Search Results

In order to improve understanding of the primary atomization process for diesel-like sprays, a collaborative experimental and computational study was focused on the near-nozzle spray structure for the Engine Combustion Network (ECN) Spray D single-hole injector. These results were presented at the 5th Workshop of the ECN in Detroit, Michigan. Application of x-ray diagnostics to the Spray D standard cold condition enabled quantification of distributions of mass, phase interfacial area, and droplet size in the near-nozzle region from 0.1 to 14 mm from the nozzle exit. Using these data, several modeling frameworks, from Lagrangian-Eulerian to Eulerian-Eulerian and from Reynolds-Averaged Navier-Stokes (RANS) to Direct Numerical Simulation (DNS), were assessed in their ability to capture and explain experimentally observed spray details. Due to its computational efficiency, the Lagrangian-Eulerian approach was able to provide spray predictions across a broad range of conditions.

Abstract The issue of material compatibility of biodiesel has been discussed by few researchers but the reported corrosion rates were alarmingly high. This study addresses the corrosion issue of biodiesel with automotive materials with a different but systematic approach following SAE J1747 standard. In earlier studies while conducting material compatibility studies with biodiesel, mention of any specific standard/s has not been generally observed. Earlier studies were conducted by storing the samples for a long time without any change of fuel. However in actual automotive application, change of fuel is always on a periodic basis due to consumption of fuel and the SAE standard recommends for the same. This difference has a significant effect on the material compatibility as this periodic change does not result in making the fuel particularly biodiesel more acidic which is otherwise when stored for a long time during the test period.

Abstract The selective catalytic reduction (SCR) of nitrogen oxides with ammonia is a promising solution to meet upcoming emission regulations for lean-burning combustion engines. Due to the toxicity of ammonia, exclusively SCR systems with precursor substances, e.g., a urea-water solution (UWS), are available or being developed. The determining factors for the efficiency of SCR systems are sufficient ammonia generation and homogenization upstream of the catalytic converter. In the first part, this study presents an experimental investigation of the occurring mechanisms during ammonia generation from UWS droplets; including the evaporation of water, the thermal decomposition of urea, and droplet-wall interactions. In the second part, the observed physical and chemical phenomena are mathematically described and constitute the basis for the development of a simulation model. For this purpose, experiments by means of TGA were conducted to thoroughly investigate the UWS decomposition.

Abstract The need for high efficiency automotive engines has led to more complex air handling and fuel injection systems, higher compression ratios, more advanced combustion and aftertreatment systems, and the use of fuels with higher octane ratings. Higher octane fuels have a lower propensity to knock. This work studies the influence of changing fuel octane rating on two modern production gasoline vehicles, one with a naturally aspirated, port injected engine and the other with a turbocharged, direct injected engine, using fuels with four different octane number grades (with 85, 87, 91, and 93 anti-knock indices) and operated over a variety of driving cycles and temperature conditions. Unlike previous studies, this effort develops and demonstrates a methodology that isolates fuel effects on fuel consumption and provides a clear view of the octane impact on existing vehicles.

Abstract In current study, the combustion and emission characteristics of hydrotreated vegetable oil (HVO) were studied and compared to those of conventional marine gas oil (MGO). The main goal was to verify its applicability as an alternative marine fuel. All experiments were performed using generator set and propeller-law test cycles, i.e., standardized E2 and E3 cycles respectively. Additional emphasis was paid to the particulate matter (PM) emissions combining gravimetric and particle number measurements. The obtained results indicate average 10-15 % reduction in nitrogen oxides (NOx) emissions, while total unburned hydrocarbons (THC) emissions were reduced by 50-55 %. It is believed that a much higher cetane number of HVO together with its superior chemical composition (overall higher H/C ratio, absence of aromatics, and heavy-boiling compounds) plays a vital role here.

Abstract Lubricity is a very important issue for diesel fuel injectors and pumps (of an engine) that are lubricated by the fuel itself. Biodiesel as an alternative fuel has a number of technical advantages compared to conventional diesel. It is required to perform more research about the tribological behavior of biodiesel blends under run-in period conditions at different rotational speeds. Friction characteristics of biodiesel (mixture of sunflower and soybean methyl ester) were studied by using a four-ball wear testing machine. Results indicated that the friction was reduced with the increase in rotational speed under the run-in period conditions. Moreover, the results showed that the friction coefficient decreases at rotational speeds of 600 and 900 rpm as the proportion of biodiesel increases in the fuel blend.

Abstract Three-dimensional patterns representing crosshatched plateau-honed cylinder bores based on two-dimensional Fast Fourier Transform (FFT) of measured surfaces were generated and used to calculate pressure flow, shear-driven flow, and shear stress factors. Later, the flow and shear stress factors obtained by numerical simulations for various surface patterns were used to calculate lubricant film thickness and friction force between piston ring and cylinder bore contact in typical diesel engine conditions using a mixed lubrication model. The effects of various crosshatch honing angles, such as 30°, 45°, and 60°, and texture heights on engine friction losses, wear, and oil consumption were discussed in detail. It is observed from numerical results that lower lubricant film thickness values are generated with higher honing angles, particularly in mixed lubrication regime where lubricant film thickness is close to the roughness level, mainly due to lower resistance to pressure flow.

