Groove Parameters Research Articles

Multi-Objective Optimization for Controlling Conflicts in Roadway Surrounding Rock Induced by Floor Stress-Relief Groove

This paper studies the effectiveness of the stress-relief groove on the floor of deep coal roadway and determines the influence of the stress-relief groove parameters on the surrounding rock through qualitative analysis. Based on the displacement conflict problem, evaluation indicators were established, and the optimal solution set was obtained. The innovations of this research include: 1. For geotechnical numerical simulations, novel stress monitoring and plastic zone monitoring techniques have been introduced to accurately reflect the condition of the surrounding rock; 2. The effects of floor relief grooves in deep roadway on surrounding rock have been analyzed, and the advantages and utilities of central and corner relief grooves have been determined; 3. The usability of small datasets has been enhanced by applying SEGA to optimize machine learning models with data augmentation techniques; 4. Multi-objective optimization algorithms have been applied to geotechnical engineering, providing valuable references for decision making. The results demonstrate that multi-objective optimization can significantly enhance the effectiveness of surrounding rock control, resolve conflicts, and achieve more reasonable construction plans. This research provides new theoretical foundations and practical guidance for deep mine roadway-surrounding rock control.

Research on fatigue life of carbon fiber reinforced polymer strengthened single-sided butt welded joints utilizing resin pre-coating for strong adhesive bonding

Single-sided butt welding is a common connection method used in box beam structures such as excavator booms. Single-sided butt weld joints are prone to fatigue failure since the structures are subjected to cyclic loads over extended periods. The purpose of this study is to improve the fatigue performance of single-sided butt welded joints. Carbon fiber reinforced polymer (CFRP) strengthened single-sided butt welded joint specimens with permanent backing plates were prepared by pre-coating method, and constant-amplitude tension–tension fatigue tests were carried out on the specimens. The effects of welding groove parameters and CFRP reinforcement on fatigue life were studied. The test results show that the CFRP-strengthened specimens without blunt edges and with a groove angle of 40° show the highest average fatigue life. The single-sided bonding of 10 layers of CFRP sheets effectively inhibits the propagation of fatigue cracks and significantly improves the fatigue life of welded joints. In the CFRP/welded joint composite structure, the strain monitoring results show that the peak strain of the interface is the largest in the middle position, and the peak strain rises sharply in the rapid crack propagation stage, which indicates that the real-time interface strain peak can reflect the fatigue crack propagation. It provides an early warning method for real-time monitoring of fatigue life failure of welded structures in practical engineering.

A biparametric analysis on the steady performance of bidirectional pumping hydrodynamic-static hybrid dry gas seal

Purpose The purpose of this paper is to obtain the matching relationship between spiral groove, equalizing groove and operation parameters through the biparametric analysis for the bidirectional pumping hydrodynamic-static hybrid dry gas seal (BP-HHDGS). Design/methodology/approach The large eddy simulation (LES) model in Fluent is used to simulate the flow field of BP-HHDGS, and the biparameter variables method is chosen to analyze the effects of different parameters on the performance of BP-HHDGS. Findings BP-HHDGS has a greater opening force than hydrostatic dry gas seal (HDGS); the vortex is formed after lubricating gas is exhausted from the throttle. Increasing the depth of the equalizing groove and spiral groove has a synergistic enhancement effect on the opening force and leakage of BP-HHDGS. There is a matching relationship between spiral angle and rotational speed. The preferred parameter ranges in current conditions are found as follows: spiral angle αa = 15°–24°; groove-dam ratio λ = 0.4–0.7; equalizing groove depth hj > 35 µm; spiral groove depth hg = 5-10 µm. Originality/value The high starting capacity of HDGS is given to the hydrodynamic type seal, and thus the application promotion of HDGS in high-speed working condition is realized at the same time. This work also provides precise and quick theoretical guidance for the selection and design of hydrodynamic-static dry gas seal and further promotion.

