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Technical Paper

Phenomena that Determine Knock Onset in Spark-Ignition Engines

Experiments were carried out to collect in-cylinder pressure data and microphone signals from a single-cylinder test engine using spark timingsbefore, at, and after knock onset for toluene reference fuels. The objective was to gain insight into the phenomena that determine knock onset, detected by an external microphone. In particular, the study examines how the end-gas autoignition process changes as the engine's spark timing is advanced through the borderline knock limit into the engine's knocking regime. Fast Fourier transforms (FFT) and bandpass filtering techniques were used to process the recorded cylinder pressure data to determine knock intensities for each cycle. Two characteristic pressure oscillation frequencies were detected: a peak just above 6 kHz and a range of peaks in the 15-22 kHz range. The microphone data shows that the audible knock signal has the same 6 kHz peak.
Technical Paper

Effects of Variations in Market Gasoline Properties on HCCI Load Limits

The impact of market-fuel variations on the HCCI operating range was measured in a 2.3L four-cylinder engine, modified for single-cylinder operation. HCCI combustion was achieved through the use of residual trapping. Variable cam phasing was used to maximize the load range at each speed. Test fuels were blended to cover the range of variation in select commercial fuel properties. Within experimental measurement error, there was no change in the low-load limit among the test fuels. At the high-load limit, some small fuel effects on the operating range were observed; however, the observed trends were not consistent across all the speeds studied.
Technical Paper

Comparative Analysis of Automotive Powertrain Choices for the Next 25 Years

This paper assesses the potential improvement of automotive powertrain technologies 25 years into the future. The powertrain types assessed include naturally-aspirated gasoline engines, turbocharged gasoline engines, diesel engines, gasoline-electric hybrids, and various advanced transmissions. Advancements in aerodynamics, vehicle weight reduction and tire rolling friction are also taken into account. The objective of the comparison is the potential of anticipated improvements in these powertrain technologies for reducing petroleum consumption and greenhouse gas emissions at the same level of performance as current vehicles in the U.S.A. The fuel consumption and performance of future vehicles was estimated using a combination of scaling laws and detailed vehicle simulations. The results indicate that there is significant potential for reduction of fuel consumption for all the powertrains examined.
Technical Paper

Contribution of Liquid Fuel to Hydrocarbon Emissions in Spark Ignition Engines

The purpose of this work was to develop an understanding of how liquid fuel transported into the cylinder of a port-fuel-injected gasoline-fueled SI engine contributes to hydrocarbon (HC) emissions. To simulate the liquid fuel flow from the valve seat region into the cylinder, a specially designed fuel probe was developed and used to inject controlled amounts of liquid fuel onto the port wall close to the valve seat. By operating the engine on pre-vaporized Indolene, and injecting a small amount of liquid fuel close to the valve seat while the intake valve was open, we examined the effects of liquid fuel entering the cylinder at different circumferential locations around the valve seat. Similar experiments were also carried out with closed valve injection of liquid fuel at the valve seat to assess the effects of residual blowback, and of evaporation from the intake valve and port surfaces.
Technical Paper

Development of Ice Crystal Facilities for Engine Testing

The Gas Turbine Laboratory of the National Research Council of Canada (NRC) has been involved in icing certification testing of gas turbine engines for over 60 years. It has become evident from flight incident reports in recent years, that ice crystals can have serious effects on the performance of the core of a gas turbine. This has led to the proposal of a new certification requirement for turbofan engines. This paper describes the test facilities and procedures, as well as the analysis and verification methods, which have been used recently to develop a new ice crystal generating system. The paper describes the ice crystal production and delivery systems, as well as the design and development version for business jet sized engines. In addition, a description of some component testing using ice crystals on a heated flat plate is included to demonstrate that the facility can replicate rapid ice crystal build-up on surfaces which are significantly above the melting point.
Technical Paper

Modeling the Extravehicular Mobility Unit (EMU) Space Suit: Physiological Implications for Extravehicular Activity (EVA)

Extravehicular activity (EVA) is investigated through experiments testing an actual extravehicular mobility unit (EMU) performing several EVA tasks in the laboratory, and a dynamic model of the EMU space suit is developed. Building directly on earlier work in EVA simulation, the space suit model was created from mass, inertia, and performance data to augment the unsuited 12-segment human model used in previous studies. A modified Preisach model was used to mathematically describe the hysteretic torque characteristics of joints in a pressurized space suit, and implemented numerically based on observed suit parameters. Computational simulations, based loosely on a 1995 EVA involving manipulation of the Spartan astrophysics payload, were performed to observe the effect of suit constraints on simulated astronaut performance.
Technical Paper

New Safety Technologies for the Automotive Industry

With the increasing complexity of automotive systems and the related increasing use of software in them, new approaches are needed to ensure safety. In these new types of automotive systems, safety and reliability are different and require different engineering approaches. Accidents are increasingly due to design errors and to dysfunctional interactions among components rather than component failure. In addition, safety must be engineered and built into the design from the beginning; it is not possible to effectively and affordably add safety devices onto a finished design. This paper describes the need for new approaches to automotive safety and describes an alternative to the traditional reliability-based approaches to safety engineering. The new approach is based on systems theory and views accidents in terms of lack of control or enforcement of the behavioral constraints required to ensure safety.
Technical Paper

