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The emissions and efficiency of modern internal combustion engines need to be improved to reduce their environmental impact. Many strategies to address this (e.g., alternative fuels, exhaust gas aftertreatment, novel injection systems, etc.) require engine calibrations to be modified, involving extensive experimental data collection. A new approach to modeling and data collection is proposed to expedite the development of these new technologies and to reduce their upfront cost. This work evaluates a Gaussian Process Regression, Artificial Neural Network and Bayesian Optimization based strategy for the efficient development of machine learning models, intended for engine optimization and calibration. The objective of this method is to minimize the size of the required experimental data set and reduce the associated data collection cost for engine modeling.

The concentration of carbonaceous particulate matter in the exhaust of diesel engines depends on the rates of formation and oxidation of soot in the combustion chamber. Soot forms early in the combustion process when local fuel-rich areas exist, whereas soot oxidation occurs later when more air is entrained into the fuel spray. Based on this understanding, a phenomenological combustion model is established. In the model, the cylinder volume is divided into four zones: a rich fuel spray core, a premixed-burning/burned gas zone, a mixing controlled burning zone and a lean air zone. Soot formation takes place in the mixing controlled burning zone where the local C/O ratio is above the critical value. Soot oxidation occurs in the premixed-burning/burned gas zone as air is entrained. By using a quasi-global chemical reaction scheme, the oxidation of soot particles by different species can be investigated.

Use of natural gas-diesel dual-fuel (NDDF) combustion in compression ignition engines is a method of reducing the net greenhouse gas (GHG) and particulate matter (PM) emissions of these engines. Compressed natural gas (NG) is injected into the intake manifold of the engine and the air-NG mixture is ignited by a direct injection of diesel in the cylinder. One of the main challenges with NDDF combustion is the methane (primary component of NG) slip at low and medium loads, which reduces the engine efficiency and offsets the advantage of lower carbon dioxide emissions of the NG combustion. In order to address this issue, an intake manifold insert is devised with the objective to alter the intake flow profile into the engine and ultimately reduce the methane slip. This is a novel strategy for an NDDF engine since modifying the in-cylinder flow profile can intensify the mixing between diesel and air-NG mixture in order to improve the NG utilization in the cylinder.

Data is presented from a number of flight research aircraft, which have been involved in the research of the effects of inflight icing, in a variety of atmospheric supercooled droplet and mixed-phase icing environmental conditions. The aircraft Types considered cover both Pneumatic and Thermal Ice Protection Systems (IPS). Icing includes supercooled droplet impact icing upon airframe and propeller blades and cold-soaked frost icing. The drag effects of inflight icing, from mixed-phase small and large droplets encountered during the course of SALPEX cloud physics research operations, upon a Fokker F-27 turboprop transport aircraft, have been analyzed. Furthermore, during the course of AIRS 1.5 and AIRS II inflight icing flight research operations, the NRC Convair conducted aerodynamic characterization maneuvers, following and during icing accretion in a wide range of environmental conditions of altitude, air temperature, LWC and droplet spectra.

One of the main applications for aluminum extrusions in the automotive sector is crash structures including crash rails, crash cans, bumpers and structural body components. The objective is usually to optimize the energy absorption capability for a given structure weight. The ability to extrude thin wall multi-void extrusions contributes to this goal. However, the alloy used also plays a significant role in terms of the ability to produce the required geometry, strength - which to a large extent controls the energy absorption capability and the “ductility” or fracture behavior which controls the strain that can be applied locally during crush deformation before cracking. This paper describes results of a test program to examine the crush behavior of a range of alloys typically supplied for automotive applications as a function of processing parameters including artificial ageing and quench rate.

An introduction to the operational and design features of the transonic fan stage of a modern turbofan engine can give the student an example of highly developed turbomachinery whose performance and design can be readily appreciated from fundamental knowledge of compressible fluid flow and boundary layer separation. Application of continuity and momentum principles along with the constraint of a limiting tip-diameter Mach number (relative to the blade) can serve to determine the required fan size, RPM, blade angles and blade spacing for a given mass flow rate and inlet stagnation pressure and temperature. Sensitivity of fan design parameters to limiting Mach number, hub-tip ratio and stall safety margin is readily determined by a simplified model which is compatible with the results of detailed design procedures.

The operation of S.I. engines on lean or diluents containing gaseous fuel-air mixtures is attractive in principle since it can provide improved fuel economy, reduced tendency to knock and low NOx emissions combined with a possible improvement to the operational life of the engine. However, the overall flame propagation rates then tend to drop sharply as the operational mixture is excessively leaned or diluted with CO2 or N2. The paper presents experimental data obtained in a single cylinder, variable compression ratio, S.I., CFR engine when operated on a number of gaseous fuels and some of their mixtures. A gradual leaning of the operating mixture can affect adversely in turn, emissions of CO and unburned fuel and cyclic variation. The extent of deterioration in these operating parameters is shown to correlate well with the corresponding values of the combustion period, a key combustion indicator. Similar effects were observed when adding diluents to stoichiometric CH4-air mixtures.

