Pitch Circle Diameter Research Articles

Simulation and Experimental Study of Ultrasonic Vibratory Grinding of Internal Splines

As an important component of mechanical transmission systems, internal splines are widely used in aerospace, industrial equipment, and other fields. However, internal splines are prone to deformation and shrinkage after heat treatment. At present, most internal splines with a pitch circle diameter greater than φ60 mm can be processed and shaped by ordinary corundum grinding wheels, but there is no effective processing method for the shaping of small- and medium-sized internal splines. This paper establishes a single abrasive material removal model; uses Abaqus to simulate three-body free grinding; and analyzes the effects of abrasive rotation angle, rotation speed, and grinding depth on material removal under different conditions. By comparing the tooth lead deviation and tooth direction deviation before and after internal spline grinding, the experimental results show that after ultrasonic vibration grinding, the internal spline tooth profile deviation is reduced by 41.9%, and the tooth direction deviation is reduced by 44.1%, which provides a new processing method for the deformation recovery of internal splines after heat treatment.

CFD—ANN study on axial dispersion in helical and serpentine millimetric coils

CFD simulations are reported to compare hydrodynamic/axial dispersion in a classical helical-shaped and planar serpentine-shaped tubular reactor at a millimetric scale (1-5 mm) for the first time. A two-step simulation approach is validated against experimental data on residence time distribution in serpentine coils. The method is then used for parametric analysis to explore the impact of geometric parameters on the coiling factor and axial dispersion coefficient. Dean vortices in the coiling region are visualized. The findings from the parametric analysis are utilized to develop empirical correlations and Artificial Neural Network (ANN) models for estimating coiling factors and axial dispersion coefficients in both serpentine and helical coils. The absolute average relative error (AERR) in predicting the coiling factor is 3.5% for helical coils and 4.6% for serpentine coils. The AERR of the ANN model for predicting the axial dispersion coefficient is 14% for helical coils and 10% for serpentine coils. The study reveals that both axial dispersion coefficient and pressure drop are higher in serpentine coils compared to helical coils. Axial dispersion is found to be relatively unaffected by pitch (helical) or bend diameter (serpentine) and tube diameter but shows significant reduction with a decrease in pitch circle diameter (helical) or gap between bends (serpentine). The developed correlations and ANN models can aid in the precise sizing of tubular reactors designed as helical or serpentine coils. This is exemplified through a case study involving the synthesis of an ionic liquid, where the helical configuration demonstrated a performance advantage of approximately 6% over the serpentine configuration.

Reverse engineering of geometric design parameters using shape information of non‐standard spur gear

AbstractIn this study, we conducted research on a method to reverse engineer geometric design parameters from the shape information of gears. The module and normal pressure angle were tracked using the bisection method, and the profile shift coefficient was extracted from the relationship between the working pitch circle diameter, center distance modification coefficient, and working pressure angle. It was confirmed that there are limitations to reverse engineering the shape using only a coordinate measuring machine or 3D scanner because various geometric information is additionally required to trace back the design requirements for gear strength. Finally, the gear tooth bending strength was calculated using finite element analysis and theoretical formula, and through this, the required level of gear strength design was inferred, and the verification of the gear reverse engineering method presented in this study was attempted.

An optimization design method of asymmetric wheel bearing with equal friction torque and equal fatigue life in two rows

Aiming at the problem of asymmetric wheel bearings with inconsistent friction torque and service life of the left and right rows, this paper proposed a different optimization design method for asymmetric wheel bearings. Firstly, the calculation model of friction torque and fatigue life of asymmetric wheel bearings is established based on the proposed quasi-statics, and the model's accuracy is verified. Furthermore, combined with the Cooperative Equilibrium Point Method, the optimization method of equal friction and equal life for the left and right rows, that is, CEPM-NSGAII, is proposed, which takes the ratio of friction torque and the ratio of fatigue life for the left and right rows as the objective function, and optimizes the structural parameters of the left and right rows such as the rolling element diameters, the pitch circle diameters, and the number of rolling elements, and so on. After optimization, the friction torque ratio and fatigue life ratio of the left and right rows tend to be close to 1, which considerably improves the performance imbalance between the left and right rows of the bearings, meanwhile prolongs the fatigue life of the bearings and reduces the friction torque of the bearings. In addition, the superiority and reliability of the CEPM-NSGAII optimization method are verified by comparison.

