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Technical Paper

(Particle) Emissions of Small 2-& 4-Stroke Scooters with (Hydrous) Ethanol Blends

The objectives of the present work are to investigate the regulated and unregulated (particle) emissions of a classical and modern 2-stroke and a typical 4-stroke scooter with different ethanol blend fuels. There is also comparison of two different ethanol fuels: pure ethanol (E) *) and hydrous ethanol (EH) which contains 3.9% water and is denatured with 1.5% gasoline. Special attention is paid in this research to the hydrous ethanol, since the production costs of hydrous ethanol are much less than those for (dry) ethanol. The vehicles are with carburettor and without catalyst, which represents the most frequent technology in Eastern Asia and offers the information of engine-out emissions. Exhaust emissions measurements have been performed with fuels containing ethanol (E), or hydrous ethanol (EH) in the portion of 5, 10, 15 and 20% by volume. During the test systematical analysis of particle mass (PM) and nano-particles counts (NP) were carried out.
Technical Paper

10 KWe Dual-Mode Space Nuclear Power System for Military and Scientific Applications

A 10 KWe dual-mode space power system concept has been identified which is based on INEL's Small Externally-fueled Heat Pipe Thermionic Reactor (SEHPTR) concept. This power system will enhance user capabilities by providing reliable electric power and by providing two propulsion systems; electric power for an arc-jet electric propulsion system and direct thrust by heating hydrogen propellant inside the reactor. The low thrust electric thrusters allow efficient station keeping and long-term maneuvering. The direct thrust capability can provide tens of pounds of thrust at a specific impulse of around 730 seconds for maneuvers that must be performed more rapidly. The direct thrust allows the nuclear power system to move a payload from Low Earth Orbit (LEO) to Geosynchronous Earth Orbit (GEO) in less than one month using approximately half the propellant of a cryogenic chemical stage.
Technical Paper

1970s Development of 21st Century Mobile Dispersed Power

A mobile and dispersed power system is necessary for an advanced technological-industrial society. Today's petroleum-based system discharges waste products and heat and is growing exponentially. Energy resource commitment has already intersected “ultimate” low-cost petroleum supplies in the United States and will do so for the world before 2000; this portends major changes and cost increases. The twenty-first century system for mobile-dispersed power will reflect the energy source selected to replace petroleum-for example, coal, solar insolation, or uranium. It will incorporate a fuel intermediate such as methanol, ammonia, or hydrogen, and a suitably matched “engine.” The complete change will require more than 25 years because of the magnitude, fragmentation, structural gaps, complexity, and variety of the mobile-dispersed power system.
Technical Paper

1980 CRC Fuel Rating Program - The Effects of Heavy Aromatics and Ethanol on Gasoline Road Octane Ratings

A gasoline Road Octane study was conducted by the Coordinating Research Council (CRC) to evaluate the effects of heavy aromatics (C9 and heavier) and ethanol content on Road Octane performance independent of Research Octane Number (RON) and Motor Octane Number (MON). Maximum-throttle and part-throttle Road ON’s were found to be well predicted by equations containing only RON and MON terms. Heavier aromatics were found to have a small adverse effect on both maximum-throttle and part-throttle Road ON independent of its direct effects on RON and MON. The all-car data did not show a significant ethanol-content effect, but eight of the thirty-seven cars did show significant effects for ethanol content.
Technical Paper

1D Model for Correcting the Rate of Injection Signal Based on Geometry and Temperature Influence

The fuel consumption and emissions of diesel engines is strongly influenced by the injection rate pattern, which influences the in-cylinder mixing and combustion process. Knowing the exact injection rate is mandatory for an optimal diesel combustion development. The short injection time of no more than some milliseconds prevents a direct flow rate measurement. However, the injection rate is deduced from the pressure change caused by injecting into a fuel reservoir or pipe. In an ideal case, the pressure increase in a fuel pipe correlates with the flow rate. Unfortunately, real measurement devices show measurement inaccuracies and errors, caused by non-ideal geometrical shapes as well as variable fuel temperature and fuel properties along the measurement pipe. To analyze the thermal effect onto the measurement results, an available rate measurement device is extended with a flexible heating system as well as multiple pressure and temperature sensors.
Technical Paper

