Combination Of Rotational Speed Research Articles

Influence of operating parameters on the silt erosion performance of bare and coated SS304 steel

Purpose The purpose of this paper is to investigate the silt erosion performance of Bare, 75%Cr2O3 + 25%Al2O3 and 85%Cr2O3 + 15Al2O3-coated SS304 under various control parameters such as rotation speed, concentration of silt and particle size of silt used for making slurry. This can provide insight for using chromia and alumina-based coatings for hydro-turbines. Design/methodology/approach Taguchi approach was used to identify the effect of three input parameters on the bare and coated alloys. L16 orthogonal array is used for determining the signal-to-noise (S/N) ratio for each process parameter. For each level of parameters taken into consideration about the erosion wear, the arithmetic mean of the S/N ratio is calculated. On the essence of the results of S/N ratios, it is possible to determine the effect of the most dominating parameters of the erosion wear. Findings Results show that the erosion increases with an increase in silt concentration (Wt.%). It has been analyzed that the rotational speed has the most significant effect followed by the particle size and concentration on erosion wear for all uncoated and coated SS-304 samples. Maximum resistance to erosion is provided by 85%Cr2O3 + 15%Al2O3. The least erosion wear for process parameters has occurred at the optimal parametric combination of rotational speed (N) = 415 rev/min, concentration (C) = 15 Wt.% and particle size range as <53 µm for uncoated and coated stainless steel. Originality/value The study clearly shows the silt erosion performance of chromia and alumina coatings of different compositions at different input parameters. Peer review The peer review history for this article is available at: https://publons.com/publon/10.1108/ILT-01-2024-0028/

Investigation of microstructural and wear properties of stir cast and friction stir processed AA 2014-based metal matrix composites

ABSTRACT Due to the major applications in various industries, the global demand for Metal Matrix Composites (MMC) is increasing. The characteristics of manufactured composites highly depend upon the manufacturing method. The present research article showcases the manufacturing of three different compositions, namely AA 2014 + 5 wt.% SiC, AA 2014 + 10 wt.% SiC and AA 2014 + 15 wt.% SiC. A stir casting process has been implemented to manufacture these composites. While implementing the casting process one cannot get rid of the defects that are generated during the solidification. Thus, to avoid these defects in as-cast composites, friction stir processing (FSP) has been performed. FSP avoids casting defects and further enhances the distribution of reinforcement particles. The considered combinations of rotational speed and transverse speed are as follows (i) 270 rpm and 78 mm/min (E1 condition) and (ii) 190 rpm and 50 mm/min (E2 condition). Furthermore, the article compares the microstructure, microhardness and tribological properties of the as-received AA 2014 alloy, as-cast and processed composites. Irrespective of the FSP condition, AA 2014 + 10% SiC composites revealed the highest wear resistance among all the variety of specimens considered for the wear test.

An Improved Multi-Objective Optimization Decision Method Using NSGA-III for a Bivariate Precision Fertilizer Applicator

In order to boost the performance of a bivariable granular fertilizer applicator and simplify the control methodology of fertilization rate regulation, this paper proposed a fertilization decision method to obtain the optimal combination of rotational speed and opening length by selecting the accuracy, uniformity, adjustment time, and breakage rate as the optimization objectives. We processed the outlier data collected using the indoor bench test, segmented the data with the fertilization growth rate as the index, and proved the rationality of the data segmentation by an independent sample t-test. SVM, BPNN, ELM, and RVM were used to train the two data sections to create the fertilization rate prediction model, and the models with the highest accuracy in the two data sections were selected for the assembly of the final prediction model used to describe the fertilization process of the bivariate fertilizer applicator. Moreover, the fertilization performance problem model was established with the objectives of accuracy, uniformity, adjustment time, and breakage rate and was solved using the NSGA-III algorithm to gain an optimal fertilization decision. Compared with GA and MOEA-D-DE methods, the results show that, using the new method, the average relative error declines from 8.64% and 6.05% to 3.09%, and the average coefficient of variation reduces from 6.67% and 6.81% to 6.41%, respectively. In addition, the adjustment time lowers from 2.01 s and 1.33 s to 0.78 s, and the average breakage rate drops from 1.084% and 0.845% to 0.803%, respectively. It is indicated that the presented method offers the most notable improvements in accuracy and adjustment time, while the advancements in regard to uniformity and breakage rate is slight, but both are within a reasonable range.

