Hole Diameter Research Articles

The Study of the Process of Supplying Seeds of Row Crops Using a Vacuum Seed-Placing Unit

Introduction. The performance of precision seeders depends on many factors, including the functionality of their dosing systems, the modernization of which is possible only on the basis of patterns, which allows forecasting the indicators of single seed placing into a furrow.Aim of the Study. The study is aimed at analyzing the influence of the diameter of the suction holes of seed-placing units and the rarefaction created in them on the characteristics of placing seeds of the main row crops.Materials and Methods. The results of the study were obtained based on a series of experiments on sowing corn and sunflower seeds using an MS-8 seeder, the operation principle of which can be considered typical for vacuum seed-placing units.Results. There have been obtained empirical dependences of the particular features of zero and group placing seeds of such row crops as corn and sunflower on the area of the suction holes and the rarefaction in the vacuum chamber.Discussion and Conclusion. The quantitative estimates obtained may differ for seeds of the same crop, but having different technological properties. The general factor is that the frequency of missing seeds is proportional to the suction force magnitude in the working plane of the metering element, regardless of its area. At the same time, the probability of double seed placing depends on the area of the metering ports with a constant suction force, a decrease in their diameter leads to a decrease in the frequency of double seed placing. The data obtained allow considering joint variations in the magnitude of the rarefaction in the vacuum chamber and the diameter of the suction holes as effective tools for improving the seed placing quality.

Fabrication of through sapphire vias by femtosecond laser bidirectional drilling

ABSTRACT Three-dimensional (3D) heterogeneous integration has shown great promise in increasing integration density and reducing parasitic capacitance, which micro through vias on insulators are highly desired. In this work, femtosecond laser bidirectional drilling of crack-free micro through-sapphire-vias has been demonstrated. Mechanisms of material removal and defect suppression during the drilling process were studied. The bottom surface was drilled first and followed by the top surface drilling. A blind hole prefabricated by the bottom surface drilling can effectively suppress the edge collapse and extensive ablation damage on the bottom surface during subsequent top surface drilling with high pulse energy laser. Effects of incident laser parameters on the surface quality, morphology, diameter, and taper of the through hole at different drilling stages were systematically studied. Under given strategy, hole diameter down to ~50 μm on 400 μm-thick sapphire wafers can be achieved directly, showing great prospects in 3D heterogeneous integration.

Tensile Properties of Open Hole and Unhole Sugar Palm ‘Ijuk’ (SPI) Fibre Composite Treated with Sodium Hydroxide (NaOH)

This study evaluates the effects of sodium hydroxide (NaOH) treatment on tensile properties of sugar palm 'ijuk' (SPI) fibre-reinforced polymer (FRP) composites, with and without an open hole that acts as a stress concentrator. The NaOH treatment is aimed to improve the interfacial adhesion between SPI fibres and polymer matrix. Composite specimens were prepared using the hand lay-up method, incorporating SPI fibres in various orientations, and featuring a 6 mm diameter hole. Tensile tests were conducted to evaluate the mechanical performance of SPI FRP composite, including ultimate tensile strength, Young's modulus, and elongation at break. The research also compared the properties of SPI to those of synthetic glass fibre in fibre-reinforced polymer composites. The results showed that NaOH treatment significantly improves the fibre-matrix adhesion with 26% increase in tensile strength, leading to enhanced tensile properties in both samples, regardless of hole presence. The 0° orientation provides the highest strength and stiffness when the load is applied in the direction of the fibres. While for the 90° orientation, strength reduces by 14%. The impact of the hole on stress concentration and the subsequent mechanical behaviour of the open-hole specimens is substantial. The findings of this study offer insightful perspectives on the potential use ofNaOH-treated SPI fibre in structural and other applications, demonstrating its ability to withstand tensile stresses, even with geometric discontinuities like holes.

The visual measurement method of the hole diameter and center-to-center distance of the box based on simplified external parameter calibration

Abstract The hole is a significant mechanical structure type. In this paper, two visual measurement models are established for chamfered and non-chamfered holes. A concentric cylinder with a known diameter is used as a calibration object to obtain the external parameters corresponding to the end face of the measured hole. This approach overcomes limitations associated with using calibration plates for external parameter calibration and aligns better with requirements in production sites. By utilizing the obtained external parameters, three-dimensional coordinates of edge points on the measured hole can be determined, and an ellipse fitting algorithm is employed to obtain aperture and center point coordinates. In the experiment, gearbox housing is used to measure hole diameter and center-to-center distance. The measurements are compared with a coordinate measuring machine, demonstrating a measurement accuracy up to 0.1 mm. The experimental results confirm both feasibility and effectiveness of measurement model while maintaining low operational complexity.

