Search Results

Operation of flex fuel vehicles requires operation with a range of fuel properties. The significant differences in the heat of vaporization and energy density of E0-E100 fuels and the effect on spray development need to be fully comprehended when developing engine control strategies. Limited enthalpy for fuel vaporization needs to be accounted for when developing injection strategies for cold start, homogeneous and stratified operation. Spray imaging of multi-hole gasoline injectors with fuels ranging from E0 to E100 and environmental conditions that represent engine operating points from ambient cold start to hot conditions was performed in a spray chamber. Schlieren visualization technique was used to characterize the sprays and the results were compared with Laser Mie scattering and Back-lighting technique. Open chamber experiments were utilized to provide input and validation of a CFD model.

In present GDI engines, multiple injection strategies are often employed for engine cold start mixture formation. In the future, these strategies may also be used to control the combustion process, and to prevent misfiring or high emission levels. While the processes occurring during individual injections of GDI injectors have been investigated by a number of researchers, this paper concentrates on the interactions of multiple injection events. Even though multiple injection strategies are already applied in most GDI engines, the impact of the first injection event on the second injection event has not been analyzed in detail yet. Different optical measurement techniques are used in order to investigate the interaction of the two closely timed injection events, as well as the effect of dwell time and the in-cylinder conditions. The injector investigated is a GDI piezo injector with an outwardly opening needle.

Effects of fuel cell material properties on water management were numerically investigated using Volume of Fluid (VOF) method in the FLUENT. The results show that the channel surface wettability is an important design variable for both serpentine and interdigitated flow channel configurations. In a serpentine air flow channel, hydrophilic surfaces could benefit the reactant transport to reaction sites by facilitating water transport along channel edges or on channel surfaces; however, the hydrophilic surfaces would also introduce significantly pressure drop as a penalty. For interdigitated air flow channel design, it is observable that liquid water exists only in the outlet channel; it is also observable that water distribution inside GDL is uneven due to the pressure distribution caused by interdigitated structure. An in-situ water measurement method, neutron imaging technique, was used to investigate the water behavior in a PEM fuel cell.

Hat sections made of steel are frequently encountered in automotive body structural components such as front rails. These components can absorb significant amount of impact energy during collisions thereby protecting occupants of vehicles from severe injury. In the initial phase of vehicle design, it will be prudent to incorporate the sectional details of such a component based on an engineering target such as peak load, mean load, energy absorption, or total crush, or a combination of these parameters. Such a goal can be accomplished if efficient and reliable data-based models are available for predicting the performance of a section of given geometry as alternatives to time-consuming and detailed engineering analysis typically based on the explicit finite element method.

Many approaches have been taken to determine the burning velocity in internal combustion engines. Experimentally, the burning velocity has been determined in optically accessible gasoline engines by tracking the propagation of the flame front from the spark plug to the end of the combustion chamber. These experiments are costly as they require special imaging techniques and major modifications in the engine structure. Another approach to determine the burning velocity is from 3D CFD simulation models. These models require basic information about the mechanisms of combustion which are not available for distillate fuels in addition to many assumptions that have to be made to determine the burning velocity. Such models take long periods of computational time for execution and have to be calibrated and validated through experimentation.

Emissions of Unburned Hydrocarbons (UHC) from diesel engines are a particular concern during the starting process, when after-treatment devices are typically below optimal operating temperatures. Drivability in the subsequent warm-up phase is also impaired by large cyclic fluctuations in mean effective pressure (MEP). This paper discusses in-cylinder wall temperature influence on unburned hydrocarbon emissions and combustion stability during the starting and warm-up process in an optical engine. A laser-induced phosphorescence technique is used for quantitative measurements of in-cylinder wall temperatures just prior to start of injection (SOI), which are correlated to engine out UHC emission mole fractions and combustion phasing during starting sequences over a range of charge densities, at a fixed fueling rate. Squish zone cylinder wall temperature shows significant influence on engine out UHC emissions during the warm-up process.

It is well know that the internal flow field and nozzle geometry affected the spray behavior, but without high-speed microscopic visualization, it is difficult to characterize the spray structure in details. Single-hole diesel injectors have been used in fundamental spray research, while most direct-injection engines use multi-hole nozzle to tailor to the combustion chamber geometry. Recent engine trends also use smaller orifice and higher injection pressure. This paper discussed the quasi-steady near-nozzle diesel spray structures of an axisymmetric single-hole nozzle and a symmetric two-hole nozzle configuration, with a nominal nozzle size of 130 μm, and an attempt to correlate the observed structure to the internal flow structure using computational fluid dynamic (CFD) simulation. The test conditions include variation of injection pressure from 30 to 100 MPa, using both diesel and biodiesel fuels, under atmospheric condition.

