Values Of Rotational Speed Research Articles

PENGARUH SUDUT BUKAAN GUIDE VANE DAN TEKANAN AIR TERHADAP KECEPATAN PUTAR DAN DAYA OUTPUT PADA PROTOTYPE PEMBANGKIT LISTRIK TENAGA MIKROHIDRO DENGAN TURBIN CROSSFLOW

The pattern of power plants development in Indonesia is still relying on the availability of fossilfuels based energy sources. Meanwhile, Human are faced with a situation of depleting reserves offossil energy sources and increasing environmental damage due to the use of fossil fuels basedenergy sources. Renewable Energy development can be a solution to these problems. One of them isthe development of a Micro Hydro Power Plant. In the realization of Micro Hydro Power Plant inIndonesia, the crossflow water turbine type can be used. It is a type of impulse turbine with a goodcharacteristic at a low head for micro-scale generator capacity. This study analyzes the effect of guidevane opening angle and water pressure on rotation and output power of crossflow turbine. Theopening angle of the guide vane studied was 15º, 30º, 45º, 60º, 75º, and 90º in each water pressurecondition of 4 psi, 8.5 psi and 13 psi. The test is carried out by simulating direct measurements on theprototype of the Micro-hydro Power Plant that has been built. Every combination of parameterstested, the maximum value of rotational speed and output power is obtained at the guide vaneopening angle of 30º and water pressure of 13 psi. Turbine rotation values generated before and aftercoupled with a generator are 591.9 rpm and 522.7 rpm. The values of the generator rotation beforeand after the load coupled are at 3490 rpm and 2368 rpm. And the power value generated by thegenerator is 11.8 Watts.

Prediction of tensile behavior of FS welded AA7039 using machine learning

The present study deals with the application of machine learning approaches such as Gaussian process regression (GPR), support vector machine (SVM), artificial neural network (ANN), and linear regression (LR) in analyzing and predicting the tensile behavior of friction stir welded AA7039. For this, FSW experiments are conducted at different values of rotational speed, welding speed, and tilt angle whereas the ultimate tensile strength (UTS) is considered as an output parameter. Besides this, the coefficient of correlation (CC) and root mean square error (RMSE) are considered as performance measurement parameters. It is observed that for a combination of process parameters, the ANN model is most useful for predicting the tensile behavior of FS welded AA7039 with minimum values of RMSE and maximum value of CC for test data set. Conversely, the LR model is found insignificant with maximum RMSE for test data set. In addition, electron backscattered diffraction (EBSD) is used to determined the grain size of base metal and nugget zone (NZ). The minimum grain size is obtained for higher strength specimen i.e. 4 microns.

Investigation of Rotating Disk Skimmer Hydrodynamic Performance during Oil Spills Recovery (Dept.M)

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ESTABLISHING THE ROTATION SPEED VARIATION RANGE LIMITS FOR AUTO-EXCITATION OF SELF-OSCILLATING GRINDING IN A TUMBLING MILL

The influence of the structure of a two-fraction polygranular feed of the chamber on the value of the drum rotation speed at auto-excitation of self-excited oscillations with a maximum swing is considered. Such a pulsating mode of movement of the charge is used in the self-oscillating process of grinding in a tumbling mill. The coarse fraction simulated the grinding bodies was steel bullets with a relative size ψdb=0.026. The fine fraction, simulated the particles of the crushed material, was a cement clinker with a relative particle size ψdm=0.00013. Variable factors of experimental studies were: the degree of filling the chamber in the state of rest κbr=0.25; 0.29; 0.33 and the degree of filling the gaps between the particles of the coarse fraction with particles of the fine fraction κmbgr=0.0625; 0.375; 0.6875; 1. The method of visual analysis of transient processes of self-oscillating modes of feed behavior in the cross section of the rotating drum chamber is applied. Measurements of the speed limits of the drum rotation were carried out with auto-excitation of self-oscillations of the filling. The magnitude of the self-oscillation swing was estimated by the increase in the difference between the maximum and minimum values of the filling dilatancy for one period of pulsations. An increase in the upper limit of the speed range ψω2 with a decrease in κbr and κmbgr was established. The growth rate of ψω2 increases at low values of κbr and κmbgr. Some increase in the lower limit of the ψω1 range with a decrease in κbr and κmbgr was revealed. An increase in the range of speeds of rotation was recorded at the maximum range of self-oscillations ψω1–ψω2 with a decrease in the connected interaction of the intra-mill filling. This coherent interaction is due to an increase in κbr and κmbgr. The value of the ψω1–ψω2 range varies from 1.01–1.03 at κbr=0.33 and κmbg=1 to 1.22–1.66 at κbr=0.25 and κmbgr=0.0625. The range gets its maximum value with fine and superfine grinding