1D Thermo-Fluid Dynamic Simulation of a High Performance Lamborghini V12 S.I. Engine

This paper describes the development and application of the 1D thermo-fluid dynamic research code GASDYN to the simulation of a Lamborghini 12 cylinder, V 60°, 6.2 L automotive S.I. engine. The model has been adopted to carry out an integrated simulation (thermodynamic, fluid dynamic and chemical) of the engine coupled to its intake and exhaust manifolds, in order to predict not only the wave motion in the ducts and its influence on the cylinder gas exchange process, but also the in-cylinder combustion process and the pollutant emission concentration along the exhaust system. The gas composition in the exhaust pipe system is dictated by the cylinder discharge process, after the calculation of the combustion via a thermodynamic multi-zone model, based on a “fractal geometry” approach.
Technical Paper

2-Butanone Laminar Burning Velocities - Experimental and Kinetic Modelling Study

2-Butanone (C4H8O) is a promising alternative fuel candidate as a pure as well as a blend component for substitution in standard gasoline fuels. It can be produced by the dehydrogenation of 2-butanol. To describe 2-butanone's basic combustion behaviour, it is important to investigate key physical properties such as the laminar burning velocity. The laminar burning velocity serves on the one hand side as a parameter to validate detailed chemical kinetic models. On the other hand, especially for engine simulations, various combustion models have been introduced, which rely on the laminar burning velocity as the physical quantity describing the progress of chemical reactions, diffusion, and heat conduction. Hence, well validated models for the prediction of laminar burning velocities are needed. New experimental laminar burning velocity data, acquired in a high pressure spherical combustion vessel, are presented for 1 atm and 5 bar at temperatures of 373 K and 423 K.
Technical Paper

2-D Imaging of Fuel Vapor Concentration in a Diesel Spray via Exciplex-Based Fluorescence Technique

To measure the fuel vapor concentration in an unsteady evaporating spray injected into nitrogen atmosphere, the exciplex-forming method, which produces spectrally separated fluorescence from the liquid and vapor phase, was applied in this study. Two experiments were conducted to investigate the qualitative and quantitative applicability of the technique in a high temperature and high pressure atmosphere during the fuel injection period. One is to examine the thermal decomposition of TMPD dopant at a high temperature and a high pressure nitrogen atmosphere during a short period of time. The other is to calibrate the relationship between fluorescence intensity and vapor concentration of TMPD at different vapor temperatures. And then, the qualitative measurement of fuel vapor concentration distributions in diesel sprays was made by applying the technique.
Technical Paper

2-D Soot Visualization in Unsteady Spray Flame by means of Laser Sheet Scattering Technique

The two-dimensional distribution of a soot cloud in an unsteady spray flame in a rapid compression machine(RCM) was visualized using the laser sheet scattering technique. A 40 mm x 50 mm cross section on the flame axis was illuminated by a thin laser sheet from a single pulsed Nd:YAG laser(wavelength 532 nm). Scattered light from soot particles was taken by a CCD camera via a high speed gated image intensifier. The temporal variation of the scattered light images were presented with the injection pressure as a parameter. The results showed that scattered light was intense near the periphery of the flame tip and that the scattered light becomes weaker significantly and disappears fast after the end of injection as injection pressure is increased. This technique was also applied to the visualization of the two-dimensional distribution of liquid droplets in the non-evaporating spray to correlate it with the soot concentration distribution.
Technical Paper

2-Stroke CAI Operation on a Poppet Valve DI Engine Fuelled with Gasoline and its Blends with Ethanol

Controlled Auto Ignition (CAI), also known as Homogeneous Charge Compression Ignition (HCCI), is one of the most promising combustion technologies to reduce the fuel consumption and NOx emissions. Currently, CAI combustion is constrained at part load operation conditions because of misfire at low load and knocking combustion at high load, and the lack of effective means to control the combustion process. Extending its operating range including high load boundary towards full load and low load boundary towards idle in order to allow the CAI engine to meet the demand of whole vehicle driving cycles, has become one of the key issues facing the industrialisation of CAI/HCCI technology. Furthermore, this combustion mode should be compatible with different fuels, and can switch back to conventional spark ignition operation when necessary. In this paper, the CAI operation is demonstrated on a 2-stroke gasoline direct injection (GDI) engine equipped with a poppet valve train.
Technical Paper