Consideration of Power Transmission Characteristics in a Micro-Gear Train.

Characteristics related to power transmission in the micro-domain, based on dry rolling contact of the gears, were investigated using a 3D-printed gear train with a pitch circle diameter of 84 µm in order to experimentally compare the power transmission efficiency in the macro- and micro-domains. For a basic gear train with two intermeshing gears, it was shown that the gear train in the micro-domain was capable of transmitting power to the same extent as in the macro-domain. However, in gear trains with complex power transmission paths, assuming a planetary gear train with multiple meshing gears, it has been shown that the power transmission characteristics of micro-domain gears differ from those in the macro-domain. The use of gear trains in the micro-region necessitates consideration of the loss of transmitted torque due to contact between tooth surfaces, which is unique to the micro-region and different from its use in the macro-region.

Numerical study on effects of nozzle hole spacing distance on steam submerged jet condensation from triangular holes spray nozzle

Steam-water direct contact condensation (DCC) is a phenomenon which is frequently found in the industrial sector due to its rapid and efficient heat and mass exchange rates. In this work, three dimensional numerical study of steam injection from triangular hole nozzles (with different holes pitch circle diameter, PCD = 6, 8,10 and 12 mm) into subcooled water tank has been carried out using Eulerian multiphase flow model along with realizable k-epsilon turbulence model. The thermal phase change model as User Defined Function (UDF) was employed in Fluent software for capturing submerged steam jet condensation. The simulation results were validated using experimental results as well as previously published numerical study and a fairly good agreement was observed. The effects of nozzle hole spacing distance on distributions of various thermal hydraulics parameters including velocity, pressure, temperature, heat and transfer characteristics have been studied. The axial distribution of the velocity, temperature, heat transfer coefficient and mass transfer computed at the centerline of the nozzle was found weaker than observed at the centerline of the nozzle holes. However, these distributions were not weak at nozzle centerline for nozzle with PCD 6 mm. The heat transfer coefficient has been found in the ranges of 1.75–2.3 MW/m2 K. The results reveal that the heat transfer coefficient for nozzle PCD 8 mm is higher than rate obtained for other nozzles. The rate of mass transfer at the holes centerlines has been found increasing with the holes PCD. The axial distribution of the mass transfer curve shifts downstream for nozzle with smaller PCD. Additionally, the mutual shielding effect of the jets weakens as holes PCD increases.

Influence of bottom regiment distributions on the mixing efficiency in a BOF converter

ABSTRACT Within steelmaking processes, the required energy is consistently transferred from the bottom gas into the melt, which assures the mixing efficiency of the bath. In this paper, physical experiment and numerical simulation are established to investigate the influence of bottom nozzles with different arrangements and blowing gas intensities on the dynamic conditions of a 260-t converter. The results indicate that the shortest mixing time was achieved as the outer regiments maintained a pitch circle diameter ratio (PCD) of 0.6 at an angle of 15°. Under the gas flowrate of 960 Nm3·h−1, the minimum mixing time was 40 s, and the minimum proportion of inactive zone was 0.022. Meanwhile, the synergy of bottom-blowing gas flows can help drive the rapid motion of molten steel. It is concluded that 0.5–0.6 PCD is the rational location for the outer regiments to enhance the synergistic effect of flow streams in a BOF converter.

Design and optimization of aluminium alloy wheel rim in automobile industry

The unsprung mass of a vehicle is an essential parameter for considering the effective handling of a vehicle. The higher the reduction in the unsprung mass, the higher the handling of the vehicle can be obtained. The part of a wheel that surrounds the circumference of the cylinder and serves as a support for the tyre is called the rim. The rim's primary purpose is to provide support for the tyre and to ensure that it is properly sealed to the wheel. The rim ensures that the tyre fits properly to the rim and maintains the air pressure within the tubeless tyre. The wheel rim is considered for optimization in this project. To reduce the vehicle's unsprung mass and evaluate its steerability, the wheel rim is designed in SolidWorks and the analysis is performed in Ansys academic 2021. The material used for analysis is aluminium alloy Al6061-T4 and the magnesium alloy is AZ80. The parameters such as the pitch circle diameter, lug nut pattern, and the thickness of the rim are considered parameters for design. The existing design is being studied and optimized to get a weight reduction of nearly 58.33 % without any compromise on the safety parameters of the rim. Considering the cost of the material, it is found that aluminium alloy is comparatively lower in cost than magnesium alloy.

