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Lean NOx trap (LNT) is a great potential NOx abatement method for lean-burn gasoline engines in consideration of exhaust aftertreatment cost and installation space. NOx firstly is adsorbed on storage sites during the lean-burn period, then reduced to N2 under catalysis of the catalyst sites in the rich-burn phase. There must be a spillover of NOx species between both types of sites. For a better understanding of this spillover process of NOx species between Pt (as the catalytic center) and BaO sites (as storage components in commercial catalyst), this work focused on the vital first step of spillover, the adsorption of NOx on clean substrate surface (γ-Al2O3 (110) surface) and Ba\Pt cluster supported by the surface. Based on first principles software VASP (Vienna Ab-initio Simulation Package), the most stable adsorption structures of NO with Pt3 clusters and (BaO)3 clusters on carrier γ- Al2O3 (110) surface were confirmed and the adsorption energy of these structures were compared.

Noise source identification and separation of internal combustion engines is an effective tool for engine NVH (noise, vibration and harshness) development. Among various experimental approaches, noise source identification using signal processing has attracted extensive attention because of that the signal can be easily acquired and the requirements for equipment is relatively low. In this paper, variational mode decomposition (VMD) combined with independent component analysis (ICA) is used for noise source identification of a turbo-charged gasoline engine. Existing algorithms have been proved to be effective to extract signal features but also have disadvantages. One of the key problems in presently used method is that the main components of the signal, i.e. the main source of the noise, are unknown in advance. Thus the parameters selection of signal processing algorithms, which has a significance influence on the identification result, has no uniform criterion.

As a major power source, diesel engines are being widely used in a variety of fields. However, because of complex structure, some faults which cannot be detected by direct signals would occur on engines and even lead to accidents. Among all kinds of indirect signals, vibration signal is the most common choice for faults detection without disassemble because of its convenience and stability. This paper proposed a novel approach for detecting multiple engine faults based on block vibration signals using variational mode decomposition (VMD) and echo state network (ESN). Since the quadratic penalty has a great influence on adaptable VMD that may make expected component signals cannot be extracted exactly, this paper proposed a dynamic quadratic penalty value, which will change with decomposing level. This paper selected a best dynamic quadratic penalty value by analyzing a large amount of data and results showed that this approach can decompose signals more exactly.

The increasing demand for lightweight design of the whole vehicle has raised critical weight reduction targets for crash components such as front rails without deteriorating their crash performances. To this end the last few years have witnessed a huge growth in vehicle body structures featuring hybrid materials including steel and aluminum alloys. In this work, a type of tapered tailor-welded tube (TTWT) made of steel and aluminum alloy hybrid materials was proposed to maximize the specific energy absorption (SEA) and to minimize the peak crushing force (PCF) in an oblique crash scenario. The hybrid tube was found to be more robust than the single material tubes under oblique impacts using validated finite element (FE) models. Compared with the aluminum alloy tube and the steel tube, the hybrid tube can increase the SEA by 46.3% and 86.7%, respectively, under an impact angle of 30°.

Transparent materials such as Plexiglas and glass are applied in airplane and boat widely as the windows and hatches. There are three type stresses in the structure made of Plexiglas or glass, which are residual stresses from the casting, residual stresses due to manufacturing process involving sheet forming structure and the stresses from serving period. In the paper the stresses are studied by laser scattered Photoelasticy method. Phase shift method is presented to recognize scattered light patterns automatically. The residual stresses in Plexiglas plate and shell were analyzed by thin plate-shell theory. Stresses in the Plexiglas and shell were tested by laser scattered Photoelastic method.

The inverse boundary element method (IBEM) is presented to accurately identify the noise sources of a diesel engine in this study. The sound pressures on four near-field planes were measured as inputs for the method. Then, the acoustic model of the full diesel engine was established using the boundary element method, and the acoustic transfer vectors (ATV) between the surface normal velocity and acoustic pressure at field points were calculated over the frequency range of interest. Based on the measured sound pressure and the ATVs, the surface normal velocity distribution of the diesel engine was reconstructed by the IBEM. The reconstructed pressures at two reference field points were compared with the measured ones. Furthermore, the panel contribution of each engine component was analyzed through the reconstructed surface velocity.

A new kind of diesel particulate after-treatment system (EDPF) has been developed. It uses stainless steel nets as the particulate trapping part and uses reverse blowing unit combining with centrifugal collector as the regeneration part. In order to improve the filtering efficiency of stainless steel nets, corona-discharging technology is applied to charge particles before the stainless steel nets. The test result on the 6110 Diesel bench scale shows that the filtering efficiency of the EDPF system can reach to about 70% and the EDPF system is successful.