Numerical simulations of friction stir welding of dual phase titanium alloy for aerospace applications

Dual phase titanium alloy is mainly used in aircraft industries due to low density, greater strength and superior thermal properties. However, titanium alloy is highly reactive to all materials and easy immersion of interstitial constituent leads to material embrittlement, so it is difficult to process and weld. So experimental investigation of friction stir welding (FSW) process is expensive. To overcome these, in the present work a finite element simulation has been developed in ABAQUS software for the FSW process to comprehend the process physics and to predict the mechanical properties of FSW component. The simulation has been carried out by changing the parameters and the performed simulation results such as stress strain plots, percentage elongation, yield and ultimate tensile strength has been verified and calibrated with experiment results. The FSW welding parameters have been optimized using Genetic algorithm to get better weld quality. The fitness function for genetic algorithm is evaluated using regression analysis. The optimized value of rotational and transverse speed to achieve maximum yield and ultimate tensile strength are 1000 rpm and 4 in./min respectively. The optimized results have also been compared with the Taguchi method.

Experimental investigation of tool probe shape and rotational speed on weld quality of friction stir welding of aluminium alloy

Abstract Friction stir welding (FSW) is generally recommended for welding of aluminium alloys as it eliminates many of the common problems of fusion welding. In FSW, the weld quality depends on the tool probe shape and rotational speed of the tool probe. In this paper, aluminium alloy (AA6061) is used for experimentation. Three different tool probe shapes are used to find the effectiveness of tool shape on the mechanical properties of the joint. Five different rotational speeds for each shape of the tool are used for conducting the experiments. The result shows that the square pin profile tool resulted in higher joint efficiency of 85% followed by a triangular pin and cylindrical pin tool. For all cases, with an increase in rotational speed, nugget microhardness, tensile strength, and bending strength value tends to increase with an increase in rotational speed up to 1000 rpm; however, with further increase in rotational speed has no impact on weld region rather decreased in weld strength.

The Effect of Misalignment to Vibration, Electric Current and Shaft Rotation Speed on The Coupling Transmision

Coupling is one of the components are widely used in various industries. Coupling is widely used as a power transfer transmission. Coupling have a long life time, it mean coupling was damage if out of the maintenance. The one factor is misalignment. This study aim to determine the effect of misalignment on the coupling transmission to vibration, electric current and shaft rotation speed. In this study, was done alignment process with variations of misalignment on the coupling transmission and was done measurement value of vibration, electric current and shaft rotation speed. The study results show that the changed of misalignment would give a positive impact to vibration and electric current. For the effect misalignment to shaft rotation speed, the study results show that the changed of misalignment would give a negative impact to shaft rotation speed.

An Inter-Comparison of Dynamic, Fully Coupled, Electro-Mechanical, Models of Tidal Turbines