This paper presents the emission characteristics of a HCCI engine operation using n-heptane. The experiments were conducted in a single cylinder Co-operative Fuel Research (CFR) engine equipped with an air-assist port fuel injector. The effects of intake temperature, air/fuel ratio, compression ratio, turbo-charging, and EGR rate on exhaust emissions were explored. The analysis of the exhaust gases included oxides of nitrogen (NOx), nitrous oxide (N2O), carbon monoxide (CO), total hydrocarbon (THC), and soot. The hydrocarbon species present in exhaust gases and their concentrations at several operating conditions were also characterized. The strategies to obtain low HC, CO and NOx emissions are presented and discussed. The approaches to effectively retard HCCI combustion phase without deteriorating combustion efficiency are examined. It was found that HCCI combustion produces extremely low soot and NOx emissions.

In North America, heavy-duty diesel engines for on-road use have to meet strict regulations for their emissions of nitric oxide and nitrogen dioxide (cumulatively referred to as ‘NOx’) besides other criteria pollutants. Over the next decade, regulations for NOx emissions are expected to becoming more stringent in North America. One of the major technical barriers for achieving in-use NOx emissions commensurate with the levels determined from in-laboratory test procedures required by regulations is controlling NOx emissions during cold start and engine idling. Since the exhaust gas temperature can be low during these conditions, the effectiveness of the exhaust after-treatment (EAT) system may be reduced. Under colder climate conditions like in Canada, the impact may be even more significant.

Natural gas (NG)-diesel dual-fuel combustion can be a suitable solution to reduce the overall CO2 emissions of heavy-duty vehicles using diesel engines. One configuration of such a dual-fuel engine can be port injection of NG to form a combustible air-NG mixture in the cylinder. This mixture is then ignited by a direct injection of diesel. Other potential advantages of such an engine include the flexibility of switching back to diesel-only mode, reduced hardware development costs and lower soot emissions. However, the trade-off is lower brake thermal efficiency (BTE) and higher hydrocarbon emissions, especially methane, at low load and/or high engine speed conditions. Advancing the diesel injection timing tends to improve the BTE but may cause the NOx emissions to increase.

In this paper a study of the squish-generated charge motion in the combustion chamber of a natural gas engine is reported. A combination of both numerical simulations and actual engine tests was used to correlate the turbulence level at the spark plug location with performance and cylinder pressure data for three different chamber configurations. The higher-turbulence combustion chamber showed an average 1.5% reduction in brake specific fuel consumption in comparison with the lower turbulence level combustion chambers. The emission levels from the high-turbulence case were, however, generally higher than those from the lower-turbulence combustion chambers.

In recent years, light weight components have been an area of significant importance in automotive design. This has led to the replacement of steel and cast iron with aluminum alloys for many automotive components. For instance, Al-Si alloys have successfully replaced nodular and gray cast iron in the production of large automotive components such as engine blocks. However, excessive residual strain along the cylinder bores of these engine blocks may result in cylinder distortion during engine operation. Therefore, in this study, neutron diffraction was used to evaluate residual strain along the aluminum cylinder bridge and the gray cast iron liners of distorted and undistorted engine blocks. The strains were measured in the hoop, radial, and axial orientations. The results suggest that the residual strain along the aluminum cylinder bridge of the distorted engine block was tensile for all three measured components.

Continuous efforts to develop a lightweight alloy suitable for the most demanding applications in automotive industry resulted in a number of advanced aluminum (Al) and magnesium alloys and manufacturing routes. One example of this is the application of 319 Al alloy for production of 3.6L V6 gasoline engine blocks. Aluminum is sand cast around Fe-liner cylinder inserts, prior to undergoing the T7 heat treatment process. One of the critical factors determining the quality of the final product is the type, level, and profile of residual stresses along the Fe liners (or extent of liner distortion) that are always present in a cast component. In this study, neutron diffraction was used to characterize residual stresses along the Al and the Fe liners in the web region of the cast engine block. The strains were measured both in Al and Fe in hoop, radial, and axial orientations. The stresses were subsequently determined using generalized Hooke's law.