Recent toxicological and epidemiologic studies have shown that diesel emissions have been a significant toxic air contaminant. Catalyzed DPF (CDPF) not only significantly reduces the PM mass emissions (>90%), but also further promotes carrier self-regeneration and oxidize more harmful gaseous pollutants by the catalyst coated on the carrier. However, some ultrafine particles and potentially harmful gaseous pollutants, such as VOCs species, originally emitted in the vapor-phase at high plume temperature, may penetrate through the CDPF filter. Furthermore, the components and content of catalyst coated on the CDPF could influence the physicochemical properties and toxicity intensity of those escaping ultrafine particles and gaseous pollutants. In this work, (1) we investigated the influence of precious metal content as a variable parameter on the physicochemical properties and catalytic activities of the small CDPF samples.

Due to the increasing consumption of fossil fuels, alternative fuels in internal combustion engines have attracted a lot of attention in recent years. Ethanol is the most common alternative fuel used in spark ignition (SI) engines due to its advantages of biodegradability, positively impacting emissions reduction as well as octane number improvement. Meanwhile, acetone is well-known as one of the industrial waste solvents for synthetic fibers and most plastic materials. In comparison to ethanol, acetone has a number of more desirable properties for being a viable alternative fuel such as its higher energy density, heating value and volatility.

The evolution of surface functional groups (SFGs) and the graphitization degree of soot generated in premixed methane flames are studied and the correlation between them is discussed. Test soot samples were obtained from an optimized thermophoretic sampling system and probe sampling system. The SFGs of soot were determined by Fourier transform infrared spectroscopy (FT-IR) and X-ray photoelectron spectroscopy (XPS) after removing the soluble impurities from the soot samples, while the graphitization degree of soot was characterized by Raman spectrum and electron energy loss spectroscopy (EELS). The results reveal that the number of aliphatic C-H groups and C=O groups shows an initial increase and then decrease in the sooting history. The large amount of aliphatic C-H groups and small amount of aromatic C-H groups in the early stage of the soot mass growth process indicate that aliphatic C-H groups make a major contribution to the early stage of soot mass growth.

Multi-dimensional models coupled with a reduced chemical mechanism were used to investigate the effect of fuel on exergy destruction fraction and sources in a reactivity controlled compression ignition (RCCI) engine. The exergy destruction due to chemical reaction (Deschem) makes the largest contribution to the total exergy destruction. Different from the obvious low temperature heat release (LTHR) behavior in gasoline/diesel RCCI, methanol has a negative effect on the LTHR of diesel, so the exergy destruction accumulation from LTHR to high temperature heat release (HTHR) can be avoided in methanol/diesel RCCI, contributing to the reduction of Deschem. Moreover, the combustion temperature in methanol/diesel RCCI is higher compared to gasoline/diesel RCCI, which is also beneficial to the lower exergy destruction fraction. Therefore, the exergy destruction of methanol/diesel RCCI is lower than that of gasoline/diesel RCCI at the same combustion phasing.

As the intake noise is a major contributing factor to automotive passenger compartment noise levels, it has received much more attention than before. Because the plastic manifolds could induce and transmit more noise owing to their lighter weight, aerodynamic noise has become a more serious problem in plastic manifolds than in conventional aluminum-made manifolds. Due to the complexity of aerodynamic noise of the intake system, it is difficult to predict the noise precisely, especially for the part whose frequency is higher than 1000 Hz. This paper introduces a new co-simulation method to simulate the aerodynamic noise at the engine inlet. With the coupled simulation between two programs, GT-Power and Fluent, it could simulate the gas flow inside the engine intake system, under the actual running condition of engine.

It is a new idea and beneficial attempt that the microwave heating technology is applied to regenerate the Diesel Exhaust Particulate Filters (DEPF). In this paper, the microwave regenerating mechanism of DEPF is studied and some laws in the process of microwave regeneration are found by experimental and theoretical analyses. Some basic measurements and calculations of microwave characteristic factors of three kinds of selected DEPF and the pure particulate are presented. A Microwave Regenerating Test System (MRTS) is set and the microwave regeneration of DEPF is tested. A mathametical model of two dimensional axi-symmetrical non-steady temperature field is set up which is suitable for microwave regenerating process of ceramic foam filters. The numerical calculation and practical analyses are stated. It is proved by these studies that the particulate in DEPF is selectively heated by microwave energy and moreover the microwave energy is less absorbed by the pure ceramic filters.