Crashworthiness of Thin Ultra-light Stainless Steel Sandwich Sheets: From the Design of Core Materials to Structural Applications

Thin sandwich sheets hold a promise for widespread use in automotive industry due to their good crash and formability properties. In this paper, thin stainless steel sandwich sheets with low-density core materials are investigated with regard to their performance in crashworthiness applications. The total thickness of the sandwich materials is about 1.2mm: 0.2mm thick facings and a 0.8mm thick sandwich core. Throughout the crushing of prismatic sandwich profiles, the sandwich facings are bent and stretched while the sandwich core is crushed under shear loading. Thus, a high shear crushing strength of the sandwich core material is beneficial for the overall energy absorption of the sandwich profile. It is shown theoretically that the weight specific shear crushing strength of hexagonal metallic honeycombs is higher than the one of fiber cores - irrespective of their relative density or microstructural geometry.
Technical Paper

Future Light-Duty Vehicles: Predicting their Fuel Consumption and Carbon-Reduction Potential

The transportation sector in the United States is a major contributor to global energy consumption and carbon dioxide emission. To assess the future potentials of different technologies in addressing these two issues, we used a family of simulation programs to predict fuel consumption for passenger cars in 2020. The selected technology combinations that have good market potential and could be in mass production include: advanced gasoline and diesel internal combustion engine vehicles with automatically-shifting clutched transmissions, gasoline, diesel, and compressed natural gas hybrid electric vehicles with continuously variable transmissions, direct hydrogen, gasoline and methanol reformer fuel cell hybrid electric vehicles with direct ratio drive, and battery electric vehicle with direct ratio drive.
Technical Paper

A New Approach to Ethanol Utilization: High Efficiency and Low NOx in an Engine Operating on Simulated Reformed Ethanol

The use of hydrogen as a fuel supplement for lean-burn engines at higher compression ratios has been studied extensively in recent years, with good promise of performance and efficiency gains. With the advances in reformer technology, the use of a gaseous fuel stock, comprising of substantially higher fractions of hydrogen and other flammable reformate species, could provide additional improvements. This paper presents the performance and emission characteristics of a gas mixture of equal volumes of hydrogen, CO, and methane. It has recently been reported that this gas mixture can be produced by reforming of ethanol at comparatively low temperature, around 300C. Experiments were performed on a 1.8-liter passenger-car Nissan engine modified for single-cylinder operation. Special pistons were made so that compression ratios ranging from CR= 9.5 to 17 could be used. The lean limit was extended beyond twice stoichiometric (up to lambda=2.2).
Technical Paper

A Study on the Emissions of Chemical Species from Heavy-Duty Diesel Engines and the Effects of Modern Aftertreatment Technology

A comparative analysis was made on the emissions from a 2004 and a 2007 heavy-duty diesel engine to determine how new engine and emissions technologies have affected the chemical compounds found in the exhaust gases. Representative samples were collected from a source dilution sampling system and analyzed for both criteria and unregulated gaseous and particulate emissions. Results have shown that the 2007 regulations compliant engine and emissions technology not only reduced the specifically regulated exhaust pollutants, but also significantly reduced the majority of unregulated chemical species. It is believed that these reductions were achieved through the use of engine optimization, aftertreatment system integration, and ultra-low sulfur diesel fuel.
Technical Paper

Effect of In-Cylinder Liquid Fuel Films on Engine-Out Unburned Hydrocarbon Emissions for an SI Engine

An experimental study was performed in a firing SI engine at conditions representative of the warmup phase of operation in which liquid gasoline films were established at various locations in the combustion chamber and the resulting impact on hydrocarbon emissions was assessed. Unique about this study was that it combined, in a firing engine environment, direct visual observation of the liquid fuel films, measurements of the temperatures these films were subjected to, and the determination from gas analyzers of burned and unburned fuel quantities exiting the combustion chamber - all with cycle-level resolution or better. A means of deducing the exhaust hydrocarbon emissions that were due to the liquid fuel films in the combustion chamber was developed. An increase in exhaust hydrocarbon emissions was always observed with liquid fuel films present in the combustion chamber.
Technical Paper

Influence of Material Properties and Pore Design Parameters on Non-Catalyzed Diesel Particulate Filter Performance with Ash Accumulation

Diesel particulate filters (DPF) are a common component in emission-control systems of modern clean diesel vehicles. Several DPF materials have been used in various applications. Silicone Carbide (SiC) is common for passenger vehicles because of its thermal robustness derived from its high specific gravity and heat conductivity. However, a segmented structure is required to relieve thermal stress due to SiC's higher coefficient of thermal expansion (CTE). Cordierite (Cd) is a popular material for heavy-duty vehicles. Cordierite which has less mass per given volume, exhibits superior light-off performance, and is also adequate for use in larger monolith structures, due to its lower CTE. SiC and cordierite are recognized as the most prevalent DPF materials since the 2000's. The DPF traps not only combustible particles (soot) but also incombustible ash. Ash accumulates in the DPF and remains in the filter until being physically removed.
Technical Paper

