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RADIATION can produce almost instantaneous failure of modern aircraft lubricants, tests at Southwest Research Institute show. Two types of failures demonstrated are rapid viscosity rise and loss of heat conductivity. Furthermore, it was found that lubricants can become excessively corrosive under high-level radiation. Generally speaking, the better lubricants appeared to improve in performance while marginal ones deteriorated to a greater extent under radiation. When the better lubricants were subjected to static irradiation prior to the deposition test, there was a minor increase in deposition number as the total dose was increased.

In recent years, Nearfield Acoustical Holography (NAH) has been used to identify stationary vehicle exterior noise sources. However that application has usually been limited to individual components. Since powertrain noise sources are hidden within the engine compartment, it is difficult to use NAH to identify those sources and the associated partial field that combine to create the complete exterior noise field of a motor vehicle. Integrated Nearfield Acoustical Holography (INAH) has been developed to address these concerns: it is described here. The procedure entails sensing the sources inside the engine compartment by using an array of reference microphones, and then calculating the associated partial radiation fields by using NAH. In the second part of this paper, the use of farfield arrays is considered. Several array techniques have previously been applied to identify noise sources on moving vehicles.

The objectives of this project were to investigate the corrosivity of condensate in a stoichiometric spark-ignited (SI) engine when running exhaust gas recirculation (EGR) and to determine the effects of sulfur-in-fuel on corrosion. A 2.0 L turbocharged direct-injected SI engine was operated with low-pressure EGR for this study. The engine was instrumented for visual, thermodynamic, and electrochemical analyses to determine the potential for corrosion at locations where condensation was deemed likely in a low-pressure loop EGR (LPL-EGR) engine. The electrochemical analysis was performed using multi-electrode array (MEA) corrosion probes. Condensate was also collected and analyzed. These analyses were performed downstream of both the charge air cooler (CAC) and the EGR cooler. It was found that while conditions existed for sulfuric acid to form with high-sulfur fuel, no sulfuric acid was detected by any of the measurement methods.

The confluence of fuel economy improvement requirements and increased use of ethanol as a gasoline blend component has led to various studies into the efficiency and performance benefits to be had when using high octane number, high ethanol content fuels in modern engines. As part of a comprehensive study of the autoignition of fuels in both the CFR octane rating engine and a modern, direct injection, turbocharged spark ignited engine, a series of fuel blends were prepared with market relevant ranges of octane numbers and ethanol blends levels. The paper reports on the first part of this study where fuel flow measurements were done on a single cylinder research engine, utilizing a GM LHU combustion system, and then used to predict drive cycle fuel economy. For a range of engine speeds and manifold air pressures, spark timing was adjusted to achieve either the maximum brake torque (MBT) or a matched 50 % mass fraction burnt location.

A project was conducted by Southwest Research Institute on behalf of the California Air Resources Board and the South Coast Air Quality Management District to demonstrate the technical feasibility of utilizing closed-loop three-way catalyst technology in off-road equipment applications. Five representative engines were selected, and baseline emission-tested using both gasoline and LPG. Emission reduction systems, employing three-way catalyst technology with electronic fuel control, were designed and installed on two of the engines. The engines were then installed in a fork lift and a pump system, and limited durability testing was performed. Results showed that low emission levels, easily meeting CARB's newly adopted large spark-ignited engine emission standards, could be achieved.

Radioactive tracer technology (RAT) is an important tool in measuring component wear in an operating engine on a real-time basis. This paper will discuss the use of RAT to study and evaluate boundary lubricant and surfactant chemistries aimed at providing benefits in wear control. In particular, RAT was employed to study ring and bearing wear as a function of engine operating condition (speed, load, and temperature) and lubricant characteristics. Prior to testing, the engine's compression rings and connecting rod bearings were subjected to bulk thermal neutron bombardment in a nuclear reactor to produce artificial radioisotopes that were separately characteristic of the ring and bearing wear surfaces. The irradiated parts were installed in the test engine, after which testing to a specific test matrix was accomplished.

The objective was to demonstrate the feasibility of operating a natural gas two-stroke engine using glow plug ignition with very lean mixtures. Based on the results obtained, the term SCGI (stratified charge glow plug ignition) was coined to describe the engine. An JLO two-stroke diesel engine was converted first to a natural gas fueled spark-ignited engine for the baseline tests, and then to an SCGI engine. The SCGI engine used a gas operated valve in the cylinder head to admit the natural gas fuel, and a glow plug was used as a means to initiate the combustion. The engine was successfully run, but was found to be sensitive to various conditions such as the glow plug temperature. The engine would run very lean, to an overall equivalence ratio of 0.33, offering the potential of good fuel economy and low NOx emissions.

