Lan Ying Wu

The interface morphology of a spherical crystal in the undercooled melt affected by a far-field uniform flow

The effect of the convective flow caused by the far-field uniform flow on the interface morphology of a spherical crystal is studied by using the matched asymptotic expansion method. For the case that the far-field uniform flow is far less than the characteristic velocity of the interface, we obtain the uniformly valid asymptotic solution of the spherical crystal in the entire melt region. The analytical results show that the far-field uniform flow has significant effect on the interface morphology of the spherical crystal. The convection flow makes the interface of the growing spherical crystal enhance growth velocity in the upstream direction of the far-field uniform flow, inhibit growth in the downstream direction and decrease growth velocity on the two sides of the spherical crystal. The drag effect of the far-field uniform flow makes the interface morphology of the spherical crystal evolve into a pearlike oval shape. Our analytical result is consistent with the experimental and simulation results.

Finite Element Analysis on the Blade Structure of Centrifugal Pump

The centrifugal pump is the common mechanical equipment, which is extensively applied in the water conservancy, ships and other projects, and the blade structure is a very important part in the centrifugal pump. In this paper, the stress distribution and concentration of single blade in the impeller are analyzed under the different pressure field of the blade structure surface, and the fatigue failure of blade is also studied. The research results show that the we can get the stress and strain of the blade accurately and intuitively through the analysis for the blade structure, the stress concentration of the centrifugal pump blade is mainly in the root and junction of the wheel cover, and the import value of stress concentration is larger than the outlet; the stress concentration may be caused easily as the stress increases rapidly in the blade, which has a great impact on the fatigue strength, the fatigue limit of the blade with the stress concentration is decreased more obviously than the fatigue limit of the smooth blade.

Study on the Preparation Method of Nanoparticle Reinforced Copper Alloy and Mechanical Test

In this paper,on the basis of a certain kind of Tin bronze alloy,a new nanoparticle reinforced copper alloy with additions of some alloy is produced by using vacuum melting and centrifugal casting technology.The mechanical properties of the alloy have increased significantly than the Tin bronze alloy.The tensile strength, yield strength,elongation of as-cast nanoparticle reinforced copper alloy are 477~535MPa,221~280MPa,28.0~35.6%,respectively.Compared with the conventional Tin bronze alloy, the strength and plastic of the nanoparticle reinforced copper alloy are obviously improved.

Research of Casting Process about Cover and Pump Body of Tonghai Pump and Mechanical Properties Test

In order to obtain cover and pump body of tin bronze Tonghai pump that is dense and good pressure resistance,the casting mold of the cover of Tonghai pump is metal mold. The casting method of Tonghai pump is vacuum counter-pressure casting.The method of casting pump body of Tonghai pump is vacuum investment casting. This research is about reasonable casting process parameters of vacuum counter-pressure casting and vacuum investment casting.Finally qualified castings of cover and pump body of Tonghai pump can be obtained.

Optimal design study on the radian and length of the guide plates for the pipeline elbow

Pipeline elbows are extensively applied in the liquid-conveying piping system, which vibration and noise control are always difficult and critical. The structural style of the guide plates for the liquid-conveying pipe noise eliminating elbow is numerical calculated in this paper, then we find that the fluid liquidity in the liquid-conveying pipe elbow is improved very well by the cross-sectional bending radian and export length of the guide plates, and the two parameters are also optimal designed. The calculated results show that the total pressure difference in the liquid-conveying pipeline elbow decreases first and then increases with the cross-sectional bending radius of the guide plate increases; The total pressure difference decreases first and then increases with the export length of the guide plate increases; When the guide plates according to the gold ratio arrangement, the number, the cross-sectional bending radius and the length are 2, 200 mm and 40 mm respectively, we obtain the total pressure difference is 10707.87 Pa in the liquid-conveying pipeline elbow, comparing it to the result of the original program, it decreases 38.58%, so the internal flow field is improved better, the optimal design has a very obvious effect.

