Height Of Slot Research Articles

Design and heat transfer numerical analysis of high-speed continuous casting mold water slot system

The water slot structure can reduce the temperature of the mold and increase the heat transfer between the mold and cooling water. It has significant impacts on high-speed continuous casting. Therefore, a three-dimensional model of heat transfer from mold to cooling water was used to analyze the influence of water slot size on the cooling capacity of a single water slot. Then, the fluid flow, heat transfer, and solidification three-dimensional models were used to analyze the temperature distribution and cooling effect of three kinds of water slot molds and non-water slot molds. Finally, the water slot mold was designed to achieve high-speed continuous casting. The results show that to make full use of the cooling water in the water slot, the width and height of a single water slot should be less than 8 mm. Compared with the conventional mold without the water slot structure, the temperature of the mold with the water slot structure significantly decreases. The final design of the mold water slot system is as follows: the water slot width and depth are 8 mm, and the number of water slots on one side of the mold is 9. The water slots have a symmetrical distribution, and the symmetrical plane is the middle plane of the mold. The high-speed continuous casting experiment was carried out, and the casting speed can reach 4–4.5 m/min. The water slot mold in this study can be applied in the high-speed continuous casting process.

Characterization of two-dimensional cartridge type bidirectional proportional throttle valve

A novel bidirectional proportional throttle valve with a two-dimensional (2D) plug-in structure is proposed in this paper. The valve integrates the 2D valve module and the logic valve into one component, with high integration degree, response speed, and control accuracy. The mathematical model of the 2D valve module is established based on the continuity equation of flow and kinematic equation, and the stability criterion of the valve is established. The effects of the inclination angle, width, and initial overlapping height of the oblique slot and rectangular slot on the dynamic response of the valve are explored by AMESim simulation, and appropriate structural parameters are selected to design and manufacture the prototype valve. A dedicated test bench is built, and the feasibility of the valve design is verified by testing the valve under different system pressures and different load variations. The experimental results show that, at a system pressure of 21 MPa, the prototype valve has a flow rate of 53.5 L min−1, a hysteresis of 0.8%, a linearity of 5%, and a step response time of 6.5 ms. When the analog valve opening is changed by inputting 0.1 Hz signals with different waveforms under different system pressures, the maximum fluctuation of the main spool displacement is less than 1 μm, and the maximum stabilization time does not exceed 110 ms.

Comprehensive Analysis of Influencing Factors of AC Copper Loss for High-Speed Permanent Magnet Machine with Round Copper Wire Windings

AC copper loss from stator winding is one of the main losses of the high-speed permanent magnet machines (HSPMMs) and directly affects the performance of the machines. AC copper losses are influenced by many factors, including the frequency, conductor diameter, temperature performance, etc. These factors cause the AC losses to increase significantly at high frequencies due to the skin effect and proximity effect. In this paper, a comprehensive analysis of the AC copper losses of HSPMMs with round copper wire windings is presented. Firstly, the structure and parameters of a 60 kW, 30,000 rpm high-speed permanent magnet machine are provided. Then, based on this parameter, a 2D-finite element model (2D-FEM) is established to obtain the AC copper loss. Through the eddy-current field analysis, the current density distribution of the stator winding and the variation trends of AC copper losses under different frequencies are observed. In addition, by comparing the winding current density distribution and the AC copper loss value under different conditions, the influencing factors of AC winding losses are comprehensively analyzed, including the frequency, conductor diameter, number of conductors per slot, notch height of the stator slot, and working temperature. Finally, four stator coil cases are manufactured, which have different conductor diameters and wire strands. The AC losses of the four cases at different frequencies are tested, and the theoretical results are verified by measuring the AC/DC loss ratios (kac) of different conductor cases at various frequencies.

Multi-objective optimization of disc brake structure based on heat transfer performance

As an important basis for its structural optimization design, the heat transfer performance has a key influence on the reliability of automobile brake. Based on the finite element method, the transient heat transfer of automobile disc brake is analyzed under the condition of dynamic convection heat transfer coefficient. According to the simulation results, the CCD (Central Composite Design) sampling scheme is used to transform the optimization variable and target variable into multiple design points in the decision space. The optimization variable includes the total thickness, the height of the ventilation slot, the angle between the sides of the ribs, the number of ribs while the target variable includes the mass and temperature peak. According to the multiple quadratic regression model, the response surface function is constructed, and the approximate model of optimization analysis is obtained. The error analysis shows that the response surface function is equipped with good fitting accuracy. In order to facilitate the extremum search, the optimization of the quality is transformed into the constraint condition, and the multi-objective optimization problem of the brake disc is transformed into the single objective optimization problem. Through the sequential quadratic programming method, the Pareto optimal solution set of the optimal mathematical model is found. The results show that the temperature peak value is reduced by 7.8 % under the condition where the quality of the ventilation plate is basically unchanged. By weighting the Pareto optimal solution sets of different quality intervals, a good result evaluation of ventilation panel optimization is achieved.