Analysis and prediction of uncertain responses using regression and fuzzy logic for friction stir welding of AA2014 under n-MQL

AA2014 is an Al-Cu alloy friction stir welded under different combinations of rotational speed (800, 1000 and 1200 rpm) and transverse speed (44, 60, 72 mm/min) under minimum quantity lubrication condition with graphene nanofluid as coolant. Design of experiments is performed using Taguchi L9 orthogonal array. Analysis of variance technique is adapted to find the most influencing input parameter (rotational speed, transverse speed) of each output response (ultimate tensile strength, % elongation, microhardness and grain size). Regression and fuzzy logic based models are developed to predict the output responses. The reliability of the predicted results is tested by calculating the correlation coefficient. The predicted results from regression and fuzzy logic are then compared with the experimental results. The results of trend analysis exhibit the substantial influence of both the input parameters on the output responses. The results from ANOVA reveals that the rotational speed highly influences ultimate tensile strength and grain size while transverse speed majorly influences microhardness. The error in prediction using fuzzy model is observed to be significantly limited with correlation coefficients in the range of 0.70–0.96. The developed models are observed to be highly efficient and therefore can be used for prediction in any uncertain engineering applications.

Effect of Friction stir processing parameters on microstructure and microhardness of aluminium based Metal matrix composites

The present article demonstrates the Friction Stir Processing (FSP) of the stir cast Aluminium Alloy based Metal Matrix Composites (MMC). Generally, composites manufactured using the stir casting process tends to have several casting defects along with some agglomeration of reinforcement particles. These defects in stir cast composites can be resolved by implementing FSP. MMC was manufactured using the matrix of aluminium alloy 2014, which was reinforced with different weight percent of Silicon Carbide (SiC) particles (5%, 10% and 15%). FSP was performed by considering two different combinations of rotational speed and transverse speed i.e. (i) 270 rpm and 78 mm/min (First Combination) and (ii) 190 rpm and 50 mm/min (Second Combination). The article discusses the variation in microstructure and microhardness of all the friction stir processed composites and the effects of process parameters were examined. Lastly, the conclusion of the article suggests the best combination of processes parameters for performing FSP of manufactured composites.

Wind speed characterization of active turbulence generators installed upstream and downstream of the wind tunnel test section

The current study designed and fabricated multi-fin active turbulence generators (ATGs) and evaluated their wind speed characteristics with the long term aim of reproducing atmospheric flow in a lab environment. Two ATGs designed for the study are: (1) upwind ATG which consists of 24 square and triangular fins and is installed upwind from the test section and (2) downwind ATG which consists of 3 rectangular fins and is installed downwind from the test section. Experiments are conducted for several combinations of rotational speed and rotational angle and the amplitude of wind speed variation (uA) which is the difference between minimum and maximum wind speeds for each cycle is used to describe the characteristic of the ATGs. For the upwind ATG, values of uA decrease significantly with downstream distance. uA is large for larger rotational angle, but the effect of rotational speed is not very significant. For the ATG downwind, magnitude of uA is smaller compared to upwind ATG. However, uA does not vary significantly with streamwise location and maintains strong correlation with the cyclic motion of the ATG fins.