Abstract The compatibility of four potential bio-derived blendstock molecules with infrastructure elastomers was determined by measuring the volume change following exposure. The blendstock molecules included 1-propanol, diisobutylene, cyclopentanone, and a furan mixture. The elastomers included two fluorocarbons, six nitrile rubbers (NBRs), and one each of fluorosilicone, neoprene, polyurethane, and silicone. The elastomers were exposed to the fuel molecules as blends ranging from 0 to 30 vol.% in both a blendstock for oxygenate blending (BOB) formulation and an E10 fuel. Silicone exhibited excessive swelling in each test fuel, while the other elastomers showed good compatibility (low swell) with diisobutylene, 1-propanol, and the furan mixture when BOB was used as the base fuel. The E10 base fuel produced high (>30%) swell in neoprene, polyurethane, and some nitrile rubbers. In most cases diisobutylene produced the least amount of volume expansion.

Abstract The manufacturing of diesel injector nozzles requires precision processing to produce multiple micro-holes. An abrasive fluid containing a mixture of mineral oil and hard particles is used for rounding them, ensuring the hydrodynamics of the injection. As verified in a previous investigation, the viscosity of the fluid undergoes uncontrolled changes during hydro-erosive (HE) grinding. Such undesired viscosity changes are detrimental to the process and difficult to assess. The current investigation aims to study the possibility of using the refractive index of the oils used in the HE grinding for assessing their viscosities. A calibration curve correlating the refractive index and viscosity was obtained from the analysis of samples produced by mixing two distinct mineral oils in different proportions. The determined calibration curve was tested with 45 samples of filtered oil, collected directly from the tanks during the HE grinding.

Abstract Gasoline fuel lubricity is key to reducing wear and energy losses from friction in engines. The High-Frequency Reciprocating Rig (HFRR) test protocol recommended for gasoline fuels has been modified to evaluate the wear and friction properties of additized fuels. Adapted from the American Society for Testing and Materials (ASTM) D6079 test for diesel lubricity and literature-based procedures developed for gasoline fuels, the protocol and hardware used in this study allow for differentiation of fuels with unique additive chemistries and varying additive treat rates (EPA-approved lowest additive concentration, LAC, or higher). Supplementing HFRR tests, measurements of acoustic emissions corroborate friction coefficient trends using different additized fuels. Anti-wear performance of fuels during engine tests was characterized by roller-follower pin wear and metal concentration in engine oil, further distinguishing LAC from alternate additized fuels.

Abstract The 2010 Environmental Protection Agency (EPA) Emission Standard for heavy-duty engines required 0.2 g/bhp-hr over certification cycles (cold and hot Federal Test Procedure [FTP]), and the California Air Resources Board (CARB) standards require 0.02 g/bhp-hr for the same cycles leading to a 90% reduction of overall oxides of nitrogen (NOx) emissions. Similar reductions may be considered by the EPA through its Cleaner Trucks Initiative program. In this article, aftertreatment system components consisting of a diesel oxidation catalyst (DOC); a selective catalytic reduction (SCR) catalyst on a diesel particulate filter (DPF), or SCR-F; a second DOC (DOC2); and a SCR along with two urea injectors have been analyzed, which could be part of an aftertreatment system that can achieve the 0.02 g/bhp-hr standard.

Abstract The compatibilities of fuel system elastomers and plastics were evaluated for test fuels containing 16 vol.% isobutanol (iBu16) and 10 vol.% ethanol (E10). Elastomers included two fluorocarbons, four acrylonitrile butadiene rubbers (NBRs), and one type of fluorosilicone, neoprene, and epichlorohydrin/ethylene oxide. Plastic materials included four nylon grades, three polyamides, polytetrafluoroethylene (PTFE), polyvinylidene fluoride (PVDF), ethylene tetrafluoroethylene (ETFE), polyphenylene sulfide (PPS), high-density polyethylene (HDPE), polybutylene terephthalate (PBT), polyoxymethylene (POM), flexible polyvinylchloride (PVC), polyetherimide (PEI), polyetheretherketone (PEEK), and a phenol formaldehyde reinforced with glass fiber (GFPF). For each polymer material, the volume, mass, and hardness were measured before and after drying. Dynamic mechanical analysis (DMA) measurements were also performed on the dried specimens.

Abstract The fuel injection pressures used in gasoline direct injection (GDI) engines have increased in recent years to improve fuel efficiency and reduce emissions. Current GDI engines use injection pressures of up to 350 bar, and there is evidence that even higher fuel injection pressures could yield further improvements in atomization. Higher injection pressures could also improve mixture formation by increasing the spray velocity; however, the research with higher injection pressures over 1000 bar is limited due to a limit of mechanical components. This manuscript summarizes experimental investigations into the effect of injection pressure, injection mass, and nozzle shape on spray-induced air motion with ultrahigh injection pressure over 1000 bar.

