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A new type of catalytic converter has been developed for the coming TLEV (Transitional Low Emission Vehicle) standards. It is a “Front Curve Catalytic Converter (FCCC)” using a curved cordierite ceramic honeycomb substrate. During this development, an optimum location and volume of the front curve catalytic converter were determined from the view points of thermal deterioration of the catalyst and hydrocarbon conversion performance. Based on CAE (Computer Aided Engineering) analysis, the best curvature radius of the substrate was selected to minimize a pressure drop of the front curve catalytic converter. The emission conversion and light-off performances of the front curve catalytic converter were compared with a conventional straight design. A series of durability tests; hot vibration, engine dynamometer and vehicle fleet tests were also conducted to confirm the reliability of the new front curve catalytic converter.

A model has been developed which predicts engine-out hydrocarbon (HC) emissions for spark-ignition engines. The model consists of a set of scaling laws that describe the individual processes that contribute to HC emissions. The model inputs are the critical engine design and operating variables. This set of individual process scaling relations was then calibrated using production spark-ignition engine data at a fixed light-load operating point. The data base consisted of engine-out HC emissions from two-valve and four-valve engine designs with variations in spark timing, valve timing, coolant temperature, crevice volume, and EGR, for five different engines. The model was calibrated separately for the three different engines to accommodate differences in engine design details and to determine the relative magnitudes of each of the major sources. A good fit to this database was obtained.

A sampling system was developed to measure the evolution of the speciated hydrocarbon emissions from a single-cylinder SI engine in a simulated starting and warm-up procedure. A sequence of exhaust samples was drawn and stored for gas chromatograph analysis. The individual sampling aperture was set at 0.13 s which corresponds to ∼ 1 cycle at 900 rpm. The positions of the apertures (in time) were controlled by a computer and were spaced appropriately to capture the warm-up process. The time resolution was of the order of 1 to 2 cycles (at 900 rpm). Results for four different fuels are reported: n-pentane/iso-octane mixture at volume ratio of 20/80 to study the effect of a light fuel component in the mixture; n-decane/iso-octane mixture at 10/90 to study the effect of a heavy fuel component in the mixture; m-xylene and iso-octane at 25/75 to study the effect of an aromatics in the mixture; and a calibration gasoline.

A Lagrangian random vortex-boundary element method has been developed for the simulation of unsteady incompressible flow inside three-dimensional domains with time-dependent boundaries, similar to IC engines. The solution method is entirely grid-free in the fluid domain and eliminates the difficult task of volumetric meshing of the complex engine geometry. Furthermore, due to the Lagrangian evaluation of the convective processes, numerical viscosity is virtually removed; thus permitting the direct simulation of flow at high Reynolds numbers. In this paper, a brief description of the numerical methodology is given, followed by an example of induction flow in an off-centered port-cylinder assembly with a harmonically driven piston and a valve seat situated directly below the port. The predicted flow is shown to resemble the flow visualization results of a laboratory experiment, despite the crude approximation used to represent the geometry.

This paper describes the use of a modified quasi-dimensional spark-ignition engine simulation code to predict the extent of cycle-to-cycle variations in combustion. The modifications primarily relate to the combustion model and include the following: 1. A flame kernel model was developed and implemented to avoid choosing the initial flame size and temperature arbitrarily. 2. Instead of the usual assumption of the flame being spherical, ellipsoidal flame shapes are permitted in the model when the gas velocity in the vicinity of the spark plug during kernel development is high. Changes in flame shape influence the flame front area and the interaction of the enflamed volume with the combustion chamber walls. 3. The flame center shifts due to convection by the gas flow in the cylinder. This influences the flame front area through the interaction between the enflamed volume and the combustion chamber walls. 4. Turbulence intensity is not uniform in cylinder, and varies cycle-to-cycle.

A detailed description of flow rate measurement technique for automotive exhaust is presented. The system consists of a sector field mass spectrometer for continuous analysis of helium concentration in the exhaust gas and a mass flow controller which injects pure helium at a constant rate into the intake manifold of an engine. The exhaust flow rate can be calculated by helium injection flow rate dividing by the concentration since the concentration value is a measure of the ratio of helium dilution taking place in the engine. The advantages of the technique consist of (1) no disturbance from strong pulsed flow present when an engine is idling, (2) easy time alignment with gas analyzers, and (3) measurement of dry based flow rate that can be directly multiplied by dry based gas concentration to obtain mass emission rate.