Experimental and numerical investigation on heat transfer and pressure drop of SiO2 and Al2O3 oil-based nanofluid characteristics through the different helical tubes under constant heat fluxes

In the present paper, a numerical and experimental study has been performed to investigate the heat transfer and pressure drop properties of Al2O3 and SiO2/Base oil nanofluid flow in a helical tube under constant heat fluxes. The nanofluids were prepared by using SN-300 base oil as a working fluid for 0.05%, 0.1%, 0.3%, and 0.5% mass concentrations. The experiments were carried out with two constant heat fluxes of 3950 W/m2 and 5280 W/m2 at 30, 40, 50, and 60 °C. The impact of various parameters, including flow Reynolds number, fluid temperature, two different nanoparticles, and various weight concentrations, on the heat transfer factor and pressure drop of the flow, are investigated. To examine the impact of different geometries on the heat transfer rate, simulations were conducted over four different helical tubes by changing the pitch circle diameter and steps. The results indicated that the heat transfer factor and pressure drop were increased by utilizing nanofluid instead of the base fluid. In addition, in the same mass concentration, the Al2O3 nanofluid increased the heat transfer coefficient more than the SiO2 nanofluid. The maximum heat transfer rate corresponds to 0.5% mass concentrations of Al2O3 and SiO2 nanofluids, which are 41.4% and 27.3% more than base oil, respectively. The helical tube compared to the straight tube increased heat transfer by 19.5%. Moreover, heat transfer was improved by 6% and 16.5%, respectively, by reducing helical pitch and pitch circle diameter.

CFD modelling and prototype testing of a Vertical Axis Wind Turbines in planetary cluster formation

This study aims to improve the applicability of Vertical Axis Wind Turbines (VAWTs) by investigating their feasibility in a novel planetary cluster configuration by observing its effect on efficiency and overall power density. Computational Fluid Dynamics (CFD) simulations were carried out using a two-dimensional vertical axis wind turbine model in ANSYS Fluent 2020 R1. This software was used to solve the transient k-omega (SST) turbulence model. For the isolated VAWT the wind velocity, rotor radius and tip speed ratio were varied to find the optimum turbine performance at a given parameter. A peak efficiency of 34.05% was attained and equivalent configuration used as the “sun” turbine in the novel planetary design. The parametric study of the novel set up was conducted with the PCD (Pitch Circle Diameter) and oblique angular (ϕ) position of the smaller “planet” turbines being varied in relation to the “sun” turbine. The planetary system was then evaluated in terms of efficiency improvements against the isolated VAWT model. Use of the “planet” turbines resulted in power extraction from the free stream which in turn creates varying wind velocities and improved the efficiency of the central “sun” turbine. The optimal PCD was found to be 5D (3.75 m) and the optimum angular position of the “planets” was discovered at 30°. Ultimately this gave a percentage increase of 1.01% from 33.04% to 34.05% when comparing the “sun” turbine of the planetary arrangement to the optimum isolated respectively. An average improvement of 4% over the range of tip speed ratios (TSR) was found. Lastly, a scale model of the isolated VAWT was constructed and tested through wind tunnel experiments. The characteristic curve correlation was found between the CFD and experimental results which allowed validation of the CFD models.