Dynamic analysis of a high-speed micro compressor supported by spiral-grooved hydrodynamic air bearing

Spiral-grooved hydrodynamic air bearings are used in high-speed machines due to their advantages of oil-free, low friction, and compact structure. This paper aims to investigate the dynamic characteristics of a high-speed rotor supported by spiral-grooved hydrodynamic air bearings and the effects of spiral groove parameters. A mathematical model of the rotor-bearing system is developed by coupling the rotor nonlinear motion equations and the bearing dynamic Reynolds equation. The finite element method combined with the Runge-Kutta method is employed simultaneously to obtain the nonlinear trajectory of the rotor-bearing system. The theoretical model is verified by experiments on the built micro compressor prototype. The numerical predicted onset speed of the sub-synchronous motion of the rotor-bearing system agrees well with the experimental observations. Furthermore, the effects of radius clearance, groove depth, groove angle, groove axial and circumferential width on the dynamic performance of the rotor-bearing system are analyzed. The results show that radius clearance has the most significant influence, followed by groove depth, groove axial, and then circumferential width. The groove angle has the least impact.

Design of coma-free Hettrick-Underwood type spectrometers for high energy resolution RIXS experimental station.

The Hettrick-Underwood (HU) type design, consisting of a pre-focusing mirror and a varied-line-spacing planar grating (VLS-PG), for the high resolution resonant inelastic x-ray scattering spectrometer is considered. The light path of the HU design is analyzed, and the analytical functions determining the groove parameters of VLS-grating are given. Efforts are made to compare the different choices of the pre-focusing mirrors, circular cylindrical (HU-CM) and elliptical cylindrical (HU-EM). Although the HU-EM type offers great tuning properties with variable-included-angle, it imposes high requirement on the optical element manufacturing accuracy, while the HU-CM type design couples the coma contributions from the pre-mirror and the grating, allowing for mutual compensation of the manufacturing errors of the two optical elements.

Large amplitude and small size ultrasonic milling for BT40 tool holders

Abstract The current ultrasonic milling tool holders are relatively long in structure, and the tool is susceptible to generating detrimental radial vibrations during high-speed rotation. To achieve high-quality milling of difficult-to-machine materials, a longitudinal-torsional ultrasonic oscillator suitable for BT40 tool holders has been proposed, which can generate a large amplitude while maintaining a compact length. A longitudinal vibration ultrasonic transducer with an exponential front cover is designed using the analytical method. Based on the principle of acoustic wave reflection, four spiral grooves are introduced on the exponential variable cross-section bar to convert the longitudinal vibration into longitudinal-torsional composite vibration. The effects of groove width, groove depth, and spiral angle on the longitudinal-torsional resonance were analyzed using the single-factor method in finite element software, and the optimal spiral groove parameter combination was determined. The longitudinal-torsional ultrasonic transducer is assembled with the BT40 tool holder to construct a longitudinal-torsional ultrasonic tool holder model, and modal analysis was performed. The resonant frequency was determined to be 22, 845 Hz. An experimental platform was established to carry out impedance analysis and amplitude testing on the longitudinal-torsional ultrasonic tool holder. The results show that its resonant frequency is 22, 152 Hz, which is slightly different from the simulation value. The tool holder’s maximum longitudinal amplitude is 11.2 μm, and the maximum torsional amplitude is 4.3 μm, with a torsional-to-longitudinal ratio of 0.38. The performance of the longitudinal-torsional ultrasonic tool holder meets the processing requirements of most ultrasonic milling applications, and the correctness of the design method is verified.

An Optimization Study of Circumferential Groove Casing Treatment in a High-Speed Axial Flow Compressor

In this paper, a numerical optimization study of single-groove casing treatment was conducted on a high-speed axial compressor. One of the aims is to find the optimal structure of a single groove that can improve compressor stability with minimal loss in efficiency. Another aim is to explore suitable parameters for rapidly evaluating the compressor stall margin. A design optimization platform has been constructed in this paper, which utilizes NSGA-II and a Radial Basis Function (RBF) neural net model to carry out the optimization. The stall margin of the compressor with A single groove was accurately determined by calculating its entire overall performance line. A Pareto front is obtained through optimization, and the optimal design can be selected from the Pareto front. By considering both stall margin and efficiency loss, one of the optimal designs was found to achieve a 7.49% improvement in stall margin with a 0.24% improvement in peak efficiency. Based on the database, the effect of design parameters of a single groove on compressor stability and performance is analyzed. A series of evaluation parameters of stall margin were compared to their degree of correlation with the real stall margin calculated by the entire overall performance line. As a result, tip blockage and momentum ratio can be used as efficient parameters for quickly evaluating the compressor stall margin without the need to calculate the entire performance curve of the compressor.

