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The fuel injection process in the port of a firing 4-valve SI engine at part load and 25°C head temperature was observed by a high speed video camera. Fuel was injected when the valve was closed. The reverse blow-down flow when the intake valve opens has been identified as an important factor in the mixture preparation process because it not only alters the thermal environment of the intake port, but also strip-atomizes the liquid film at the vicinity of the intake valve and carries the droplets away from the engine. In a series of “fuel-on” experiments, the fuel injected in the current cycle was observed to influence the fuel delivery to the engine in the subsequent cycles.

EQUIPMENT for measuring vibration in airplane structures and powerplants during actual flight is described in this paper. This development is the result of a cooperative research program carried out by the Bureau of Aeronautics of the U. S. Navy and the Massachusetts Institute of Technology with contributions of improvements in design and new features by the Sperry Gyroscope Co., Inc. In its essentials, the M.I.T.-Sperry Apparatus consists of a number of electrical pickup units which operate a central amplifying and recording unit. The recorder is a double-element photographic oscillograph. Each pickup is adapted especially to the type of vibration that it is intended to measure and is made so small that it does not appreciably affect the vibration characteristics of the member to which it is attached rigidly. By using a number of systematically placed pickups, all the necessary vibration information on an airplane can be recorded during a few short flights.

This paper reviews a validation project on CFD commercial codes organized by Society of Automobile Engineers of Japan (JSAE) in 2001. As benchmark problems, four major objects of vehicle flow design are selected for Vehicle aerodynamics, Engine cylinder flow, Air-conditioning and Defroster duct flow. 14 titles of commercial software sold in Japan are applied to these problems. The results of each problem are compared with reference experimental data and evaluated in vi ews of vehicle design and development. Feasibility of auto-meshing techniques and computation cost in recent hardware are also discussed.

Ethanol and acetaldehyde emissions from a direct ignition spark ignition were measured using mass spectrometry. Previous methods focused on eliminating or minimizing interference from exhaust species with identical atomic mass and fragment ions created in ionization process. This paper describes a new technique which exploits the fragment ions from ethanol and acetaldehyde. A survey of mass spectra of all major species of exhaust gas was conducted. It was found that ethanol contributes most ions in mass number 31 and that no other gas species produces ions at this mass number. Acetaldehyde detection suffers more interference. Nevertheless, it was estimated that detection at mass number 43 is possible with 10% error from 2-methylbutane. This new technique was validated in an engine experiment. By running the engine with pure gasoline and E85, the validity of the technique can be checked.

We developed a two-degree-of-freedom (2-DOF) control system for a diesel engine airpath system. First, a physical airpath model of the diesel engine was developed, followed by a nonlinear feedforward controller developed based on the inverse characteristics of the developed physical model. The dynamics of turbocharger and manifolds were considered in the feedforward controller to improve the transient response. The feedback controller was designed by H∞ control theory considering plant nonlinearities as uncertainties. The feedforward and feedback controllers were implemented as a 2-DOF freedom control scheme. The effectiveness of the proposed method was evaluated by conducting simulation and experiment.

Our study unveils what smart cars are needed to minimize congestion by traffic stability. We have previously considered pacer cars with single lane road networks based on a car following model, e.g. adaptive cruise control (ACC). However, pacer cars may have a limitation with multi-lane roadways in terms of lane distribution of traffic and shockwave suppression. Therefore, we motivate building a new smart car which extends the capability of pacer cars allowing lane changing at the timing of congestion detection. In essence, the congestion detection plays a role of adjusting the (time) headway of smart cars to determine whether lane changes should be undertaken. Lane changes can be used to uniformize (or equalize) lane distribution for traffic (flow) stability. Our simulation study has suggested that the proposed smart cars enforce the capability of traffic stability more than manual and pacer cars.

