Applied Mechanics and Materials Vol. 248

Abstract: The main function of a fuel injector nozzle is to break fuels into droplets, form the spray pattern, and propel the droplets into a combustion chamber. The amount of spray volume at a given operating pressure, the travel speed, and spacing between the jets of fuel can also be determined by the nozzle. In fuel injection, the smallest possible droplet size is desired for the most flow. This work presents an opportunity to use the Schlieren arrangement as a visualization method to view the flow of fuel from a three-hole fuel injector nozzle which cannot be seen by the naked eye. The jet flow of diesel Fuel was investigated by Schlieren photography. A test rig was designed and constructed to accommodate the nozzle; optical mirrors were arranged according to Schlieren specifications in order to allow the jet to be photographed. The breakaway pressure of the nozzle was varied between 60bar to 80bar. Each hole of the nozzle is 0.26mm in diameter and 120° apart; the third jet could not be seen from the images because the camera took x-y dimension images. The spray pattern observed from the two dimensional images of the jets developed were seen to be well dispersed. Su et al [3] found that emissions could be reduced in diesel engines if the injector nozzle produces smaller and more dispersed droplets.

Abstract: This paper discussed the mechanism of internal fogging in automotive lamp based on the principle of water vapor condensation, and put forward the concept of the critical fogging humidity of lamp according to the structure and engineering characteristics. It given out a simple way to judge lamp fogging on the base of lamp temperature field, and verified the existence of the critical fog humidity by the test. All of these are very meaningful on the evaluation of the lamp's structure and raise the level of lamp design

Abstract: In this paper, based on the car suspension parameters of OEM, the ADAMS software was used to establish 1/4 car suspension model. To get the better ride comfort, the comprehensive analysis of spring stiffness and damping was conducted to obtain the optimal suspension parameters. The simulation results and the experimental results are consistent, which laid a good foundation for further analysis other design of cars.

Abstract: Geometric mobiles is a new kinetic art which become a new technique combined with basic science and modern art. Geometric mobiles design and calculation by mechanics and mathematics in order to have a slowly and elegant movements. An innovative and efficient design method is first established based on virtual technology and polymorphs small cell centroid point analytical rule. The method reveals the intrinsic relationship between Geometric mobiles and mathematics & mechanics modeling, provides the mathematics foundation for art works innovative and next research.

Abstract: In this paper, we present a zigbee wireless ammonia sensor system which based on quartz crystal microbalance (QCM) coated with ZnO nanowires as sensing element. This system concludes two parts: one is the base station which is constructed with zigbee coordinator linked computer, the other is called the sensor transmitter module which is zigbee coordinator linked ZnO-nanowires-modified QCM sensor. We use star network of zigbee protocol to construct ammonia wireless sensing system. Experimental results indicate that the wireless sensing system has quite good stability and reproducibility. The interaction distance between the computer and RFD can be as far as 100 m in a buliding. The proposed system is potential to construct the low-cost, real-time online wireless gas sensor system, which can be used to monitor the pollutants in the family and the harsh environment.

Abstract: Current practices to estimate the pressure loads on the hull of small high-speed craft in a seaway are based on determination of the wave loads by applying rules and standards which itself relies either on often conservative methods, leading to a craft that is heavier and slower than it could be otherwise. There are rather large uncertainties in the wave load predictions for ships mainly caused by not necessarily sufficient theoretical basis of the calculation methods. Direct pressure measurement techniques can only provide data at each transducer location and classical analytical techniques require a large amount of experimental data to be collected to relate pressure to the structures response. The evaluation of wave generated hydrodynamic loads is less reliable as the dynamic nature of the loading as well as transient effects such as slamming and green water on deck still demands more investigations. Therefore, a novel technique is required to overcome these limitations by providing a method of measuring the pressure load with relatively few sensors and minimal data collection. This paper reports on research undertaken to develop an inverse problem approach utilising an Artificial Neural Network (ANN) for quantification of in-service, transient loads in real-time acting on the craft from the craft’s structural response (strain response to load). This study investigates suitability and performance of utilising ANN as an inverse problem approach to estimate impact loads applied to up to 13 locations on the structure in real-time from 16 strain measurements.

Abstract: Ni0.5Zn0.5Fe2O4-Pb(Zr_0.52Ti_0.48)O₃ (NZFO-PZT) composite films were prepared using sol–gel method on Si (100) substrate with different bilayer structures, namely, the NZFO/PZT (NP) and the PZT/NZFO (PN). Their structure, magnetic and ferroelectric properties were characterized by X-ray diffractometer (XRD), vibration sample magnetometer (VSM) and ferroelectric testing unit. Both the NP and the PN films exhibit coexistence of magnetic and ferroelectric properties. The overlapping sequence has much influence on the electrical properties. Whereas, such an overlapping structure of the films has slightly effect on its magnetic properties. The NP structured composite film is more suitable to get a promising magnetoelectric coupling.

Abstract: A numerical simulation has been conducted to investigate the effect of the external vibration referred to as g-jitter on the marangoni convection in liquid bridge of high Pr number fluid by taking both the dynamic free surface deformation and ambient air effects into consideration. The Navier-Stokes equations coupled with the energy conservation equation are solved on a staggered grid, and the free surface deformation is captured by introducing the mass conserving level set approach. The pressure distributions within the liquid bridge under external vibrations were investigated, and the results show that the pressure in liquid bridge presents periodic oscillation under external vibration. The closer to the hot disk, the greater the relative pressure value is. Moreover, the surface deformation and the surface amplitude under external vibration were investigated as well.

Abstract: Specially designed SEM in-situ tensile tests have been conducted to trace the entire process of crack initiation and propagation induced by inclusions in X80 pipeline steel. The main inclusions are complex oxides containing aluminum, calcium and magnesium with round or oval shape, and their sizes are in the range of 3~20μm. Cracks initiate firstly in inclusions and also easily initiate among inclusions if they distribute in the steel as an inclusion chain. The size of an inclusion has little effect on the initiation stress of the first crack, which mainly depends on the yield strength of the steel. Once a crack initiates in X80 pipeline steel, it zigzag propagates along the direction of maximum shear stress that orients in about 45° to the loading direction till failure. In the process of crack propagation, the crack experiences propagation, anti-crack, bluntness and new micro-cracks initiation again and again. These valuable experimental results reveal the harmful effect of inclusions in micro-scale and are helpful for understanding failure mechanisms of the advanced steel components.

Abstract: The paper presents an integral core/shell fabrication of ceramic casting mould for hollow turbine blades by combining SL (Stereolithography) with gelcasting. This method could guarantee the positional accuracy between ceramic cores and shell, thus achieving the rapid fabrication of complex turbine blade castings. The paper focuses on the design of resin mould for gelcasting, the preparation of ceramic slurry, the pyrolysis of resin prototype and the sintering of ceramic green body. The feasibility and effectiveness of above mentioned method were verified through successful manufacturing of hollow turbine blades with double-walled structure.