Anthropometric and Blood Flow Characteristics Leading to EVA Hand Injury

The aim of this study was to explore if fingernail delamination injury following EMU glove use may be caused by compression-induced blood flow occlusion in the finger. During compression tests, finger blood flow decreased more than 60%, however this occurred more rapidly for finger pad compression (4 N) than for fingertips (10 N). A pressure bulb compression test resulted in 50% and 45% decreased blood flow at 100 mmHg and 200 mmHg, respectively. These results indicate that the finger pad pressure required to articulate stiff gloves is more likely to contribute to injury than the fingertip pressure associated with tight fitting gloves.
Technical Paper

Requirements and Potential for Enhanced EVA Information Interfaces

NASA has long recognized the advantages of providing improved information interfaces to EVA astronauts and has pursued this goal through a number of development programs over the past decade. None of these activities or parallel efforts in industry and academia has so far resulted in the development of an operational system to replace or augment the current extravehicular mobility unit (EMU) Display and Controls Module (DCM) display and cuff checklist. Recent advances in display, communications, and information processing technologies offer exciting new opportunities for EVA information interfaces that can better serve the needs of a variety of NASA missions. Hamilton Sundstrand Space Systems International (HSSSI) has been collaborating with Simon Fraser University and others on the NASA Haughton Mars Project and with researchers at the Massachusetts Institute of Technology (MIT), Boeing, and Symbol Technologies in investigating these possibilities.
Technical Paper

Implications of Contingency Planning Support for Weather and Icing Information

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.
Technical Paper

Development, Validation and ECM Embedment of a Physics-Based SCR on Filter Model

SCR on Filter (SCRoF) is an efficient and compact NOX and PM reduction technology already used in series production for light-duty applications. The technology is now finding its way into the medium duty and heavy duty market. One of the key challenges for successful application is the robustness to real world variations. The solution to this challenge can be found by using model-based control algorithms, utilizing state estimation by physics-based catalyst models. This paper focuses on the development, validation and real time implementation of a physics-based control oriented SCRoF model. An overview of the developed model will be presented, together with a brief description of the model parameter identification and validation process using engine test bench measurement data. The model parameters are identified following a streamlined approach, focusing on decoupling the effects of deNOx and soot phenomena.
Technical Paper

Design and Durability of Vanadium-SCR Catalytic Aftertreatment System to Meet Tier 4 Emission Regulations in a Locomotive Application

An advanced exhaust aftertreatment system (ATS) for Tier 4 compliant locomotive applications was successfully designed and developed for use on Cummins QSK95 engines. The engine and ATS were introduced in late 2016. This system provided nitrogen oxides (NOx) reduction capability in excess of 95%. Vanadia-based selective catalytic reduction (V-SCR) extruded catalyst technology was chosen over other readily available component technologies such as diesel oxidation catalyst (DOC) or a combination of DOC and SCR systems to address the stringent Tier 4 standards. In addition to NOx reduction, substantial oxidation of gaseous hydrocarbons (HCs) from unburnt fuel and lubricating oil soluble organic fraction (SOF) was also achieved. This dual functionality (oxidation and reduction capability) was one of the key factors in adopting this technology as the prime path and rendering it suitable for the harsh locomotive application environment.
Technical Paper

Continuous Particulate Filter State of Health Monitoring Using Radio Frequency Sensing

Reliable means for on-board detection of particulate filter failures or malfunctions are needed to meet diagnostics (OBD) requirements. Detecting these failures, which result in tailpipe particulate matter (PM) emissions exceeding the OBD limit, over all operating conditions is challenging. Current approaches employ differential pressure sensors and downstream PM sensors, in combination with particulate filter and engine-out soot models. These conventional monitors typically operate over narrowly-defined time windows and do not provide a direct measure of the filter’s state of health. In contrast, radio frequency (RF) sensors, which transmit a wireless signal through the filter substrate provide a direct means for interrogating the condition of the filter itself.
Technical Paper

Real World Performance of an Onboard Gasoline/Ethanol Separation System to Enable Knock Suppression Using an Octane-On-Demand Fuel System

Higher compression ratio and turbocharging, with engine downsizing can enable significant gains in fuel economy but require engine operating conditions that cause engine knock under high load. Engine knock can be avoided by supplying higher-octane fuel under such high load conditions. This study builds on previous MIT papers investigating Octane-On-Demand (OOD) to enable a higher efficiency, higher-boost higher compression-ratio engine. The high-octane fuel for OOD can be obtained through On-Board-Separation (OBS) of alcohol blended gasoline. Fuel from the primary fuel tank filled with commercially available gasoline that contains 10% by volume ethanol (E10) is separated by an organic membrane pervaporation process that produces a 30 to 90% ethanol fuel blend for use when high octane is needed. In addition to previous work, this paper combines modeling of the OBS system with passenger car and medium-duty truck fuel consumption and octane requirements for various driving cycles.