Influence of corrugated jet plates on internal heat transfer and flow dynamics of double-wall cooling: experimental-numerical approach

In the present study, combined experimental and numerical investigations were carried out to analyze the fluid flow dynamics and heat transfer of impinging jets in a corrugated double-wall structure for exhaust nozzle cooling operating at high temperatures. The sinusoidal wavy plate, with multi-jet holes positioned at its trough, served as the jet plate, creating a staggered configuration with respect to the effusion holes. The transient thermochromic liquid crystal (TLC) method was employed to determine the local distribution of the Nusslet number on the flat effusion plate in a wind tunnel at small Reynolds numbers (ranging from 450 to 2700 based on the jet hole diameter (d)). In the numerical part of the study, the k-ω SST turbulence model verified with the TLC data was used to solve the RANS equations. The effects of jet-to-plate spacing (Have/d = 1.6–3.6), corrugated plate amplitude (A/d = 0.2–0.8), effusion hole diameter (de/d = 0.6–1.5), and Reynolds numbers were examined in detail. Our results showed that the introduction of the corrugated structure in the jet plate altered the high-velocity region pattern within the jet hole, leading to a 16 %-81 % reduction in jet core length compared to the flat jet plate. At a relatively high wave amplitude (A/d ≥ 0.5), the vortex structure underwent significant changes, inducing a higher level of turbulence kinetic energy in the near-wall region of the target chamber. This led to enhanced heat transfer near the stagnation and effusion hole regions compared to the flat double-wall cooling. The effusion hole diameter exerted a minimal effect on the overall Nusselt number of the corrugated double-wall cooling. At very low Reynolds numbers (Rej 〈900), the flow and heat transfer characteristics in corrugated double-wall cooling resembled those observed in flat double-wall cooling.

SEQUENTIAL PARS PLANA VITRECTOMY AND INVERTED INTERNAL LIMITING MEMBRANE FLAP TECHNIQUE FOR RHEGMATOGENOUS RETINAL DETACHMENTS WITH PERIPHERAL BREAKS AND CONCOMITANT NONCAUSATIVE MACULAR HOLE IN NONHIGHLY MYOPIC PATIENTS.

To present the anatomical and functional results of sequential pars plana vitrectomy for treating rhegmatogenous retinal detachment with peripheral breaks and concomitant noncausative macular holes (MHs) in nonhighly myopic patients. Medical records of patients who underwent rhegmatogenous retinal detachment surgical repair between 2017 and 2023 were reviewed. Of 980 patients with rhegmatogenous retinal detachment, 10 had concurrent MH and underwent sequential pars plana vitrectomy for rhegmatogenous retinal detachment repair and air endotamponade, followed by MH repair using the inverted internal limiting membrane flap technique and C2F6 endotamponade after a minimum of 1 week. The main outcomes measured were best-corrected visual acuity change, retinal reattachment rate, MH closure rate, and closure type. The retinal reattachment rate was 90% after the primary surgery and 100% after subsequent surgery. Macular hole closure was achieved in all cases. Macular hole diameters ranged from 291 to 702 µm. Anatomical recovery showed mainly 1A closure types (90%). Functional recovery demonstrated significant best-corrected visual acuity improvement, with a mean visual acuity gain of 1.58 ± 0.41 the logarithm of the minimum angle of resolution. For this infrequent pathology, sequential surgery using the inverted internal limiting membrane flap technique and air/gas endotamponade yielded favorable anatomical and functional outcomes. This controlled and standardized approach using sequential surgeries contributes to the achievement of consistent results.

Heat transfer characteristic and optimization design of alter diameter array impingement cooling structure

The fine design of blade cooling is one of the leading directions in the development for blade manufacturing technology, attaining optimal and consistent cooling efficiency is the common research concern in the field of fine design. In the current work, the alter diameter hole arrays are applied to reasonably regulate the distribution of cold air flow, which aims to achieve uniform cooling performance of impinging cooling technology. Experiment involving temperature sensitive paint technology and simulation based on SST k-w turbulence model are conducted. Subsequently, the mechanism of cooling performance increasement is investigated; the impact of structural elements on the heat transfer properties is discussed. Moreover, the correlation between the Nu number of the target surface and the comprehensive influence factors was fitted based on response surface method; the optimal structure in the range of the structural parameters is calculated based on NSGA-II and TOPSIS method. The results reveal that the influence of d and x on average surface Nusselt number is remarkable. In addition, the response surface model fitting model is accurate to predict the structure parameter effect on cooling performance of alter impingement cooling, with the prediction error less than 2.67 %. Compared with the basic EDI, the Nu of the ADI structure with ∇T constraint is increased by 5.2 %, the temperature inhomogeneity is reduced by 53.4 %. The significant improvement of temperature inhomogeneity indicates the practicality of ADI structure and optimized procedure used in improving impingement cooling efficiency which shows promising performance increasement.

