Values Of Rotational Speed Research Articles

Experimental Study and 3D Optimization of Small-Scale Solar-Powered Radial Turbine Using 3D Printing Technology

Small-Scale Turbines (SSTs) are among the most important energy-extraction-enabling technologies in domestic power production systems. However, owing to centrifugal forces, the high rotating speed of SSTs causes excessive strains in the aerofoil portions of the turbine blades. In this paper, a structural performance analysis is provided by combining Finite Element Methods (FEM) with Computational Fluid Dynamics (CFD). The primary objective was to examine the mechanical stresses of a Small-Scale Radial Turbine (SSRT) constructed utilizing 3D printing technology and a novel plastic material, RGD 525, to construct a SSRT model experimentally. After introducing a suitable turbine aerodynamics model, the turbine assembly and related loads were translated to a structural model. Subsequently, a structural analysis was conducted under various loading situations to determine the influence of different rotational speed values and blade shapes on the stress distribution and displacement. Maximum von Mises and maximum main stresses are significantly affected by both the rotor rotational speed and the working fluid input temperature, according to the findings of this research. The maximum permitted deformation, on the other hand, was more influenced by rotational speed, while the maximum allowable fatigue life was more influenced by rotating speed and fluid intake temperature. Also, the region of the tip shroud in the rotor had greater deflection values of 21% of the blade tip width.

Analysis of Factor Effects in Process of Vertical Centrifugal Casting

ABSTRACT The effects of mold rotation speed, pouring temperature, preheating mold temperature, pouring rate and coating thickness on the solidification time, shrinkage porosity and melt velocity in vertical centrifugal casting were investigated. To minimize computation time and obtain adequate estimate of the effects, a Fractional Two – Level Factorial Design 2(5–1) was applied. The results were obtained by numerical simulations using ProCAST software. The regression model was developed using Design Expert software. The analysis of variance revealed that the coating thickness had the most pronounced effect on the solidification time and shrinkage porosity. Finally, the procedure for selecting the optimal factors was carried out by application of multi objective optimization. The shortest solidification time was 20.68 s, while the shrinkage porosity was negligible, and it was achieved with the highest value of mold rotation speed and the lowest values of pouring temperature, preheating mold temperature, pouring rate and coating thickness.

Evaluation of dissimilar 7075 aluminum/AISI 304 stainless steel joints using friction stir welding

Friction stir welding of dissimilar 7075 aluminum/AISI 304 stainless steel joints was done using different tool rotational speed values. The weld was mainly formed in the aluminum part due to the offset value, and stainless steel particles were surrounded with the stirred fine-grained Al matrix. Intermetallic compounds consisting of FeAl3, Fe3Si, FeAl, Fe4Al13 and Fe3Al2Si4 were found in the weld bead. The thickness of the intermetallic compound layers was increased up to 6 µm by increasing the tool rotational speed. Moreover, the stir zone was mainly characterized by a composite-like structure. The weld strength was increased significantly by decreasing the tool’s rotational speed. The maximum strength of joints was about 72% of 7075 aluminum strength. The formation of extensive intermetallic compound layers could be the reason for the reduced joint strength. In specimens with higher tool rotational speeds, fracture occurred within the stir zone.

Analyzing the S-characteristic of pump-turbine under the same head condition from the perspective of flow energy dissipation

The S region on the full characteristic curve of pump-turbine is one of the important key features that affect its operation stability. In S region, one specific rotational speed value ( n11) corresponds to three specific flow rate values ( Q11), which causes the unit to fluctuate between different operation conditions. In this paper, focusing on the special region of pump-turbine, based on the combination of model experiment and numerical simulation, the S-region dynamic model of pump-turbine is established. The internal flow mechanism of pump-turbine is analyzed in detail from the perspective of Flow Energy Dissipation (FED). The results show that the high FED component is different at different operating points, but the flow energy maintain balance in the pump-turbine unit. High FED area displayed in near-wall or inter-channel of different components under different flow conditions. Besides, the generation of S region is related to the dynamic balance of energy especially in the no-load region. The analysis results of this paper provide theoretical basis for scientific and stable operation of pump-turbine.