The tooth surface error will affect the contact pattern and transmission error of the hypoid gear, which may result in an unfavorable dynamic response. The tooth surface error can be generated by machine tool errors, such as blade wear. The most common forms of blade wear are the positive cutter radius and the positive blade angle error. In addition, in the cutting process of face-hobbed hypoid gear, the continuous indexing motion will aggravate the blade wear due to the alternating cutting force. Most previous studies on the influence of hypoid gear tool errors only focus on the contact pattern and static transmission error. However, there are very few studies about the effect of tool errors on hypoid gear dynamic responses. In this paper, a hypoid gear tooth surface, mesh, and linear dynamic model with tool errors were established. The tooth surface deviation distribution of different tool errors was analyzed.

For liquid fueled engine, the fuel atomization affects fuel’s evaporation, combustion, noise and vibration characteristics eventually. In this study, the effects of fuel species on the internal flow and near field primary breakup characteristics of a nozzle “Spray C” are investigated. Based on the framework of OpenFOAM, the newly developed solver which coupled cavitation model and the multifluid-quasi-VOF (Volume-of-Fluid) model, and combines the LES (Large Eddy Simulation) are applied to simulate the nozzle inner flow and near field jet breakup when using diesel and biodiesel respectively. The transient characteristics of nozzle inner flow and near field spray of two different fuels were analyzed, and the variation of axial pressure and velocity of nozzle was obtained. The simulation results show that the cavitation of biodiesel with high viscosity and low saturated vapor pressure develops slower and weaker.

As a critical power source, the diesel engine is widely used in various situations. Diesel engine failure may lead to serious property losses and even accidents. Fault detection can improve the safety of diesel engines and reduce economic loss. Surface vibration signal is often used in non-disassembly fault diagnosis because of its convenient measurement and stability. This paper proposed a novel method for engine fault detection based on vibration signals using variational mode decomposition (VMD), K-means, and genetic algorithm. The mode number of VMD dramatically affects the accuracy of extracting signal components. Therefore, a method based on spectral energy distribution is proposed to determine the parameter, and the quadratic penalty term is optimized according to SNR. The results show that the optimized VMD can adaptively extract the vibration signal components of the diesel engine. In the actual fault diagnosis case, it is difficult to obtain the data with labels.

The vehicle axle gear whine noise and vibration are key issues for the automotive industry to design a quiet, reliable driveline system. The main source of excitation for this vibration energy comes from hypoid gear transmission error (TE). The vibration transmits through the flexible axle components, then radiates off from the surface of the housing structure. Thus, the design of hypoid gear pair with minimization of TE is one way to control the dynamic behavior of the vehicle axle system. In this paper, an approach to obtain minimum TE and improved dynamic response with optimal tooth profile modification parameters is discussed. A neural network algorithm, named Back Propagation (BP) algorithm, with improved Particle Swarm Optimization (PSO) is used to predict the TE if some tooth profile modification parameters are given to train the model.

During the aero-engine operation, the compressor blades are subjected to periodic inertial force and aerodynamic excitation caused by blade rotation and airflow disturbance, respectively. Under the coupling alternating loads, the blade is prone to high cycle fatigue failure. In this paper, a time domain calculation model of fluid-structure interaction (FSI) is established to study the vibration characteristics of the blade and its failure modes are analyzed. Then, the fatigue damage of the blade under multi-level loading is evaluated by the nonlinear damage accumulation model. Considering the coupling effect of the airflow and the blade, computational fluid dynamics (CFD) is applied to calculate the aerodynamic parameters on the blade surface under different working conditions, which is imported to the finite element (FE) model to analyze the dynamic characteristics.

Proton exchange membrane (PEM) fuel cell is widely recognized as an outstanding portable power plant and expected to be possibly commercialization in the near future. As is well known, mechanical stresses implemented on the bipolar plates during the assembly procedure should have prominent influences on mass and heat transfer behavior inside the cell, as well as the resultant performance. In this study, an analytical model is proposed to comprehensively investigate the influence of clamping force on the mass transport, electrochemical properties and overall cell output capability of a PEM fuel cell. The results indicate that proper clamping force not only benefits the gas leakage prevention but also increases the contact area between the neighboring components to decrease the contact ohmic resistance.

In order to improve the combustion and emissions for high-speed marine diesel engines, numerical investigations on effects of different combustion chamber structures combined with oxygen enriched air have to be conducted. The study uses AVL Fire code to establish three-dimensional combustion model and simulate the in-cylinder flow, air-fuel mixing and combustion process with the flow dynamics metrics such as swirl number and uniformity index, analyze the interactional effects of combustion chamber structures and oxygen enriched air against the experimental data for a part load operation at 1350 r/min, find the optimized way to improve engine performance as well as decrease the NOx and soot emissions. The novelty is that this study is to combine different oxygen concentration with different combustion chamber structures including the re-entrant chamber, the straight chamber and the open chamber.