Movable Block Research Articles

Algorithms and mathematical model for determining shunt power of intelligent track section control sensor

The normal operating state of jointless and butt track circuits depends on the state of change in the insulation resistance; respectively, the correct choice of the maximum and minimum limit resistance characteristics should be considered. The maximum and minimum limit resistance depends on the power consumption of the unlimited track circuit in the normal and the mode of movement of the wheelset at the supply end of the rail line. The article presents a study of an intelligent track circuit without insulated joints, where logical elements replace all the equipment of mechanical and electrical energy converters. The research aims to determine the shunt that affects the definition of the movable block, respectively, the definition of the power of the shunt. The method consists in choosing a sensor, namely an intelligent track control sensor, and developing a mathematical model for determining the shunt power, which provides the influence of the shunt on the track circuit. Research carried out for track circuits with insulating joints has shown that with the value of the argument, modulus, and synthesis of the maximum-minimum limit resistance when the supply end is shunted, the maximum power will be the least minimum Rkmax. Because of the lack of more accurate data for an intelligent control sensor, studies were carried out.

Development and research of a multistage hydraulic gear-multiplier drive for metallurgical presses

The paper presents one of the solutions to reduce the installed power and increase efficiency of hydraulic pump drive of high power pressing equipment used in metallurgical plants. The authors have developed a multistage hydraulic drive based on a block gear-multiplier. Plungers of all cylinders form a movable block, the cylinders – a stationary one. The mode of operation (reduction, multiplication) is provided by a combination of output cylinders supplying fluid to the power cylinder by switching some of them to drain. Analysis of a four-stage drive with a three-stage multiplier gearbox is presented in comparison with a simple pump drive. A four-stage drive with two output cylinders provides a reduction gear and two multiplier stages, with which a stage of fluid supply to the power cylinder directly from the pumps (pump stage) is combined. Power and kinematic parameters of the drive were determined by the power loading during the working stroke and speed mode during the working cycle (forward (idle and working stroke) and reverse stroke). It is advisable to use a multi-stage drive with a smoothly increasing load over the entire length of the working stroke (upsetting, drawing operations). Analysis of the basic and additional combination of stages for linearly increasing power load, which was determined by the pressure at the beginning of Р0 , and the maximum pressure at the end of the working stroke Рmax was carried out. In the basic version, a gear stage (idle stroke), pump stage and two multiplier stages (working stroke) are sequentially combined. With an additional combination, the reduction stage covers idle stroke and initial part of the working stroke. Analysis was carried out under the condition of equality of pressure and power of the pumps in stages and the condition of equality of direct stroke time of the compared drives. The ratio of pump capacities was estimated. Dependences of the main parameters of the developed drive, reduction and multiplication factors were obtained. With the accepted initial data, it is possible to reduce the pressure and power of the developed drive pumps (in comparison with the simple one) by 28 – 37 % with an additional combination of stages (increases with an increase of an idle stroke). It is lower for the basic combination by 5 – 9 % (reduction is greater at lower idle stroke values). The use of an additional combination is limited by the ratio P0/Pmax ≤ 0/4.

Experimental investigations on plasma-assisted wood pellet ignition for the start-up of biomass-fired power stations

The share of power production from biomass-fired plants in the fuel mix energy system is increasing. These plants are responsible to compensate the residual load and therefore need to provide a high level of flexibility. Plasma-assisted ignition for biomass power plants is an alternative start-up technology that offers a carbon-free start-up with high flexibility. The application of an electrical ignition system, using a plasma torch, is investigated in a 400 kW pilot-scale facility at the Institute of Combustion and Power Plant Technology at the University of Stuttgart. A DC arc plasma torch is integrated centrally in a movable block swirl burner which is to be used as a start-up burner. Milled wood pellets are considered for this study to investigate the applicability of the electrical ignition system for cold start-ups of biomass-fired power plants. An evaluation method is developed to characterize the ignition and flame status under various operational conditions. Additionally, the flame stability is evaluated by post-processing the flame images recorded by a high-speed camera. Several operational parameters, such as burner load, air ratio, and primary air flow rate are used to optimize the burner configurations for a successful ignition and a stable flame. The results showed that biomass particles can be ignited at the burner load of 25%, but a rise of 13% in the load is required to produce a stable flame cloud. The flame is formed at the burner mouth with the support of the plasma torch. Nevertheless, when the plasma system is turned off, a flame lift-off is observed in most cases. The investigation of the effect of air ratio on combustion performance highlights the importance of the available heat for the combustion reactions, which is directly related to the burner load.