Impact of starter culture on biochemical properties of sourdough bread related to composition and macronutrient digestibility

Due to the desire for nutritionally dense foods, there is interest in whole grain and sourdough bread products. This research study was carried out to evaluate the effect of different starter cultures and stone mill settings on the nutritional attributes of sourdough bread. Using a stone mill, a blend of three hard red spring wheat varieties was ground into whole-grain flour. Three different gap settings and two different rotation speed values were used to produce flour samples with six different treatments, and those six flour samples were used to make sourdough bread with two different starter cultures. The experimental design was a randomized complete block design with a factorial arrangement. Significant differences (p < 0.05) were observed in dietary fiber content, arabinoxylan content, total starch content, and protein digestibility between sourdough bread made with rye and wheat starter cultures. Higher protein digestibility values were observed for most of the sourdough samples with the rye starter culture compared to the wheat starter culture. In addition, the protein digestibility showed a strong negative correlation (r = −0.85) with the coarse particles and a positive correlation (r = 0.70) with the fine particle size fraction. These results demonstrated that selected starter cultures and the raw material with the desired particle size could improve sourdough bread's nutritional attributes and potential application in the baking industry.

Investigation of Data Pre-Processing Algorithms for Power Curve Modeling of Wind Turbines Based on ECC

Data pre-processing is the first step of using SCADA data to study the performance of wind turbines. However, there is a lack of knowledge of how to obtain more effective data pre-processing algorithms. This paper fully explores multiple data pre-processing algorithms for power curve modeling. A three-stage data processing mode is proposed, namely, preliminary data filtering and compensation (Stage I), secondary data filtering (Stage II), and single-valued processing (Stage Ⅲ). Different data processing algorithms are selected at different stages and are finally merged into nine data processing algorithms. A novel evaluation method based on energy characteristic consistency (ECC) is proposed to evaluate the reliability of various algorithms. The influence of sliding mode and benchmark of Binning on data processing has been fully investigated through indicators. Four wind turbines are selected to verify the advantages and disadvantages of the nine data processing methods. The result shows that at the same wind speed, the rotational speed and power values obtained by MLE (maximum likelihood estimation) are relatively high among the three single-valued methods. Among the three outlier filtering methods, the power value obtained by KDE (kernel density estimation) is relatively large. In general, KDE-LSM (least square method) has good performance in general. The sum of four evaluating index values obtained by KDE-LSM from four wind turbines is the smallest.

Evaluation of the rotary kinematics between actual and set speeds of X-Smart Plus, VDW.Silver and iRoot motors.

The present study evaluated the actual rotational speed of three different endodontic motors compared to the values provided by the manufacturers. A total of three endodontic motors (X-Smart Plus, VDW.Silver, and iRoot) were tested at 400 rpm and 800 rpm and 2 N/cm2 torque. The kinematics of the devices was recorded by using a custom angle-measuring disc with a 50-mm diameter attached to the handpiece provided by the manufacturer, whereas their movement was captured by a high-speed camera at 2,400 frames per second, 800 x 800 pixel-resolution and distance of 0.3 m from the target object. Statistical analysis was performed at a significance level of 5%. At 400 rpm, the iRoot motor had a value of 17.94 rpm above that indicated by the manufacturer, which was significantly different from those of X-Smart Plus (5.20 rpm below that indicated by the manufacturer) and VDW.Silver (0.62 rpm above that indicated by the manufacturer) motors (P < 0.05). At 800 rpm, the iRoot motor had a value of 51.34 rpm below that indicated by the manufacturer, whereas the X-Smart Plus motor had a value of 13.00 rpm below that indicated by the manufacturer (P > 0.05). The VDW.Silver motor statistically differed from the iRoot and X-Smart Plus ones, showing a value of 1.68 rpm above that indicated by the manufacturer. In conclusion, the X-Smart Plus, VDW.Silver, and iRoot motors showed lower variations in the rotational speed values compared to those reported by their manufacturers. The endodontic motors presented different behaviors between them, with the VDW.Silver motor presents the most accurate values and the iRoot presents the most divergent values.