Investigation of grease lubricated deep groove ball bearing with multi-defected outer race using vibration signature analysis

Failure of any rotary machine is mainly due to bearing failure being the key element. Defect frequency is the function of speed, ball diameter, and pitch circle diameter of bearing. The number of defects does not affect the excitation frequency, but increase in the level of vibrations is observed in total. The inner race is mounted on the rotary shaft, and the outer race is fixed in the housing. Hence, a defect on the outer race does not rotate with the shaft. This article highlights the study of the multi-crack detection technique at a comparatively higher speed. Amplitudes of vibrations increase with speed, but with load, they almost remain the same. The experiment has been performed at the range from 1000 to 5000 r/min with 5 kg load on the test bearing. The location and size of the defect affect the level of vibrations with noticeable increase. However, the presence of a second defect with respect to the load zone plays an important role. As the defect is at the peak position in the load zone, outer race defect frequency excites more in the vibration spectra. The location and size of the second defect are varied, and acceleration amplitude parameters like RMS, peak, and peak to peak are compared. The current work emphasizes the effect of location and severity of the second defect on the vibration spectra and amplitude parameters of the vibrations.

Determination of allowances at continuous running-in grinding of teeth of cylindrical wheels

A computational and analytical method for determining the allowances on the lateral surface of the teeth of cylindrical wheels is developed. Experimental studies carried out on a modern gear grinding machine using a highly porous abrasive wheel made it possible to give recommendations on determining the optimal values of allowances depending on the modulus and pitch circle diameter of cylindrical gear wheels. Keywords: gear grinding, grinding wheel, allowance, dressing, balancing, teeth accuracy alexandr_kalashnikov45@rambler.ru

Lean six-sigma: Panacea to reduce rejection in gear manufacturing industry

This paper has covered the elimination of process variation to remove the wastages in the gear manufacturing industry. The well-known DMAIC (Define-Measure-Analyze-Improvement-Control) approach, which is the part of Six Sigma was used to decrease process variability, which contributes to a decrease the waste, thus improves total business efficiency. DMAIC methodology has been adopted for this research work in which various tools have been used, such as SIPOC (Supplier, Input, Process, Output, Customer), Pareto analysis, MSA (Measurement System Analysis), SPC (Statistical Process Control), Root & Cause analysis. A Bull gear product of the Company was selected for the improvement as this product has the highest rate of rejection. The variation in Measurement over Teeth (MOT) and Pitch circle diameter (PCD) were two defects which had a major contribution to rejection. When the framework was successfully deployed, Bull Gear rejection level was reduced from 10641.08 to 13193.21 ppm (part per million) and the sigma level increased from 4.37 to 4.81 with the sigma shift. These results demonstrated the impact of the lean six-sigma initiative at the gear company, which has operational efficiency and improved consistency to improve business performance and accommodate customer’s needs.

Continuous flow microwave system with helical tubes for liquid food heating

Abstract The structural parameters of tubes (straight or helical tubes) might affect the heating liquid foods in continuous flow microwave system. Therefore, the objectives were to build a mathematical model for continuous flow microwave heating system with helical tubes for liquid foods heating. A finite element calculation was used for the model, and distilled water, as a representative of liquid foods, was used to validate experimentally and numerically. This model was employed to analyze the liquid heating efficiency with different pitch circle diameters (PCDs), tube diameters, and screw pitches of helical tubes. The heating efficiency was affected by electromagnetic power density distribution, secondary flow intensity, and dielectric properties of heated fluid. Furthermore, the optimal heating efficiency with these variations were given. This study is expected to provide advice to enhance the heating efficiency of liquid foods in design and optimization studies for continuous flow microwave system.

Выбор рационального расположения электродов в многоэлектродной дуговой печи постоянного тока