Structural design and simulation of herringbone groove bearing lubricated with liquid metal

Abstract We designed a novel herringbone groove sliding bearing suitable for gallium-based liquid metal lubrication, taking advantage of the excellent fluidity, high thermal conductivity, and strong stability of gallium-based liquid metal at room temperature. We used the finite element method to analyze how eccentricity affected the bearing pressure variation and chose the best structural parameters by comparing how different groove parameters affected the peak pressure and carrying capacity. The results show that the herringbone groove reduces bearing friction resistance and causes the bearing pressure variation to exhibit a herringbone pattern. The herringbone groove structural parameters have a significant impact on the peak pressure and carrying capacity of the bearing. The gallium-based liquid metal bearing works well when the herringbone angle is 50°, the groove depth is between 15 μm and 25 μm, and the groove ratio is between 0.7 and 0.9.

Optimization of noise rhythmizing parameters for musical road using finite element simulation

Vehicle noise pollution has recently attracted increasing attention. The concept of rhythmizing road noise, which generates musical notes while driving, has emerged as a potential solution for alleviating noise pollution and enhancing the driving experience. This study utilized a simulation method combining ABAQUS and MATLAB to develop a numerical model that describes the coupling between tires and road grooves. The results indicate that the average relative error between the frequency corresponding to the peak acoustic pressure level of the vibro-acoustic pressure model and the theoretically calculated frequency was only 2.4 %. Consequently, the parameter settings in the numerical model were coincided with the actual grooves on the road surface. Subsequently, the effects of various factors including vehicle speed, road groove spacing, road groove width, and road groove depth on the acoustic properties of musical roads were investigated. Finally, the optimal ranges of vehicle speed and road groove parameters were determined to enhance the musical features of musical roads. The optimal vehicle speed range for the designed musical road is 40–60 km/h, whereas the preferred depth range for the road grooves is 3–5 mm. Moreover, the road groove width should be set to a minimum of 20 mm. Specifically, the optimal combination of parameters for the road grooves is a groove depth of 4 mm and width of either 24 or 26 mm. Additionally, the optimal voice range and road groove parameters were justified using actual engineering projects. The results of this study can provide valuable insights for optimizing the design and construction of musical roads and promote their widespread application.

Laser treated novel textures for adhesion performance of aluminum alloy joints exposed to corrosion

The aim of this study was to investigate novel laser-treated structures designed to improve the adhesion performance and corrosion resistance of AA7075-T6 bonded joints. The spacing, position, and surface area parameters of the laser-treated grooves were investigated to understand their role in adhesion performance even under corrosion conditions. Laser-treated surfaces were analyzed using microscopic, topographic, and chemical methods to determine their scientific contribution to adhesion and corrosion performance. Laser-treated adherends were also bonded to mechanically test their bond strength both before and after exposure to corrosion for varying periods of time. Roughness and therefore surface area have a significant effect on adhesion performance; however, it is worth noting that the best adhesion performance both before and after corrosion exposure was achieved when the required surface area was properly designed and, laser treated according to the salt water exposure directions to inhibit its diffusion into the adhesion interface. The performance of the novel laser-treated structures in terms of adhesion performance under corrosive atmosphere was also supported by failure analysis. The mixed failure mode was significantly shifted to the cohesive failure mode, especially for bonded joints with box-type laser-treated structures.

