Applied Mechanics and Materials Vol. 733

Abstract: In this paper, we make the kinematics and dynamics analysis of a micro-robotic platform [3] driven by inertial force generated by eccentric masses. We establish the mathematical model and get the displacement, velocity and acceleration relationships of the platform. According to movement and stability requirements of the micro-robotic platform, we get a conclusion that the minimum angular velocity of the motor when the platform moves and the maximum angular velocity of the motor when the platform jumps.

Abstract: The oscillating hydrofoil current generation device utilizes a typical movement type, which can transform energy effectively from current. The study shows that the geometrical profile of blades is the fundamental factor to the efficiency. In order to resolve the problem, this paper adapt the BEM(blade elements momentum) theory, which plays an important role in resolving the turbine blade design. Use the MATLAB to calculate of the constraint equations, then translate the coordinates which has got through the calculation to Solidworks which is a convenient 3D modeling soft. In the end we will give an example which has modeled 3-D hydrofoil BEM theory.

Abstract: Inertial propulsion is a kind of special drive converting rotating motion to a one-way movement. This triggers a lot of attention, but also causes many controversies. This paper researches the inertial mechanism under the condition of no friction contact. Mathematical model is established, equations of motion are got, influence of impact force of the eccentric mass during the process of start to steady state is analyzed, movement simulation is made, and the experiment on the water is done through ultrasonic sensor. The conclusion is that the inertial mechanism we researched can only do reciprocating movement under no friction contact and one-way movement cannot be realized.

Abstract: Numerical simulations are used to investigate the influence of different de-swirl angles on the flow and heat transfer in rotor-stator cavity system The results show that: de-swirl angle has great influence on the swirl number; radial velocity increases with the increase of de-swirl angle; the smaller de-swirl angle is, the more smooth radial velocity distributes; it is favorable for disc flow and heat transfer when θ=45°.

Abstract: Hood is an important part of the automobile, which directly affects the vehicle performance. This paper takes the hood as an example, first of all the three-dimensional model in CATIA was imported into Hypermesh, then it was simplified and meshed, the constrained mode and the stiffness of several conditions were calculated by Optistruct. By using the Size Optimization based on sensitivity analysis, the minimum hood mass is defined as the objective function; each component’s thickness was optimized under the prerequisite of ensuing stiffness and the first modal of hood. The results show that: the optimized hood meets stiffness requirements, the whole vehicle performance can be improved, therefore, the lightweight design in this paper is effective.

Abstract: In order to reduce the turbine flow, injecting an airstream into the mainstream of the low-pressure turbine from the casing. A CFD analysis has been carried out to study the impact of jet parameters (jet position, Angle, flow rate and velocity) to the turbine flow. The calculation results show that when the low-speed region caused by the jet flow locates at the throat the flow regulating effect is the most obvious. In additional, when the jet is against the main stream or with a big flow rate, the turbine flow regulation is better, but the loss efficiency of the turbine will be significantly increased. The jet Mach number has little influence on the effect of flow regulation.

Abstract: The reverse circulation drilling technology of hollow through DTH air hammer is a set of efficient coring with DTH air hammer, full-hole reverse circulation with drilling fluids, and continuous coring without power lack. It been successfully applied in mineral resources exploration, water well drilling, infrastructure construction and other fields. We designed a new type of annular reverse circulation drilling bit in order to prevent drilling accident when drilling in complex strata, such as breakage and leakage. In this paper, the computational fluid dynamics (CFD) code, FLUENT, is employed to simulate the flow phenomena of reverse circulation drill bit. Numerical simulation results show that the values of negative pressure of new type annular reverse circulation drill bit which formed in the center channel and the bottom of hole were larger than those of the normal bit. Under the same conditions, the suction quantity from annulus of annular drilling bit is 1.4 times to the normal one.

Abstract: A wind tunnel experiment is carried out employing 2D-PIV technique to visualize the qualitative flow field and to obtain the quantitative velocity profile respectively in the wake of 1 Hz pitching oscillating airfoil of 6 degrees amplitude. In order to validate the experiment for future’s study, the experimental velocity data are compared to relative CFD ones. The CFD results are obtained from a code called Map Flow that is able to deal with the flow around pitching and plunging oscillating airfoil. From the vortices maps it is shown that the experimental results and CFD ones are well compared with respect to the size and the shape of the vortices patterns. Quantitatively, the differences between experiment and CFD with respect to the velocity profile are acceptable.

Abstract: LNG tank has extremely low operating temperature, hazardous storage medium and large capacity storage space, therefore it is necessary to carry out temperature field analysis for LNG tank under Ultra-low temperature, and the temperature of LNG tank under Ultra-low temperature is simulated based on finite element method. Firstly, the finite element model of temperature field is analyzed. Secondly, the simulation parameters of LNG tank under Ultra-low temperature are given. Finally, the simulation results are carried out, and the temperature field of LNG tank under Ultra-low temperature is obtained.

Abstract: Measurement of curved surface having large radius of curvature is still a problem for the modern industry measurement. The method of measurement based on laser range finder is a method commonly used in modern industry measurement, which can solve this problem. The system has larger measurement range and higher precision, it belongs to the non-contact measurement systems, so the measured piece could be freely set. Establish an appropriate measurement system based on surface features; obtain the spatial coordinate of the detection points of the measured curved surface through laser ranging; acquire the three-dimensional diagram of the surface features of the curved surface with matlab-based curved surface fitting software; automate the detecting system via the singlechip-based automatic control system. The present device had advantages of high accuracy, convenience and shortcut, low cost and strong adaptability to environmental conditions, which can effectively compensate for the present vacant situation of the portable large curved surface measuring device and have wide applications.