves at an angle symmetric to the exhaust valve closing. Depending on the engine load, different valve open/close timings with respect to the crank position are used to trap different amounts of residual gases. It is critical to coordinate the change in the valve open/close timings with the change in the injected fuel quantity during load transients in order to maintain stable combustion.

An experimental investigation of the spectral characteristics of turbulent flow in a scale model of a high pressure diesel fuel injector nozzle hole has been conducted. Instantaneous velocity measurements were made in a 50X transparent model of one hole of an injector nozzle using an Aerometrics Phase/Doppler Particle Analyzer (PDPA) in the velocity mode. Turbulence spectra were calculated from the velocity data using the Lomb-Scargle method. Injector hole length to diameter ratio (L/D) values of 1.3, 2.4, 4.9, and 7.7 and inlet radius to diameter ratio (R/D) values of approximately 0 and 0.3 were investigated. Results were obtained for a steady flow average Reynolds number of 10,500, which is analogous to a fuel injection velocity of 320 m/s and a sac pressure of approximately 67 MPa (10,000 psi). Turbulence time frequency spectra were obtained for significant locations in each geometry, in order to determine how geometry affects the development of the turbulent spectra.

Due to concerns regarding pollutant and CO2 emissions, advanced combustion modes that can simultaneously reduce exhaust emissions and improve thermal efficiency have been widely investigated. The main characteristic of the new combustion strategies, such as HCCI and LTC, is that the formation of a homogenous mixture or a controllable stratified mixture is required prior to ignition. The major issue with these approaches is the lack of a direct method for the control of ignition timing and combustion rate, which can be only indirectly controlled using high EGR rates and/or lean mixtures. Homogeneous Charge Progressive Combustion (HCPC) is based on the split-cycle principle. Intake and compression phases are performed in a reciprocating external compressor, which drives the air into the combustor cylinder during the combustion process, through a transfer duct. A transfer valve is positioned between the compressor cylinder and the transfer duct.

The focus of this paper is to discuss the modeling and control of intake plenum pressure on the Powertrain Control Research Laboratory's (PCRL) Single-Cylinder Engine (SCE) transient test system using a patented device known as the Intake Air Simulator (IAS), which dynamically controls the intake plenum pressure, and, subsequently, the instantaneous airflow into the cylinder. The IAS exists as just one of many devices that the PCRL uses to control the dynamic boundary conditions of its SCE transient test system to make it “think” and operate as though it were part of a Multi-Cylinder Engine (MCE) test system. The model described in this paper will be used to design a second generation of this device that utilizes both continuously and discretely actuating valves working in parallel.

This paper describes how a blend of silicon polymers, mixed with the right combination of fillers, enables the production of durable rubber IC engine head and exhaust gaskets. The resin blend, when mixed with glass fiber reinforcement, produces a liquid sealant suitable for exhaust gasket applications. The exhaust sealant and laminate head gaskets were tested on Ford 460 truck engines at Jasper Engine Company and completed more than 5,000 hours of durability testing without incident. Fabric reinforced polymer (FRP) head and exhaust gaskets can be laser cut from molded laminates, creating a ceramic glass-sealed edge. Thermogravimetric scans of typical gasket laminate material reveal an 88%-yield at 1000°C. FRP head gaskets also enable the cost-effective production of multiple spark ignition (MSI) head gaskets.

Regenerative testing methods can be used to allow the testing of hydraulic pumps and motors at significantly higher power and flow levels than that of the power supply used. This method can also increase the accuracy of system efficiency measurements. The increase in accuracy is realized because only the power added to compensate for the system losses needs to be measured with great accuracy. Typically, for the operation points of interest this will be a much smaller quantity than the overall power of the system. Knowing that the error in flow measurements is a function of the quantity measured, the benefit of measuring the losses becomes clear. An additional, distinct advantage of regenerative testing is that no dynamometer or load is needed. This results in a much simpler test setup. This paper documents the development of such a test program at the University of Wisconsin-Madison.

A four valve controller and electronic control circuits were developed to control the displacement of hydrostatic pump/motors (P/M's) utilized in an automobile with a hydrostatic transmission and hydropneumatic accumulator energy storage. Performance of the control system was evaluated. The controller uses four high-speed, two-way, single-stage poppet valves, functioning in the same manner as a 4-way, 3-position spool valve. Two such systems were used to control the displacement of two P/Ms, each system driving a front wheel of the vehicle. The valves were controlled electronically by a distributed-control dead-band circuit and valve driver boards. Testing showed that the control system's time response satisified driving demand needs, but that the control system's error was slightly larger than desired. This may lead to complications in some of the vehicle's operating modes.

It is well known that the accuracy of simulations of combustion processes in diesel and spark ignited (SI) engines depends on the initial conditions within the cylinder at intake valve closure (IVC). Residual gas affects the engine combustion processes through its influence on charge mass, temperature and dilution. In SI engines, there is little oxygen in the residual gas, and thus the dilution effect on flame propagation is more significant than in compression ignited (CI) engines. However, in CI engines, the ignition delay depends strongly on the in-cylinder gas temperature, which is proportional to the gas temperature at IVC. Furthermore, ignition delay is significantly affected by how much oxygen is present, which is also partly determined by the residual gas fraction. Therefore, it is of extreme importance to determine residual gas concentrations accurately.