Characteristics of Flame Stability and Gaseous Emission of Bio-Crude Oil from Coffee Ground in a Pilot-Scale Spray Burner

Coffee ground has been recently considered as a new biomass resource in relation to the increasing coffee consumption worldwide. The bio-crude oil can be produced by fast pyrolysis of coffee ground, and it has advantages of larger heating values in comparison with those from other biomass. But the bio-crude oil from coffee ground has a significantly high viscosity which can hinder the application to conventional burners. In this study, a pilot-scale burner system with a 35 kW capacity with an air-blast atomizing nozzle was developed for the combustion of bio-crude oil from coffee ground with a high viscosity. A downward fuel injection system was adopted to enhance the ignition of fuel spray and the flame stabilization, and a movable block swirl generator was installed for the combustion air. The bio-crude oil was blended with ethanol at the volumetric ratio of 9:1 to enhance the combustion characteristics. The effect of various atomizing air pressures, swirl intensities, and overall equivalence ratios on the flame stability and gaseous emission were investigated to find out the optimum operating conditions for a bio-crude oil burner.

The Measurements of the Shear Stress Distribution at the Cavity Surface during Melt Filling in an Injection Mold

Measurement of shear stress distribution is important for examining phenomena occurring in the interface between the mold cavity surface and molten resin in injection molding. The authors developed a high precision measurement technique for shear stress distribution using a movable block and 3-component force transducer. In this study, we analyzed the influence of resins, cavity surface properties, and cavity thicknesses on shear stress distribution. The results are summarized below：

Development and research of hydraulic drive of sheet shears

The paper describes the pump gear-multiplier drive of sheet shears with a two-cylinder power unit. The description of the developed drive scheme with the use of dual dispensers (reducer and multiplier) of periodic action is given. The gear is engaged at idle, the multiplier – at work. Their charging comes up at the reverse course of the power unit. Each dispenser has an input cylinder connected to the pump and two dosing (output) cylinders connected separately with the power cylinders of the power unit. In this case, the cylinder bodies form a fixed block, and the plungers (pistons) – a movable block. It solves the main task: synchronization of movement of the pistons (plungers) of the power cylinders during all operation periods. Due to different ratio of the area of pistons (plungers) of inlet (Fв ) and dosing cylinders (2Fд ), a direct stroke mode with two stages of pump speed and pressure is provided. For the reducer, ratio (Fв /(2Fд )) determines reduction coefficient (Kp < 1), for the multiplier – the coefficient of multiplication (Kм > 1). As a result, the idling speed of the pistons of the power cylinders and pressure developed by the pumps increase, and during the working stroke – these values decrease. Working pressure of the pumps is equalized at a direct flow at a reduced level, which determines reduction of their installation power (up to 30 %). The analysis of graphs of power loading and speed was made. The condition of constant load at each of three main periods of the drive operation was accepted as: idle, working and reverse. Determinant parameters of the considered drive are the coefficients Kр (reduction), Kм (animation) and Kс – the gain of the power unit. The paper presents a comparative analysis of the considered and simple pump drive in order to establish the received combination and range of these values.

Experimental Investigation of Global Combustion Characteristics in an Effusion Cooled Single Sector Model Gas Turbine Combustor

This paper presents experimental investigations in an effusion cooled single sector gas turbine combustor under close-to-reality boundary conditions, i.e. elevated pressure and combustor inlet temperature, under varying staging conditions. Flow field, flame structure and gas-phase temperature measurements are performed using particle image velocimetry (PIV), planar laser induced fluorescence of the hydroxyl radical (OH-PLIF) and coherent anti-Stokes Raman scattering (CARS), respectively. Additionally, isothermal mixing of the pilot and main stage is investigated using Acetone-PLIF. The influence of the pilot on the measured quantities can be identified up to 30 mm downstream of the burner head plate. These measurements are conducted within a novel test rig dedicated to the investigation of swirl-stabilized pressurized flames and effusion-cooling. The rig features full optical access for non-intrusive laser diagnostics from three sides and a modular effusion liner geometry. Important process parameters can be controlled independently in a wide range, providing a high versatility and reliability in terms of boundary conditions. Oxidizer and cooling air mass flows can be conditioned independently to 773 K and 973 K, respectively. Fuel staging can be gradually varied between 0% (fully premixed) and 100% (pilot only) at thermal loads up to 150 kW and a maximum pressure of 1,0 MPa. A movable block radial swirler allows for varying geometrical swirl numbers.