Pressure Drop and Particle Collection Efficiency of Multivortex Separator

The purification of gas emissions from dispersed particles is presently one of the mandatory measures to protect the air basin for most industrial enterprises. The authors developed a device for gas cleaning with separation elements in the form of a profile with rectangular vertical slots. Such a design creates numerous small vortices, which leads to an increase in collection efficiency. The paper aims to numerically determine the effect of the design and operating conditions on the particle deposition efficiency and the pressure drop of the multivortex separator. The height of the rectangular slots varied from 55 to 94 mm. In addition, the size of the dispersed particles changed from 1 to 15 μm in diameter. The results show that a decrease of resistance coefficient is observed with an increase in the height of the rectangular slot in the separation element. The results indicate that separation elements should be designed with a small height of rectangular slots and located in the lower part to collect fine particles in the multivortex separator efficiently.

Elaboration of a lubrication system for universal spindle hinges of rolling mills

The experience of running drives of most of heavy-duty rolling mills shows that the designs of universal spindles with blade hinges under conditions of increased alternating loads are most acceptable comparing with other spindles types. Open friction surfaces are the drawbacks of these types of spindles, which complicate the matter of continuous supply of lubrication. Perfected effective system of forced lubrication of rolling mill spindles hinges proposed. The facility for their lubrication has a bearing support of balancing design, spindle, in radial holes of which spring-loaded plungers are installed in a diametrically opposite order. Besides, the facility has suction valves and force valves installed in the spindle axial holes, connecting with the radial ones. A methodology proposed to select the eccentricity of the internal cylindrical surface of the bearing support of the spindle hinge, the axis of which is located eccentrically relative the spindle rotation axis. A calculating scheme and a mathematical model of the process of lubrication supply into joints of rolling mill spindle hinge elaborated. A differential equation of lubrication motion in the conical slot of the hinge between a blade and insertions drawn up. Parameters of hydrodynamic motion of lubrication in the conical slot established. Modes of the lubrication motion in the conical slot between roller blade and hinge insertion determined. Based on experience of operation of friction couple bronze-steel, a lubrication for rolling mills universal spindles proposed. To improve the operation characteristics of hinges based on the friction couple bronze-steel, a thick lubrication having antifriction properties namely based on oils with additives ИП-10, КП-10 and ДФ-11 proposed. Dependence of pressure distribution along the length of the hinge conical slot presented for various lubrications of low viscosity (ИП-10 + ДФ-11) and high viscosity (КП-10 + ДФ-11). The quality effect of the speed of roller blade movable wall on distribution of speeds of lubrication layer motion over the height of the hinge conical slot for comparatively low and comparatively high boundary speeds demonstrated.

THz 2-D Frequency Scanning Planar Integrated Array Antenna With Improved Efficiency

A THz 2-D frequency scanning planar integrated array antenna is developed in this letter. Eight THz leaky-wave antennas are combined with a true-time-delay (TTD) phase-shifting feeding network to steer the beam in two directions by sweeping the frequency. Several H-plane 90° bends with linearly increased length are adopted to achieve the scalable TTD phase shift. The feeding lines are closely spaced to reduce the phase-shifting network occupied area in this progressive phase-shifting scheme. Besides, the E-plane 180° bend is used to construct the double-layer phase-shifting network, maintain the number of multiple scanning sweeps and improve the aperture efficiency. Moreover, in the used microelectromechanical systems (MEMS) fabrication technique, the minimum height of the radiation slot is 0.2 mm, which is too thick and deteriorates the radiating performance. When the double-layer step-profiled radiating slot is used instead of the thick slot, a THz leaky-wave antenna with higher radiation efficiency and better gain flatness can be achieved. Finally, a prototype antenna is fabricated and experimentally validated. The operating frequency range is 325-400 GHz and the beam scanning range is 22.7° × 60° with a maximum radiation gain of 25.28 dBi.

