Herringbone Grooves Research Articles

Static Characteristics of Hybrid Water-Lubricated Herringbone Groove Journal Bearing

Abstract The hydrodynamic herringbone groove journal bearing (HGJB) performs exceptionally well at high speeds but is limited by a low load-carrying capacity, largely due to the lubrication characteristics of water. To address this issue, a hybrid water-lubricated HGJB is proposed in this study. A lubrication model for the high-speed hybrid water-lubricated HGJB is developed, taking into account turbulence, thermal effects, and tilt. A comparative analysis of the static characteristics is conducted between the hybrid HGJB and both the hydrodynamic HGJB and the hybrid plain journal bearing (PJB). The results show that the proposed hybrid water-lubricated HGJB offers significantly greater load-carrying capacity than the conventional hydrodynamic HGJB, particularly during start-up or at low speeds. For example, when the bearing operates at 1,000 rpm with an eccentricity ratio of 0.5, the load-carrying capacity of the water-lubricated hybrid HGJB under a supply pressure of 1.6 MPa reaches 650 N, compared to just 261 N for the water-lubricated hydrodynamic HGJB. Additionally, the hybrid water-lubricated HGJB demonstrates a higher flow rate and lower temperature rise than the traditional hybrid PJB, thanks to the improved pumping effect of the herringbone grooves at high speeds.

Influence of Herringbone Grooves Inspired by Bird Feathers on Aerodynamics of Compressor Cascade under Different Reynolds Number Conditions

Nowadays, high aerodynamic load has made blade separation an issue for compact axial compressors under high-altitude low-Reynolds-number conditions. In this study, herringbone grooves inspired by bird feathers were applied to suppress the suction side separation and reduce loss. To study the effect of bio-inspired herringbone grooves on the aerodynamic performance of compressor cascades, a high subsonic compressor cascade was taken as the research object. Under the conditions of different Reynolds numbers, the effects of herringbone grooves of different depths on the flow separation were numerically studied. The research results show that at a high-Reynolds-number condition (Re = 5.6 × 105), the sawtooth-shaped wake induced by herringbone grooves increases the turbulent mixing loss near the suction surface, and the blade performance deteriorates. At a low-Reynolds-number condition (Re = 1.3 × 105), the span-wise secondary flow and micro-vortex structure induced by the herringbone grooves effectively suppress the laminar separation on the suction surface of the blade, and there is an optimal depth for the herringbone grooves that reduces the profile loss by 8.33% and increases the static pressure ratio by 0.55%. The selection principle of the optimal groove depth with the Re is discussed based on the research results under six low-Reynolds-number conditions.

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.

Carbon nanotubes integrated photonic barcodes in Herringbone Microfluidics for Multiplex Biomarker Quantification

Early monitoring of cardiovascular disease (CVD) is crucial for its treatment and prognosis. Hence, highly specific and sensitive detection method is urgently needed. In this study, we propose a novel herringbone microfluid chip with aptamer functionalized core-shell photonic crystal (PhC) barcode integration for high throughput multiplex CVD detection. Based on the PhC derived from co-assembled carboxylated single-wall carbon nanotubes and silicon dioxide nanoparticles, we obtain core-shell PhC barcodes by hydrogel replicating and partially etching. These core-shell PhC barcodes not only retain the original structural colors coding element, but also fully expose a large number of carboxyl elements in the ore for the probe immobilization. We further combine the functionalized barcodes with herringbone groove microfluidic chip to elucidate its acceptability in testing clinical sample. It is demonstrated that the special design of microfluidic chip can significantly enhance fluid vortex resistance and contact frequency, improving the sample capture efficiency and detection sensitivity. These features indicate that our core-shell PhC barcodes-integrated herringbone microfluidic system possesses great potential for multiplex biomarker detection in clinical application.

In-line Raman imaging of mixing by herringbone grooves in microfluidic channels.