Production of electricity using hydrokinetic tidal turbines has many challenges that must be overcome to ensure reliable, economic and practical solutions. Kinetic energy from flowing water is converted to electricity by a system comprising diverse mechanical and electrical components from the rotor blades up to the electricity grid. To date these have often been modelled using simulations of independent systems, lacking bi-directional, real-time, coupling. This approach leads to critical effects being missed. Turbulence in the flow, results in large velocity fluctuations around the blades, causing rapid variation in the shaft torque and generator speed, and consequently in the voltage seen by the power electronics and so compromising the export power quality. Conversely, grid frequency and voltage changes can also cause the generator speed to change, resulting in changes to the shaft speed and torque and consequently changes to the hydrodynamics acting on the blades. Clearly, fully integrated, bi-directional, models are needed. Here we present two fully coupled models which use different approaches to model the hydrodynamics of rotor blades. The first model uses the Blade Element Momentum Theory (BEMT), resulting in an efficient tool for turbine designers. The second model also uses BEMT, combines this with an actuator line model of the blades coupled to an unsteady computational fluid dynamics simulation by OpenFOAM (CFD/BEMT). Each model is coupled to an OpenModelica model of the electro-mechanical system by an energy balance to compute the shaft speed. Each coupled system simulates the performance of a 1.2 m diameter, three-bladed horizontal axis tidal turbine tested in the University of Edinburgh FloWave Ocean Energy Research Facility. The turbulent flow around the blades and the mechanical-electrical variables during the stable period of operation are analysed. Time series and tabulated average values of thrust, torque, power, and rotational speed, as well as, electrical variables of generator power, electromagnetic torque, voltage and current are presented for the coupled system simulation. The relationship between the mechanical and electrical variables and the results from both tidal turbine approaches are discussed. Our comparison shows that while the BEMT model provides an effective design tool (leading to slightly more conservative designs), the CFD/BEMT simulations show the turbulence influence in the mechanical and electrical variables which can be especially important in assessing an additional source of stresses in the whole electro-mechanical system (though at an increased computational cost).

DEM study of particles flow on an industrial-scale roller screen

In this work, the screening process of an industrial-scale roller screen was simulated based on the validated discrete element method (DEM). The effects of the feed rate, rotational speed of rollers, inclination angle of screen deck and the cohesion force between wet particles on the screening process were investigated. The results show that screening efficiency decreases with the increase of feed rate, which remains above 0.80 when the feed rate is less than 700 kg/s. The optimal values of rotational speed and inclination for high efficiency are 100 r/min and 6°, respectively. Working parameters have a significant effect on both the passing percentage and the average velocity of different size fractions. Hence, reasonable working parameters should be adopted to avoid the accumulation of particles on the deck. Moreover, both particle shape and cohesion force have little effect on the screening processes of the roller screen.

Thrust force evaluation for a ROV (Remont Operating Vehicle) propeller

The underwater vehicles operated remotely, known from the specialized literature under the name of ROV are common and are intensively used in the maritime industry. Depending on the area of use, ROV must satisfy numerous constructive and functional requirements, which are difficult to achieve in practice and the simulation is a challenging alternative. The big challenge is the simulation of the thrust force generated by the propeller. The present work aims to present such a simulation realized with the Ansys Fluid Dynamics software package. The simulation presented uses a 3D model of an asymmetrical propeller in the duct, having as reference the T100 propeller marketed by Blue Robotics. The fluid volume extracted after the model was made was separated into two domains one static and other rotating around the propeller, which was discretized using the default grid generator. The solution was obtained under stationary conditions using only the flow equations together with the standard k-ε model for turbulence modelling. The calculation was made for rotation speed values in the working domain. In the end, using the facilities of the program, the thrust force of the propeller was calculated. The obtained results were compared with the experimental measurements and critical analysis will be done.

Numerical Simulation of the Flow and Heat Transfer in an Electric Steel Tempering Furnace

Heat treatments, such as steel tempering, are temperature-controlled processes. It allows ferrous steel to stabilize its structure after the heat treatment and quenching stages. The tempering temperature also determines the hardness of the steel, preferably to its optimum working strength. In a tempering furnace, a heat-resistant fan is commonly employed to generate moderate gas circulation to obtain adequate temperature homogeneity and heat transfer. Nevertheless, there is a tradeoff because the overall thermal efficiency is expected to reduce because of the high rotating speed of the fan. Therefore, this study numerically investigates the thermal efficiency changes of an electric tempering furnace due to changes in the rotating speed of the fan and the effects on temperature homogeneity and the heat transfer rate to the load. Heat losses through the walls were calculated from the external temperature measurement of the furnace. Four different speeds were simulated: 720, 990, 1350, and 1800 rpm. Thermal homogeneity was improved at higher rotating speeds; this is because the recirculation zone caused by the fan improved the flow mixing and the heat transfer. However, it was found that the thermal efficiency of the tempering furnace decreased as the rotating speed values increased. Therefore, these characteristics should be modulated to obtain a profit when controlling the rotating speed. For example, although thermal efficiency decreases by 20% when the rotating speed is doubled, the heat transfer rate to load is increased by up to 50%, which can be beneficial in decreasing the process of tempering times.