Control and analysis of floating ability of aeronautical cylindrical spiral groove gas seal based on F-K model

The slip flow phenomenon caused by the gas floating seal in ultra-thin gas films and high-altitude rarefied gas environments occurs frequently. This study represents the first attempt to calculate the gas film floating force by considering the coupling relationship among the slip flow effect, the surface micro-grooves, and the eccentricity using a high-precision eight-node finite difference method based on the linearized Boltzmann equation for a spiral-grooved cylindrical gas seal. Furthermore, the influence of slip flow on the operational and groove parameters of the spiral-grooved cylindrical gas seal is investigated and discussed. Results show that the velocity gradient of the lubrication gas is reduced and the effect of the fluid hydrodynamic pressure is weakened because of slip flow, particularly in high-speed, low-pressure, and high-eccentricity fields. However, increases in groove depth, number, and length improve the gas film floating force, which strengthens the slip flow response in the grooves. Therefore, the slip flow reduces the gas film floating force, but when the groove depth exceeds 32 μm and the groove length is greater than 45 mm, the slip flow may become negligible. The results presented here provide a theoretical basis to broaden the application scope of dynamic seals in the aerospace field.

Research Progress on the Dynamic Stability of Dry Gas Seals

Concerning the application of high-precision, enormous rotating equipment under harsh working conditions, the advantages of dry gas sealing technology are increasingly obvious. Herein, research on the dynamic stability of dry gas seals is reviewed based upon their operating mechanisms. The influence of the dry gas seal structure, vibration response, and dynamic followability on the reliability of the shaft end sealing system of rotating machinery is the focus of current dry gas sealing technology. This work reviews the research history; analyzes the key coefficient of the instability of the sealing system under external disturbances, and the existing research on stability models; discusses the influence of starting and stopping characteristics, working conditions, and groove parameters on the stability of dry gas seals; and points out the shortcomings in the existing research. In addition, potential developments in dynamic stability are proposed, including improving model accuracy, improving experimental techniques, or applying intelligent control and optimization methods to enhance the dynamic stability of the sealing system. Finally, the development prospects for dry gas sealing technology in intelligent monitoring and wide temperature range adaptations are discussed, and theoretical guidance for improving a dry gas seal system is provided.

Study on working mechanism and performance of deep groove seal at high temperature and high speed in mixed lubrication

The deep groove seal is a kind of mechanical seal with millimeter depth grooves on the end face of the sealing ring, widely used in aviation and nuclear fields. However, its working mechanism and sealing performance are still unclear. In this research, a fluid-solid-thermal coupling numerical analysis model at high temperature and high speed in mixed lubrication is established to solve these problems. Mechanism analysis indicates that deep grooves cause circumferential waviness of micron level on the end face, strongly affecting the sealing performance. A quantitative characterization method is proposed, solving the characteristic parameters and analytical expression of deep groove seal waviness, so that the deep groove seal can be approximately equivalent to the waviness seal and be explained by the law of the waviness seal. The sealing performance can be controlled through the design of groove parameters. The results have been verified by the experiment. The fluid-solid-thermal coupling model and characterization method of equivalent waviness parameters for the deep groove seal proposed in this article provide a theoretical basis for further study of the mechanism and performance of the deep groove seal.

The design of chip breaking grooves for spade drill inserts

A chip breaking groove was designed on a spade drill insert to break chips. The effects of the anti-chip angle, width and height of chip breaking groove on the chip curl radius were investigated with simulations and drilling experiments. The forces acting on the chip were analyzed to clarify the chip breaking processes. The chip breaking process of a spade drill insert with chip breaking groove was simulated with the finite element technique to study the chip breaking mechanism. The calculation formulas for calculating the width, height and radius of the chip breaking groove were established. The research results show that the chip curl radius is affected by the chip breaking groove parameters. The chip curl radius increases with the anti-chip angle but decreases as width decreases or height increases. When the values of anti-chip angle, width and height of chip breaking groove reach thresholds, the chip wind or piling phenomenon will occur during the drilling experiments. The formulas for calculating chip breaking grooves are feasible. A design method of chip breaking grooves for spade drill inserts is proposed. Spade drill inserts whose chip breaking groove parameters are calculated according to formulas of the width, height and radius can effectively break chips at different drilling parameters.

