Investigation on Spray Behavior and NOx Conversion Characteristic of a Secondary Injector for a Lean NOx Trap Catalyst

Lean NOx trap (LNT) catalyst has been used to reduce NOx emissions from diesel engines. The LNT absorbs NOx in lean condition and discharges N2 by reducing NOx in rich conditions. Thus, it is necessary to make exhaust gas lean or rich conditions for controlling LNT system. For making a rich condition, a secondary injector was adopted to inject a diesel fuel into the exhaust pipe. In the case of secondary injector, the behavior of spray is easily affected by high temperature (i.e., 250 ～ 350 °C) occurred in the exhaust manifold. Therefore, it is needed to investigate the spray behavior of diesel fuel injected into an exhaust manifold, as well as the conversion characteristics for a lean NOx trap of a diesel engine with LNT catalyst. The characteristics of exhaust emissions in NEDC (New European Driving Cycle) mode were analyzed and spray behaviors were visualized in various exhaust gas conditions. The results show that as the exhaust gas mass flow increases, the spray cone angle becomes broad and the fuel is directed to the flow field. Besides, the cone angle of spray is decreased by centrifugal force caused in exhaust gas flow field. In addition, the effects of nozzle installation degree, injection quantity, and exhaust gas flow on NOx conversion performance were clarified.     

Crashworthiness of chromium plated plastic radiator grille

The use of plastic in vehicle development has increased. In particular, a design trend has resulted in chromiumplated plastics being used in exterior panels. Recently, as the appearance has become more important in design, the plastic radiator grille has become larger, to where it can become the primary member when a front collision happens. The radiator grille should be designed with considerations of the geometric structure, such as delamination, and material characteristics, when plastics are plated with chromium. The enlarged grille has to pass regulations like FMVSS Part 581. Although the material property of plastic has been studied before, what seems to be lacking is study on the crashworthiness of plastic radiator grilles that are plated using chromium. In this paper, in order to evaluate the crashworthiness, tensile test and front collision analysis using finite element method are performed. Tensile test is conducted with 4 types of materials, and then material properties of chromium-plated plastics are obtained. Meanwhile radiator grille’s crashworthiness is evaluated using finite element analysis method. Analysis result is evaluated according to failure criterion. Through this study, method of the assessment of plastic radiator grille’s crashworthiness considered material properties of chromium plated plastics is proposed, and it can be predicted the delamination and the failure point of radiator grille at the design step.     

Effect of tumble-home on roof strength of a vehicle

This study reports on the effect of vehicle tumble-home (side body inclination) on roof strength. The steep inclination of the side body of a vehicle increases its roof strength. Comprehensive analysis of the impact of high roof strength driven by the steep inclination on dynamic roof strength in rollover is described. Here, we have developed a numerical model using the ADAMS, which is capable of characterizing both of the static and the dynamic roof strength. According to the FMVSS 216 protocol, we achieve the strength to weight ratio (SWR; static roof strength) by applying loading plates to the roof of a vehicle. The Controlled Rollover Impact System (CRIS) allows us to quantitatively characterize the displacements of the top end of A-pillar and B-pillar, thus determining the dynamic roof strength by comparing the results. We demonstrated that the roof intrusion was one of the most critical causes which lead to injuries of occupants fastening seat belts. Our analysis revealed that the increase of the side body inclination of vehicles enhanced the static roof strength whereas it could not reduce the roof displacement (intrusion) in the dynamic rollover.     