COMPUTER-AIDED PHASE IDENTIFICATION AND FRAME-TO-FRAME ANALYSIS OF ENDODONTIC ASYMMETRIC RECIPROCATION ROTATION: A PRELIMINARY STUDY

To perform a detailed evaluation of reciprocating motion using a computer-aided phase identification and frame-to-frame analysis, continuous rotation at 300 rpm, RECIPROC ALL mode and WAVEONE ALL-mode were recorded with a high-speed camera. Movie files were automatically analyzed with digital video analysis and modeling tool. RECIPROC ALL mode parameters were 186.34°±1.02 at 428.32 rpm ±7.61 and 65.07°±0.93 at 261.06 rpm ± 7.72; WAVEONE ALL-mode parameters were 191.39°±1.32 at 523.83 rpm ±14.36 and 70.13°±1.26 at 316.06 rpm ± 8.75. The variability of rotational speed during the cycle and distinct acceleration –deceleration patterns, was similar for both reciprocating modes. The computer-aided frame-to-frame analysis revealed that asymmetrical reciprocating motion has more complex kinematics demonstrating high peak rotational speed values and different patterns of acceleration and deceleration. While there was a difference in reciprocating cycle duration and rotational speed, both cycles demonstrated a similar dynamic of rotational speed during the cycle.

Research on spiral angle optimization for longitudinal road header's cutting head

The cutting head is the key component of a road header in tunnel excavation, where the concept of the spiral angle design directly affects the comprehensive performance, which includes cutting resistance, fluctuation coefficient, specific energy consumption, cutting head stress distribution, and so on. Based on the theory of rock-breaking by pick, the mechanical model of pick was established, and the three-dimensional force vector in the WORKBENCH coordinate system was determined. The 3D model of the proposed cutting head was designed using PRO/E and the static simulation was carried out using WORKBENCH, while the stress information of key parts was obtained. Furthermore, a four-dimensional fitting method was used to investigate the influence of the horizontal swing speed, rotational speed, and spiral angle of the cutting head, on the stress of the cutting head assembly. By setting the horizontal swing speed, rotational speed and the spiral angle as design variables and the specific energy consumption, total cutting resistance, fluctuation coefficient, power consumption, and stress on cutting head assembly as the objective function; the multiobjective optimization function of the cutting head was established. By using genetic algorithm, the complex problem has been solved. The solution of this optimization function provides the horizontal swing speed, rotational speed, and spiral angle values, where the optimal performance is achieved, in the aspect of energy consumption, cutting resistance, fluctuation coefficient, cutting power, and cutting motor power. This method provides solid guidance and is a great reference in spiral angle design and optimization.

Hydropower Generation Through Pump as Turbine: Experimental Study and Potential Application to Small-Scale WDN

Pump-As-Turbine (PAT) technology is a smart solution to produce energy in a sustainable way at small scale, e.g., through its exploitation in classical Water Distribution Networks (WDNs). PAT application may actually represent a suitable solution to obtain both pressure regulation and electrical energy production. This technology enables one to significantly reduce both design and maintenance costs if compared to traditional turbine applications. In this work, the potential hydropower generation was evaluated through laboratory tests focused on the characterization of a pump working in reverse mode, i.e., as a PAT. Both hydrodynamic (pressure and discharge) and mechanical (rotational speed and torque) conditions were varied during the tests, with the aim to identify the most efficient PAT configurations and provide useful hints for possible real-world applications. The experimental findings confirm the good performances of the PAT system, especially when rotational speed and water demand are, respectively, larger than 850 rpm and 8 L/s, thus leading to efficiencies greater than 50%. Such findings were applied to a small municipality, where daily distribution of pressure and discharge were recorded upstream of the local WDN, where a Pressure Reducing Valve (PRV) is installed. Under the hypothesis of PRV replacement with the tested PAT, three different scenarios were studied, based on the mean recorded water demand and each characterized by specific values of PAT rotational speed. The best performances were observed for the largest tested speeds (1050 and 1250 rpm), which lead to pressure drops smaller than those actually due to the PRV, thus guaranteeing the minimum pressure for users, but also to mechanical powers smaller than 100 W. When a larger mean water demand is assumed, much better performances are reached, especially for large speeds (1250 rpm) that lead to mechanical powers larger than 1 kW combined to head drops a bit larger than those observed using the PRV. A suitable design is thus fundamental for the real-world PAT application.

