Advanced Materials Research Vols. 1070-1072

Abstract: In this paper, a 3-D finite element model was established for stop log gates. It is used for researching its force situation in process of power on and power off. The vertical pressure distribution around stop log gates shows that with water depth increasing, the difference of downstream pressure and upstream pressure of gates become more obvious. Between power on and power off processes, the stop log gates’ pressure differences and horizontal displacements are opposite.

Abstract: An experiment by taking photos of the spray field behind plain orifice atomizer was conducted to study its atomization in preheated air flow. The air flow condition was 0.14~0.2 Mach number and 300~400°C. Fuel-to-air momentum flux ratio Q varied from 0.4 to 9, and Weber number We covered the range of 60~140. Photos were analyzed by Matlab image processing toolbox. The results indicate that under the experiment conditions: (1) Under the same temperature, jet breakup length increases with Q increasing, and decreases with the increase of We. (2) As the air flow temperature increases from 300°C to 400°C, jet and air flow interaction affect the liquid column breakup more greatly than surface tension. (3) Under the same temperature, spray angle increases with the increase of Q. (4) As the air flow temperature increases from 300°C to 400°C, evaporation affects the atomization more greatly than pneumatic nebulization.

Abstract: In order to analyze the emission performance during the process of refueling, the mathematical models of refueling emission for vehicle under the proper simplified conditions were established based on the principle of time-varying and mass transfer in this paper. The models were applied to calculate the refueling emission rate of the fuel tank with and without a charcoal canister respectively, and simulation results of the model were analyzed numerically. Conclusions can be obtained as follows: the refueling emission rate of the fuel tank is 1.1201g / L without a charcoal canister; and 1.0815g / L with one, which is 3 - 4% less than the former on average. In addition, the refueling emission rate is positive related to the average temperature of the fuel tank, fuel average temperature and fuel Reid vapor pressure (RVP).

Abstract: Engine energy-saving technology is the key direction of passenger car energy-saving. This paper has built energy-saving potential model, which could forecast the potential of engine energy-saving technology in 2015 and 2020 under such two constraints: overall target requirement of fuel consumption and curb weight range. Afterwards, the model was used to calculate energy-saving potential of narrow sense passenger cars (including basic car + SUV + MPV), which were equipped with single turbo charging technology, single GDI technology and the above two kinds of technologies integration. The research results will provide decision-making support for enterprises’ technology selection and product development.

Abstract: Algorithm and structure of automatic pressure control in main oil pipeline are proposed in the article. Model of a process is being researched. Obtained results are being described terms energy losses minimization during pressure control. Crucial feature of an algorithm is an application of additional bypass valve.

Abstract: Based on the three-dimensional Reynolds-Averaged N-S equations and the standard k-ε turbulence model, the inner flow of a multistage vane water centrifugal pump was simulated. The distribution law of inner flow was analyzed by using the SIMPLEC algorithm and multiple reference frame (MRF) model provided by CFD software Fluent. The pressure and velocity distribution law in impeller and vane diffuser are obtained. Results indicated that the lowest pressure area , where cavitation was easy to occur, was in the inlet of the first impeller blade back. There is reverse flow in outlet of impeller. An area of low pressure can be seen in the inlet of return guide vanes. The guide vane could reduce fluid velocity and eliminated fluid rotating component.

Abstract: In order to improve classification ability and diagnostic accuracy of centrifugal fan signals, a new feature extraction method from fault signals of centrifugal fan vibration based on manifold learning method (MLM) that is a kind of reduction method of data dimension is proposed in this paper.The MLM is able to remain nonlinear information of original signal, to improve the classification and diagnostic ability of fault better than traditional reducing dimension methods. The results in this paper show that, fault feature information of centrifugal fan vibration is extracted effectively by the MLM and the fault feature information of different types are separated effectively in themselves areas. The diagnostic accuracy by feature extracted by the MLM is significantly higher than by the wavelet packet analysis method.

Abstract: An experiment was conducted to investigate bag breakup process of round liquid jets in crossflow. The objective of this study is to research pulsation law. Specifically, this study measures the onset position of bag, the breakup position of bag, the breakup position of the jet. High-speed camera was used to observe the formation and breakup of bags. The diameter of the nozzle used in the experiment was 0.5mm, 0.8mm, 1mm. The test liquid was tap water. We_a number covers the range of 6~30, and liquid-to-air momentum flux ratio varied from 22 to 211. Present results indicate that in the direction perpendicular to the gas flow, the dimensionless pulsating amount of the onset point of bags (y_onset/d) is linear to q, while the dimensionless pulsating amount of breakup point of bags (y_bag/d) and the dimensionless pulsating amount of breakup point of the jet (y_jet/d) is linear to ln (q). The dimensionless pulsating amount of these points in the direction of gas flow is irregular.

Abstract: Various methods –direct methods, structure function methods and dimensional analysis-have been proposed to estimate the dissipate rate of turbulent kinetic energy. In this study these methods were appraised using LES data of a turbulent flow in the straight pipe at Re=5300. The fact that the corrected second-order structure function method is robust can be found. Note that when approaching to the wall at low Reynolds number, structure function methods and dimensional analysis method usually become inaccurate since they can not reflect information about the radial gradients. Direct computation methods now give acceptable trend and good estimation. Methods mentioned above lead to the same order of magnitude as values from DNS data most times.

Abstract: The effects of blade thickness on impeller performance is seldom considered when design the low specific speed centrifugal pump and only considered crowding coefficient when use the speed coefficient method calculate the head of the impeller was designed. It was didn't consider the fundamental relationship how leaf thickness and low specific speed centrifugal impeller performance effect each other. The three-dimensional of flow area would have large influence if the leaf thickness changes . Here the best true thickness of the low specific speed centrifugal impeller blade was obtained though study how the thickness of blade influence on the performance of low specific speed centrifugal pump.