With technological breakthroughs in electric land vehicles revolutionizing their respective industry, maintenance, repair, and overhaul (MRO) facilities in aviation are also adopting digital technologies in their practices. But despite this drive towards digitalization, the industry is still dominated by manual labor and subjective assessments. Today, several technologies, processes, and practices are being championed to resolve some of these outstanding challenges. Considering this, it is important to present current perspectives regarding where the technology stands today and how we can evaluate capabilities for autonomous decision support systems that prescribe maintenance activities. Overlooking some of these unsettled domain issues can potentially undermine any benefits in speed, process, and resilience promised by such systems.

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.

Throttle ramp rate effects on the in-cylinder fuel/air (F/A) excursion was studied in a production engine. The fuel delivered to the cylinder per cycle was measured in-cylinder by a Fast Response Flame Ionization detector. Intake pressure was ramped from 0.4 to 0.9 bar. Under slow ramp rates (∼1 s ramp time), the Engine Electronic Control (EEC) unit provided the correct compensation for delivering a stoichiometric mixture to the cylinder throughout the transient. At fast ramp rates (a fraction of a second ramps), a lean spike followed by a rich one were observed. Based on the actual fuel injected in each cycle during the transient, a x-τ model using a single set of x and τ values reproduced the cycle-to-cycle in-cylinder F/A response for all the throttle ramp rates.

In military applications, diesel engines are required to achieve high power outputs and therefore must operate at high loads. This high load operation leads to high piston component temperatures and heat rejection rates limiting the packaged power density of the powertrain. To help predict and understand these constraints, as well as their effects on performance, a thermodynamic engine model coupled to a finite element heat conduction solver is proposed and validated in this work. The finite element solver is used to calculate crank angle resolved, spatially averaged piston temperatures from in-cylinder heat transfer calculations. The calculated piston temperatures refine the heat transfer predictions as well requiring iteration between the thermodynamic model and finite element solver.

The paper considers the thermodynamic irreversibility in Stirling cycle machines at the interface between components with different thermodynamic characteristics. The approach of the paper is to consider the simplest possible cases and to focus on the factors that influence the thermodynamic losses. For example, an ideal adiabatic cylinder facing an ideal isothermal heat exchanger is considered. If there is no mixing in the cylinder (gas remains one dimensionally stratified), there will be no loss (irreversibility) if the gas motion is in phase with the gas pressure changes. If there is a phase shift, as required to have a network for the cylinder, there will be a loss (entropy generation) because the gas will not match the heat exchanger temperature. There will also be a loss if the gas in the cylinder is mixed rather than stratified. Similar simple interface conditions can be considered between components and interconnecting open volumes and between heat exchangers and regenerators.

This paper describes the thermal management and design challenges of testing packaged integrated circuit (IC) devices, specifically device thermal conditioning and device-under-test (DUT) temperature control. The approach taken is to discuss the individual thermal design issues as defined by the device type (e.g. memory, microcontroller) and tester capabilities. The influence of performance-parameter specifications, such as the DUT parallelism, test time, index time, test-temperature range and test-temperature tolerance are examined. An understanding of these performance requirements and design constraints enables consideration of existing test handler thermal processing systems (e.g., gravity feed, pick and place), future test handler thermal concepts, and future high-parallelism testing needs for high-wattage memory and microprocessor devices. New thermal designs in several of these areas are described.

In a recent paper (Hoult & Meador, [1]) a novel method of estimating the costs of parts, and assemblies of parts, was presented. This paper proposed that the metric for increments of cost was the function log (dimension/tolerance). Although such log functions have a history,given in [1], starting with Boltzman and Shannon, it is curious that it arises in cost models. In particular, the thermodynamic basis of information theory, given by Shannon [2], seems quite implausible in the present context. In [1], we called the cost theory “Complexity Theory”, mainly to distinguish it from information theory. A major purpose of the present paper is to present a rigorous argument of how the log function arises in the present context. It happens that the agrument hinges on two key issues: properties of the machine making or assembling the part, and a certain limit process. Neither involves thermodynamic reasoning.

The objective of this work was to develop an experimental system to support development and validation of a model for the lubrication of two-piece Twin-Land-Oil-Control-Rings (hereafter mentioned as TLOCR). To do so, a floating liner engine was modified by opening the head and crankcase. Additionally, only TLOCR was installed together with a piston that has 100 micron cold clearance to minimize the contribution of the skirt to total friction. Friction traces, FMEP trend, and repeatability have been examined to guarantee the reliability of the experiment results. Then, engine speed, liner temperature, ring tension, and land widths were changed in a wide range to ensure all three lubrication regimes were covered in the experiments.