China has become the world’s largest vehicle market in terms of sales volume. Automobiles sales keep growing in recent years despite the declining economic growth rate. Due to the increasing attention given to the environmental impact, more stringent emission regulations are being drafted to control traditional internal combustion engine emissions. In order to reduce vehicle emissions, environmentally-friendly new-energy vehicles, such as electric vehicles and plug-in hybrid vehicles, are being promoted by government policies. The Chinese government plans to boost sales of new-energy cars to account for about five percent of China’s total vehicle sales. It is well known that more electric and electronic components will be integrated into a vehicle platform during vehicle electrification.

The spark ignition (SI) engine has been known to exhibit several different abnormal combustion phenomena, such as knock or pre-ignition, which have been addressed with improved engine design or control schemes. However, in highly boosted SI engines, Low-Speed Pre-Ignition (LSPI), a pre-ignition event typically followed by heavy knock, has developed into a topic of major interest due to its potential for engine damage. Previous experiments associated increases in hydrocarbon emissions with the blowdown event of an LSPI cycle [1]. Also, the same experiments showed that there was a dependency of the LSPI activity on fuel and/or lubricant compositions [1]. Based on these findings it was hypothesized that accumulated hydrocarbons play a role in LSPI and are consumed during LSPI events. A potential source for accumulated HC is the top land piston crevice.

Because of the thermodynamic relationship of pressure, temperature and volume for processes which occur in an internal-combustion engine (ICE), and their relationship to ideal efficiency and efficiency-limiting phenomena e.g. knock in spark-ignition engines, changing the thermo-chemical properties of the in-cylinder charge should be considered as an increment in the development of the ICE engine for future efficiency improvements. Exhaust gas recirculation (EGR) in spark-ignited gasoline engines is one increment that has been made to alter the in-cylinder charge. EGR gives proven thermal efficiency benefits for SI engines which improve vehicle fuel economy, as demonstrated through literature and production applications. The thermal efficiency benefit of EGR is due to lower in-cylinder temperatures, reduced heat transfer and reduced pumping losses. The next major increment could be modifying the constituents of the EGR stream, potentially through the means of a membrane.

The effect of combustion chamber wall-wetting on the emissions of unburned and partially-burned hydrocarbons (HCs) from gasoline-fueled SI engines was investigated experimentally. A spark-plug mounted directional injection probe was developed to study the fate of liquid fuel which impinges on different surfaces of the combustion chamber, and to quantify its contribution to the HC emissions from direct-injected (DI) and port-fuel injected (PFI) engines. With this probe, a controlled amount of liquid fuel was deposited on a given location within the combustion chamber at a desired crank angle while the engine was operated on pre-mixed LPG. Thus, with this technique, the HC emissions due to in-cylinder wall wetting were studied independently of all other HC sources. Results from these tests show that the location where liquid fuel impinges on the combustion chamber has a very important effect on the resulting HC emissions.

Small (up to 1% by volume) amounts of hydrogen (H2) were added to the intake charge of a single-cylinder, stoichiometric spark ignited engine to determine the effect of H2 addition on EGR tolerance. Two types of tests were performed at 1500 rpm, two loads (3.1 bar and 5.5 bar IMEP), two compression ratios (11:1 and 14:1) and with two fuels (gasoline and natural gas). The first test involved holding EGR level constant and increasing the H2 concentration. The EGR level of the engine was increased until the CoV of IMEP was > 5% and then small amounts of hydrogen were added until the total was 1% by volume. The effect of increasing the amount of H2 on engine stability was measured along with combustion parameters and engine emissions. The results showed that only a very small amount of H2 was necessary to stabilize the engine. At amounts past that level, increasing the level of H2 had no or only a very small effect.

The spark ignition (SI) engine has been known to exhibit several different abnormal combustion phenomena, such as knock or pre-ignition, which have been addressed with improved engine design or control schemes. However, in highly boosted SI engines - where the engine displacement is reduced and turbocharging is employed to increase specific power - a new combustion phenomenon, described as Low-Speed Pre-Ignition (LSPI), has been exhibited. LSPI is characterized as a pre-ignition event typically followed by heavy knock, which has the potential to cause degradation of the engine. However, because LSPI events occur only sporadically and in an uncontrolled fashion, it is difficult to identify the causes for this phenomenon and to develop solutions to suppress it. Some countermeasures exist that OEMs can use to avoid LSPI, such as load limiting, but these have drawbacks.

Spray angle and penetration length data were taken under cold start conditions for a Direct Injection Spark Ignition engine to investigate the effect of transient conditions on spray development. The results show that during cold start, spray development depends primarily on fuel pressure, followed by Manifold Absolute Pressure (MAP). Injection frequency had little effect on spray development. The spray for this single hole, pressure-swirl fuel injector was characterized using high speed imaging. The fuel spray was characterized by three different regimes. Regime 1 comprised fuel pressures from 6 - 13 bar, MAPs from 0.7 - 1 bar, and was characterized by a large pre-spray along with large drop sizes. The spray angle and penetration lengths were comparatively small. Regime 2 comprised fuel pressures from 30 - 39 bar and MAPs from 0.51 - 0.54 bar. A large pre-spray and large drop sizes were still present but reduced compared to Regime 1.

