Advanced Materials Research Vol. 977

Abstract: In this paper, computational fluid dynamics software to simulate three-dimensional flow of marine propeller applications was introduced and described the 3D-CAD model building process, complex moving mesh division methods of the region, three-dimensional rotating turbulence model selection and analysis of the results. Visual image obtained the pressure distribution, flow velocity distribution of the marine propellers, and focused on analyzing the reasons for producing results.

Abstract: The derrick of a drilling ship is a kind of dynamic ocean derrick which is often applied to drilling operations for ocean engineering. Comparing with land rig derrick, the operating environment of drilling derrick is more complicated with not only the regular functions of static force but also the dynamic loads induced by wind, wave and current. Therefore, this paper takes a drilling derrick as example to make clear of the dynamic characteristics of the drilling derrick under the action of dynamic loads from outside environment with the finite element software ANSYS as tool to accomplish the modal analysis of the drilling derrick. According to the natural frequency and the vibration mode of the drilling derrick after modal analysis, the deformation response and the weak parts of the drilling derrick under different motivation can be predicted, and some improving suggestions can also be illustrated as well. This paper completed the dynamic analysis of the drilling derrick by modal analysis, and moreover, the displacement response and the stress of the drilling derrick varied with time can also be obtained. As consequence, the conclusion can be taken as reference for design of the drilling derrick, safety application and life sustainment.

Abstract: The key equipment of Light HVDC Technology is the converter and the filter. The main function of the converter is AC / DC conversion, which plays a vital role in converter station. The filter is also an important tool for harmonic suppression. Therefore, in this paper, the HVDC converter and the harmonic suppression are studied. Our paper discussed the advanced converter VSC which is currently being put into operation, its key technology--the MMC topology and the connection mode of VSC. Meanwhile, the production, effect and suppression of the harmonic are analyzed. Compared active power filter to the passive filter, finally, we chose the active filter as the research object. Successful experience of the HVDC Light project which has been put into operation or will be put into use showed that, the technology is in great progress and will be widely used.

Abstract: For large warships, aircrafts play an important role in the war. So during the development of large warships, the safety of the aircrafts takeoff and landing becomes the key technology, which requires the air-wake around large warship decks provide a safety environment for its busy work. However, for the warships with flush deck, superstructure is the main reason of causing air turbulence on the ship surface. At the same time, the states of motion also have an effect on air-wake such as pitch, rolling, etc. It will lead to air crash or inability of takeoff and landing if the air-wake around decks cannot meet the work requirements of the aircrafts. Therefore, the numerical simulation of air-wake around decks is very important for the development of large warships during the war.

Abstract: Dimensionless mathematical models of the fluid flow in the semi-infinite long porous media with constant production pressure on the inner boundary conditions are built, which include the effect of threshold pressure gradient (TPG). The analytical solutions of these dimensionless mathematical models are derived through new definitions of dimensionless variables. Comparison curves of the dimensionless moving boundary under different values of dimensionless TPG are plotted from the proposed analytical solutions. For the case of constant production pressure, a maximum moving boundary exists, beyond which the fluid flow will not occur. The value of maximum boundary distance decreases with increasing TPG. However, the velocity of pressure propagation decreases with time. The larger the TPG is, the steeper the curve of pressure depression cone is and the shorter the distance of the pressure propagation is.

Abstract: Muzzle strong impact is a new test method of gun firing simulation test method. Based on the virtual prototyping technology, hydraulic simulation technology and rubber tests, gun model, power system model and material model of waveform generator were established. Finally, simulation model of gun firing simulation test machine was obtained. Simulation results indicated that the test machine can simulate the dynamic characteristic of recoil mechanism and load distribution of key components, for example, turret race, trunnion, belt segment, torsional axis and sprocket and so on..

Abstract: Recoil distance is an important evaluation index to reflect the performance of gun recoil mechanism. It can not allow to fire of artillery if recoil distance exceeding the prescribed distance. So it played an important role to ensure the normal firing of artillery. Previous artillery recoil distance is read by artificial indicator through the recoil, which affects the firing efficiency and has no conducive to the implementation of fast attack. This paper designed the gun recoil distance memory and alarm device by using the sensor technology and SCM programming. The device not only can record the recoil distance of each firing projectile and the total number of it but also can alarm if the recoil distance exceeds the specified maximum. The device effectively solves the problem that the recoil indicator artificial read and record. It has practical significance to improve the efficiency of the shooting.

Abstract: The Buck circuit has been widely used in DC drive, charging and storage circuit, switching power supply and other power electronic devices. There exists very strong duality in the Buck circuit with input LC filter, especially in the structure of circuit, the equivalent circuits and the waveforms of input and output parts. On the basis of a theoretical model established in our work, an experiment is conducted to validate the equivalent circuits of both input and output parts, as well as the waveforms of associated capacitors and inductors. By choosing appropriate component parameters, the experimental results confirm the predictions of the theoretical model proposed.

Abstract: the origins and characteristics of linear and nonlinear aeroelasticity are analyzed.And the deforming mesh , fluid-structure coupling schemes, the design method of aerodynamic module and structure module interface are also analyzed. their advantages and disadvantages are Pointed out. Finally, several recommendations are given for the development orientation of aeroelasticity in the future.

Abstract: In this paper, Dynamic analysis for the process of opening net is studied base on a new anti-riot device, focusing on the problem that dynamics modeling of fully compliant anti-riot net during the process, a new equivalent method is proposed. This method regards the anti-riot net as a variable drag coefficient rigid body, and regards four traction heads as a suppositional traction head, so the process of opening net can be transformed to the problem for movement of two rigid bodies, furthermore, the dynamic equations for the process of opening net was derived from this method. These equations are used to simulate the process of opening net; the simulation results are compared with test results to verify the practicability of the method.