Numerical study on effect of design parameters of the single-circumferential groove on tip leakage flow reduction in a transonic turbine

In order to investigate the impact of design parameters (depth, width, and location) of the single-circumferential groove (SCG) on tip leakage flow (TLF) reduction in a transonic turbine stage, a systematic investigation was conducted by high-precision numerical simulation method. The numerical results show that the introduction of SCG could improve the stage efficiency (η) of turbine significantly. The optimal design parameters of depth coefficient (ζ), width (W), and location (L) were ζ = 3, W = W3, and L = 20%Cax (where Cax denotes the axial chord of the blade), which could reduce tip clearance leakage rate (m*) by 28.9% and improve the η by 0.56%. The implementation of flow field display methods reveals that the introduction of SCG influences the formation and development of the vortex system at the rotor tip region. The circumferential groove vortex (CGV), induced by SCG, divided the tip leakage vortex (TLV) into two segments TLV_1 and TLV_2 due to its blocking effect. TLV_1 interacted with the passage vortex (PV) and depress the strength of PV. Meantime, TLV_2 would regenerate from the trailing edge of SCG, due to its limited development range and insufficient growth, the strength and scale of TLV_2 were weakened. Given that the TLF passing through SCG flows in an opposite direction to the original TLF, the SCG at appropriate location could lead to a fact that the net flow rate of the leakage flow reached the minimum value, thereby considerably reducing the m* and flow loss caused by TLF.

A simple yet efficient solution for TE scattering from a right trapezoidal groove

AbstractA simple yet efficient solution to the problem of transverse electric (TE) scattering by a two‐dimensional right trapezoidal groove placed in a perfect electric conductor (PEC) surface is presented. Using superposition of plane waves and applying the Neumann boundary condition at the groove walls, the transverse magnetic field is expressed as the sums of infinite series of waveguide modes. Considering the equivalent magnetic current on the aperture, a Fredlholm's integral equation with logarithmic singular kernel is extracted and then discretised by a collocation method based on a piecewise constant approximant. The extracted linear system of equations can be easily solved by the matrix methods for the unknown coefficients. Numerous examples are presented to verify the results and show the ability of the proposed method. Finally, this method is employed to examine the effect of the groove parameters and incidence angle on the scattering signatures.

Theoretical study on the pressure expansion mechanism of diffused self-pumping hydrodynamic mechanical seal

The pressure expansion performance is the key and basis for the diffused self-pumping hydrodynamic mechanical seal to achieve its good cooling performance, self-cleaning performance, and sealing performance. Using the moment of momentum theorem and Stodola's formula, the pressurization effect of the spiral groove on the fluid was analyzed, and the energy head equation of the work done by the spiral groove on the fluid is established. According to the principle of conservation of energy, the energy equation and Bernoulli equation of the work done by the spiral groove on the fluid are derived, the mathematical expression of the conversion of fluid kinetic energy into hydrostatic pressure in the diffuser groove was established, the energy change and energy distribution problems of the fluid after the work of the spiral groove are clarified, and the pressure expansion mechanism is revealed. Through numerical simulation, the relationship between the fluid pressure at the sealing interface, the position and size of the high-pressure field, the opening force, and the leakage rate under different rotational speeds and the structural parameters of the diffuser groove were explored. Finally, the pressure expansion performance of the ordinary self-pumping hydrodynamic mechanical seal and diffused self-pumping hydrodynamic mechanical seal is compared. The results show that the diffuser groove can effectively convert part of the fluid kinetic energy into pressure energy, improve the opening force of the sealing interface, and have a good pressurization effect on the sealing end face. With the widening of the diffuser groove, the pressure peak of the sealing interface increases, the high-pressure field area continues to expand and tends to expand toward the outer diameter of the seal ring, and the opening force also increases significantly; increasing the depth of the diffuser groove will cause the pressure peak of the sealing interface to become smaller, and the area of the high-pressure field will also decrease rapidly, which is not conducive to improving the opening force of the sealing end face.

