Applied Mechanics and Materials Vols. 84-85

Abstract: In this paper, the trailing edge film cooling flow field of a heavy duty gas turbine cascade has been studied by central difference scheme and multi-block grid technique. The research is based on the three-dimensional N-S equation solver. By way of analysis of the temperature field, the distribution of profile pressure, and the distribution of film-cooling adiabatic effectiveness in the region of trailing edge with different cool air injection mass and different angles, it is found that the impact on the film-cooling adiabatic effectiveness is slightly by changing the injection mass. The distribution of profile pressure dropped intensely at the pressure side near the injection holes line with the large mass cooling air. The cooling effect is good in the region of trailing edge while the injection air is along the direction of stream.

Abstract: Ancient pyrometallurgical zinc generated large amounts of slag. Natural leaching from ancient pyrometallurgical zinc sites had contaminated the soil closed to the deposits. Enhanced electrokinetic removal technology was adopted to treat these slags. In this paper, atomic fluorescence spectrometer and scanning electronic microscope were used to investigate the total metal concentration and the surface topography of slags. The results showed that the heavy metals content in slags was high. The content of zinc in slags was up to 114550mg/kg. The surface topography of slags indicated that that the slags were corroded obviously by rainwater and lots of poisoning elements had released to the surroundings. The optimized BCR sequential extraction procedure was used to analyze the chemical speciation of heavy metals in slags. It could be determined that the evironmental activity of ancient pyrometallurgical slag decreased obviously after the treatment with electrokinetic removal technology and part of the residual fraction of heavy metals in slags transformed to the other fractions during the electrokinetic removal process.

Abstract: Hydrous-ethanol is reformed to hydrogen-rich mixture gas which is an excellent fuel for engines. The advantages of this approach are that fossil fuel consumption and CO2 emissions are reduced, and the waste heat from engine exhaust can be used as energy source for hydrous-ethanol evaporating and reforming. The experiment is carried out on a gasoline engine as primary engine with only modest changes. The results indicate that the hydrogen-rich mixture gas allows operation at much higher compression ratio due to its intrinsic octane number which could contribute to the power performance, and the NOx, CO, THC emissions are reduced remarkably because of lean combustion realized in the cylinder.

Abstract: In this thesis, in the double preheating system of air and gas, the high temperature air combustion process of low calorific value gas, in which the FLUENT software is used as the calculating tool and furnace model as the object, is numerically simulated by use of the k-ε turbulent two-way model, the PDF combustion model, discrete-ordinates-method radiative heat transfer model and the modified NOX -generation thermal model. Get the flow field, temperature field and concentration field inside the furnace in different times.

Abstract: A numerical investigation on natural convection heat transfer in a 2-dimensional enclosure heated from below has been conducted with microencapsulated phase change material (PCM) slurries. The microencapsulated PCM slurry exhibits pseudoplastic non-Newtonian fluid behavior and has a peak value in the specific heat capacity. The viscosity of the slurry is assumed to follow the Ostwald-de Waele power law fluid model with the power-law index n and the consistency coefficient K. Both dynamic and heat transfer characteristics are discussed on Rayleigh-Bénard natural convection. Characteristics on natural convection heat transfer have been numerically investigated for different value of the width-height aspect ratio of the enclosure. According to the comparison of the two kinds of fluid with PCM and without PCM, the start of natural convection is earlier for the fluid with PCM.

Abstract: A 320×240 readout circuit (ROIC) for the uncooled pyroelectric infrared detector was fabricated in the double-poly-double-metal (DPDM) N-well CMOS technology. Composed of X- and Y-shift register, column amplifier and correlated double sampling (CDS) circuit, the readout circuit integrated signal from the detector for frame time. It has the pitch of 50um and power dissipation of less than 50 mW. The circuit configuration, operation and testing result are described. Testing result indicates that the designed circuit meets with the requirement. Thermal images were obtained by the hybrid-integrated sensing array.

Abstract: Take the German Scheuerler’s four-axle trailer steering mechanism for the study, establish the simulation model of the steering system. After this, the simulation optimization and analysis to model was done with ADAMS software. The results of the analysis show that the objective function’s value of the optimal vehicle steering mechanism model is superior to the objective function’s value of the initial model.

Abstract: There was a new down-hole BOP that was designed to control blowout effectively in exploiting petroleum gas. The BOP was a new blowout preventer with a good development prospect which can not only automatically shut underground, but also control and automatically discharge shut up-hole state on the ground. Through introducing structure and working principle of the BOP, as well as the finite element analysis of some key components, there has been showed that the down-hole blowout preventer met the strength requirements and had relatively high security. The down-hole blowout preventer with a simple structure can not only work reliably but also complete the act of preventing blowout and unlocking many times to prevent blowout effectively and to improve drilling operations safety and efficiency. It will have a bright development prospect.

Abstract: This paper proposed a novel mechanism for an unmanned electric vehicle with four-wheel independent driving (4WID), independent steering (4WIS), independent suspending and independent braking. This unmanned electric vehicle adopted the technologies of driving by wire, steering by wire and braking by wire. Which improved the maneuverability of the vehicle greatly and made it achieving straight, oblique, lateral movement, zero radius turning and other movement patterns. Detailed implementation mechanism and virtual prototype of the vehicle were given in this paper. The hydraulic circuit schematic diagram and control method of the braking system were given also.

Abstract: To enable wind turbine and the power converter have the ability to protect itself without disconnection to power grids during the fault, protection for crowbar and chopper should be designed properly. Optimal resistors value of crowbar and chopper are calculated under PVdq controller and Fmac controller according to the proposed index which embody the effect of rotor current, reactive power, converter capacitor voltage and the electrical torque. Simulation results obtained by using PSCAD show that DFIG should be designed with different optimal crowbar and chopper resistors under different controllers. Moreover, DFIG with Fmac controller has better fault ride-through capability than that with PVdq controller.