Catalytic performance can be improved by increasing geometric surface area (GSA) and reducing bulk density (BD), namely heat capacity, using high cell-density / thinwall advanced ceramic substrates. The advanced substrates, such as 3 mil/600 cpsi and 2 mil/900 cpsi have improved the catalytic performance over the conventional substrates, and are expected to help in complying with future emission regulations, as well as catalyst downsizing. This paper describes the effects of GSA and BD using Pd-based catalysts. The reduction of hydrocarbons emissions was demonstrated significantly at close-coupled location, and dual bed design was proven effective. The effectiveness at under-floor location was not as significant as the close-coupled location.

The MIT-based Mars Gravity Biosatellite payload engineering team has been engaged in designing and prototyping sensor and control systems for deployment within the rodent housing zone of the satellite, including novel video processing and atmospheric management tools. The video module will be a fully autonomous real-time analysis system that takes raw video footage of the specimen mice as input and distills those parameters which are of primary physiological importance from a scientific research perspective. Such signals include activity level, average velocity and rearing behavior, all of which will serve as indicators of animal health and vestibular function within the artificial gravity environment. Unlike raw video, these parameters require minimal storage space and can be readily transmitted to earth over a radio link of very low bandwidth.

Human explorers of planetary surfaces would benefit greatly from a spacesuit design that facilitates locomotion. To aid in the development of such an extravehicular activity suit, a design effort incorporating the concept of mechanical counter pressure (MCP) was undertaken. Three-dimensional laser scanning of the human body was used to identify the main effects of knee flexion angle on the size and shape of the leg. This laser scanning quantified the changes in shape that must be supported by an MCP garment and the tension that must be developed to produce even MCP. Evaluation of a hybrid-MCP concept using inextensible materials demonstrated strong agreement between experimental data and a mathematical model with rigid cylinder geometry. Testing of a form-fitting garment on the right lower leg of a subject demonstrated successful pressure production. Further research is required to evaluate how evenly pressure can be distributed using the hybrid-MCP concept.

Frictional losses in the piston ring-pack of an engine account for approximately half of the total frictional losses within the power cylinder of an engine. Three-dimensional honing groove texture was modeled, and its effect on piston ring-pack friction and engine brake thermal efficiency was investigated. Adverse effects on engine oil consumption and durability were also considered. Although many non-conventional cylinder liner finishes are now being developed to reduce friction and oil consumption, the effects of surface finish on ring-pack performance is not well understood. A rough surface flow simulation program was developed to calculate flow and stress factors that adjust the solution of the Reynolds equation for the effects of surface roughness as has been done in the literature. Rough surface contact between the ring and liner was modeled using a previously published methodology for asperity contact pressure estimation between rough surfaces.

In order to use modeling as a predictive tool for real-world particulate filter designs (segmented filters, non-axisymmetric designs), it is necessary to develop reliable 3-dimensional models. This paper presents a 3 d modeling approach, which is validated against engine-bench measurements with both FBC and CDPF systems. Special emphasis is given to the prediction of the transient inlet flow distribution, which is realized without resorting to external CFD software. The experimental and modeling results illustrate the 3-d nature of the problem, induced by the heat capacity and conductivity effects of the cement layers. It is possible to predict the localization of regeneration in certain areas of the filter (partial regeneration), as a result of poor heat transfer to thermally isolated regions in the filter. The accuracy of the model was validated by extensive comparisons with temperature measurements in 30 positions inside the filters and at various operating conditions.

The possibility to employ a single-brick system with a catalyzed filter (CDPF) for the after-treatment of diesel engines is potentially a promising and cost-effective solution. In the first part of this paper, the effectiveness of a single brick CDPF system towards reducing the gaseous CO and HC emissions is investigated experimentally and computationally. The second part of the paper deals with the behavior of single brick catalyzed filters compared with two brick systems comprising an upstream oxidation catalyst. The main differences of the two systems are highlighted in terms of regeneration efficiency and thermal loading, based on simulation results. The modeling work is based on a 3-dimensional model of the catalyzed filter and an axi-symmetric model of the oxidation catalyst. Model validations are presented based on engine bench testing.

The development of a cycle simulation model for the jet ignition prechamber stratified charge engine is described. Given the engine geometry, load, speed, air-fuel ratios and pressures and temperatures in the two intakes, flow ratio and a suitable combustion model, the cycle simulation predicts engine indicated efficiency and NO emissions. The relative importance of the parameters required to define the combustion model are then determined, and values for ignition delay and burn angle are obtained by matching predicted and measured pressure-time curves. The variation in combustion parameters with engine operating variables is then examined. Predicted and measured NO emissions are compared, and found to be in reasonable agreement over a wide range of engine operation. The relative contribution of the prechamber NO to total exhaust NO is then examined, and in the absence of EGR, found to be the major source of NO for overall air-fuel ratios leaner than 22:1.