Modulating the Acoustic Vibration Performance of Wood by Introducing a Periodic Annular Groove Structure

The acoustic vibration performance of wood affects the quality of many musical instruments, and the variability of wood causes obvious differences between individual timber samples. To mitigate the variations among the individual timber samples intended for musical instruments, in this study, we combined finite element simulation with experimental testing to investigate the effect of the periodic annular groove structure on the comprehensive acoustic vibration characteristics of wood. The results revealed that there are discernible correlations between the structural parameters of the periodic annular groove and the key acoustic parameters of wood, including the resonant frequency, equivalent dynamic modulus of elasticity, equivalent specific dynamic modulus of elasticity, equivalent acoustic radiation quality constant, and equivalent acoustic impedance. These relationships can be used to fine-tune the overall acoustic vibration performance of wood and harmonize the acoustic vibration characteristics among different timber specimens. The effects of the periodic annular groove structure on the five acoustic vibration parameters obtained through finite element simulations exhibited minimal differences to the corresponding results from experimental tests. Furthermore, there was a remarkably strong correlation between the outcomes of the finite element simulations and the experimental test results, with the coefficient of determination exceeding 0.99.

Flow and thermal behavior of solar air heater with grooved roughness

A simple and eco-friendly solar air heater (SAH) converts renewable solar energy into useful thermal energy. The implementation of roughness on the absorber plate of a solar air heater improves its air heating capability. The hot air thus produced is used in different applications such as agricultural, dairy, food processing, and cement industries. Towards that, a 2D numerical study is carried out with rectangular groove as a roughness with the RNG k−Ɛ turbulent model. The study has been carried out to find a SAH with higher performance. Two thermodynamic models are adopted to identify and qualify the best channel. The performance of the best SAH channel has been identified by the highest thermal enhancement factor (TEF) and to increase the exergetic ratio (Ɛth). A detailed study of introducing rectangular groove on heat transfer, pressure drop, thermal enhancement factor (TEF) and exergetic ratio (Ɛth) is conducted, by varying the geometrical parameters of rectangular grooves in the range of Re from 7000 to 17000. Geometrical parameters such as relative length (α), relative pitch (β) and relative height (λ) are varied in the range of 0.0067–0.040, 0.0333 to 0.10, and 0.1 to 0.5, respectively, to optimize the performance of the SAH. Higher exergetic ratio is found around the same parametric values where we get the highest TEF value. The maximum TEF is found around 1.455 at α = 0.020, β = 0.0667, and λ = 0.30 at Re of 17000 and the corresponding exergetic ratio is found around 0.9949. The length of the groove is found to augment both heat transfer and pressure drop of the solar air heater due to increased disruption of thermal and hydrodynamic boundary layers. Rate of augmentation of heat transfer decreases in case of α≥ 0.0333 due to formation of an additional stagnant zone inside the groove. The flow and thermal analysis shows that although local heat transfer within the rectangular groove is less, the rectangular groove improves the channel's overall heat transfer. Convective heat transfer coefficient is found relatively higher where there is a change in shear stress gradient.

Groove parameters optimization of rotary excitation control valve using computational fluid dynamics coupled with response surface method

A rotary excitation control valve is proposed in this paper. In order to study the interaction of the valve core groove parameters on the output flow velocity and pressure of the rotary excitation control valve, a dynamic simulation of the internal flow field of the rotary excitation control valve is carried out based on the Multiple Reference Frame Model (MRF), and the simulation results are experimentally verified. Based on the quadratic regression orthogonal test method, a significant non-lossy regression model of the groove parameters with the output flow velocity and pressure is established, and the response surface of the groove parameter interaction is obtained. The results show that the influence of groove parameters on flow velocity is in the order of width > depth > length, and the interaction between length and depth is the most significant; the influence of groove parameters on pressure is in the order of width > depth > length, and the interaction between width and depth is the most significant. The Response Surface Methodology (RSM) is used to optimize the groove parameters, and the best combination of groove parameters obtained is 20.00 mm in length, 5.65 mm in width and 8.00 mm in depth.