Applied Mechanics and Materials Vols. 448-453

Abstract: Self-excited oscillation pulsed jet is the new jet which is superior to the traditional continuous jet. In view of the insufficiency of the widely used organ pipe and Helmholtz resonator at present, firstly, with the actual needs of production as the background, a tandem Self-excited oscillation pulsed jet nozzles is presented in this paper. Then on the basis of previous studies, some new ideas are put forward after the cavity Self-excited oscillation mechanism is analyzed theoretically. Finally, numerical simulation of the nozzle flow field is carried out using FLUENT, then ideal pressure distribution contours and the streamline of the flow field are got, verifying the analysis of the oscillation mechanism.

Abstract: The paper summarizes the technology development status of ore crushing and grinding from many angles, and analyzes the future development trend. The development of mineral processing automation at home and abroad are introduced, and points out the new progress of particle size analyzer and grade analyzer and other important mineral analysis instruments.

Abstract: Boiler tube leakage is the major reason of affecting the safe operation of the unit now, there are 3 methods of the "four tube" leakage detection: Traditional method, filtering method and acoustic spectrum analysis, acoustic spectrum analysis is the common method, but this method have low sensitivity and the sensor damage easily. Therewith, designed the special acoustic catheter with acoustic resonance cavity type, proved by experiments, the acoustic catheter with acoustic resonance cavity type can enhance leakage sound, can accurately extract leakage signals, has high sensitivity, and can avoid the effect of sensor by fire and hot-gas when the furnace is in positive pressure situation, reduce the installation and maintenance costs of the boiler tube leakage monitor system.

Abstract: Keywords: ion nitriding furnace cooling system vacuum system Abstract. About fuction of vacuum plasma nitriding furnace cooling system, and its design and calculation of main parts, in particular control of water consumption. The cooling water system have been set into the water flowing through the four heat shield, and gradually take the heat, then the coolant out by outlet pipe. Cooling water flows through layers of insulation to varying degrees of cooling, to ensure that each level of temperature, precise calculation of water flow can only be guaranteed to ensure the maximum water savings and cooling the furnace down. This article provide the basis for vacuum furnace cooling system design in the future.

Abstract: Keywords: Ion Nitriding Vacuum System PCVDAbstract. Vacuum system design is an important part of the heat treatment furnace. In this paper, the vacuum system of ion nitriding and PCVD composite treatment furnace is advanced a complete and thorough design and calculation to select a vacuum system that is composed of mechanical booster pump and a mechanical vacuum pump, which is also called roots vaccum pumps—mechanical vacuum pumps.

Abstract: Aiming at ash deposit problem of wind turbine blades, a cleaning device for 10kW horizontal axis wind turbines was designed by applying the mechanism that ash deposit on blades surface was purged by high-speed flows from nozzle. Using fluent software, a numerical simulation was carried out in cleaning device, and its pressure field and velocity field in different cross section of wind turbine blades were simulated under cleaning state. The results showed that positive pressure zone created by cleaning device was formed on blades surface, and high-speed airflow purging blades surface was formed. As a result, the purpose of cleaning is achieved.

Abstract: This paper summarizes three methods of gear tooth profile generation. Geometry coordinate positions on their profile are compared. A detailed finite element model of mating gear pairs, containing fine meshes and coarse meshes, is presented. Contact stress analysis of three finite element models are conducted to investigate the influence of different generation methods on contact stress. Then, a spur bevel gears pair in Power Split Device is generated by CATIA Law Curve method, and contact stress under the special operating condition is analyzed. The results show few differences of three methods in geometry coordinate positions and tooth contact stress, and the displacement of spur bevel gear in axial direction may cause uneven stress distribution.

Abstract: To achieve electro-hydraulic control requirements of tractor hitch system, TMS320F2812 was chosen as control chip, to collect sensor signals and control the hitch system. Hardware system was designed to finish the signal collections of force sensor, position sensor and PWM signal output. Through the simulation, the reliability of design was verified, meeting the work requirements of electrohydraulic hitch system.

Abstract: In order to assess switchgear insulation status, a novel association rule mining (ARM) algorithm is presented. It is used to recognize the severity of switchgear cabinet partial discharge. The algorithm uses fuzzy C-means clustering (FCM) to divide partial discharge feature interval, candidate sets meeting minimum support and minimum confidence are sought based on an improved Apriori algorithm. Multiple recursions and scans are performed on candidate sets to generate association rules library for classification. Fuzzy reasoning based on association rules are performed over multiple needle corona partial discharge signals sampled in 10KV switchgear cabinets. The results show that partial discharge classification rate using association rules is high and classification conclusions are accurate. It has provided theoretical basis and practical value for insulation status assessment of switchgear cabinets.

Abstract: With the development of the city sewage treatment, the request of the specific speed of axial flow pump has been higher and higher. At present China is lack of the system theory and method to design axial flow pump above 1400 specific speed. Selection methods of design parameters depend on experience. This paper used the improved lifting method to design axial flow pump. Optimize design of axial flow pump from cascade solidity, blade number, ratio hub and the airfoil of impeller. The feasibility of such optimize methods had been validated from theoretical analysis. Put forward new selection methods of design parameters. Design an impeller model. The rated condition of flow rate is 3000 m³/h and the rated condition of lift is 1 m. A useful reference of axial flow pump design, improvement and optimization was obtained.