Significance of underwater friction stir welding on the weld integrity of thin sheets of aluminum (AA1050-O) and brass (CuZn34) joints

Classical friction stir welding (C-FSW), because of its solid-state joining nature, offers several benefits over traditional fusion welding for joining dissimilar materials. C-FSW conducted in open air, are affected by several weld flaws and thick Intermetallic Compounds (IMCs) that reduce the weld joint quality. In this study, FSW of thin sheets of aluminum alloy (AA1050-O) and brass (CuZn34) in lap joint configuration was performed in air and underwater. The main objective of this study was to investigate the feasibility of underwater-FSW (UW-FSW) for obtaining aluminum and brass (Al-Brass) joints at different values of shoulder plunge depth (SPD) and tool rotational speed (N). To determine the effect of welding temperature at different values of SPD and N on the formation of weld joints, K-type thermocouples were used. Underwater welding reduced the welding temperature and thermal cycle time. The optical images of C-FSW joints revealed the presence of kissing bonds, wavy patterns, cracks, tunnels, and void defects. In UW-FSW, the faster cooling rate significantly reduced these weld flaws. Electron backscattered diffraction (EBSD) and transmission electron microscopy (TEM) were used for the microstructural characterization. EBSD and TEM results show fine microstructure and precipitates in UW-FSW specimens. The X-ray diffraction results demonstrated that the weld joint interface primarily consisted of Al-Cu & Cu-Zn IMCs in the form of Al4Cu9, Al2Cu, AlCu3, AlCu4, CuZn5, and Cu5Zn8. The amount of IMCs was less in the joints produced by UW-FSW. The obtained results were used to understand the variation in the weld strength of C-FSW and UW-FSW joints at different values of SPD and N. To further evaluate the interface of the Al-Brass weld joint, energy dispersive spectroscopy (EDS) and scanning electron microscopy (SEM) were employed. EDS confirmed the presence of brass fragments in the stirred zone of aluminum substrate. TEM and SEM images illustrated fine precipitates and formation of thin IMC layers in UW-FSW. The tensile test result shows that the UW-FSW remarkably improved the joint strength. The percentage increase in the joint tensile strength for UW-FSW was found 42%, 30% and 50% higher than C-FSW for lower, medium and high heat input welding conditions. The lower heat input in UW-FSW significantly suppressed the formation of weld flaws and IMCs, which collectively improved the tensile strength of the weld joint.

Statičko ponašanje funkcionalno stepenovanih rotirajućih konzolnih greda korišćenjem B-splajn tehnike kolokacije

The present work reports the static behaviour of functionally graded rotating beam based on Timoshenko beam theory, which includes the effect of shear deformation. The principle of virtual displacement is applied to derive a governing equation for the functionally graded (FG) rotating beam, considering the centrifugal stiffening effect. The B-spline collocation technique is employed to solve the differential equation and material properties are function of power law distribution. The effect of material power index and rotational speed on the static characteristics of functionally graded rotating cantilever beams has been investigated for two different slenderness ratios. The obtained results demonstrate the beam deflection and the beam normal and shear stresses for the power gradient and rotational speed values. The results help to conclude that material gradation can be utilized to improve the functioning of the rotating structures such as helicopter rotor, aircraft propellers, windmill blades etc.

Rotor Wake Investigation Under Autorotation Condition in Water Tunnel

This paper focuses on the wake features of autorotation status mainly including the induced velocity and tip vortex trajectory in order to preliminary explanation the principle of rotation. In this work, the flow features of autorotating rotor were investigated in water tunnel via particle image velocimetry (PIV) technique. The experiments were conducted with a two-blade single rotor which can freely rotate. The stable rotational speed with various pitch and shaft backward angle was recorded and analyzed. The results show that there is a threshold value of stable rotational speed at shaft backward angle and an optimal region at pitch angle. The PIV results showed that the velocity of the internal wake was much lower than the external, indicating a consuming of energy from the flow, which was in accord with momentum theory. The vortices have three prominent parts: tip vortices, wake sheets and root vortices. There is no apparent interference between wake sheets and tip vortices. The vorticity of the tip was observed to increase in near wake due to lesser interference with the sheets. The Beddoes’s model was employed to calculate the tip vortex location with respect to the rotor. The experimental results are in good agreement with the calculated results. It is meaningful for the study to enrich the autorotation theory of rotor and develop underwater rotorcraft.

Mechanical Properties Enhancement of Dissimilar AA6061-T6 and AA7075-T651 Friction Stir Welds Coupled with Deep Rolling Process.