This paper presents a model-based control system for SCR urea dosing employing an embedded real-time SCR chemistry model and a NH3 sensor. The control algorithm consists of a number of control features designed to enhance ammonia storage control and closed-loop compensation using the mid-brick NH3 sensor. An adaptive control algorithm is developed to demonstrate robustness of the feedback control system to compensate for catalyst aging, urea injection malfunction, or dosing fluid concentration variation. Simulation and engine dynamometer testing following ESC and FTP emission cycles are used to demonstrate the advantages of this control approach for meeting both NOx emission requirements and NH3 slip targets. Furthermore this paper demonstrates potential of a NH3 sensor for on-board diagnostics. Additionally the feasibility of implementing model based algorithms in a 32-bit floating-point environment with an automotive controller is examined.

The objective of this research is to investigate the effect of the blast load on the vehicle and occupant and identify the sensitivity of the vehicle parameters to the blast load, therefore figure out the design solution to protect the vehicle and occupant. CAE explicit commercial code, LSDYNA, is applied in this research with adopting CONWEP method for the blast load. The LSDYNA 95th percentile Hybrid III dummy model is used for occupant simulation. Seat, seat belt, and underbody and underbody armor are interested areas in the design to meet the survivability and weight target. The results show the protection can be effectively achieved through employing the new design method in three areas mentioned above.

This paper presents a monitoring, feedback and control system for SCR urea dosing utilizing an embedded model and NH3 sensing after the SCR for loop closing control. A one-dimensional SCR model was developed and embedded in a Simulink/Matlab environment. This embedded model is utilized for on-line, real time control of 32.5% aqueous urea dosing in the exhaust stream. Engine testing and simulation are used with the embedded SCR model and NH3 sensor closed loop feedback to demonstrate the advantages of this control approach for meeting both NOx emission requirements and NH3 slip targets. The paper explores these advantages under heavy duty FTP cycle conditions. The potential benefits include SCR size optimization and fuel consumption rate reduction under certain operating conditions.

Most times in ECU system function testing, the sensor input signals are directly set to a known value in order to drive the corresponding software variable to within a range of an expected value. This works only if the transfer function from the physical signal input to the software variable is well defined such as the measurement on MAP, A/C pressure, etc. Nevertheless, there are times the transfer function is not clearly defined and it is difficult to drive the software variable to an expected value. One example is throttle position sensor (TPS) test in an electronic throttle control (ETC) system, where TPS is not directly driven by the driver accelerator pedal sensor (APS) and it is very difficult to get TPS to an expected range by only changing APS. This paper introduces a method to use feedback in an HIL based ECU testing system to control outputs to an expected range. In this case study, the signal to be controlled is connected back to the HIL system to provide feedback.

By taking advantage of high-intensity and high-brilliance x-ray beams available at the Advanced Photon Source (APS), ultrafast (150 ps) propagation-based phase-enhanced imaging was developed to visualize high-pressure high-speed diesel sprays in the optically dense near-nozzle region. The sub-ns temporal and μm spatial resolution allows us to capture the morphology of the high-speed fuel sprays traveling at 500 m/s with a negligible motion blur. Both quality and quantitative information about the spray feature can be readily obtained. In the experiment, two types of single-hole nozzles have been used, one with a hydroground orifice inlet and the other with a sharp one. Within 3 mm from the nozzle, the sprays from these nozzles behave differently, ranging from laminar flow with surface instability waves to turbulent flow. The sprays are correlated with the nozzle internal geometry, which provides practical information for both nozzle design and supporting numerical simulation models.

Self recirculation casing treatment has been showed to be an effective technique to extend the flow range of the compressor. However, the mechanism of its surge extension on turbocharger compressor is less understood. Investigation and comparison of internal flow filed will help to understand its impact on the compressor performance. In present study, experimentally validated CFD analysis was employed to study the mechanism of surge extension on the turbocharger compressor. Firstly a turbocharger compressor with replaceable inserts near the shroud of the impeller inlet was designed so that the overall performance of the compressor with and without self recirculation casing treatment could be tested and compared. Two different self recirculation casing treatments had been tested: one is conventional self recirculation casing treatment and the other one has deswirl vanes inside the casing treatment passage.

The advantages of Variable Valve Actuation (VVA) in the aspects of improved engine performance, fuel economy and reduced emissions are well known in the industry. However, the design and optimization of such systems is complex and costly. The design process of VVA mechanisms can be greatly accelerated through the use of sophisticated simulation tools. Predictive numerical analysis of systems to address design issues and evaluate design changes can assure the required performance and durability. One notable requirement for the analysis and design of novel mechanically-actuated VVA systems is a general-purpose fast and easy-to-use planar mechanism kinematics analyzer with cam solution/design features, which can be applied to general mechanisms.