Optimal fuel injection strategies are obtained with a micro-genetic algorithm and an adaptive gradient method for a nonroad, medium-speed DI diesel engine equipped with a multi-orifice, asynchronous fuel injection system. The gradient optimization utilizes a fast-converging backtracking algorithm and an adaptive cost function which is based on the penalty method, where the penalty coefficient is increased after every line search. The micro-genetic algorithm uses parameter combinations of the best two individuals in each generation until a local convergence is achieved, and then generates a random population to continue the global search. The optimizations have been performed for a two pulse fuel injection strategy where the optimization parameters are the injection timings and the nozzle orifice diameters.

The design of a pressure compensated hydraulic valve is optimized using CFD analysis. The valve is used in a hydraulic system to control implement movement. High flow rates through the valve resulted in unacceptably high pressure drops, leading to an effort to optimize the valve design. Redesign of the valve had to be achieved under the constraint of minimal manufacturing cost. The flow path of hydraulic oil through the valve, the spool design, and various components of the valve that caused the high pressure drops were targeted in this analysis. A commercially available CFD package was used for the 3D analysis. The hydraulic oil flow was assumed to be turbulent, isothermal and incompressible. The steady-state results were validated by comparison with experimental data.

Studies of transient diesel spray characteristics at high injection pressures were conducted in a constant volume chamber by utilizing a high speed photography and light extinction optical diagnostic technique. Two different types of nozzle hole entrances were investigated: a sharp-edged and a round-edged nozzle. The experimental results show that for the same injection delivery, the sharp-edged inlet injector needed a higher injection pressure to overcome the higher friction loss, but it produced longer spray tip penetration length, larger spray angle, smaller droplet sizes, and also lower particulate emission from a parallel engine test. For the round-edged and smooth edged tips at the same injection pressure, the sharp-edged inlet tip took a longer injection duration to deliver a fixed mass of fuel and produced larger overall average Sauter Mean Diameter (SMD) droplets.

Diesel engine in-cylinder combustion processes have been studied using computational models with particular attention to spray development, vaporization, fuel/air mixture formation and combustion. A thermodynamic zero-dimensional cycle analysis program was used to determine initial conditions for the multidimensional calculations. A modified version of the time-dependent, three-dimensional computational fluid dynamics code KIVA-II was used for the computations, with a detailed treatment for the spray calculations and a simplified model for combustion. The calculations were used to obtain an understanding of the potential predictive capabilities of the models. It was found that there is a strong sensitivity of the results to numerical grid resolution. With proper grid resolution, the calculations were found to reproduce experimental data for non- vaporizing and vaporizing sprays. However, for vaporizing sprays with combustion, extremely fine grids are needed.

The fuel film thickness resulting from diesel fuel spray impingement was measured in a chamber at conditions representative of early injection timings used for low temperature diesel combustion. The adhered fuel volume and the radial distribution of the film thickness are presented. Fuel was injected normal to the impingement surface at ambient temperatures of 353 K, 426 K and 500 K, with densities of 10 kg/m3 and 25 kg/m3. Two injectors, with nozzle diameters of 100 μm and 120 μm, were investigated. The results show that the fuel film volume was strongly affected by the ambient temperature, but was minimally affected by the ambient density. The peak fuel film thickness and the film radius were found to increase with decreased temperature. The fuel film was found to be circular in shape, with an inner region of nearly constant thickness. The major difference observed with temperature was a decrease in the radial extent of the film.

Control of the flow of thermal energy in an air-cooled engine is important to the overall performance of the engine because of potential effects on engine performance, durability, design, and emissions. A methodology is being developed for the assessment of thermal flows in air-cooled engines, which includes the use of cycle simulation and in-cylinder heat flux measurements. The mechanism for the combination of cycle simulation, the measurement of in-cylinder heat flux and wall temperatures, and comparison of predicted and measured heat flux in the methodology is presented. The methodology consists of both simulation and experimental phases. To begin, a one-dimensional gas dynamics code (WAVE) has been used in conjunction with a detailed in-cylinder flow and combustion model (IRIS) in order to simulate engine operation in a variety of operating conditions. The methods used to apply the model to the air-cooled engine case are described in detail.

Since the advent of P/M technology as a near net shape production process, millions of mechanical components of various shapes and sizes have been produced. Although P/M continues to be one of the fast growing shaping processes, it suffers from the inability to produce intricate geometry's such as internal tapers, threads or recesses perpendicular to pressing direction. In such cases application of machining as a secondary forming operation becomes the preferred alternative. However, machining of P/M parts due to their inherent porosity is known to decrease tool life and increase tool chatter and vibration. Consequently, several attempts have been made to improve the machinability of P/M materials by either addition of machinability enhancing elements such as sulfur, calcium, tellurium, selenium, etc., or by resin impregnation of P/M parts.

This paper details results of a numerical and experimental investigation into the relative performance of vaned and vaneless mixed flow turbines for application to medium and heavy-duty diesel engines utilizing pulse exhaust systems. Previous investigations into the impact of nozzle vanes on turbine performance considered only open turbine housings, whereas a majority of medium and heavy-duty diesel engine applications are six-cylinder engines using pulse exhaust systems with divided turbines. The two turbine stages for this investigation were carefully designed to meet the constraints of engines with pulse exhaust systems and to control confounding factors that would undermine the vaned vs vaneless performance comparison. Detailed CFD analysis and turbine dynamometer test results confirm a significant efficiency advantage for the vaned turbine stage under both full and partial admission conditions.