The main purpose of this research was to enhance the mechanical properties of friction stir welds (FSW) in the dissimilar aluminum alloys 6061-T6 and 7075-T651. The welded workpiece has tensile residual stress due to the influence of the thermal conductivity of dissimilar materials, resulting in crack initiation and less fatigue strength. The experiment started from the FSW process using the 2k full factorial with the response surface methodology (RSM) and central composite design (CCD) to investigate three factors. The experiment found that the optimal rotation speed and feed rate values were 979 and 65 mm/min, respectively. Then, the post-weld heat treatment process (PWHT) was applied. Following this, the 2k full factorial was used to investigate four factors involved in the deep rolling process (DR). The experiment found that the optimal deep rolling pressure and deep rolling offset values were 300 bar and 0.2 mm, respectively. Moreover, mechanical property testing was performed with a sequence of four design types of workpieces: FSW, FSW-PWHT, FSW-DR, and FSW-PWHT-DR. It was found that the FSW-PWHT-DR workpiece had an increase in tensile strength of up to 26.29% and increase in fatigue life of up to 129.47% when compared with the FSW workpieces, as well as a maximum compressive residual stress of −414 MPa.

The influence of tool rotation speed on the low-cycle fatigue behavior of AA2519-T62 friction stir welded butt joints

The subject of this study were the friction stir welded butt joints of the 5 mm thick AA2519-T62 alloy obtained with four various values of tool rotation speed: 200, 400, 600 and 800 rpm, and the constant welding velocity of 100 mm/min. The examination involved macro and microstructure observations, microhardness, tensile, and fatigue testing. An increase in the stir zone size and microhardness has been reported together with increasing tool rotation speed. The weld obtained with the lowest value of tool rotation speed (200 rpm) is characterized by a significant reduction of microhardness in the SZ, which makes it very susceptible to plastic deformation. In terms of tensile properties, there is a tendency of increasing welds’ yield and tensile strength together with increasing applied tool rotation speed. The tensile failures occur in the LHZ, which is located, depending on tool rotation speed, at the SZ (200 rpm), at the HAZ/TMAZ interface (400 rpm) or at the SZ/TMAZ interface (600 and 800 rpm). For AA2519-T62 and its FSW joints, the cyclic strain hardening is stronger than monotonic strain hardening. The LCF behavior of the FSW joints have been described by the parameters of the Manson-Coffin-Basquin, taking into account the Smith-Watson-Topper parameter. The established fatigue parameters indicate that the joints produced with the 400–600 rpm tool rotation speed exhibit the lowest reduction in fatigue strength coefficient. The fractured surfaces have a typical fatigue striation pattern with the participation of secondary cracks and small Al2Cu particles.

Evaluation of three-phase centrifugal separator machine (Tricanter) for olive oil extraction

One of the most important machines in the olive oil extraction line is the horizontal three-phase centrifugal separator machine or Tricanter. The purpose of this paper is to evaluate the machine designed on the basis of Tricanter and to evaluate the quality of extracted olive oil. For this purpose, four different olive cultivars from Gilan Province in Iran were used. In this research the rotational speed of the Tricanter machine was tested at three levels of 2 500, 3 000, and 3 500 rpm and the content of water added to olive paste was used at three levels of 10, 20, and 30% of the paste mass. Peroxide value (PV) and percentage of acidity were measured for oil extracted from all four olive cultivars. The results of the analysis of variance (ANOVA) test showed that rotational speed and the content of added water had an effect on the acidity and PV for all samples of olive cultivars. The measured values showed that the best speed for the Tricanter machine is 3 500 rpm. At this rotational speed, the peroxide and acidity values are lower than the standard values.

Effect of Operating Parameters and Energy Expenditure on the Biological Performance of Rotating Biological Contactor for Wastewater Treatment

