Abstract: Rotor blade design relies heavily on the aerodynamic theory. Extensive calculations are necessary in order to determine the blade parameters such as chord and thickness distributions, twist angle distribution and taper that is matched with the selected airfoil sections. For practical purposes, the engineers need a convenient means to verify their design. Wind turbine blades must be designed to operate in desirable performance. This research proposes a computer aided method that helps the engineers to examine the design and amend it in time. The numerical example shows good applicability of the methodology proposed. The proposed methodology not only lets us verify our design scientifically but also makes us understand the associated physical insight. The numerical example demonstrated here showed the converted power by the rotor can be evaluated easily by Flow Simulation according to the aerodynamics theory.
Abstract: Based on the theories of rotor dynamics, a dynamic model of rotating blade was built. Taking account of the effect of spin softening, the research on vibration characteristics of high-speed rotating blades was carried out under different speeds. The results had shown that frequency of blade vibration increased with rising rotating velocity, whilst the frequency of all orders declined with the influence of spin softening. Meanwhile, the change of each mode shape of blade was not very large at different speed. The conclusion derived from this paper had both theoretical and empirical value on retrofitting, optimal-designing, as well as engineering application for high-speed rotating blades.
Abstract: Vehicle rear vision system formed by exterior mirrors and wide-angle lens plays a significant roll in the vehicle safety system. Existing vehicle rear view mirror system still has many problems unsolved, such as blind space during vehicle steering. This paper proposes a new design of intelligent vehicle rear vision system which can automatically adjust the angle of exterior vehicle mirrors in two dimensions in different driving conditions. The affecting factures includes vehicle steering angle, driving speed, and vehicle size parameters. The design uses an AT90C516RD + microcontroller as core control unit. The system adds a new automatic mode with existing manual functions remained. Upon theoretical simulation and model testing, the design has been proved to be fully functional and accepted by customer investigation with industrial potential.
Abstract: Harvesting grain directly has been the development trend of modern maize combine harvester. To satisfy the demand of harvesting grain straightly type maize combine harvester for large feeding rate, low damage rate, high threshing rate, the longitudinal axial flow threshing and separating device was designed. It could also increase the separating rate of grain and miscellaneous, and reduce the burden of cleaning device. Threshing gap was adjustable in the range of 30 to 60mm, which reduced the incidence of jam faults effectively in the threshing process. Spiral blade on feeder, threshing rasp-bar and separating nail were replaceable, which improved the efficiency for threshing and separating.
Abstract: The purpose of this design is to realize the function of the suitable aging intelligent sit in the vertical lift of the seat plate and a certain angle. The design of the stepper motor, trapezoidal screw rod, motor, mechanical structure of composite roller bearing and other mechanical parts, to achieve steady and rapid upgrade to the designated seat height, and the inclined seat plate in a certain range, convenient for the user to contact with the hip seat board, lack of auxiliary force users (especially the old people sit down to the toilet) to complete the action, reducing the population toileting difficulties.
Abstract: This paper assesses the performance of three two-equation turbulence models viz. the SST k-ω, the RNG and realizable k-ε for the simulations of a rotating blade in a wind tunnel experiment where k, ε and ω are turbulent kinetic energy, dissipation rate and specific dissipation respectively. The experiments showed the stall-delay phenomenon at the inboard of the rotating blade at a Reynolds number of 4800. This trend of suction peaks was captured by all three turbulence models albeit not matching the experimental coefficient of pressure accurately. All three models also showed radial flow at the inboard which is consistent with the experiments while the SST predicted the least k at low wall values.
Abstract: Abstract.In order to ensure higher accuracy and better electrical performance of large antennas in future,this paper does some research for deformation of antenna’s reflector:modeling for 25m antenna and reappearing deformation when elevation changes every 15° just considering gravity by using ANSYS.Using results of simulation obtains deformation error curves with elevation changes, creates the conditions for compensating distortion and has a certain value. By using Ruze formula, deeply studies the regular about antenna’s electrical performance influenced by deformation because of elevation changes,obtains meaningful data and tables of relationship between elevation and parameters of electrical performance in nine bands of 25m antenna.It finds out that when working in high-frequency band, efficiency and gain loss of antenna will be more affected by elevation angle changes.Finally creates conditions for optimizing antenna parameters and performing high reliability tasks such as deep space exploration and aerospace communication.
Abstract: This article provides a comprehensive analysis on an explosion of welded insulted cylinder for liquid oxygen during unloading occurred in a company in 2014. The possible causes of the accidents are deduced through analysis on the operating principles of welded insulated cylinders, explosion energy estimation and related performance tests. On the basis of the accident analysis, this article presents that great importance should be attached to the safety in filling of welded insulated cylinders, replacement prior to filling and regular inspections, and also indicates the gap in currently existing rules on periodic examinations of welded insulated cylinders in China.
Abstract: With the rail vehicle industry development and increasing request to the riding comfort, to reduce the structure vibration and noise caused by the gearbox is increasingly valued. Multibody dynamics method is proved to be very effective to structure optimization for noise control in gearbox design process. This paper aims to find an optimization way for the gearbox structure to increase the structure noise performance. Initially gear shafts and the casing were discretized using the finite element method, subsequently the multi-flexible body of low floor gearbox was established in the SIMPACK which considering the time-varying mesh stiffness and backlash, bearings were modelled via radial, axial and rotational stiffness elements, then the multi-flexible body dynamic response were analyzed and the structure noise was predicted. Finally, optimization schemes, in terms of gear modification and structure improvement, were proposed to improve the structure noise performance.
Abstract: In conventional special concentrically braced frame (SCBF) structures, the buckling of the braces leads to severe reduction in system strength and stiffness. Therefore soft story mechanisms followed by large permanent deformation are commonly observed in SCBF structures. The strongback system using additional structural components along the height of the building to resist local deformation is able to improve the distribution of the drift. This research conducted case studies to investigate the effects of strength and stiffness of the strongback system on the behavior of typical three-story SCBF system. The primary variables to be investigated are stiffness factor α (strongback stiffness/SCBF stiffness) and strength factor β (strongback strength/SCBF strength). We conducted nonlinear dynamic analyses to evaluate the effectiveness of α and β on structural demand parameters including maximum drift ratio and drift concentration factor (DCF). Analyses results show that although strongback system with excessively high α and β will reduce maximum drift ratio and DCF of SCBF systems, it is noneconomic. On the other hand, strongback systems with low α and β (α<0.0048 and β<0.054) have only little effects on improving structural behavior. The case studies suggested that 0.0096≤α≤0.0168 and 0.081≤β≤0.134 accounting for both efficiency and economics can be used in the design of the selected SCBF systems.