Ash inside a honeycomb-configured diesel particulate filter (DPF) inlet channel accumulates both as a cake layer along the channel walls and as a “plug” towards the back of the channel. Experimental studies of DPF ash distribution have shown both an axial variation of deposits along channels and accumulation towards the end plugs. This study evaluates the sensitivity of DPF pressure drop on ash axial distribution and the potential to reduce flow restrictions by controlling and optimizing the spatial distribution of ash inside DPF channels. A computational model has been used in conjunction with experimental data to illustrate the sensitivity of ash spatial distribution on DPF performance. The classical constant-thickness DPF one-dimensional models have substantially been updated to include layer thickness axial variations. Material properties, such as ash characteristics, are provided by recent experiments at the authors' laboratory.

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.

Internal combustion engines currently face increasing regulatory reform which has motivated investigation of alternative combustion modes, particularly for spark ignition engines. Fuel economy regulations, among others, are presently driving the need for technological advances in the automotive sector. Stationary power generation is facing emissions standards that will be increasingly difficult to achieve with combustion-based current practices, particularly in the case of nitrogen oxides (NOx). Ultra-lean (λ > ~1.6; air-fuel ratio > 23:1) combustion via air dilution is one such combustion mode that provides the benefits of reduced fuel consumption and reduced NOx emissions. Jet ignition is a pre-chamber-based combustion system that enables enleanment beyond what is achievable with traditional spark ignition engines. Previous studies of MAHLE’s Jet Ignition® concept have primarily focused on light-duty gasoline engines.

In spark ignited engines, thermal efficiency is strongly influenced by the quality of the combustion process as initiated by the ignition system. Jet Ignition is a combustion concept that utilizes a small pre-chamber to produce reactive jets which distribute ignition energy throughout the main combustion chamber. This distributed ignition energy can be leveraged to induce ignition in traditionally difficult-to-ignite regimes, such as in highly dilute mixtures. Highly dilute jet ignition combustion has been proven to produce thermal efficiencies significantly higher than those of conventional spark ignition combustion. To fully exploit the efficiency potential of active jet ignition, multiple aspects of the engine architecture and peripheral systems must be adjusted. Efficiency sensitivities to compression ratio, boost system, and intake port design have been explored extensively.

Increasingly stringent US fuel economy regulation has emphasized the need for automotive engines to achieve greater levels of efficiency. Lean operation in spark ignition engines has demonstrated the ability to increase thermal efficiency, but this is typically accompanied by increased nitrogen oxides (NOx) emissions. Ultra-lean operation (λ > 2), however, has demonstrated increased thermal efficiency and the potential for significant reductions in NOx. Turbulent Jet Ignition (TJI) enables ultra-lean operation by utilizing radical turbulent jets emerging from a pre-chamber combustor as the ignition source for main chamber combustion in a spark ignition engine. This study seeks to better understand the interaction between the pre-chamber and main chamber combustion events, specifically the effect that particular TJI design parameters have on this interaction.

The effects of charge motion and laminar flame speeds on combustion and exhaust temperature have been studied by using an air jet in the intake flow to produce an adjustable swirl or tumble motion, and by replacing the nitrogen in the intake air by argon or CO₂, thereby increasing or decreasing the laminar flame speed. The objective is to examine the "Late Robust Combustion" concept: whether there are opportunities for producing a high exhaust temperature using retarded combustion to facilitate catalyst warm-up, while at the same time, keeping an acceptable cycle-to-cycle torque variation as measured by the coefficient of variation (COV) of the net indicated mean effective pressure (NIMEP). The operating condition of interest is at the fast idle period of a cold start with engine speed at 1400 RPM and NIMEP at 2.6 bar. A fast burn could be produced by appropriate charge motion. The combustion phasing is primarily a function of the spark timing.