In direct-injection engines, combustion and emission formation is strongly affected by injection quality. Injection quality is related to mass-flow rate shape, momentum rate shape, stability of pulses as well as mechanical and hydraulic delays associated with fuel injection. Finding these injector characteristics aids the interpretation of engine experiments and design of new injection strategies. The goal of this study is to investigate the rate of momentum for the single and post injections for high-pressure direct-injection natural gas injectors. The momentum measurement method has been used before to study momentum rate of injection for single and split injections for diesel sprays. In this paper, a method of momentum measurement for gas injections is developed in order to present transient momentum rate shape during injection timing. In this method, a gas jet impinges perpendicularly on a pressure transducer surface.

As global energy demands continue to be met with ever evolving and stricter emissions requirements, natural gas (NG) has become a highly researched alternative to conventional fossil fuels in many industrial sectors. Transportation is one such field that can utilize the benefits of NG as a primary fuel for use in internal combustion engines (ICEs). In the context of heavy-duty on-highway transportation applications, diesel-ignited dual-fuel (DIDF) combustion of NG has been identified as a commercially viable alternative technology. Previous investigations of DIDF have examined the various trends present across the spectrum of DIDF operating space. However, in-cylinder processes are still not well understood and this investigation aims to further understanding in this area. An in-cylinder, local infrared absorption fuel concentration sensor is used to examine in-cylinder processes by comparison with previous optical and thermodynamic studies.

A joint program between Bell Helicopter Textron Canada and the Flight Research Laboratory of Canada's National Research Council was initiated to address the aerodynamic modelling challenges of the Bell M427 helicopter. The primary objective was to use the NRC parameter estimation technique, based on modified maximum likelihood estimation (MMLE), on a limited set of flight test data to efficiently develop an accurate forward-flight mathematical model of the Bell M427. The effect of main rotor design changes on the aircraft stability characteristics was also investigated, using parameter estimation. This program has demonstrated the feasibility of creating a forward-flight rotorcraft aerodynamic mathematical model based on time-domain parameter estimation, and the ability of a 6 degree-of-freedom MMLE model to accurately document the impact of minor rotor modifications on aircraft stability.

An experimental investigation of the autoignition of transient gaseous fuel jets in heated and compressed air is conducted in a shock tube facility. Experiments are performed at an initial pressure of 30 bar with initial oxidizer temperatures ranging from 1150 K to 1400 K, injection pressures ranging from 60 bar to 150 bar, and with injector tip orifice diameters of 0.275 mm and 1.1 mm. Under the operating conditions studied, increasing temperature results in a significant decrease in autoignition delay time, td. The smaller orifice results in an increase in ignition delay time and variability, as compared with the larger orifice. For initial temperatures below about 1250K, ignition is rarely achieved with the smaller orifice, whereas ignition is always achieved with the larger orifice down to 1150 K. Under the conditions studied, increasing the injection pressure decreases ignition delay, a result dynamically consistent with larger orifice size decreasing ignition delay time.

An experimental investigation of the autoignition and emission characteristics of transient turbulent gaseous fuel jets in heated and compressed air was conducted in a shock tube facility. Experiments were performed at an initial pressure of 30 bar with initial oxidizer temperatures ranging from 1200 to 1400 K, injection pressures ranging from 60 to 150 bar, and injection durations ranging from 1.0 to 2.5 ms. Methane and 90.0% methane/10.0% ethane blend were used as fuel. Under the operating conditions studied, increasing temperature resulted in a significant decrease in autoignition delay time. Increasing the injection pressure decreased ignition delay as well. The downstream location of the ignition kernel relative to the jet penetration distance was found to be in the range, 0.4

This paper examines issues related to planning, programming and execution of machining operations by a robot in the context of machining large parts with complex geometries by a gantry-mounted robotic system. Parts were created from surface data in a CAD/CAM environment. The same environment was used to generate tool paths using a conventional machine tool approach. These paths were converted to robot trajectories and validated using mathematical kinematic models of the robotic system. Validation was performed according to various criteria related to process performance. Associated robot programs were then automatically generated. The manufacturing cell was progressively integrated according to requirements resulting from iterative process characterization. A metrology-based calibration procedure was designed that considerably improved the system's positioning precision.

The use of carbon fiber reinforced thermoset composites has doubled in the last decade raising questions about the waste generated from manufacturing and at end-of-life, especially in the aircraft industry. In this study, 2.5 cm long carbon fibers were recovered from thermoset composite waste using a commercial scale pyrolysis process. Scanning electron microscopy, density measurements, single filament tensile testing as well as micro-droplet testing were performed to characterize the morphology, mechanical properties, and surface adhesion of the fibers. The recycled fibers appeared to be mostly undamaged and clean, exhibiting comparable mechanical properties to virgin carbon fibers. A carding process followed by an ultrasound treatment produced randomly aligned recycled fiber mats. These mats were used to fabricate composite plates, with fiber volume fractions up to 40 %, by infusion / compression molding.