A Novel Z-blade Reaction Type Turbine for Low Head Low Flow Water Condition

This paper discusses the performance characteristics on efficiency and applicability of the test unit under low-head and low-flow condition for a novel Z-blade reaction type hydraulic turbine. Unlike large hydro power system, this technology’s superiority lies in the fact that it can harness electrical energy even from a small stream of water as energy sources and it does not poses any adverse environmental impact. This turbine was developed for an ideal and practical case which investigated applying the principal equations that were derived using the philosophies of conservation of mass, momentum, and energy. Assuming frictional losses factor or k-factor for different operating head, the relationship between rotor diameter, angular speed, flow rate, and power output was plotted and elaborated with allusion to the experimental data. Experiments were carried out at 5m head and below with the water flow rate less than 2.5L/sec, and it was evaluated against theoretical results. The turbine has a capability to achieve high values of rotational speed (up to 500 rpm) with minimal mass flow rate and high efficiency (up to 78%) at low head water condition (5m)

Survival of hollow glass microspheres in drilling fluids applications – Effect of drill bit/formation contact

This study concentrates on materials called hollow glass spheres (HGS), also known as glass bubbles, which are used to reduce the drilling fluid density below the base fluid density and overcome the shortcomings of compressible drilling fluids. The most important physical properties of the microspheres for oil field applications are their low specific gravity and high collapse strength. The lower the specific gravity, the greater their density reduction capabilities, meaning that less product is required to achieve the drilling fluid target density. High crush strength (and/or survivability) is equally important, as maintaining the target density is key to achieve and maintain bottom hole pressure control.The performance of drilling fluids made with HGS was evaluated for different drilling weight on bit (WOB) and rotation speed (RPM) values while controlling the flow rates. Experimental results show that when the HGS particles are subjected to mechanical contact between bit and formation, they will break. However, it was observed that the majority of HGS will not be exposed to contact between the cutter element and formation. Instead, they pass through the nozzle exit, leave the bit face region in a short period of time, and go directly into annulus, with minimum time of expose for contact. A mathematical model was developed to quantify the amount of HGS that become in contact between bit and formation, depending on various operational parameters, including effective blade length, flow rate and RPM. Finally, results from experiments and estimation models were compared, suggesting that the studied HGS successfully reduce the density of the base drilling fluid, and can survive the tested conditions.In summary, reducing the density of liquid based incompressible drilling fluids with glass bubbles is an alternative to available compressible underbalanced drilling fluid options at depleted zones or offshore wells with a very narrow density window.

МОДЕЛИРОВАНИЕ ЭНЕРГЕТИЧЕСКИХ ХАРАКТЕРИСТИК СТРУЙНО-РЕАКТИВНОЙ ТУРБИНЫ

The aim of the work is to develop a methodology for studying the gas flow in the flowing part of a jet-reactive turbine stage, consisting of a supply nozzle and an impeller, using the FlowVision software package, as well as calculating the parameters and characteristics of this stage. In the process of modeling and research, a large number of types of boundary conditions, initial grids and adaptation levels, time calculation steps, etc. were used and verified. The results of calculations of the energy characteristics of a jet-reactive turbine when setting the pressure and temperature of the braked flow at the inlet to the stage 701325 Pa (overpressure - 600000 Pa) and 288 K, respectively, and the static pressure at the exit from the stage 1010325 Pa are presented. The characteristics of the turbine on the circumference of the impeller, that is, without taking into account the moment of aerodynamic drag during rotation of the turbine rotor in a viscous gas environment are received. The main parameter necessary for calculating the power and efficiency of the turbine is the moment. It is shown that the circumferential (driving) moment of a jet-reactive turbine during calculations using the FlowVision software package can be determined in several ways, based on the results of the calculated parameters displayed in the information window. Comparison of the values of the driving moment obtained in different ways, including the one-dimensional theory, showed that they differ slightly: up to 12%. The dependences of the change in this moment on the rotor speed are given. The values efficiency of the circumferential power and circumferential efficiency on the rotor speed are obtained, and they are compared with the results of calculating these dependences according to the one-dimensional theory for the calculated and non-calculated regime of flow from the driving nozzle. The highest values of the peripheral power and peripheral efficiency are achieved in the range of rotation speed values of 24000-26000 rpm; maximum values of efficiency are in the range of 45-48%. It is shown that the proposed technique is the most reliable from the point of view of the adequacy of the processes inside the machine and the time-spending from the point of view of calculating the stationary mode. Verification of the obtained results was carried out according to the dependence of the starting moment on the pressure at the inlet of the jet-reactive turbine through comparing the calculation results by using the FlowVision software package with experimental data and the calculation results according to the one-dimensional theory.