3-D Numerical Analysis Investigating Distribution of Contact Pressures for a Number of Cylindrical Bearing Axial Profiles When Placed Under Radial Load Conditions

Increased torque values passing from engine to transmission have, increasingly become a problem regarding shaft misalignment. Engineers are restricted with regard to applying ISO standards when investigating bearing life cycles as they tend only to cover normal [radial thrust] load conditions. Depending on the application, the need has arisen for numerical models to determine reduction in normal life cycles due to abnormal running conditions. The Simulia Finite Element package Abaqus v6.7 provides trends in the deformations, contact pressures and their respective distribution. It was found the most efficient profile, with regards to a uniform contact pressure, under both radial and misaligned conditions is the toroidal profile.
Technical Paper

3-D Numerical Study of Flow Mixing in Front of SCR for Different Injection Systems

The urea Selective Catalytic Reduction (SCR) exhaust system has been proved to be the reliable aftertreatment device with the capability of reducing tail pipe NOx emission by 75% to 90%, HC by 50% and Particulate Matter (PM) by 30%. Constrained by increasingly stringent packaging envelope, flow mixing in front of substrate is becoming one of the major concerns to achieve ideal performance of higher NOx conversion and lower ammonia (NH3) slip. Three dimensional CFD simulations are performed in current study to investigate flow mixing phenomenon in a SCR system. First, for a traditional tube injector with single or multiple nozzles, the effects of mass flow rates of injected NH3 and exhaust gas on flow mixing and pressure loss are investigated. Then, a concept of ring shape injector with multiple nozzles are initiated and built for 3-D CFD simulations. The comparisons of flow mixing index and injection pressure are made between two type injectors.
Technical Paper

3-D Numerical Study of Fluid Flow and Pressure Loss Characteristics through a DPF with Asymmetrical Channel size

The main objective of the current paper was to investigate the fluid flow and pressure loss characteristics of DPF substrates with asymmetric channels utilizing 3-D Computational Fluid Dynamics (CFD) methods. The ratio of inlet to outlet channel width is 1.2. First, CFD results of velocity and static pressure distributions inside the inlet and outlet channels are discussed for the baseline case with both forward and reversed exhaust flow. Results were also compared with the regular DPF of same cell structure and wall material properties. It was found that asymmetrical channel design has higher pressure loss. The lowest pressure loss was found for the asymmetrical channel design with smaller inlet channels. Then, the effects of DPF length and filter wall permeability on pressure loss, flow and pressure distributions were investigated.
Technical Paper

3-D PIV Analysis of Structural Behavior of D.I. Gasoline Spray

Three-dimensional behaviors of direct injection (D.I.) gasoline sprays were investigated using 2-D and 3-D particle image velocimetry (PIV) techniques. The fuel was injected with a swirl type injector for D.I. gasoline engines into a constant volume chamber in which ambient pressure was varied from 0.1 to 0.4 MPa at room temperature. The spray was illuminated by a laser light sheet generated by a double-pulsed Nd:YAG laser (wave length: 532 nm) and the succeeding two tomograms of the spray were taken by a high-resolution CCD camera. The 2-D and 3-D velocity distributions of the droplet cloud in the spray were calculated from these tomograms by using the PIV technique. The effects of the swirl groove flows in the injector and the ambient pressure on the structural behavior of the droplet cloud in the spray were also examined.
Technical Paper

3D Beam Forming Measurements Using 3D-Microphone Arrays

Traditional acoustic measurements inside any cavity have historically been conducted with a small number of microphones. By this means it is possible to gain information about parameters like frequencies, orders and sound pressures. However, a space-selective analysis is nearly impossible and it is not feasible to find the position of the sound sources in space in a practical way. While traditional beam forming systems with planar microphone arrays have enlarged the possibilities of acoustic measurements, they do not give comprehensive information about the sound sources in the entire vehicle interior. Therefore, the components of the Acoustic Camera of the GFal were extended by a spherical, acoustically transparent and omni-directional array. A new option is to map onto a common 3D-CAD-model of the object of interest, for instance a vehicle interior. The advantages and disadvantages of 2D- and 3D-mappings will be discussed in the paper.
Technical Paper