Achievable Thrust Expansion Control at Current Saturation of Variable-Pitch Propeller for Drones

On drones, which have become popular in recent years, the installation of variable pitch propellers is being considered and researched for industrial applications such as large drones and flying mobility. A variable-pitch propeller not only provides higher responsiveness than control by rotational speed alone, but also expands the thrust that can be achieved by optimizing the combination of rotational speed and pitch angle. In this paper, it is experimentally verified that, in the current saturation region of a variable-pitch propeller motor, the control method using simple frequency-separated command values for rotational speed and pitch angle causes an inverse response in transient conditions, and we attempt to explain this response by a linearized model including unstable zero. Basing on the model, we proposed a control method in which the pitch angle is controlled by a first-order filter while the maximum current is applied. The proposed method enables control design with a trade-off between initial undershoot and settling time with one parameter. The effectiveness of the proposed method is verified by simulation and experiment.

Shoulder Related Temperature Thresholds in FSSW of Aluminium Alloys.

Friction Stir Spot Welding (FSSW) is assumed as an environment-friendly technique, suitable for the spot welding of several materials. Nevertheless, it is consensual that the temperature control during the process is not feasible, since the exact heat generation mechanisms are still unknown. In current work, the heat generation in FSSW of aluminium alloys, was assessed by producing bead-on-plate spot welds using pinless tools. Coated and uncoated tools, with varied diameters and rotational speeds, were tested. Heat treatable (AA2017, AA6082 and AA7075) and non-heat treatable (AA5083) aluminium alloys were welded to assess any possible influence of the base material properties on heat generation. A parametric analysis enabled to establish a relationship between the process parameters and the heat generation. It was found that for rotational speeds higher than 600 rpm, the main process parameter governing the heat generation is the tool diameter. For each tool diameter, a threshold in the welding temperature was identified, which is independent of the rotational speed and of the aluminium alloy being welded. It is demonstrated that, for aluminium alloys, the temperature in FSSW may be controlled using a suitable combination of rotational speed and tool dimensions. The temperature evolution with process parameters was modelled and the model predictions were found to fit satisfactorily the experimental results.

Fabrication and processing of aluminum alloy metal matrix composites

ABSTRACT The present article demonstrates the procedure for fabrication of aluminum alloy 2014 based metal matrix composites having particulates of silicon carbide as reinforcement. Using the stir casting route, three different compositions of aluminum alloy metal matrix composites were fabricated. Microstructure of as-cast composites revealed a homogeneous distribution of silicon carbide particles along with few agglomeration and casting defects. Friction stir processing was performed to avoid such agglomeration and casting defects present in as-cast composites. The influence of friction stir processing parameters, that is, rotational speed and transverse speed on metallurgical properties, was investigated. Two combinations of rotational speed and transverse speed were considered: (i) 270 rpm and 78 mm/min and (ii) 190 rpm and 50 mm/min, respectively. As a result of friction stir processing, the microstructure of processed composites revealed the presence of fine silicon carbide particles along with the magnificent reduction in grain size. Composites processed with a rotational speed of 270 rpm and transverse speed of 78 mm/min were found to have higher grain refinement and as a result of this, the enhancement in microhardness was also observed. Except for a few cases, the average microhardness of all processed composites under both processed conditions was still lower than that of as–cast composites.

The effects of the operating conditions and tooth fault on gear vibration signature

The dynamic response of gear transmissions holds essential information for the recognition of faults in the system. A realistic nonlinear dynamic model is used to predict the vibration regime of spur gear transmissions. This model was validated experimentally for both healthy and damaged conditions. The model allows to simulate each combination of rotational speed, load and surface roughness, and to isolate its influence on the dynamic response. An experimental study would be limited due to the large amount of cases to consider. The simulated surface roughness enables a more realistic evaluation of the condition indicators robustness. The first part of the study examines the effects of the operating conditions, e.g. speed, load and surface roughness, on the vibration signature of a healthy gearbox. It was found that the levels at the gear mesh frequencies (GMF) have a strong dependency on speed and load. The energy of the frequency modulation (FM) sidebands depends mainly on speed but hardly affected by load. The second part of the study examines the manifestation of a single tooth face fault in the vibration signature. Based on the conclusions of the first part, the analysis was focused on the synchronous average spectrum and the difference signal. The investigation using hundreds of simulations shed a new light on the physical phenomena in the dynamic response - the fault’s expression is amplified around the natural frequencies of the gears. Based on this insight, it was found that the analysis of the spectrum around the natural frequencies allows the detection of incipient faults that cannot be detected using the analysis of the difference signal. The understanding of the physical phenomena, based on the dynamic model, enabled the generalization of this new finding.