The rotating biological contactor (RBC) is resistant to toxic chemical and shock loadings, and this results in significant organic and nutrient removal efficiencies. The RBC system offers a low-energy footprint and saves up to 90% in energy costs. Due to the system’s low-energy demand, it is easily operable with renewable energy sources, either solar or wind power. An RBC was employed to degrade pollutants in domestic wastewater through biodegradation mechanisms in this study. The high microbial population in the RBC bioreactor produced excellent biological treatment capacity and higher effluent quality. The results showed that the RBC bioreactor achieved an average removal efficiency of 73.9% of chemical oxygen demand (COD), 38.3% of total nitrogen (TN), 95.6% of ammonium, and 78.9% of turbidity. Investigation of operational parameters, disk rotational speed, HRT, and SRT, showed the biological performance impact. Disk rotational speed showed uniform effluent quality at 30–40 rpm, while higher values of disk rotational speed (&gt;40 rpm) resulted in lower effluent quality in COD, TN, and turbidity. The longer hydraulic retention time and sludge retention time (SRT) facilitated higher biological performance efficiency. The longer SRTs enabled the higher TN removal efficiency because of the higher quantity of microbial biomass retention. The longer SRT also resulted in efficient sludge-settling properties and reduced volume of sludge production. The energy evaluation of the RBC bioreactor showed that it consumed only 0.14 kWh/m3, which is significantly lower than the conventional treatment methods; therefore, it is easily operable with renewable energy sources. The RBC is promising substitute for traditional suspended growth processes as higher microbial activity, lower operational and maintenance costs, and lower carbon foot print enhanced the biological performance, which aligns with the stipulations of ecological evolution and environment-friendly treatment.

Estimation of wind turbine output power using soft computing models

ABSTRACT Among renewable energy generation technologies, wind energy has become one of the most outstanding issues, especially in the last decade. Wind speed is the most critical parameter influencing the power obtained from a wind turbine. The unstable structure of the wind causes an impossibility to receive a direct theoretical relation between wind power and speed. Accordingly, obtaining a simulation of the generated turbine power concerning the approaching wind speed has become vitally essential, nowadays. In the current study, generated wind turbine power (P) has been predicted using three forecasting methods. The computer was trained using wind speed (V) and the turbine rotor rotational speed (ṅ) as the inputs of the forecasting methods. The methods used for this purpose were to include adaptive neuro-fuzzy inference system (ANFIS), Elmanneural network (ENN), and feed-forward neural network (FNN) approaches. In the training of the programs, among the cumulative of 43,800 wind speed, turbine rotor rotational speed, and wind power data, 80% and 20% of the total data were used for training and testing stages of the algorithms, respectively. The statistical results of the computations demonstrated that among three methods, ANFIS gave better outcomes when compared to ENN and FNN, in both the training and testing stages of the algorithms. The proposed models of the current study have revealed low and acceptable mean absolute error (MAE) and root mean square error (RMSE) statistical error results of ANFIS tool; corresponding to 52.448 kW and 87.204 kW error, respectively, were obtained at the training stage, whereas 48.675 kW and 78.453 kW error, respectively, were obtained at the testing stage. For the estimation of wind power, while the coefficient of determination (R 2) was detected as R2 = 0.9948 and 0.9961 in training and testing stages, respectively, with ANFIS model, it was found out as R2 = 0.9942 and 0.9957 with ENN model and R2 = 0.9943 and 0.9956 with FNN model. Namely, it has been reported that ANFIS tool can be successfully applied in wind output power estimations, as long as wind speed and turbine rotor rotational speed values are provided without the need for numerous experimental measurements, which induces additional time, labor, and measurement expenses.

Hydrothermal and Entropy Investigation of Nanofluid Mixed Convection in Triangular Cavity with Wavy Boundary Heated from below and Rotating Cylinders.

Nanofluids have become important working fluids for many engineering applications as they have better thermal properties than traditional liquids. Thus, this paper addresses heat transfer rates and entropy generation for a Fe3O4/MWCNT-water hybrid nanoliquid inside a three-dimensional triangular porous cavity with a rotating cylinder. The studied cavity is heated by a hot wavy wall at the bottom and subjected to a magnetic field. This problem is solved numerically using the Galerkin finite element method (GFEM). The influential parameters considered are the rotating cylinder speed, Hartmann number (Ha), Darcy number (Da), and undulation number of the wavy wall. The results showed that higher Da and lower Ha values improved the heat transfer rates in the cavity, which was demonstrated by a higher Nusselt number and flow fluidity. The entropy generation due to heat losses was also minimized for the enhanced heat transfer rates. The decrease in Ha from 100 and 0 improved the heat transfer by about 8%, whereas a high rotational speed and high Da values yield optimal results. For example, for Ω = 1000 rad/s and Da = 10−2, the enhancement in the average Nusselt number is about 38% and the drop in the Bejan number is 65% compared to the case of Ω = 0 rad/s and Da = 10−5. Based on the applied conditions, it is recommended to have a high Da, low Ha, one undulation for the wavy wall, and high rotational speed for the cylinder in the flow direction.