One of the main design parameters of multi-electrode furnaces, which largely determines their heat and eco-nomic indicators, is the ratio of the pitch circle diameter of electrodes to the bath diameter Dp/Db. The existing methods for choosing rational design parameters are more relevant to arc furnaces operating on alternating current of industrial frequency. For multi-electrode direct current furnaces, which use magnetohydrodynamic effects to improve mixing conditions and temperature homogenization of the melt, there is no relationship between the heat transfer parameters and the pitch circle diameter of electrodes. This work is a continuation of a number of patents and articles. Elsewhere, the design was justified, a mathematical model of magnetohydrodynamic and thermal processes in the melt of the furnace containing three roof arc and three bottom electrodes was developed, the model was verified through the results of physical experiments, and the parameters of heat transfer in the furnace at Dp/Db ≈ 0,2 were studied. The proposed type of furnace requires the study of the Dp/Db effect on the heat transfer parameters in the melt, which will allow a rational choice of the design parameter. The results were obtained using a three-dimensional mathematical model of magnetohydrodynamic and thermal processes in the steel melt constructed with the non-induction approximation and taking into account the k- turbulence model. The results were processed using methods of analysis of vortex structures and estimation of the integral parameters of hydrodynamic and thermal processes in the molten bath. Numerical experiments have been carried out with the design parameter Dp/Db varying from 0,2 to 0,5. New scientific data on the patterns of changes in the structure of flows and heat transfer parameters in the molten pool of a six-electrode furnace have been obtained. Dp/Db increase within the indicated range causes the increase of intensity of vertical vortex flows circulating between the axis of the corresponding electric arc and the axis of the bath and of the azimuthal flows circulating in horizontal sections of the bath. Vortex flows formed due to natural convection near the side walls of the furnace are suppressed. The maximum value zones of the effective thermal conductivity that reaches 1,8·105 W/(m·K) are redistributed to the central part of the bath, which contributes to increasing temperature distribution efficiency in the bath. The obtained results allow recommending a rational range of values of Dp/Db within 0,4–0,5, which decreases the volume of stagnant zones in the proposed six-electrode furnace by more than 40 % and increases the integral values of the Nusselt number over the depth of the horizontal section of the bath on average by more than 10 %. The obtained data revealing the possibility of improving the mixing conditions and increasing the heat transfer efficiency in the melt of the six-electrode furnace can be recommended for choosing the Dp/Db ratio when designing high power furnace.

Numerical analysis of air entrainment and exit temperature of a real scale conical infrared suppression (IRS) device

A numerical analysis has been performed on a real-scale infrared suppression device to estimate the air entrainment and corresponding temperature drop of the exhaust gases flowing through it. The analysis of the IRS device is done for the exhaust of a gas turbine plant installed on a naval warship. The operational data used in the analysis has been taken from LM2500 series gas turbine from GE. The numerical method solves the three dimensional, incompressible Navier-Stokes equations, the mass continuity equation and the two-equation based eddy viscosity model for the turbulent k-epsilon equations along with the energy equation in the flow field. The effect of using different number of nozzles at the gas turbine exit on the air entrainment and the exit plume temperature has been discussed. The results show that the maximum air entrainment and minimum plume temperature can be achieved by using four to six numbers of nozzles. The air entrainment and the exit plume temperature are also affected by the pitch circle diameter of the nozzle placement. The maximum air entrainment and minimum exit temperature is achieved at a pitch circle diameter of 1.6 m. The air entrainment considerably increases with the nozzle-exit Reynolds number (Re). The higher Reynolds number also ensures the minimum plume temperature at the exit of IRS device. Air entrainment gradually reduces with the nozzle protrusion. The highest entrainment is observed when the nozzles are flush with the bottom plane of the IRS device. However, the nozzle protrusion does not affect the exit plume temperature significantly. The funnel overlap height adversely affects the performance of the IRS device i.e. the air entrainment continuously decreases with increasing funnel overlap height. Moreover, increasing funnel overlap also causes the exit plume temperature to rise considerably.

AN INVESTIGATION OF EFFECT OF CONTROL JETS LOCATION AND BLOWING PRESSURE RATIO TO CONTROL BASE PRESSURE IN SUDDENLY EXPANDED FLOWS

The drag force is an essential factor in any projectile, from road vehicles to rocket or aircraft. The total drag includes skin friction drag, wave drag, and base drag. The base drag is the drag due to low pressure in the base region of the projectile. In the case of suddenly expanded flows, due to the sudden expansion of flow from the nozzle into the enlarged duct, the low pressure is created in the base region of the enlarged tube, which results in base drag and hence overall thrust reduced. In this paper, Computational Fluid Dynamic (CFD) analysis is used to analyze the effect of secondary air blowing jets called control jets to control base pressure in the base region of suddenly enlarged duct. These control jets are placed at different Pitch Circle Diameters (PCD) on the base face of the enlarged pipe. The objective of this work is to increase the base pressure up to atmospheric pressure and hence reduces the base drag. Mach number 3.0 is considered for analysis. The CFD analysis is done for different combinations of Area Ratios (AR) (2, 5 and 8), Nozzle Pressure Ratios (NPR) (2, 5 and 8), and PCD (d1, d2, and d3). Further analysis is done for different air blowing pressure ratios (BPR) to optimize air blowing pressure. The analysis results are plotted for different area ratios, nozzle pressure ratios, and PCD of control jets. By observing results, it can be concluded that the base pressure is strongly influenced by AR, NPR, and PCD of control jets. The air blowing pressure should be optimum to save energy, and the optimum values can be selected from the results.