一点欣慰 一点遗憾——大众新宝来C-NCAP碰撞试验点评

大众宝来,作为一款典型的德系紧凑型轿车,自2001年在中国上市以来,凭借其出色的制造工艺,灵活的操控性,高速行驶的稳定性,被消费者誉为“驾驶者之车”,并拥有了一大批忠实的拥趸,累计销量超过了37万辆。2008年10月,新款宝来隆重登场,尽管开始的几个月市场表现一直没有太多亮点,但2009年3月,新宝来的月销量猛蹿到10240辆,充分证明了这款在中国有着传统根基的德系车仍然有着不少的“粉丝”。     

Instantaneous 2-D visualization of spray combustion and flame luminosity of GTL and GTL-biodiesel fuel blend under quiescent ambient conditions

An experimental study has been performed on spray combustion and two-dimensional soot concentration in diesel (ULSD), GTL and GTL-biodiesel fuel jets under high-pressure, high-temperature quiescent conditions. Instantaneous images of the fuel jets were obtained with a high-speed camera. It was confirmed that by blending GTL with 20% rapeseed biodiesel, certain fuel properties such as kinematic viscosity, density, surface tension, volatility, lower heating value and others may be designed and improved to be more like those of conventional diesel fuel but with considerable decrease in the amount of sulfur, PAH, cold filter plugging point, etc. The results showed that the spray tip penetration increased and the spray cone angle decreased when 20% biodiesel fuel was added to GTL fuel. Autoignition of the GTL-biodiesel blend occurred slightly earlier than that of diesel fuel. Experiments under high-pressure, high-temperature conditions showed that higher injection pressure induced a lower soot formation rate. The integrated flame luminosity, which serves as an indicator of soot concentration in the fuel jet, was slightly higher for the GTL-biodiesel blend than for pure GTL fuel due to the slightly higher sulfur content of pure biodiesel fuel.     

The Causal Effects of Place Attachment and Tourism Development on Coastal Residents' Environmentally Responsible Behavior

Coastal areas are generally known as high-usage areas for residential, recreational, and tourism purposes. Coastal residents, as well as local visitors, therefore, can play an important role in protecting coastal resources. The purpose of this study was to identify important factors that could promote residents' environmentally responsible behavior (ERB). The two concepts, place attachment and attitudes toward tourism development (ATTD), were included to verify causal relationships of ERB. For data analysis, confirmatory factor analysis (CFA) and structural equation modeling (SEM) were conducted. Study results showed that place identity fully mediated the relationship between place dependence and ERB. With respect to the two dimensions of ATTD, there was a positive relationship between perceived benefits and ERB, while perceived concerns mediated this relationship. To promote ERB, the study emphasized the importance of developing place identity by providing diverse economical, socio-cultural, and recreational coastal benefits. In addition, involving those residents, who are positively and negatively impacted by tourism development, in the process of sustainable tourism development will develop more effective sustainable development strategies by reflecting local residents' opinions and preferences.     

Comparison between a reanalyzed product by 3-dimensional variational assimilation technique and observations in the Ulleung Basin of the East/Japan Sea

Reanalyzed products from a MOM3-based East Sea Regional Ocean Model with a 3-dimentional variational data assimilation module (DA-ESROM), have been compared with the observed hydrographic and current datasets in the Ulleung Basin (UB) of the East/Japan Sea (EJS). Satellite-borne sea surface temperature and sea surface height data, and in-situ temperature profiles have been assimilated into the DA-ESROM. The performance of the DA-ESROM appears to be efficient enough to be used in an operational ocean forecast system.Comparing with the results from Mitchell et al. [Mitchell, D. A., Watts, D. R., Wimbush, M., Teague, W.J., Tracey, K. L., Book, J. W., Chang, K.-I., Suk, M.-S., Yoon, J.-H., 2005a. Upper circulation patterns in the Ulleung Basin. Deep-Sea Res. II, 52, 1617-1638.], the DA-ESROM fairly well simulates the high variability of the Ulleung Warm Eddy and Dok Cold Eddy as well as the branching of the Tsushima Warm Current in the UB. The overall root-mean-square error between 100 m temperature field reproduced by the DA-ESROM and the observed 100-dbar temperature field is 2.1 °C, and the spatially averaged grid-to-grid correlation between the two temperature fields is high with a mean value of 0.79 for the inter-comparison period.The DA-ESROM reproduces the development of strong southward North Korean Cold Current (NKCC) in summer consistent with the observational results, which is thought to be an improvement of the previous numerical models in the EJS. The reanalyzed products show that the NKCC is about 35 km wide, and flows southward along the Korean coast from spring to summer with maximum monthly mean volume transport of about 0.8 Sv in August–September.     