Characterizations of weld defects, intermetallic compounds and mechanical properties of friction stir lap welded dissimilar alloys

This experimental investigation describes the effect of tilt angle and rotational speed on the characteristics of welding defects, intermetallic compounds, weld strength and micro-hardness in friction stir welding of thin sheets of AA6061-T6 and AISI304. Qualitative and quantitative assessments of the welding defects have been made by using X-ray micro computed tomography and metallographic study. Three-dimensional tomography and special distribution of internal voids (pores) have been discussed by correlating it to different values of tool rotational speed and tilt angle. Internal defects were localized in the stir zone. Welding at a tilt angle of 1° reduced both surface and internal defects. Non-uniform thickness of intermetallic compound (FexAly) layer has been found in the weld zone whose thickness varied with the values of process parameters. Higher weld porosity, bigger steel hook defect and increased layer thickness of intermetallic compound caused a significant reduction in the joint strength and elongation.

Experimental investigation of cutting temperature during drilling of float glass specimen

In today’s industrialization, hard and brittle material such as float glass are widely used in various applications such as micro-fluidic devices, bio-medical parts, automotive glass, and optical lenses. Due to its difficult-to-machine characteristic, drilling of float glass leads to defects related to drilled hole quality. These defects exemplify as chipping, crack and surface roughness. All these defects are directly depend upon the temperature which could affect the drilling quality. Hence, authors tried to investigate the influence of cutting temperature of float glass specimen using rotary ultrasonic drilling. The experimentation is performed at two conditions with constant value of ultrasonic amplitude (20 μm), feed rate (6 mm/min) and spindle rotation speed (5000 rpm). These conditions are without coolant and with-coolant drilling. It is noticed that maximum cutting temperature reached with coolant drilling is 50.56°c and without coolant is 62.11°c. Consequently, it is revealed that drilling with coolant (water) should be adopted to improve the hole quality. Since, it reduced the formation of stresses during drilling operation which are induced due to rise in temperature. Microstructure images are carried out to visualize the hole quality.

Galaxy Rotation in the Space of Four Distance Dimensions

This study contains the solution of the dark matter mystery of spiral galaxies by using the space of four distance dimensions x, y, z, x', in which x' is the fourth distance dimension. The calculation of galaxy rotation has been presented in the space of four dimensions by using two dimensional section x, x' and three dimensional section x, y, x'. The four dimensional mass M which generates the main gravitation field of galaxy is located at the fourth dimension at the distance x' = X' and other dimensions are zero x = 0, y = 0, z = 0. The method to calculate the speed distribution curve of four dimensional mass VM: the speed distribution curve VM is calculated by using the equation in which the gravitational force is equal to the centrifugal force of rotation. The solution of this equation yields the speed distribution component VM of the four dimensional mass M and the value of the mass M. In the publication [1] has been presented rotational speed distributions curves of the galaxy NGC 3198. The speed distribution curve of galactic halo in that publication corresponds to the speed distribution curve VM of four dimensional mass M of this study. In order to find out how well this four dimensional model functions, the speed distribution curve VM of four dimensional mass M has been calculated by using two pairs of rotational radius and speed values. The conclusions and findings: the calculated distribution curve VM was a good match for the halo curve of the publication [1]. Furthermore, four rotational speed distribution curve VM was calculated using different values of the distance X', which yielded different values for the maximum radius of galaxy. In this manner the different galaxy models of the publication [2] were obtained. By that means the solution of dark matter mystery has been proved.