The control over fluid flow achievable in microfluidic devices creates opportunities for applications in many fields. In simple microchannels, flow is purely laminar when one solvent is used, and hence, achieving reliable mixing is an important design consideration. Integration of structures, such as grooves, into the channels to act as static mixers is a commonly used approach. The mixing induced by these structures can be validated by determining concentration profiles in microfluidic channels following convergence of solvent streams from separate inlets. Spatially resolved characterisation is therefore necessary and requires in-line analysis methods. Here we report a line-focused illumination approach to provide operando, spatially resolved Raman spectra across the width of channels in the analysis of single- and multi-phase liquid systems and chemical reactions. A scientific complementary metal oxide semiconductor (sCMOS) sensor is used to overcome smearing encountered during spectral readout of images with CCD sensors. Isotopically labelled probes, in otherwise identical flow streams, show that z-confocality limits the spatial resolution and certainty as to the extent of mixing that can be achieved. These limitations are overcome using fast chemical reactions between reagents entering a microchannel in separate solvent streams. We show here that the progression of a chemical reaction, for which only the product is observable, is a powerful approach to determine the extent of mixing in a microchannel. Specifically resonance enhancement of Raman scattering from a product formed allows for determination of the true efficiency of mixing over the length and width of microchannels. Raman spectral images obtained by line-focused illumination show onset of mixing by observing the product of reagents entering from the separate inlets. Mixing is initially off-centre and immediately before the apex of the first groove of the static mixer, and then evolves along the entire width of the channel after a full cycle of grooves.

Analysis of Second-Order Dynamic Coefficients for Herringbone Grooved Hydrodynamic Thrust Bearings Considering Misalignment

Analysis of Second-Order Dynamic Coefficients for Herringbone Grooved Hydrodynamic Thrust Bearings Considering Misalignment

Rapid mixing achieved using Coriolis force and grooves in rotating microchannels

Mixing is a critical process in reagent reactions used in biomedical applications. Nevertheless, achieving rapid mixing in microfluidics is challenging because of the low-Reynolds region. This study numerically investigated the mixing performance of a rotating channel based on the Coriolis force with herringbone grooves. In the absence of grooves, the mixing was maximized when the Coriolis force was appropriately balanced with the centrifugal force. As the aspect ratio increased from 0.5 to 2.0, rapid mixing was achieved owing to the decreased transverse distance between the rotating flows. Mixing improved with the herringbone grooves, achieving up to >90% for the shortest channel length (20 mm) among the various microchannels. This enhancement resulted from the flow split and recombination induced by the combination of the Coriolis force and grooves. This study will help create and design microchannels for disk chip miniaturization, automation, and integration into lab-on-a-disk-based biomedical procedures, such as point-of-care diagnosis.

Modelling approach of hybrid air herringbone grooved journal bearing considering the angular misalignment and centrifugal expansion

Performance improvements can be achieved after introducing herringbone grooves into conventional plain aerostatic bearings at high speeds. However, the existing literature lacks a comprehensive model that accurately calculates the static and dynamic characteristics of this hybrid air bearing. To address this gap, this paper proposes a modeling method for high-speed hybrid air journal bearings with herringbone grooves, considering the effects of angular misalignment and centrifugal expansion. Based on the established model, effect of the grooves on the bearing performances is systematically studied. Furthermore, influences of the bearing angular misalignment and the rotor centrifugal expansion on the rotor’s vibration characteristics are illustrated through an unbalance response analysis for an industrial air spindle. The presented model provides an analysis tool for structure design and performance study of the herringbone grooved hybrid air journal bearings.

Experimental study on lubrication characteristics and leakage inhibition of oil-lubricated seal with herringbone grooves

Experimental research was conducted on mechanical seals with pressurized lubricated-oil, focusing on lubrication and leakage inhibition of herringbone-grooved face seals. Through the visualization experiments and axial displacement tests, this study evaluated the performance of the inner-diameter-side (IDS) and middle-diameter-side (MDS) herringbone grooved seals based on the measured cavitation region, leakage rate, friction torque, surface temperature of stator, and axial displacement of the primary ring. The experiment results show that, increasing the width of the seal dam can reduce the hydrodynamic effect and cavitation development of the liquid film but enhance the hydrostatic effect, maintain a small leakage range, the maximum leakage rate is less than 19 mL∙min−1. Zero-leakage can be achieved in MDS due to cavitation suction. The axial displacement curves indicate that the runout amplitude of IDS is smaller than that of MDS, the maximum axial displacement difference is about 25 µm, the stability of IDS is better than MDS. Comparisons of surface temperature and friction torque demonstrates that the lubrication of MDS is better than that of IDS.