Electrical triggering of earthquakes: results of laboratory experiments at spring-block models

Recently published results of field and laboratory experiments on the seismic/acoustic response to injection of direct current (DC) pulses into the Earth crust or stressed rock samples raised a question on a possibility of electrical earthquake triggering. A physical mechanism of the considered phenomenon is not clear yet in view of the very low current density (10−7–10−8 A/m2) generated by the pulsed power systems at the epicenter depth (5–10 km) of local earthquakes occurred just after the current injection. The paper describes results of laboratory “earthquake” triggering by DC pulses under conditions of a spring-block model simulated the seismogenic fault. It is experimentally shown that the electric triggering of the laboratory “earthquake” (sharp slip of a movable block of the spring-block system) is possible only within a range of subcritical state of the system, when the shear stress between the movable and fixed blocks obtains 0.98–0.99 of its critical value. The threshold of electric triggering action is about 20 A/m2 that is 7–8 orders of magnitude higher than estimated electric current density for Bishkek test site (Northern Tien Shan, Kirghizia) where the seismic response to the man-made electric action was observed. In this connection, the electric triggering phenomena may be explained by contraction of electric current in the narrow conductive areas of the faults and the corresponding increase in current density or by involving the secondary triggering mechanisms like electromagnetic stimulation of conductive fluid migration into the fault area resulted in decrease in the fault strength properties.

Stability analysis of statically indeterminate blocks in key block theory and application to rock slope in Jinping-I Hydropower Station

Using the movability analysis in block theory, one can easily determine all movable blocks. However, only for a movable block with no more than two structural surfaces, called the statically determinate block, can the factor of safety be determined by the static analysis, which limits more extensive application of key block theory. In order to analyze general movable blocks with multiple structural planes, an optimization model for solving the safety factor of blocks is built in this paper. In the model, the safety factor as well as the normal stress on the slip surface is taken as independent variables; and the objective function is specified as the safety factor alone. The statically admissible conditions include the system of equilibrium equations, non-negativity of both normal stress on the slip surface and thrust inside the block. Since the objective function is linear and the constraint functions are polynomials of no more than degree-2, it is weak in nonlinearity and can be solved by those conventional optimization techniques, and disadvantages of the conventional block theory are overcome. After some typical examples are tested, the stability of the left bank rock slope of Jinping-I Hydropower Station is conducted in detail, and the stability evolution due to excavation is systematically studied by this method.

Study on the Fast Tool Servo (FTS) with the Replaceable Flexible Hinge

It is a FTS with flexible hinge that can be replaceable. It includes flexible hinges, a movable block, piezoelectric ceramic driver and framework. The flexible hinge is installed on inner side of the frame, and the other side is connected with the movable block. The piezoelectric ceramic driver is installed in movable block, and its other end is installed on the end beam of the frame. There is a tool base in the front end of the movable block on which the diamond tools can be fixed. Under the support of the flexible hinges, the tool can move back and front driven be piezoelectric ceramic driver. Through the simulation analyses with finite element technology and experiment, it is certify that the design of FTS is successful and practical to further study.

Coupled-Field Finite Element Analysis of MEMS Compound Electrostatic Actuator by Using the ANSYS Software

MEMS (Microelectromechanical Systems) electrostatic actuators have been successfully applied in a number of areas, including accelerometers, gyroscopes, pressure sensors, and optical devices. In this paper, the actuator optimization of a silicon bulk-micro machined MEMS compound electrostatic actuator of an optical device is discussed. The actuator uses folded-beam structure to enhance the electromechanical performance. The movable block is connected to the compound electrostatic actuator through unequal-height folded-beam springs. The lower-height springs connect the block with parallel plates, and can convert the descending motion of the plates into out-of-plane tilting motion of the block efficiently Additionally, the block is capable of in-plane motion by applying the driving force of the comb-drive actuator through structural connection. ANSYS FEM simulation is used to extract the device electromechanical performance and resonant frequency of the device. By gradually varying the design parameters in ANSYS simulation, the relationship between the actuator electromechanical performance and various design parameters is derived. The curves of actuator electromechanical performance versus beam length and beam height are derived and they are in good agreement with theoretical prediction. From the analysis it is concluded that the actuator behavior strongly depends upon various actuator parameters. By adjusting design parameters, desired electromechanical performance can be obtained. Based on the simulation results, a set of optimized design parameters for the compound electrostatic actuator is decided. The above-proposed MEMS compound electrostatic actuator may be used for many applications, such as optical device and micro-operating.

LES of Premixed Flame Propagation in a Free Straight Vortex

The paper presents experimental and numerical investigations of flame propagation in a free straight vortex which is formed by a movable block swirl generation device. PIV was used to characterize the isothermal flow experimentally and high speed video films were used to gain informations on the flame propagation. Numerical simulations have been performed using the LES technique. The simulations rely on presumed-PDF combustion modeling with a chemical mechanism reduced by an ILDM approach which has been validated on two test cases. Numerical and experimental study confirm that the phenomenon of the combustion induced vortex breakdown can take place in an unconfined turbulent vortex with a strong inner axial flow. The LES analysis allowed to determine the main physical mechanisms of this phenomenon.

