Advanced Materials Research Vols. 516-517

Abstract: To analyze the variation of electromagnetic field distribution, a mathematical model of the eddy current brake (ECB) is established and the two-dimensional simulation and three-dimensional simulation are comparatively analyzed. Then the curves of the braking torque of the ECB at different speeds are obtained by the simulations. The characteristics of two-dimensional and three-dimensional simulation of the electromagnetic field of the ECB are summarized by contrasted comparative curves between simulation date and test date. The analysis is helpful to optimizing the application of electromagnetism by using software.

Abstract: In Multiple Index Orthogonal Test Design, the key question is how to determine the influence degree of each test index on the whole test results and according to the influence degree to get test data calculation and eventually gain the optimal plan to achieve the purpose of orthogonal test design. A method of matrix analysis is introduce in this article, with which the weighs of the factors and levels having influences on the tests’ results can be calculated, and then the optimal plan of multiple index orthogonal test and the important order of the factors’ influences on the tests’ index values can be determined according to the weights. Using this method to carry out the test analysis of the passing performance of the swamp bulldozer, the optimal scheme selection problem of Multiple Index Experiment of the Orthogonal Test can be solved, and obtains feasible experimental results .

Abstract: Based on similarity modeling, the failure prognostic system is rooted in mass of historical data that can provide easy and rapidly implementary and reliable failure prognostic system for power plant .The system can find equipment fault symptom before fault formation, so measures can be taken in advance to avoid the occurrence of failure. In this paper, the similarity theory, modeling and applications of failure prognostic systems are described detially. The prognostic example of a power plant in Shanxi is used to demonstrate that the system can detect abnormal changes of equipment in a timely manner, and the prognostic effect is achieved .

Abstract: At present, there have been a lot of accidents happened in the wind-water combined slag coolers of the Circulating Fluidized Bed (CFB) boiler power plants, which usually caused the low-load or even stop of the units along with great financial losses. Comprehensively considering the actual conditions of the domestic CFB boiler power plants, the theoretical analysis and thermodynamic calculation were conducted aiming to solve the specific problems found in the operation. There were new designs and retrofitting measures in the integral structure and some key components, such as the slag inlet-tube. The operation effect of the slag coolers, i.e. the stability and heat-recovery efficiency etc., were significantly improved by retrofitting the devices.

Abstract: In this study, a coupled methodology is proposed for the aerodynamic behavior of wind turbine airfoils. The idea is to combine a Navier-Stokes solver with a free vortex model. The zone for the calculation of CFD is confined to the surrounding of the airfoil, whilst the free vortex model accounts for the far field of the airfoil. The flow around the airfoil is assumed to be two-dimensional (2D) incompressible fully turbulent flow, which is modeled by two equation turbulence models. The computed aerodynamic coefficients are presented for two wind turbine airfoils and compared with wind tunnel data.

Abstract: The fouling on flow path of steam turbine would lead to the changes of thermal parameters and significantly deteriorated efficiency. In this paper, a qualitative analysis of fouling on flow path based on measured parameters was described for the preliminary diagnosis, and the zooming thermoeconomic diagnosis model combined with the equivalent flow area diagnosis model was proposed to diagnose the specific location of fault. Then the flow performance of a 630 MW supercritical unit was analyzed, and the possible fouling stages were also discussed according to the thermoeconomic diagnosis and quantitative analysis. The result of diagnosis was consistent with the situation of uncovering cylinder, which indicated that though the actual system was complex, the coupling multiple faults of flow path could be diagnosed by combining the above diagnosis models.

Abstract: For the controlled gasoline engine MR479Q, the crank speed, camshaft position, fuel injection, spark ignition timing signals and their relationships under control mode of group ignition and fuel sequential injection were deeply analyzed, then an electronic control unit (ECU) hardware platform solution based on Freescale 16-bit microcontroller MC9S12XEP100 was given out. Taking advantages of the hardware platform itself, a crank event based fuel injection and spark ignition timing control strategy was proposed to enhance traditional fuel injection and ignition reliability. Fuel pulse width, ignition coil dwell time and spark advance control under different engine operating conditions were then designed in detail respectively. The bench test results show that, the fuel injection and spark ignition timing control signals of ECU are accurate and stable enough under steady operating conditions, even under transient operating conditions when step disturbance exists in throttle opening, the fuel pulse width, dwell time and spark advance are also delivered correctly and reliably. The strategy is feasible enough to accomplish precise control of fuel injection and spark ignition.

Abstract: Based on the analysis of the gas fuel resources, the development potential of gas engines in China is evaluated. And contribution of application of gas engines on the reduction of Green House Gas (GHG) emissions as well as harmful emissions is estimated. Since gas engines are different from conventional internal combustion engines on fuel system and combustion system, the key technologies relating to developing gas engines are introduced, and the major difficulties of popularizing of gas engines are discussed. With the foundation of the analysis, development strategy of gas engines is proposed.

Abstract: In this paper an extensive CFD simulation of a four-stroke diesel engine is done. The flow in the intake valve is calculated in the steady state condition and the flow in eight work statuses –four kinds of pressure differences are analyzed, with two kinds of valve rising degree researched .The aim of the work is to characterize the influence of the intake pressure difference of the intake port.As a conclusion we find that as the pressure difference increases, the discharge coefficient decreases. The analysis results of the three dimensional flow field of the intake port show that in the conditions of low pressure difference and big valve rising the vortex will appear. In addition, in different pressure differences, the ratio of the pressure drop in the same region is different.

Abstract: First by analyzing the physical and chemical properties of different blend proportion on ethanol-diesel fuel, determined the mixing ratio of ethanol being were 0-15% by volume in the blend fuel; and then make the bench test on 4102Q diesel, focused analysis the influence on exhaust emissions and dynamic performance of diesel engine fueled with 5%, 10%, and 15% of ethanol-diesel blend fuel. The engine tests indicated that under the premise of the diesel engine without any changes, the volume fraction of 10% ethanol content is the optima blend proportion. The engine fueled with this proportion of ethanol-diesel fuel can make the exhaust meet National Ⅲemission standard, and the rated power drop down no more than 0.2% at the same time.