Dynamic characteristics of a non-Newtonian lubrication mechanical seal with herringbone grooves considering cavitation effect

This research investigated the effect of lubricant's non-Newtonian properties on dynamic characteristics of a herringbone grooved liquid film seal (HG-LFS) considering cavitation. A modified steady-state perturbation Reynolds equation of the non-Newtonian was derived. Visualized experiments were conducted to verify the accuracy of calculations. The non-Newtonian effect on stiffness, cavitation, damping coefficients, and other sealing performance of the liquid film seal at different velocity, pressure and film thickness were discussed and analyzed. The results indicate that the seal has larger stiffness and damping coefficients with the dilatant lubricant, the cavitation can be inhibited by the shearing-thinning lubricant, and the impact of non-Newtonian on the seal stability decreases with the increase of film thickness. This study would contribute to the design and theoretical research of liquid film seals.

Numerical and experimental investigation on the performances of a liquid metal bearing with spiral groove structures

Liquid metal is a perfect lubricant due to its low melting point, good fluidity at room temperature, higher thermal conductivity and high temperature stability. In this work, the novel hydrodynamic liquid metal bearing with spiral grooves is studied. Influences of the eccentricity, the bearing radius clearance, and the groove structural parameters on the pressure distributions and the load carrying capacity of journal liquid metal bearing are deeply numerically investigated. Meanwhile, the bearing clearance and the structure parameter of herringbone grooves on pressure distribution and load carrying capacity of thrust liquid metal bearing are also numerically conducted and experimentally validated. Numerical studies are conducted based on the finite element method. Results show that the pressure distribution and the load carrying capacity of journal liquid metal bearing are significantly affected by the eccentricity, the bearing clearance and the groove structural parameters. Specifically, for journal bearing, the load carrying capacity increases with the growth of the eccentricity and the groove spacing, while it decreases with the increase of radius clearance, the groove depth and the groove ridge ratio. Besides, it turns out that when the spiral angle is larger than 37.5 degree, the increase of the groove spiral angle results in a decrease of the load carrying capacity, while when the spiral angle is lower than 37.5 degree, the value of load carrying capacities at different spiral angle depends on the specific value of eccentricity. As for thrust bearing, the load carrying capacity increases with the decrease of bearing clearance, and the increase of groove depth. Besides, the groove numbers of 13 and the angle between two vertices of herringbone groove of 13 degree are beneficial for improving the load carrying capacity of thrust liquid metal bearings. Based on the above observations, optimal design parameter sets are selected to obtain much higher load carrying capacities up to four times for both journal and thrust bearings compared with the bearings with original parameters.

Adhesive cryogel particles for bridging confined and irregular tissue defects

BackgroundReconstruction of damaged tissues requires both surface hemostasis and tissue bridging. Tissues with damage resulting from physical trauma or surgical treatments may have arbitrary surface topographies, making tissue bridging challenging.MethodsThis study proposes a tissue adhesive in the form of adhesive cryogel particles (ACPs) made from chitosan, acrylic acid, 1-Ethyl-3-(3-dimethylaminopropyl) carbodiimide (EDC) and N-hydroxysuccinimide (NHS). The adhesion performance was examined by the 180-degree peel test to a collection of tissues including porcine heart, intestine, liver, muscle, and stomach. Cytotoxicity of ACPs was evaluated by cell proliferation of human normal liver cells (LO2) and human intestinal epithelial cells (Caco-2). The degree of inflammation and biodegradability were examined in dorsal subcutaneous rat models. The ability of ACPs to bridge irregular tissue defects was assessed using porcine heart, liver, and kidney as the ex vivo models. Furthermore, a model of repairing liver rupture in rats and an intestinal anastomosis in rabbits were established to verify the effectiveness, biocompatibility, and applicability in clinical surgery.ResultsACPs are applicable to confined and irregular tissue defects, such as deep herringbone grooves in the parenchyma organs and annular sections in the cavernous organs. ACPs formed tough adhesion between tissues [(670.9 ± 50.1) J/m2 for the heart, (607.6 ± 30.0) J/m2 for the intestine, (473.7 ± 37.0) J/m2 for the liver, (186.1 ± 13.3) J/m2 for muscle, and (579.3 ± 32.3) J/m2 for the stomach]. ACPs showed considerable cytocompatibility in vitro study, with a high level of cell viability for 3 d [(98.8 ± 1.2) % for LO2 and (98.3 ± 1.6) % for Caco-2]. It has comparable inflammation repair in a ruptured rat liver (P = 0.58 compared with suture closure), the same with intestinal anastomosis in rabbits (P = 0.40 compared with suture anastomosis). Additionally, ACPs-based intestinal anastomosis (less than 30 s) was remarkably faster than the conventional suturing process (more than 10 min). When ACPs degrade after surgery, the tissues heal across the adhesion interface.ConclusionsACPs are promising as the adhesive for clinical operations and battlefield rescue, with the capability to bridge irregular tissue defects rapidly.