Combined effects of pitch angle, rotational speed and site wind distribution in small HAWT performance

Constant speed horizontal axis wind turbines operate at power coefficients different than its maximum due to operation at different tip speed ratios (TSRs). Whereas rotational speed and the site wind speed distribution determine the TSR range of the operation, the pitch angle is significant for the aerodynamic performance of the wind turbine. In this paper, a blade element momentum approach is used to study the power production effects of pitch angle and rotational speed of NREL Phase VI wind turbine at different site wind distributions (characterized by Weibull distributions). It is shown that the best combination of rotational speed and pitch angle always occurs at the same pitch angle, but for different rotational speeds (other than the best one) the best pitch angle may vary. The best rotational speed is found to be dependent on both form and scale factors of Weibull wind speed distribution. Improvements in turbine pitch angle and rotational speed are found to increase generated energy up to four times, but the increasing factor is highly dependent on wind speed distribution: For the studied turbine, high-wind-speeds sites can benefit more from the adjustment of these parameters than low-speed ones.

Computational approach to the turbulent boundary layer of a rotating porous cylinder with strong suction based on an algebraic turbulence model

Many important technical systems operate according to the principles of momentum transfer, heat transfer and mass transfer near the surface of a cylinder rotating in a confined space. Numerical study of the Taylor–Couette flow with an imposed inward radial throughflow in the rotating inner cylinder demonstrates the possibility of flow stabilization to prevent large-scale vortices up to high rotation rates. The fluid is involved in rotation by the inner rotating cylinder only in a thin layer (boundary layer) near the cylinder surface with strong radial throughflow. Turbulence in the boundary layer may occur before the centrifugal instability, and there is a way to control the thickness of the layer as well as shear intensity and turbulence intensity near the surface of the rotating cylinder. The present work develops a compact and robust approach for the turbulent boundary layer calculation on the surface of a rotating cylinder based on an algebraic turbulence model. The generalized Cebeci–Smith model was supplemented with Richardson number-based corrections to address the centrifugal force action. It also generalized the correction used for accounting for wall suction. Analytical corrections and empirical coefficients of the model were tuned to reflect the coupled influence of the specific flow conditions. The approach, comprehensively verified in the preliminary research, was adapted to the desired geometric configuration and checked. The modified algebraic turbulent model was incorporated into an iterative calculation method developed especially for the case of axisymmetric boundary layers. The results of the algebraic turbulence model with different combinations of rotational speed and suction velocity agree well with the simulation results of the Reynolds stress turbulent model. The method proposed provides efficient practical engineering calculations and can be applied up to approaching the centrifugal instability in the boundary layer.

Stability analysis of a parametrically excited ball bearing system

In this paper, the stability analysis of a ball bearing system experiencing varying stiffness coefficients is taken into account. The presence of variable stiffness may cause the system to experience instabilities at given combinations of rotational speed, number, and the dimension of balls, thus complicating the design process. The objective is to obtain the stability boundary curves (SBCs) which separate the stable and unstable regions. The well-known Mathieu equation is adopted as the governing equations of the system in horizontal and vertical directions. In order to calculate the SBCs the equations of motion are solved applying approximate methods such as the harmonic balance method (HBM) and the multiple scales method (MSM). This procedure is straightforward if Uncoupled Mathieu equations, either Damped or Undamped, are considered, however, a realistic bearing system can be effectively described only using two coupled Mathieu equations, thus introducing two dominant frequencies which are not an integer coefficient of each other. This last Damped and Coupled set of equations applied to a bearing system is, for the first time, solved using HBM in place of resorting to cost intensive iterative methods. The accuracy of all investigated cases, Uncoupled–Undamped, Uncoupled–Damped and Coupled–Damped, is ensured by Floquet Theory.