This paper aims to develop some enhanced identification algorithms for real time characterization of battery dynamics. The core of such a system is advanced system identification techniques that provide fast tracking capability to update battery cell's individual models in real-time operation. Due to inevitable measurement noises on voltage and current observations, the identification algorithms must perform under both input and output noises, leading to more challenging issues than standard identification problems. It is shown that typical battery models may not be identifiable, unique battery model features require modified input/output expressions, and standard least-squares identification methods will encounter identification bias. This paper devises modified model structure and algorithms to resolve these issues. System identifiabihty, algorithm convergence, identification bias, and bias correction mechanisms are established.

Because of their robustness and cost performance, multi-hole gasoline injectors are being adopted as the direct injection (DI) fuel injector of choice as vehicle manufacturers look for ways to reduce fuel consumption without sacrificing power and emission performance. To realize the full benefits of direct injection, the resulting spray needs to be well targeted, atomized, and appropriately mixed with charge air for the desirable fuel vapor concentration distributions in the combustion chamber. Ethanol and ethanol-gasoline blends synergistically improve the turbo-charged DI gasoline performance, especially in down-sized, down-sped and variable-valve-train engine architecture. This paper presents the spray imaging results from two multi-hole DI gasoline injectors with different design, fueled with pure ethanol (E100) or gasoline (E0), under homogeneous and stratified-charge conditions that represent typical engine operating points.

Analysis of flow field and charge distribution in a gasoline direct-injection (GDI) engine is performed by a modified version of the KIVA code. A particle-based spray model is proposed to simulate a swirl-type hollow-cone spray in a GDI engine. Spray droplets are assumed to be fully atomized and introduced at the sheet breakup locations as determined by experimental correlations and energy conservation. The effects of the fuel injection parameters such as spray cone angle and ambient pressure are examined for different injectors and injection conditions. Results show reasonable agreement with the measurements for penetration, dispersion, global shape, droplet velocity and size distribution by Phase Doppler Particle Anemometry(PDPA) in a constant-volume chamber. The test engine is a 4-stroke 4-valve optically accessible single-cylinder engine with a pent-roof head and tumble ports.

Simulations using CFD and chemical kinetics models have been applied to gain a better understanding of the effect of the recirculated gases on the autoignition process during cold starting of a direct injection diesel engine. The cranking gases recirculated (CGR) contain fuel vapor and partial oxidation products which affect the autoignition process in different ways. Some hydrocarbons (HCs) species enhance the reaction rates and reduce ignition delay. Meanwhile other HCs species and the partial oxidation products of the autoignition process have an opposing effect. The simulation covered a wide range of the hydrocarbons and aldehydes concentrations and their effect on the ignition delay in a 1.2L Ford DIATA 4-cylinders, water cooled, turbocharged and intercooled diesel engine. The simulated opposing effects of HCs and HCHO on the ignition delay are validated by experimental results at room temperature.

The spray plume geometry and fuel atomization characteristics of the gasoline direct-injection (GDI) multi-hole injectors are of paramount importance with respect to the GDI engine homogenous-charge combustion and emission characteristics. A major component of the GDI combustion system development is the optimization of the spray-targeting and mixture preparation. Significant R&D efforts are directed towards optimization of the nozzle design and the manufacturing process in order to achieve optimum multi-plume spray characteristics. The Volume-of-Fluid Large-Eddy Simulation (VOF-LES) of the injector internal flow and near-field primary atomization has been receiving attention as a tool to enable analysis of the influence of nozzle design on the key spray parameters and reduce reliance on hardware trial-and-tests for multi-objective spray optimizations.

Requirements for reduced fuel consumption with simultaneous reductions in regulated emissions require more efficient operation of Spark Ignited (SI) engines. An advanced valvetrain coupled with Gasoline Direct injection (GDi) provide an opportunity to simultaneously reduce fuel consumption and emissions. Work on a flex fuel GDi engine has identified significant potential to reduce throttling by using Early Intake Valve Closing (EIVC) and Late Intake Valve Closing (LIVC) strategies to control knock and load. High loads were problematic when operating on gasoline for particulate emissions, and low loads were not able to fully minimize throttling due to poor charge motion for the EIVC strategy. The use of valve deactivation was successful at reducing high load particulate emissions without a significant airflow penalty below 3000 RPM. Valve deactivation did increase the knocking tendency for knock limited fuels, due to increased heat transfer that increased charge temperature.