A numerical investigation of the aerodynamics of a furnace with a movable block burner

In this work the air flow in a furnace was computationally investigated. The furnace, for which experimental test data are available, is composed of a movable block burner connected to a cylindrical combustion chamber by a conical quarl. The apertures between the movable and the fixed blocks of the burner determine the ratio of the tangential to the radial air streams supplied to the furnace. Three different positions of the movable blocks were studied at this time. A three-dimensional investigation was performed by means of the finite volume method. The numerical grid was developed by the multiblock technique. The turbulence phenomenon was addressed by the RNG k-e model. Profiles of the axial, tangential and radial velocities in the combustion chamber were outlined. The map of the predicted axial velocity in the combustion chamber was compared with a map of the experimental axial velocity. The internal space of the furnace was found to be partially filled with a reverse flow that extended around the longitudinal axis. A swirl number profile along the furnace length is presented and shows an unexpected increase in the swirl in the combustion chamber.

Fault Current Limiting Transformer With Variable Reactance

The objective of this work is to prove experimentally the ability of a transformer with variable reactance to limit the fault current and to adjust the secondary voltage. This transformer is able to change its leakage reactance by a shift of a movable iron-core block. It has three functions of voltage transformation, fault current limitation, and voltage regulation. A small trial apparatus was manufactured and these functions were demonstrated experimentally. Its characteristics and some points that should be improved are also clarified.

The three-dimensional numerical aerodynamics of a movable block burner

Computational fluid-dynamics techniques were employed to study the aerodynamics of a movable block swirl burner, developed by the International Flame Research Foundation, IFRF, which is characterized by the ability to adjust continuously and dynamically the intensity of the swirl by means of the simultaneous rotation of eight movable blocks, inserted between eight fixed blocks. Five three-dimensional grids were constructed for the burner, corresponding to five positions of the movable blocks. Both the k-e and RNG k-e isotropic turbulence models were applied. Only the latter described the existence of a central reverse flow along the annular duct. The employment of first-order and second-order interpolation schemes provided distinct results. The later provided results closer to the experimental tests. The swirl number decayed in the annular duct. The predicted swirl numbers for this movable block swirl burner were lower than the corresponding IFRF's experimental data, as was also observed by other researchers. This gave rise to the suspicion of some possible measurement error in the IFRF's experiments. On the other hand, the lack of agreement between the experimental data and the predictions regarding swirling flows could be attributed to the possible inadequate performance of the k-e model, as a consequence of its isotropic approximation. Still another possible explanation could be a phenomenon called bifurcation, in which one given swirl number can be associated with two distinct conditions of steady state flow. In addition, this complex flows requires a scrupulous development of the grids for the boundary condition and the employment of adequate interpolation schemes.

Flow restriction and heat transfer in liquid helium cooling channels

Heat transfer characteristics in vertical liquid-helium cooling channels have been examined to understand the effect of restriction of liquid and vapor flows. Simulated channels were made to examine the steady-state and transient heat-transfer characteristics. The channel had a foil heater of stainless steel, and a movable block for hindering coolant flow was located just above or below the channel. The results indicated that the critical heat flux was considerable influenced by the hydrodynamic situations if the channel was sealed at the top or bottom. The cooling capacity of the top-sealed channels was significantly reduced. In the case of buttom-sealed channels, the critical heat flux was reduced due to vapor locking when the channel was small. These phenomena are explained in terms of the flow restriction of the updrafting vapor. The transient heat transfer was almost independent of the flow restriction.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>

Filament winding machine

The utility model relates to the technical field of copying machine lamp tube machining equipment. The utility model relates to a filament winding machine. Including a base, first supporting columns are welded to the left side and the right side of the upper end of the base. Bearing pedestals are fixedly installed at the upper ends of the first supporting columns through bolts, a threaded rod is rotatably connected between the two bearing pedestals, a movable block is in threaded connection with the threaded rod, a boss is welded to the left end of the outer side face of the movable block, anda protruding column used for being connected with a limiting ring in a sleeving mode is integrally formed and connected to the right side of the movable block. The wire feeding roller is convenient to assemble and disassemble; a filament winding roller of a corresponding specification can be selected according to the specification of a filament needing to be wound, and the rotating shaft is sleeved with the filament winding roller. The rotating shaft and the filament winding roller are driven by the second motor to rotate to wind the filament, and the threaded rod is synchronously driven by the first motor to rotate, so that the moving block and the filament feeding roller move towards the filament winding direction under the limitation of the guide rod, the operation is convenient, and the working efficiency is improved.