The performance of an organic Rankine cycle (ORC) used to recover waste heat from the exhaust of a diesel and a spark ignition engine for electric power generation was modeled. The design elements of the ORC incorporated into the thermodynamic model were based on an experimental study performed at Oak Ridge National Laboratory in which a regenerative organic Rankine cycle system was designed, assembled and integrated into the exhaust of a 1.9 liter 4-cylinder automotive turbo-diesel. This engine was operated at a single fixed-load point at which Rankine cycle state point temperatures as well as the electrical power output of an electric generator coupled to a turbine that expanded R245fa refrigerant were measured. These data were used for model calibration.

The use of early intake valve closing (EIVC) can lead to improvements in spark-ignition engine efficiency. One of the greatest barriers facing adoption of EIVC for high power-density applications is the challenge of boosting as EIVC strategies reduce volumetric efficiency. Turbochargers with variable nozzle turbines (VNT) have recently been developed for gasoline applications operating at high exhaust gas temperatures. The use of a single VNT as a boost device may provide a lower-cost option compared to two-stage boosting systems or 48 V electronic boost devices for some EIVC applications. A predictive model was created based on engine testing results from a 1.6 L turbocharged gasoline direct injection engine [1]. The model was tuned so that it predicted burn-rates and end-gas knock over an engine operating map with varying speeds, loads, compression ratios and fuel types.

The size and distribution of a vehicle’s tailpipe particulate emissions can have a strong impact on human health, especially if the particles are small enough to enter the human respiratory system. Gasoline direct injection (GDI) has been adopted widely to meet stringent fuel economy and CO2 regulations across the globe for recent engine architectures. However, the introduction of GDI has led to challenges concerning the particulate matter (PM) and particle number (PN) emissions from such engines. This study aimed to compare the particulate emissions of three SI combustion strategies: conventional SI, conventional stoichiometric low-pressure exhaust gas recirculation (LP-EGR), and Dedicated-EGR (D-EGR) at four specific test conditions. It was shown that the engine-out PM/PN for both the EGR strategies was lower than the conventional SI combustion under normal operating conditions. The test conditions were chosen to represent the WLTC test conditions.

Low-Speed pre-ignition (LSPI) in modern-day, heavily downsized, boosted, and direct-injection spark ignition (SI) engines is a well-known problem. Several mechanisms contribute towards stochastic pre-ignition (SPI), the most prominent being crevice material droplet induced and deposit induced pre-ignition mechanisms. The droplet mechanism is typically dominated by the detergent additives present in the lubricant formulation; more specifically calcium and sodium-based detergent additives correlate strongly with the increased LSPI rates. Deposits flaking off the combustion chamber surfaces can also induce LSPI under certain conditions. This study aimed to develop an optical method designed to investigate the nature of pre-ignition precursors. Southwest Research Institute (SwRI) utilized an optically accessible GM 2.0 L LHU engine to study the pre-ignition phenomenon and studied the nature of pre-ignition precursors using spectral information from one of the cylinders in this engine.

To assess the contribution of structure-borne noise from an engine, it is critical to characterize the dynamic and vibro-acoustic properties of the engine components and assembly. In this paper, a component level study of a three-cylinder diesel engine block is presented. Virtual analysis was done to predict the natural frequencies and mode shapes of an engine block in the first step. Then, these results were used to decide the optimum test locations and an experimental modal test was conducted on the engine block. The initial virtual model results for the natural frequencies and mode shapes were correlated with the results from test. Then, the virtual model was updated with the damping derived from experimental modal test to match the vibration frequency response functions. Further, the virtual model was used for prediction of vibro-acoustic transfer functions. The vibro-acoustic transfer functions were also obtained from test.

A zero-dimensional cycle simulation model coupled with a chemical equilibrium model and a two-zone combustion model has been extended to predict nitric oxide formation and emissions from spark-ignited, lean-burn natural gas engines. It is demonstrated that using the extended Zeldovich mechanism alone, the NOx emissions from an 8.1-liter, 6-cylinder, natural gas engine were significantly under predicted. However, by combining the predicted NOx formation from both the extended Zeldovich thermal NO and the Fenimore prompt NO mechanisms, the NOx emissions were predicted with fair accuracy over a range of engine powers and lean-burn equivalence ratios. The effect of injection timing on NOx emissions was under predicted. Humidity effects on NOx formation were slightly under predicted in another engine, a 6.8-liter, 6-cylinder, natural gas engine. Engine power was well predicted in both engines, which is a prerequisite to accurate NOx predictions.