Study on the Acoustic Characteristics for a Novel Liquid-Conveying Pipeline Elbow Structure

Pipeline elbows are extensively applied in the liquid-conveying piping system, which vibration and noise control are always difficult and critical. In this paper, the fluid noise and its distribution of the original elbow and optimized structure will be studied based on the structural optimization and solid-liquid coupling characteristics for the liquid-conveying 90ºpipeline elbow. The results show that the max-fluid noise of original pipeline elbow is 22.44dB, the max-fluid noise appears in the original pipeline elbow inside; When the guide plates are designed according to the gold ratio, the number, the radius and the length are 2, 200mm and 40mm respectively, the max-fluid noise is 18.21dB, it decreases 4.23dB compared with the result of original pipeline elbow, the max-fluid noise appears in the original pipeline elbow inside too, when the fluid impact the guide plate, the local fluid noise will be generated.

Study on the Microstructure and Properties of Suspensory Wire in DVD CD-ROM Head

The suspensory wire is widely applied in the fields of DVD CD-ROM head and various sensors. In this paper, the suspensory wires are analyzed with the SEM, X-ray energy spectrum and Hydrogen power spectrum et al. The research results show that the alloy composition of the suspensory wire is the composite materials, which is composed of silver, beryllium and copper bimetal; The Nano-indentation hardness tester is also did using the hanging Nano-indentation experiments on the suspensory wire, it’s to obtain more accurate mechanical properties parameters of material hardness and so on, then we get the average hardness of suspensory wire is 3.891 GPa; The average elasticity modulus decreases as the aging treatment time increases, and the average tensile strength increases as the aging treatment time increases.

Study on the Influence of Internal Flow Field in Pipeline Elbow by the Guide Plate

The liquid-conveying elbow is an very important part in the piping system, in this paper, the internal flow field in the pipeline elbow is studied, its structure is optimized, and the guide characteristic is improved. The results show that the internal total pressure difference in the original elbow is 29506.27 Pa, the Max-velocity is 7.12 m/s, and the internal flow field is very uneven；The internal total pressure difference can be greatly reduced through setting up the guide plates appropriately, its internal total pressure difference decreases as the number of guide plates increases, the Max-velocity decreases first and then increases as the number increases; When the number is a constant, the optimal result of guide plate according to the gold ratio arrangement is superior to the equidistance ratio arrangement; When the export length of guide plate is 50 mm, the total pressure difference is 14942 Pa in the elbow, comparing it to the result of the original elbow, it decreases 49.26%, the optimal design has an very obvious effect.

Study on Optimization and FEM Analysis of Centrifugal Pump Body Structure

The centrifugal pump is the common mechanical equipment, which is extensively applied in the water conservancy, ships and other projects. In this paper, the centrifugal pump body structure was analyzed based on the actual working conditions, and the structure was also optimized. The research results show that the maximum equivalent stress of pump body structure is in the tongue, when the grid cell size is 6mm, the maximum equivalent stress is 36.843MPa; The maximum equivalent stress increases as the grid cell size decreases, and the unit number increases rapidly as the grid cell size decreases; When the wall thickness of pump is selected appropriately, the material can be saved about 6%, and the optimized structure of pump can be also meet the structural performance requirements.

Simulation Study on Concrete Structure Bonding with Steel Plate

The building structure reinforcement simulation system is very necessary for the rapid development of the building reinforcement industry, in this paper, the feasibility of the simulation on concrete structure bonding with steel plate was analyzed, and the influence of deformation and stress of concrete beam was studied by the thickness of steel plate and bonding layer. The research results show that the cracking load of the original concrete beam model is 8.712 KN, the limit load is 8.92 KN, and the midpoint displacement is 0.4443 mm; when the thickness of steel plate is 4 mm, the limit load is 11.579 KN, comparing it to the 8.92 KN of the original concrete beam model, the bearing capacity can be improved to 32.91%; The maximum adhesion stress at the end of the bonding layer increases first and then decreases as the thickness of the bonding layer increases, the ratio between the maximum adhesion stress and the minimum adhesion stress increases first and then decreases as the thickness of the bonding layer increases.