Experimental research on sealing performance of liquid film seal with herringbone-grooved composite textures

Based on the mechanical seal experiments, sealing performances of the mechanical face seals with the herringbone-grooves (HG) only and with composite textures of herringbone grooves and circular dimple textures (HGC) were investigated respectively. The reserve suction effect of HG observed in the experiments provided the evidence for the main inducing mechanism of zero leakage in liquid film sealing. The cavitation region of HGC decreases with the rotating speed, and the HG has the reserve effect. The HGC has lower friction torque and larger film thickness compared to HG, indicating better friction performance. Because of the circular dimples, the temperature difference in sealing rings is reduced and the corresponding thermal performance of the mechanical seal has been improved.

Thermal Analysis and Static Lubrication Performance Study of Liquid Metal Journal Bearing

The temperature distribution of liquid metal journal bearing system in X-ray tube of medical CT machine was simulated by using simulation software, and the working temperature of the herringbone groove liquid metal journal bearing was initially determined. On this basis, the lubricating properties of the liquid metal lubricant were analyzed. The lubrication model of herringbone groove liquid metal journal bearing with Galinstan liquid metal as lubricant was established, and the influence of herringbone groove structure parameters on the static lubrication performance of liquid metal journal bearings was analyzed. The results show that the Galinstan liquid metal has good high temperature stability and can act as a reliable lubricant in the high temperature working environment of the medical CT machine X-ray tube.

Flow characteristic analysis of a herringbone groove thrust bearing with shaft misalignment

PurposeHerringbone groove thrust bearings are typically used in high-speed, light-load applications, such as spindle motors for hard disk drives. In the past researches, the effect of shaft misalignment was little considered. This study aims to reveal effects of shaft misalignment on the microscopic flow regime in the water-lubricated herringbone groove thrust bearing.Design/methodology/approachThe liquid film in a thrust herringbone groove bearing was investigated by computational fluid dynamics. The effects of micro-grooves on the flow field were carefully explored. Two-dimensional liquid films at four different sites were examined for obtaining the rich flow field properties.FindingsThe distributions of pressure, temperature and water vapor volume fraction were obtained, the micro hydrodynamic effects were formed by the herringbone grooves and the effects of the shaft misalignment on lubrication and sealing performance could be found.Originality/valueThe influence of misalignment on the herringbone groove thrust bearing performance was investigated in detail. The obtained results could give the reference guideline for the bearing design.

Effect of herringbone groove structure parameters on the static performance of gas foil herringbone groove thrust bearings

The application of foil bearings technology into high speed and heavy load turbine machinery with high axial force is limited because of the insufficient load capacity of gas foil thrust bearings. This paper presents a new type gas foil thrust bearing, engraving the herringbone groove on the top foil surface of gas thrust foil bearing, relying on the pumping effect of herringbone grooves, so that the bearing load capacity of gas foil thrust bearings can be further improved by using the secondary pressure boosting effect of herringbone grooves on the basis of taper dynamic pressure effect. The physical models of non-groove gas foil thrust bearing and gas foil herringbone groove thrust bearings are established. The Reynolds equation, gas film thickness equation and foil deformation equation are coupling solved by finite difference method to obtain gas film thickness distribution and gas film pressure distribution for non-groove and herringbone grooves gas foil thrust bearing. The effects of the number of grooves, groove depth, groove width ratio, groove angle of the herringbone groove and the Taper inlet height on the friction torque, bearing load capacity and ultimate load capacity of the herringbone grooves gas foil thrust bearing are researched. Furthermore, when compared to the traditional non-groove gas foil thrust bearing, the optimal herringbone groove structure parameters are obtained, and a feasible method for optimizing the performance of gas foil thrust bearings is proposed.

