Applied Mechanics and Materials Vols. 249-250

Abstract: In order to improve diagnostic accuracy and reduce the rate of misdiagnosis to the aircraft engine gas path faulty, the methods based on data-driven and information fusion are developed and analyzed. BP neural network (NN) and RBF neural network based on data-driven single gas path fault diagnosis method is introduced firstly. Design gas path performance estimators and the fault type classification for turbo-shaft engine. Then the gas path fused diagnostic structure based on D-S evidence theory and least squares support vector machine are developed. Comparisons of the turbo-shaft engine gas path fault diagnosis verify the feasibility and effectiveness of the gas path fault diagnosis based on information fusion.

Abstract: For the current situation of automatic transmission technology which applied to small cars, it proposes a concept that electromagnetic slip clutch achieves step less speed regulation of small cars, describes its technical principle and feasibility, analysis the mechanical properties of electromagnetic slip clutch, at sometimes, the article proposes mathematical modeling technology for the electronic control system of electromagnetic slip clutch, and structures software and hardware design platform with C and 32 microcontroller. Finally, it confirms the research value of electromagnetic slip clutch for the step less speed regulation of small cars.

Abstract: Folding wings of UAV may lead to high bending and torsion deformation under flight load. In order to solve the problem, an improved folding wing mechanism is proposed, which makes support mechanism stiffness become enough big. By means of CATIA and ADAMS, a virtual prototype is set up, which can simulate dynamics of the deployment mechanism. Therefore the relationship among deployment time and friction coefficient and tension is arrived. Meanwhile finite element analysis is made on folding wing with support structure and without support structure by MSC.Nastran. And the results show that the stiffness and strength change obviously. Simulation results have a certain guiding significance for practical engineering application.

Abstract: In the light of growing global competition, organizations around the world today are constantly under pressure to produce high-quality products at an economical price. The integration of design and manufacturing (DFM) activities into one common engineering effort has been recognized as a key strategy for survival and growth. In this paper, the importance of DFM and parts information model was introduced in today's manufacturing enterprise. It describes the classification of parts information model; namely: product models, process models and cost models, the main content and research status that the model contained. The author has proposed a semantic network description method of the manufacture parts information of and details its main content, which is the core of this paper.

Abstract: In industrial machinery units in which handle with high loads, hydraulic cylinders are often used to actuate the manipulators. The nonlinear effects of friction in the hydraulic cylinders can be a problem if they disturb the motion of the hydraulic servo system.Friction compensation is a prerequisite for accurate in a hydraulic servo system. This paper presents anintelligent nonlinear friction compensation framework,which the purpose is to develop a friction compensator strategy based on adaptive twolayer fuzzy controller. Thecompensator Generalized Maxwell-Slip fuzzy,combined with fuzzy controller, will be implemented to reduce the lackperformance resulting from friction. The electiveness of this approach is demonstrated by experiments on the direct drive servo hydraulic system.

Abstract: To study the dispersion of fuel droplets in the supersonic flow and reveal the momentum and heat exchanges between two phases, a large eddy simulation (LES) and particle Lagrangian tracking model were employed to numerically simulate two-phase mixing layer flows, using the one-way coupling method. The velocity fluctuation disturbances were added to inspire the flow instabilities. The motions of droplets in different diameters and droplets’ response to the large scale eddies were analyzed. The results indicated that droplets of 1micro diameter below are corresponded with the motions of coherent vortexes in the mixing layer. The more intense momentum and heat exchange are performed with decreasing the droplet’s diameter. The well mixing of fuel droplets in turbulence would make the combustion preparedness more sufficient. The research conclusions are of important academic value for further analyzing the two-phase dynamics in the scramjet.

Abstract: Two objectives were outlined in the current study. The first objective aimed to assess the detailed flow and heat transfer features in the vicinity of a rotating grinding wheel with jet impingement directed at grinding zone by numerical investigation. The second objective aimed to assess the quantitative evaluation for heat transfer enhancement on a grinding work-piece surface subjected to the mist/air jet impingement by experimental investigation. The results show that the coupled action of swirl air entrainment and jet impingement is benefit somewhat for overall convective heat transfer in relative to stationary disk case whether the disk rotates in clockwise or contrary clockwise. When the jet impinging direction is consistent with the rotational direction of rotating disk, convective heat transfer enhancement is achieved near grinding region, especially at higher rotating speed. Furthermore, the increasing of water droplet in mist/air jet impingement showed significant enhancement of the cooling effect.

Abstract: A three-dimensional numerical study on the flow and heat transfer characteristics over a rotating disk with bottom wall subjected to uniform heat flux was conducted with the use of RNG k- turbulent model. And some experiments were also made for validation. The effects of rotating angular speed and pin configuration on the temperature maps and convective heat transfer characte-ristics on rotating surface are analyzed. As the increase of rotating velocity, the impingement of pumping jet on the centre of rotating disk became stronger and the transition from laminar to turbu-lent occurred at the outer radius of rotating disk, which resulted in heat transfer enhancement. The pins on the disk made the pumping action of a rotating disk weaker. Simultaneously, they also acted as disturbing elements to the cyclone flow near the rotating disk surface, which made the overall heat transfer to be enhanced. Under the same extend areas of different pins, needle pin has higher convective heat transfer capacity than the discrete ring pin.

Abstract: Two-phase CFD calculations using commercial code Fluent were employed to calculate the air and droplet flows with and without mist in an impinging jet. The effects of phase changing of the water droplets, the mist injection rate, the heat flux of target and the geometrical parameters of the slot were studied to reveal the cooling effectiveness. The results show that the key enhancement mechanism of mist/air impinging jet is the effect of evaporation of the droplets. The wall temperature significantly decreased because of mist injection and the injection of 5% mist has a strengthen of cooling effectiveness with 89% enhancement. This enhancement would be reduced by higher heat flux of target wall. Concentration plays a major role in the cooling performance. Increasing the mist ratio makes the cooling strengthen significantly. A mist of 5% can provide a cooling enhancement of 32% at stagnation than the mist of 1%. The effect of the mist ratio on cooling declines gradually from the impingement area to the downstream area. A fit width and height ratio had a major impact on the cooling performance of mist/air impinging jet. For constant mist/air mass flow and inlet width b, when H/b increases, the heat transfer coefficient increases first and then decreases; for constant mist/air mass flow and impinging distance H, the heat transfer coefficient increases as H/b increases.

Abstract: In order to research the effects of impeller outlet angles on flow induced vibration and noise of centrifugal pumps, a single grade end suction centrifugal pump is employed as a research object. The outlet angles were varied from 33° to 29°and 37°, but the volute and the other geometric parameters keep constant. Based on the virtual instrument data acquisition system, pump product testing system and in the centrifugal pump closed experimental rig, the flow induced vibration and noise signals of model pump with different outlet angles in the full flow range are measured and analyzed. Experimental results show that the influence of flow induced vibration on volute is the largest. With the increase of impeller outlet angle, the variation tendency of vibration intensity for 4 measure points decrease. The vibration intensity of model pump gets the minimum value, when the outlet angle is 37°. Under different conditions, the shaft frequency peak of noise signal varied intricately with the increase of impeller outlet angle. When the outlet angle is 33°, the shaft frequency peak of the model pump is relatively small under each operating condition, and gets the minimum value at the design condition.