Abstract Conventional fusion joining techniques pervasive in the automotive industry are unable to effectively join aluminum and steel. To solve this problem, a technique termed friction element welding (FEW) has been developed, which is able to join any nonferrous top sheet material to a base steel layer, independent of the base layer strength. FEW works on the same principles as friction welding, as a steel element is pushed and rotated against a nonferrous top sheet to create frictional energy which softens and flows the material around the fastener shaft and under the fastener head, exposing the steel below. The element then contacts the steel and bonds through traditional friction welding. FEW is a four-step process (penetration, cleaning, welding, compression), with two to four parameters (endload, spindle speed, displacement transition, time transition) controlling each step.

Abstract The objective of this investigation is to study the cyclic deformation behavior of SA333 Gr-6 C-Mn steel at 300°C. Low cycle fatigue tests were carried out at total strain amplitude between ±0.35 and ±1.25% at a constant strain rate of 1 × 10−3 s−1. Ratcheting tests were conducted at a various combination of mean stress and stress amplitude at a constant stress rate of 115 MPa s−1. The material SA333 Gr-6 steel exhibits cyclic hardening throughout its fatigue life. The material shows non-Masing behavior and deviation (δσo ) from Masing behavior increase with an increase of strain amplitude. Ratcheting strain accumulation increases, whereas ratcheting life decreases with an increase in mean stress or stress amplitude. With an increase in mean stress and stress amplitude, ratcheting rate also increases. The material shows hardening characteristic due to dynamic strain aging (DSA) phenomena.

Abstract Bio-fuels of the 2nd generation constitute a key approach to tackle both Greenhouse Gas (GHG) and air quality challenges associated with combustion emissions of the transport sector. Since these fuels are obtained of residual materials of the agricultural industry, well-to-tank CO2 emissions can be significantly lowered by a closed-cycle of formation and absorption of CO2. Furthermore, studies of bio-fuels have shown reduced formation of particulate matter on account of the fuels’ high oxygen content therefore addressing air quality issues. However, due to the high oxygen content and other physical parameters these fuels are expected to exhibit different ignition behaviour. Moreover, the question is whether there is a positive superimposition of the fuels ignition behaviour with the benefits of an alternative ignition system, such as a corona ignition.

Abstract The compatibility of key fuel system infrastructure plastics with 39 bio-blendstock fuel candidates was examined using Hansen solubility analysis. Fuel types included multiple alcohols, esters, ethers, ketones, alkenes and one alkane. These compounds were evaluated as neat molecules and as blends with the gasoline surrogate, dodecane and a mix of dodecane and 10% ethanol (E10D). The plastics included polyphenylene sulfide (PPS), polyethylene terephthalate (PET), polytetrafluoroethylene (PTFE), polyvinylidene fluoride (PVDF), polyoxymethylene (POM), polybutylene terephthalate (PBT), polypropylene (PP), high density polyethylene (HDPE), along with several nylon grades. These materials have been rigorously studied with other fuel types, and their volume change results were found to correspond well with their predicted solubility levels.

Abstract Decision analysis (DA), a well-established discipline in business and engineering, is entering another domain of application due to the advent of Industry 4.0. DA enables optimal decisions by finding system parameters that maximize the utility, or in the presence of uncertainty the expected utility, from the attributes of a system. Whether there is a single decision maker or all decision makers have uniform preferences, determining risk behavior and the resulting utility is well developed in the existing literature. However, variability in preferences has not been satisfactorily addressed. This gap gains added significance in the face of the demands of Industry 4.0 where cyberphysical production systems must drive autonomous decision-making on the factory floor. The decisions must accommodate a distribution of customer and designer preferences, including production auditors within the organization.

Abstract The windshield wiper is a component that is closely related to safety because it plays an important role in ensuring the driver’s vision despite external factors such as rain and dust. Here, the mechanical properties of different types of blade rubber were evaluated using a miniature tensile test machine for a structural analysis of the types of wiper blade rubber used in automobiles. In addition, a compression set and the aging characteristics of each type of rubber were determined by comparing the mechanical properties and shape changes of the blade rubber after more than one year of use to the same blade rubber before use. Using the mechanical properties as measured by a tensile test, a nonlinear structural analysis of the wiper blade system was conducted using a 3D finite element method (FEM). The contact force distribution and wiping angle of the blade rubber under a static load were measured.

Abstract Load-time histories can be used to predict vehicle durability by calculating the pseudo damage (PD) through one or more load paths for a vehicle. When the dynamics of each load path are taken into account, a PD density (damage per distance traveled) can be expressed for each load path for any given road input to a vehicle. When damage is expressed as a PD density for a segment of road, separable damaging events can be identified using the PD density in all load paths of interest for a vehicle. However, it would be beneficial if events with similar damage characteristics can be identified and grouped together to provide an additional level of durability information. The objective of this work is to develop a similarity test for identifying the similarity/dissimilarity between multiple damaging events using the damage characteristics in multiple load paths. The damage characteristics for events are defined using the distribution of PD density samples for all known load paths.