Generating cutter paths for marine propellers without interference and gouging

We generate cutter paths free of interference and gouging for manufacturing model propellers using a five-axis numerical control (NC) machine. Our approach is faster than using a general-purpose computer-aided design (CAD)/computer-aided manufacturing (CAM) system. A roughing cut is made using only three axes for efficiency, and the finishing cut is made using all five axes to avoid collisions. Elements of the cutter path that might produce gouging are eliminated and the pose of the cutter is adjusted to eliminate interference. A number of models, including surface-piercing propellers, have been manufactured.     

Low temperature premixed combustion within a small bore high speed direct injection (HSDI) optically accessible diesel engine using a retarded single injection

An optically accessible single-cylinder high speed direct-injection (HSDI) Diesel engine equipped with a Bosch common rail injection system was used to study low temperature Modulated Kinetics (MK) combustion with a retarded single main injection. High-speed liquid fuel Mie-scattering was employed to investigate the liquid distribution and evolution. By carefully setting up the optics, three-dimensional images of fuel spray were obtained from both the bottom of the piston and the side window. The NOx emissions were measured in the exhaust pipe. The influence of injection pressure and injection timing on liquid fuel evolution and combustion characteristics was studied under similar fuel quantities. Interesting spray development was seen from the side window images. Liquid impingement was found for all of the cases due to the small diameter of the piston bowl. The liquid fuel tip hits the bowl wall obliquely and spreads as a wall jet in the radial direction of the spray. Due to the bowl geometry, the fuel film moves back into the central part of the bowl, which enhances the air-fuel mixing process and prepares a more homogeneous air-fuel mixture. Stronger impingement was seen for high injection pressures. Injection timing had little effect on fuel impingement. No liquid fuel was seen before ignition, indicating premixed combustion for all the cases. High-speed combustion video was taken using the same frame rate. Ignition was seen to occur on or near the bowl wall in the vicinity of the spray tip, with the ignition delay being noticeably longer for lower injection pressure and later injection timing. The majority of the flame was confined to the bowl region throughout the combustion event. A more homogeneous and weaker flame was observed for higher injection pressures and later injection timing. The combustion structure also proves the mixing enhancement effect of the liquid fuel impingement. The results show that ultra-low sooting combustion is feasible in an HSDI diesel engine with a higher injection pressure, a higher EGR rate, or later injection timing, with little penalty on power output. It was also found that injection timing has more influence on HCCI-like combustion using a single main injection than the other two factors studied. Compared with the base cases, simultaneous reductions of soot and NOx were obtained by increasing EGR rate and retarding injection timing. By increasing injection pressure, NOx emissions were increased due to leaner and faster combustion with better air-fuel mixing. However, smoke emissions were significantly reduced with increased injection pressure.     

Development of a mobile welding robot for double-hull structures in shipbuilding

This paper describes the development of a self-driving mobile welding robot. The robot is used to weld U-shaped welding areas in enclosed double-hull structures. In order to place itself inside the double-hull structure, the robot is capable of passing through an access hole 600 mm wide and 800 mm high. This research addresses the mechanical and control systems of the robot. The mechanical system of the robot consists of an eight-axis mobile platform, and a six-axis welding unit. The control system consists of a main controller, a welding machine controller (arc sensor board), and seam tracking sensors, i.e., a touch sensor, a laser sensor, and an arc sensor. To reduce the number of cables that would be dragged by the welding robot, the main controller is designed as an embedded type that is mounted on the back of the mobile platform.