The effect on engine performance of insulating combustion chambers was simulated for a turbocharged direct injection diesel engine. We developed a low heat rejection (LHR) diesel cycle simulation. It includes a gas flow model, a heat transfer model, and a two zone combustion model. In the heat transfer model, convective and radiation heat transfer between the gas and walls was computed, taking into account the combustion chamber surface temperature swings. In the combustion model's combustion zone, the temperature and the chemical equilibrium compositions were determined. They were used to calculate the NO formation rate by assuming a modified Zeldvich mechanism. The combustion zone temperature was also used to estimate the radiation heat transfer. Simulations were performed of various combustion chamber surface materials and various LHR levels. The factors which affect thermal efficiency and exhaust emissions were deduced and their influences discussed.

Application of ceramic honeycomb wall-flow type diesel particulate filters (DPF) to heavy duty vehicles requires a large volume filter. Heavy duty vehicles produce a large volume exhaust gas, and pressure drop in the exhaust system must be maintained to a certain level. In addition, the filters must be designed to resist fracture from thermal stresses during regeneration. This is particularly important in heavy duty vehicles because of these extended mileage requirements. These studies of the effects of DPF volume on thermal shock resistance during regeneration reveal that the maximum failure temperatures are lower as DPF volume is increased, still maintaining 950°C maximum temperature with 12 ℓ volume and 9″D × 12″L size large DPF. Some thermal stress analyses with temperature profiles and finite element analysis were conducted on four different volume DPF during regeneration.

The high-temperature durability of 85 mm tip diameter silicon nitride ceramic radial turbine rotors was evaluated with a hot gas spin test rig. The rotors withstood up to a turbine tip speed of 700 m/s at TIT of 1300°C under partially loaded conditions and 570 m/s at TIT of 1300°C under fully loaded conditions, respectively. The material of the rotors was a post-HIPed silicon nitride. The basic fatigue properties of the material were measured at high temperatures. In the hot gas spin test, the temperature and stress distributions at the turbine blade were calculated with a finite element method. The results of the hot-gas spin test are discussed by means of a failure prediction analysis on the basis of the Weibull statistics.

A human-centered systems analysis was applied to the adverse aircraft weather encounter problem in order to identify desirable functions of weather and icing information. The importance of contingency planning was identified as emerging from a system safety design methodology as well as from results of other aviation decision-making studies. The relationship between contingency planning support and information on regions clear of adverse weather was investigated in a scenario-based analysis. A rapid prototype example of the key elements in the depiction of icing conditions was developed in a case study, and the implications for the components of the icing information system were articulated.

One of the goals of designing engineering systems is to maximize the system's reliability. A reliable system must satisfy its functional requirements without failure throughout its intended lifecycle. The typical means to achieve a desirable level of reliability is through preventive maintenance of a system; however, this involves cost. A more fundamental approach to the problem is to maximize the system's reliability by preventing failures from occurring. A key question is to find mechanisms (and the means to implement them into a system) that will prevent its system range from going out of the design range. Functional periodicity is a means to achieve this goal. Three examples are discussed to illustrate the concept. In the new electrical connector design, it is the geometric functional periodicity provided by the woven wire structure. In the case of integrated manufacturing systems, it is the periodicity in scheduling of the robot motion.

Knock in gasoline engines at higher loads is a significant constraint on torque and efficiency. The anti-knock property of a fuel is closely related to its research octane number (RON). Ethanol has superior RON compared to gasoline and thus has been commonly used to blend with gasoline in commercial gasolines. However, as the RON of a fuel is constant, it has not been used as needed in a vehicle. To wisely use the RON, an On-Board Separation (OBS) unit that separates commercial gasoline with ethanol content into high-octane fuel with high ethanol fraction and a lower octane remainder has been developed. Then an onboard Octane-on-demand (OOD) concept uses both fuels in varying proportion to provide to the engine a fuel blend with just enough RON to meet the ever changing octane requirement that depends on driving pattern.

Eigenvalues of a simple rotating flexible disk-shaft system are obtained using different methods. The shaft is supported radially by non-rigid bearings, while the disk is situated at one end of the shaft. Eigenvalues from a finite element and a multi-body dynamic tool are compared against an established analytical formulation. The Campbell diagram based on natural frequencies obtained from the tools differ from the analytical values because of oversimplification in the analytical model. Later, detailed whirl analysis is performed using AVL Excite multi-body tool that includes understanding forward and reverse whirls in absolute and relative coordinate systems and their relationships. Responses to periodic force and base excitations at a constant rotational speed of the shaft are obtained and a modified Campbell diagram based on this is developed. Whirl of the center of the disk is plotted as an orbital or phase plot and its rotational direction noted.