3D CFD Model of DI Diesel Low Pressure Fuel Pump System

This paper discusses the holistic approach of simulating a low pressure pump (LPP) including test stand flow dynamics. The simulation includes all lines and valves of the test stand representing realistic test operating conditions in the simulation. The capability to capture all line dynamics enables a robust design against resonances and delivers high-quality performance data. Comparison with actual test data agrees very well giving us confidence in the prediction capability of proposed method and CFD package used in the study. Despite the large spatial extent of the simulation domain, Simerics-MP+ (aka PumpLinx) is able to generate a feasible mesh, together with fast running speed, resulting in acceptable turn-around times. The ability to still model small gaps and clearance of the LPP very efficiently enables inclusion of realistic tolerances as experienced on hardware.
Technical Paper

3D Numerical Characterization of a Multi-Holes Injector in a Quiescent Vessel and Its Application in a Single-Cylinder Research Engine Using Ethanol

The fuel injection in internal combustion engines plays a crucial role in the mixture formation, combustion process and pollutants' emission. Its correct modeling is fundamental to the prediction of an engine performance through a computational fluid dynamics simulation. In the first part of this work a tridimensional numerical simulation of a multi-hole’s injector, using ethanol as fuel, is presented. The numerical simulation results were compared to experimental data from a fuel spray injection bench test in a quiescent vessel. The break up model applied to the simulation was the combined Kelvin-Helmholtz Rayleigh-Taylor, and a sensitivity analysis of the liquid fuel penetration curve, as well on the overall spray shape was performed according to the model constants. Experimental spray images were used to aid the model tuning. The final configuration of the KH-RT model constants that showed best agreement with the measured spray was C3 equal to 0.5, B1, 7 and Cb, 0.
Journal Article

3D Numerical Study of Pressure Loss Characteristics and Soot Leakage Through a Damaged DPF

Diesel Particulate Filters (DPF) are widely used to meet 2007 and beyond EPA Particulate Matter (PM) emissions requirements. During the soot loading process, soot is collected inside a porous wall and eventually forms a soot cake layer on the surface of the DPF inlet channel walls. A densely packaged soot layer and reduced pore size due to Particulate Matter (PM) deposition will reduce overall DPF wall permeability which results in increasing pressure drop across the DPF substrate. A regeneration process needs to be enacted to burn out all the soot collected inside the DPF. Soot mass is not always evenly distributed as the distribution is affected by the flow and temperature distribution at the DPF inlet. As a result, the heat release which is determined by the burn rate is locally dependent. High temperature gradients are often found inside DPF substrate as a result of these locally dependent burn rates.
Technical Paper

3D Numerical Study of Sloshing Attenuation Using Vertical Slotted Barriers

The present study deals with the reduction of fluid vibrations by dissipating the kinetic energy in a closed vibrating container partly filled using vertical slotted obstacles. The effect of the barriers on the liquid vibration inside a closed container exposed to a harmonic excitation is numerically studied. A single vertical slotted barrier (SVSB) and multivertical slotted barrier (MVSB) systems are considered for different liquid levels. The 3D liquid domain with the tank and the barrier as boundaries is modelled and solved numerically using ANSYS-CFX software. The reduction in pressures on the walls and the ceiling of the tank due to the influences of the slot size and numbers were evaluated to optimize the size and the numbers of the slots. The numerical approach shows an ability to simulate the nonlinear behavior of the liquid vibration when using vertical slotted barriers (VSB).
Technical Paper

3D Simulations And Experimental Validation of High EGR - PHCCI Combustion

The present work addresses the possibility to correctly simulate Partial Homogeneous Charge Compression Ignition (PHCCI) combustion, obtained by the application of EGR up to 60% without using detailed kinetic models. In particular, the laminar and turbulent time characteristic model has been analyzed and improved. The study illustrates the prediction capabilities that can be achieved with such an approach. The paper reports the results obtained from the simulation of a single cylinder research engine and a four-cylinder diesel engine to verify the validity of the proposed method independently of engine geometry and configuration. All numerical results are compared with experimental pressure traces and rates of heat release, as well as with NOx and soot emissions over a wide range of operating conditions. With the modified characteristic time model, realistic simulations of engine combustion up to EGR values of about 60% have been obtained for both engines.