Crack growth rate and lifetime prediction for aviation gas turbine engine compressor disk based on nonlinear fracture mechanics parameters

In this study, the fatigue crack growth and life-time prediction of aviation gas turbine engine compressor disks under operating conditions are analyzed. Different combinations of rotational speed, temperature, surface flaw forms and sizes, as well as elastic–plastic titanium alloy BT3-1 properties are considered. A crack growth rate equation, which included the fracture process zone size and nonlinear stress intensity factor, is derived. The assessments of the structural integrity of the rotating disk are compared for elastic and elastic-plastic solutions. It is indicated that the traditional elastic crack growth models overestimate the residual fatigue lifetime with respect to the nonlinear fracture mechanics approach.

Friction based joining process for high strength aerospace aluminium alloy

The present study investigates the metallurgical, mechanical and corrosion behavior on 6 mm plate, friction stir welded aluminium alloy (AA) 7475-T761. The process parameters of the welding process were optimized by using Box Behnken Method with a minimum number of trials. Optical and Scanning electron microscope (SEM) were used to evaluate the microstructure of weldment in different zones. Energy Dispersive x-ray Spectroscopy (EDS) analysis was carried out to analyze the extent of microsegregation of alloying elements in the different zones of the weldment. X-Ray diffraction (XRD) analysis was carried out to evaluate the phase formation and calculate the crystallite size, microstrain and dislocation density in the stir zone and base metal. Exfoliation corrosion was performed to evaluate the corrosion behavior of the weldment in the different zones. The results illustrate the defect-free welding was obtained by a combination of rotational speed (ω) 600 RPM, traverse speed (ν) 40 mm min−1 and axial force (p) 10 kN. The fine equiaxed microstructure was observed in the stir zone. EDS analysis shows the extent of Cu rich microsegregation in the stir zone. Weldment produced by the above combination of parameters exhibit 76% joint efficiency. Hardness value along the weldment reveal 26% improvement in stir zone compared to the base metal due to refined microstructure. X-Ray diffraction analysis point out the high dislocation density and strain induced in stir zone is caused by dynamic recrystallization. Corrosion study confirms the stir zone has higher resistance to corrosion compared to adjacent thermos-mechanical affected zone.

Microstructural and Wear Characteristics of Friction Stir Processed Al-7075/SiC Reinforced Aluminium Composite

Abstract Friction stir processing (FSP), a solid-state surface modification technique, derived from friction stir welding (FSW) process has been evolved as an efficient energy processing technique to fabricate aluminium matrix composites (AMCs). In the present investigation, FSP was used to fabricate 7075-T651 aluminium alloy surface composites using micro sized silicon carbide (SiC) particles as reinforcement. Since Aluminium 7075 alloy has a vast applications in the automotive and aerospace and having the highest strength among all commercial Al-alloys, has been selected for the matrix phase. AMCs were fabricated at different combinations of rotational speed and welding speed. The different combinations were tested for single and triple pass. The fabricated surface composites were examined for microstructure using SEM equipped with EDXS. The micro-hardness was measured and sliding wear behaviour was also evaluated using a pin on disc apparatus. It was observed that the average hardness of the FSP zone composite was 1.65-2.15 times higher than that of parent metal (78VHN). Wear rate along with the frictional force characteristics were found to be promising than the parent metal.