Estimation of the electromagnetic screens efficiency for the compensation of slot leakage fluxes in the pulsed electromechanical generator

Purpose. There are considered in the paper the four possible configurations of electromagnetic screens for compensation of the flux leakage of slots in the electromechanical pulse generator with a compression of magnetic flux. It is underlined the expediency of slot leakage inductance reduction as the method for increasing of coefficient of magnetic energy amplification in the process of flux compression. Methodology. Efficiency of each configuration of screens has been evaluated on the reduction of slot leakage inductance magnitude. To realize it the problem of pulsed field distribution in the teeth zone of generator has been solved by the finite elements method with application of professional version of software program QuickField v.6.1. Originality. There was manufactured the physical model of teeth zone in which the active conductor of slots was divided on 9 parallel sections along the height of slot. Results. With current supply from the source of alternating current at frequency 400 Hz that was measured a current distribution between the sections of active conductor both at the absence of electromagnetic screens and at their presence. Practical value. It is shown, that screening of slot leakage flux provides the more uniform distribution of current along the sections of active conductor with a corresponding reduction of slot leakage inductance..

The effects of height and vertical position of slot on the reduction of scour hole depth around bridge abutments

Abstract This paper investigates the effects of the height and vertical position of slots on the reduction of scouring on the periphery of rectangular abutments by constructing various slot models in different dimensions under varying flow conditions. For the purpose, 25 experiments were conducted under clear water conditions. The results of this study indicated that the closer the slot was placed to the bed, the more it would reduce scouring in models with slots featuring identical dimensions and heights equal to the half of the size of the flow depth. In other words, the slot model the height of which was measured from the water surface to underneath the erodible bed or more than the water depth showed the best performance among other slot models. The results of this research showed that the use of slots in abutments was more effective in reducing scouring than the use of bridge piers.

A single slot micro-ring structure for simultaneous CO2 and CH4 gas sensing

In this paper, we proposed a single silicon-on-insulator micro-ring structure for detecting two different gas components in the same time from one output spectrum. By introducing slot structure, the sensitivity and selectivity of sensor are improved. Specifically, two different sensing mechanisms are synthesized in this structure, thus output spectrum is impacted by varying concentrations of CH4 and CO2 respectively. The resonant wavelength of micro-ring resonator is the absorption peak of CH4, the concentration of CH4 can be measured with the light intensity change. Simultaneously, the combined action of CH4 and CO2 can cause the shift of resonant wavelength, and the total concentration of CH4 and CO2 gas can be obtained through the shift amount. For enhancing the evanescent field fraction in slot area and tuning the resonant wavelength of micro-ring being located on the absorption peak of CH4 (around 3.31 µm), the parameters of slot micro-ring structure, including height of slot in silicon, slot width, radius of micro-ring, waveguide width and the gap distance in coupling section, are well tailored, meanwhile, the quality factor Q of micro-ring is considered for ensuring a satisfied accuracy of sensor. A simulation based on the finite difference time domain method is implemented and the analysis results show that the sensitivity of sensor reaches 2308 nm/refractive index unit.

Thin cylindrical slot in an optical microdisk cavity for sensing biomaterials

In this paper, we propose and investigate a thin cylindrical slot etched into a disk shape optical microcavity (MC) aiming for sensing biomaterials in a label-free style. Supporting whispering gallery modes (WGMs), with remarkably large quality factor to modal volume ratio (Q/Vm) of the optical MC structures that penetrate in the slot region, enables us to perform sensing. Three different geometries for the side walls of host microdisk cavities, including vertical, 60° wedged, and half-circular cross section, are selected for investigations. In each individual case, the radial position, width, and height of the thin cylindrical slot are varied. The electromagnetic (EM) field intensity distributions (mode mapping profiles) of the WGMs show funneling of the intensified fields into the slot area that possessing nearly the same high Q values. Tuning the slot position, width, and depth for a suitably chosen WGM, sensing could be optimized for different biomaterials. Sensitivity value as high as 75 nm/RIU is calculated for the half-circular side wall microdisk. The proposed WGM-based slotted microdisk, as a state-of-the-art device which can operate, such as lab-on-chip structure, would function as a sensitive biosensor, even down to the single biomolecule levels.