Flow Mechanisms and Lubrication Performance of Water-Lubricated Thrust Bearings with Herringbone Grooves

Due to their excellent stability and zero leakage capability, thrust bearings with herringbone spiral grooves are frequently used in transmission mechanisms. However, the lubrication mechanism of thrust bearings has not been clearly understood and explained, preventing the optimization of the bearing performance. Thus, this paper is devoted to solving this problem by building a three-dimensional finite element flow model. In this model, the change in viscosity temperature is considered using Roelands equation, and the turbulence and cavitation are taken into consideration. Using the established model, the influence of parameters such as spiral angle, groove width ratio, and rotational speed on the cavitation area of the thrust bearing are analyzed. The pressure contour and speed distribution are obtained inside the clearance, as well as the volume fraction of the gas phase at the end face. Finally, according to the analysis results, the optimum structural parameter for the herringbone spiral groove structure is proposed, which enables higher bearing stability and provides a reference for engineering practice.

Numerical analysis of a hydrodynamic air bearing with electromagnetic assistance

An air bearing system with active electromagnetic assistance is proposed, and its dynamic characteristics are numerically analysed. The system is based on herringbone groove hydrodynamic journal bearings. The air bearing system adopts electromagnetic force to assist in lifting the rotor and lowering the lift-off speed of the bearing and adjusting the dynamic stiffness. The characteristics of the bearings are examined using the two-way coupled fluid-structure interaction method for different operating environments. The fluid simulation is performed in ANSYS Fluent and coupled with the motion equations. The fluid-structure interaction analytical model is cross-examined with the published experimental results and is used to analyse the proposed system. The results demonstrate that the lift-off speed is lowered by 46.04% and that the electromagnetic force can compensate for the loss of stiffness at an altitude of 4000 m.

Aptamer-Functionalized Barcodes in Herringbone Microfluidics for Multiple Detection of Exosomes.

Tumor-derived exosomes are vital for clinical dynamic and accurate tumor diagnosis, thus developing sensitive and multiple exosomes detection technology has attracted remarkable attention of scientists. Here, a novel herringbone microfluidic device with aptamer-functionalized barcodes integration for specific capture and multiple detection of tumor-derived exosomes is presented. The barcodes with core-shell constructions are obtained by partially replicating the periodically ordered hexagonal close-packaged colloidal crystal beads. As their inverse opal hydrogel shell possesses rich interconnected pores, the barcodes could provide abundant surface area for functionalization of DNA aptamers to realize specific recognition of target exosomes. Besides, the encoded structure colors of the barcodes can be maintained stably during the detection events as their hardish cores are with sufficient mechanical strength. It is demonstrated that by embedding these barcodes in herringbone groove microfluidic device with designed patterns, the specific capture efficiency and synergetic detection of multiple tumor-derived exosomes in peripheral blood can be significantly improved due to enhanced resistance of turbulent flow. These features make the aptamer-functionalized barcodes and herringbone microfluidics integrated platform promising for exosomes extraction and dynamic tumor diagnosis.

Experimental Investigation of Enhanced Grooves for Herringbone Grooved Journal Bearings

Abstract This paper presents the results of a theoretical and experimental investigation of the potential of enhanced groove geometries to increase the bearing clearance of a Herringbone Grooved Journal Bearing (HGJB) supported rotor. The theoretical study investigates various groove geometries of different complexities and their effect on the stability threshold of a particular rotor geometry. The theoretical results obtained from a rigid-body rotordynamic model suggest an increase of more than 300% in instability onset speed when enhanced groove geometries are used compared to a classical, helically grooved rotor featuring the same radial bearing clearance. As part of the experimental investigation, one rotor shaft with classical grooves, representing the baseline rotor, and four rotors of identical diameter and clearance, but featuring enhanced grooves of varying degrees of complexity, were manufactured and experimentally tested. Good agreement between the experimentally determined speed of instability onset and the prediction was found for the investigated enhanced groove patterns. Experimental results of the classical rotor suggest the onset of instability to occur at a rotational speed of 56 krpm, whereas a speed of 180 krpm was achieved when enhanced groove geometries were applied to the rotor, which agrees very well with the theoretically predicted results and confirms the potential of enhanced groove geometries to stabilize HGJBs. Furthermore, the rotor featuring only a varying groove angle along the rotor axis was found to perform similarly to fully enhanced grooves of varying groove width, depth, and angle, hence representing a good trade-off between performance increase and design cost.