Experimental Study of Drag Torque between Wet Clutch Discs

The development of automatic gearbox control systems contributes to their increasing popularity. By raising the number of gears and sophisticated algorithms, the reduction of fuel consumption is feasible regarding traditional manual transmissions. The continuously variable transmissions (CVT) are also growing their share of the market. Wet clutches are employed in all types of automatic transmissions, but because of oil viscosity, when such a type of clutch is disengaged, the drag torque phenomenon occurs. This deteriorates the global efficiency of the transmission system. To recognize the nature of this drag torque and how it is influenced by the main parameters (distance between plates, value of oil flow rate lubricating clutch, oil temperature, rotational speed between plates), a new test stand has been designed and assembled. The value of rotational speed has been studied up to 7000 rpm which is novel in literature. Due to strongly nonlinear dependences, the achieved results can contribute to designing more efficient clutch systems due to the strongly nonlinear nature of observed phenomena.

The Effect of Misalignment to Vibration, Electric Current and Shaft Rotation Speed on Gear Transmission

Gear is a rotating machine that is widely used as a power transfer transmission in many industries. Gear has a long life times. However, the gears can be damaged due to many factors such as out of the maintenance, which one factor of misalignment. This study aim is to determine the effect of misalignment on the gear transmission to vibration, electric current and shaft rotation speed. In this study, was done alignment process with variations of misalignment on the gear transmission alignment kit and was done measurement value of vibration, electric current and shaft rotation speed. The study results show the greater the misalignment, the greater the vibration that occurs either radially or axially for all conditions measured. The shaft rotation was slower with the greater misalignment. The misalignment can affect the decrease in the rotation speed of the shaft. Therefore, it can reduce the efficiency for power transmission of engine.

Neoclassical transport analysis of high rotational trace limit tungsten impurities in KSTAR tokamak

The accumulation of tungsten impurities measured in a KSTAR experiment was analyzed theoretically using a drift-kinetic code, NEO, to determine the contribution of neoclassical transport. According to the NEO simulation results, there is a certain value of impurity toroidal rotation speed maximizing the neoclassical inward convection. The inward convection decreases or the outward convection increases as the rotation increases only beyond the speed value. The non-monotonic dependency of the neoclassical convection on the rotation is analyzed by the several coefficients for many profile effects, including ion and electron profiles. The dependency of the coefficients for the main ion density gradient on the rotation is different from that for the temperature gradient, so it results in the amplification of the temperature screening beyond the certain value of the rotation. In the KSTAR case with high toroidal rotation of the tungsten (around Mach number 4.5), only in the mid-radius does the rotation reduce the inward impurity particle convection or change the inward convection to the outward convection. Thus, the rotation is a useful tool to control the impurity accumulation conditionally. The favorable condition occurs only for high rotation, which significantly depends on the radius and the collisionality due to the complicated non-monotonic dependency of the convection on the rotation speed.

Research of ecological indicators of two-way vehicle in stationary conditions

The article concerns the research on the emission of pollutants of a rail-road tractor in two stationary research tests. The purpose of the tests was to carry out control tests of pollutant emissions and their analysis. The object used during the works was approved in accordance with the Stage V standard, which requires measurements of emissivity both in stationary, dynamic and real conditions. Despite the requirement to test engines installed on a vehicle during their normal duty cycle with PEMS, the emission limits measured in this test have not yet been defined. Therefore, the work below focuses on the stationary test cycle. The measurements were carried out in accordance with the combustion engine operating points described in the approval test, and then compared with the modernized NRSC test. It contains modified measuring points and rotational speeds of the crankshaft, adopted on the basis of the most common operating parameters of agricultural tractor combustion engines in real operating conditions. The measurements were performed with the use of a mobile dynamometer and devices for measuring emissions of harmful exhaust gas compounds and recording on-board data. In the test, the vehicle drive system worked at fixed operating points, with defined values of crankshaft rotational speed and load. Based on the recorded data on the concentrations of pollutants in the exhaust gases, the specific emission of the object was determined. In the final stage of the work, these data were used to perform a comparative analysis with the emission limits contained in the standard.