The effect of slot height and difference in gas densities for coaxial jets on jet mixing in constrained swirled flow

Experiments were conducted about the effect of height of annular slot on efficiency of film cooling in a tube flow. Nonisothermal nature of flows was modelled by mixing of jets with different densities: air with argon or with helium: the concentration of foreign gas on wall was measured. The influence of nearwall jet swirling and of proportions of densities of gas flows as key factors for laminarization of mixing was considered.

EXPERIMENTAL STUDY ON EFFECT OF SLOT LEVEL ON LOCAL SCOUR AROUND BRIDGE PIER

Many bridges in the world every year for Failure to consider in the design of hydraulic elements are destroyed. During the spring floods of 1987, 17 bridges in New York and New England were damaged or destroyed by scour. In 1985, 73 bridges were destroyed by floods in Pennsylvania, Virginia, and West Virginia. In the present study investigate effect application a slot , height “D” , width” D/4”in a circular pier ,where “D” is diameter of bridge pier and the size of 6 centimeters under 3 different discharges (values 35 , 40 , 45 Liter per second) and 4 different location of slot in a flume ,length 14 meters ,height 60 and width 60 centimeters. The experimental results show when height of slot is below the stream bed as D, scour depth will be reduced about 20.34% to 39.73% in front of the pier and scour volume approximately 46.84% to 75.74%

Study on the wiping gas jet in continuous galvanizing line

In the continuous hot-dip galvanizing process, the gas-jet wiping is used to control the coating thickness of moving steel strip. The high speed gas-jet discharged from the nozzle slot impinges on the strip, and at this moment, wipes the liquid coating layer dragged by a moving strip. The coating thickness is generally influenced on the flow characteristics of wiping gas-jet such as the impinging pressure distribution, pressure gradient and shear stress distribution on the surface of strip. The flow characteristics of wiping gas-jet mentioned above depends upon considerably both the process operating conditions such as the nozzle pressure, nozzle-to-strip distance and line speed, and the geometry of gas-jet wiping apparatus such as the height of nozzle slot. In the present study, the effect of the geometry of nozzle on the coating thickness is investigated with the help of a computational fluid dynamics method. The height of nozzle slot is varied in the range of 0.6mm to 1.7mm. A finite volume method (FVM) is employed to solve two-dimensional, steady, compressible Navier-Stokes equations. Based upon the results obtained, the effect of the height of nozzle slot in the gas-jet wiping process is discussed in detail. The computational results show that for a given standoff distance between the nozzle to the strip, the effective height of nozzle slot exists in achieving thinner coating thickness.

Effects of solid and slotted baffles on the convection characteristics of backward-facing step flow in a channel

This study investigates the enhancement of the laminar forced convection characteristics of backward-facing step flow in a two-dimensional channel through the installation of solid and slotted baffles onto the channel wall. The effects of the height of baffle Hb, inclination of baffle installation ϕb, height of slot in baffle Ht, inclination of slot in baffle ϕt, and distance between the backward-facing step and baffle D on the flow structure, temperature distribution and Nusselt number variation for the system at various Re are numerically explored. Results show that a slotted baffle can enhance the average Nusselt number for the heating section of channel plate by the maximum 190% when Pr=0.7, Hs=0.5, L=5, Hb ≤ 0.3, Wb ≤ 0.2, 0.1 ≤ D ≤ 0.5, 0° ≤ ϕb ≤ 45°, Ht ≤ 0.1, 0° ≤ ϕt ≤ 45° and 50 ≤ Re ≤ 400. As for the solid baffle, the enhancement may be up by 230%. The solid baffle might cause the re-separation of main stream, and consequently result in poor local heat transfer coefficient in the end region of heating section. This disadvantage can be obviously improved as the baffle is slotted. Besides the penalty of increase in pressure drop due to the baffle installation is much higher for the situation with solid baffle.

Countercurrent Jet Device

The flow features of a jet device mounted at the bottom of a rectangular channel and issuing a plane wall jet are studied both by computational and experimental means. It is found that the countercurrent jet is able to lift the water dynamically, and that the difference of water levels in the up‐ and downstream portions depends mainly on the slot Froude number and the relative height of slot. From the practical point of view, two applications may be considered: (1) The case in which a difference in water level should be created without usual hydraulic structures such as gates or overflow structures; and (2) the case in which excess energy must be dissipated. In case 2 the slot Froude number should be large, combined with a low tailwater depth. The maximum efficiency of dissipation occurs for a transition from subcritical upstream to supercritical downstream flow, beyond which a conventional secondary stilling basin may be used. These features are shown to be analogous to the classical hydraulic jump.