Energy and Exergy Analysis of a Concrete-Based Thermal Energy Storage System

Thermal energy storage system became an answer to store the intermittent solar energy in the recent time. In this study, regenerator-type sensible energy storage (SES) of 1 MJ capacity is developed for its application in the low-temperature region and hilly region like Meghalaya. Concrete and water are chosen as the substance to store energy and heat transfer fluid, respectively, owing to their suitable thermophysical properties. The influences of embedded tube diameter and pitch circle diameter (PCD) on the heat storage ratio and heat release ratio are investigated in the present study. Computational work is carried out using COMSOL Multiphysics software, and validation results show a good match with the published results in the literature. Upon optimizing the number of tubes in the preliminary study, 25 embedded tubes are considered for the further analysis. It is found that both the heat storage ratio and heat release ratio increase with increasing pitch circle diameter and embedded tubes diameter. At the same time, both the effective charging time and effective discharging time decrease with increasing pitch circle diameter and embedded tubes diameter. Finally, exergy analysis is performed for SES system. Maximum exergy factor is found in the case of tube arrangement at 6 cm PCD with 1.71 cm embedded tube diameter.

Vibration analysis of nylon gear box utilizing statistical method

Gears are important element in a variety of industrial applications such as medical and automotive sectors. In the medical field it is used in surgical instruments, Biopsy instrumentation and Dental implant products. In automotive sectors like Electrical Throttle Controls, Steering Systems, Instrument Clusters, Window and Door Latch systems. Though the plastic gears have less heat dissipation, high wear resistance and self-lubrication properties, there may be defects in nylon gears in runtime applications. The defects include surface fatigue like pitting, scuffing, scratching and some common defects like flash, warping, bubbles etc.The gear defects are often identified under switch off condition and gear are checked. There are defect testing methods like image processing. In this work the defects were identified when the system is in running condition, by analysing the vibration signals obtained from the system under varying load and speed conditions. Gears are designed based on the parameters like module, pitch circle diameter, no of teeth and bending load capacity.In this work, the experimental setup is fabricated for testing the gears at three different sets of speeds. By varying the speed of transmission between two shafts both in loading and unloading conditions, the sound signals are acquired using sound sensor and sound signals are processed using MATLAB. The time-domain signal and frequency domain signals are used to detect the failure in nylon gear. Using the parameters like kurtosis, RMS, variance and standard deviation value the good gears and defective gears are compared. By using this method the defects in nylon gears can be identified easily.

Control of CD Nozzle Flow using Microjets at Mach 2.1

This paper reports the outcome of the wind tunnel investigation performed to study the effectiveness of the control jets to regulate the base pressure in an abruptly expanded circular pipe. Tiny jets four in a number, of 1 mm orifice diameter located at ninety degrees in cross shape along a pitch circle diameter (PCD) of 1.3 as a control mechanism were employed. The Mach numbers and the area ratio of the study were 2.1, and 4.84. The length-to-diameter (L/D) ratio of the duct tested was varied from 10 to 1. Nature of the flow in the duct, as well as static wall pressure distribution in the suddenly enlarged duct, was recorded. The main aim of this study was to assess the influence of the active control in the form of tiny jets on the flow field as well as the nature of the flow, and also the development of the flow in the duct. The results obtained in this study show that the flow field, as well as the wall pressure distribution, is not adversely influenced by the tiny jets. The minimum duct length seems to be 2D for NPR's in the range five and above. However, for all the level of expansion of the present study, the minimum duct length needed for the flow to remain attached seems to be 3D