Life-time prediction for aviation GTE compressor disk based on mixed-mode and multi-axial fracture resistance parameters

This study is concerned with analysis of fatigue crack growth and life-time prediction for aviation GTE compressor disk under operation conditions. For consideration were different combinations of rotational speed, temperature, surface flaw form and sizes as well as elastic-plastic titanium alloy BT3-1 properties are employed. A crack growth rate equation is derived involving the fracture process zone size and nonlinear stress intensity factor. The assessments of the structural integrity of the rotating disk are compared for elastic and elastic-plastic solutions. It is stated that the traditional elastic crack growth models overestimate the residual fatigue lifetime with respect to the nonlinear fracture mechanics approach.

Experimental investigation of stall inception of a low speed contra rotating axial flow fan under circumferential distorted flow condition

The present paper is aimed to understand the stall inception phenomenon and its propagation in a low speed, contra rotating axial flow fan stage, operating with circumferential inflow distortion. A 90-degree sector mesh screen is used to simulate the total pressure inflow distortion. Unsteady pressure data from casing wall-mounted sensors are used to understand the stall inception mechanism. The unsteady pressure data is analyzed using wavelet transforms and Fast Fourier Transforms (FFT). The wavelet transform is used to identify the stall inception mechanism where as FFT is also used for quantitative analysis. The rotors used in this study have relatively large tip gap and aspect ratio of 3. The study was carried out near-stall and at stall mass flow conditions for design speed and off design rotational speed combinations of the rotors. The study reveals that under circumferential inflow distortion, the stall incepts at higher mass flow compared with clean flow and the stall emerges first at the distorted sector and it propagates circumferentially based on the rotational direction of the two rotors. The wavelet transform clearly indicates that stall inception occurs mainly through long length-scale disturbances (LLSDs) for both the rotors and the spikes are observed to appear within the LLSDs. In some cases, only spike type of stall appears for rotor-1. The most interesting observation of the present study is that the casing wall pressure fluctuations and the stall frequency amplitude of rotor-2 are stronger than that of rotor-1.

Kinematic Analysis and Experimental Research on the Seedling Pick-Up Mechanism of a Second-Order Free Noncircular Planetary Gear System

<abstract> <sc><b>Abstract.</b> </sc>Potted-seedling transplantation has great significance in agriculture production. At present, potted-seedling transplanting in dryland production is accomplished by the seedling pick-up mechanism and the seedling planting mechanism. The seedling pick-up mechanism must achieve the function of picking up seedlings from the plug tray in an orderly manner and delivering seedlings to the seedling planting mechanism; the design of such a mechanism is challenging, and the efficiency and performance of the existing seedling pick-up mechanism are not perfect. The relationship between the olecranon-shaped trajectory of the noncircular planetary gear mechanism and the transmission ratio of the noncircular gear was illuminated in previous research. The seedling pick-up mechanism in the form of double manipulators controlled by a second-order free noncircular planetary gear system was studied in this article. The trajectory and attitude requirements allowing the seedling pick-up claw to attain the required motion were analyzed in detail, the mechanism‘s ideal movement objectives were proposed, and the parameters of the transmission ratio and mechanism structure were optimized. A prototype was produced to carry out the experiment, and the optimal combination of rotational speed of the mechanism, seedling pick-up azimuth angle, clamping quantity and seedling pick-up depth were found. The research results show that the seedling pick-up mechanism of a second-order free noncircular planetary gear system is efficient and is a better choice for the seedling pick-up mechanism used in potted-seedling transplantation in dryland production.

Evaluation of the Effects of Rotary Degassing Process Variables on the Quality of A357 Aluminum Alloy Castings

The effects of rotary degassing process variables on the melt and casting quality have been investigated using reduced pressure test results and quality index calculations from tensile data. The results showed that the effectiveness of the rotary degassing process of Al alloys is highly dependent on the combination of rotational speed and the gas flow rate, and that the wrong combination of these factors may result in no improvement or even degradation in quality of castings. For the first time, it has been found that the effectiveness of the pouring and filling system to produce high-quality castings can be characterized numerically. This new method of quantifying the casting system is introduced as a new quality improvement tool for materials and process engineers.