Jet array impingement heat transfer in a rectangular cavity with effusion holes

Various researchers have studied jet array impingement heat transfer in impingement/effusion cooling systems. However, there is a lack of research on impingement/effusion cooling systems installed within rectangular cavities that focus on the impact of the proximity of the jet hole to the cavity sidewalls on cooling performance. The main objective of this study is to investigate the flow and heat transfer characteristics of jet array impingement with effusion holes in a rectangular cavity, considering various spacings between the cavity sidewalls and the outermost jet hole. The design parameters in this study include the ratio of the jet hole pitch to jet hole diameter of 7.1, 10.0, and 16.7, and the ratio of the distance between the jet and impingement plates to jet hole diameter of 2, 6, and 10, with the Reynolds number based on the jet hole diameter ranging from 2500 to 15,000. Heat transfer characteristics in the stagnation region and wall jet region were examined using local Nusselt number distributions on the impingement surface, measured by liquid crystal thermography. The local Nusselt number was high in the stagnation region and decreased radially from the stagnation region as the wall jet region formed. The closer the outermost jet hole is to the sidewall, the higher the Nusselt number on the impingement surface near the sidewall. Moreover, the flow structure in the rectangular cavity was numerically investigated, and the velocity vectors and streamlines showed that primary and secondary vortices were generated in the middle of two neighboring jets and near the sidewall, respectively. This study also assessed previous average Nusselt number correlations. Based on experimentally determined average Nusselt number data with 54 center unit cells and 1296 side unit cells, new correlations to predict the average Nusselt number on the impingement surface in a rectangular cavity with effusion holes were developed.

Effect of geometric parameters on dynamic fracture toughness of compact tensile specimens

In this paper, the dynamic fracture toughness test and numerical simulation of CT specimens of 2A12-T4 aluminum alloy were carried out by using strain gauge method and finite element method based on Hopkinson tensile bar experiment device. The influence of crack transverse shape, loading hole size and dimension on the dynamic fracture performance of CT specimens was explained. The experimental and simulation results show that for CT specimens with different internal cracks, the time to reach stress equilibrium at the same tensile stress wave loading is roughly the same, while the time of initial cracking varies slightly. The dynamic fracture toughness obtained by concave arc-shaped internal crack and straight line-shaped internal crack is basically the same, while other changes in crack shape have a large impact. For CT specimens with straight line-shaped cracks, the position of the loading hole has a small effect on the dynamic fracture of the CT specimen under the same tensile stress wave. However, when the position of the loading hole is fixed, changing the diameter of the loading hole has a significant effect on the dynamic fracture toughness of the CT specimen.

Effect of Perforated Aluminum on Calotropis Gigantea Fiber Material’s Ability to Absorption Sound

Plants fibers such as Calotropis gigantea (CG) are very suitable as noise reduction material. Therefore, this research aims to determine the sound absorption coefficient of CG in the 20 mm test sample and the effect of the perforated aluminum layer on its ability. It was carried out using a test sample made with a thickness of 20 mm and 100 mm in diameter. The thickness of aluminum was 0.3 mm with hole diameters of 1 mm, 1.5 mm, and 2.5 mm. During the experiment, every sample was heated and pressed in a mold for 10 minutes at 200oC. The test equipment used is a Bruel Kjaer Type 4206 impedance tube with 100 mm in diameter. The sample was tested using the transfer function method ISO 10534-2:1998 at a frequency of 1/1 octave. The results indicated that the uncoated sample absorbed noise α = 0.01-0.07 (1-7)% higher than the sample coated with perforated aluminum. This showed that the Noise Reduction Coefficient (NRC) without aluminum coating can reduce noise by 29%, and the measured sample is categorized in class D.

PROFILING THE SURFACE OF THE PIN HOLE IN THE PISTON BODY

Minimization of the mass of the piston kit, which consists of three main parts - piston, pin and connecting rod, is connected, among other things, with the possibility of reducing the diameter of the steel pin. On the other hand, a decrease in its diameter inevitably leads to an increase in stresses in the piston pin hole (PPH) and possible destruction. It is known that reducing the mass of the piston set from 5 to 20% leads to an increase in the output parameters of the internal combustion engine - torque and power by 1% to 4.5%. The purpose of the study is to determine the possibility of reducing the stresses in the bearing due to the profiling of its surface while reducing the diameter of the piston pin. The research algorithm is presented, which consists of building a geometric model of the piston assembly, loading with excessive pressure taking into account the plasticity of the material, modifying the geometry of the PPH and checking the stresses of the loaded state. The conventional piston model has the following geometry: diameter – 80 mm; height – 60 mm; compression height – 30 mm; the diameter of the finger hole is 18 mm; the distance between the bumps is 28 mm. Piston material – aluminum-based alloy – AISI 2014-0, pin and connecting rod material – AISI 1020 steel. Pressure loading conditions: taking into account plasticity – nonlinear, harmonic, 2 cycles, maximum amplitude – 8 MPa; test - static, 6.5 MPa. A crumpling zone with residual deformations was detected in the PPH, the maximum final deformation practically does not differ in the first and second load cycles (0.0081 vs. 0.0084). Residual deformations occur 1/3 of the length from the inner edge of the head. The absolute residual deformations are given in the form of a sweep of the change in the PPH radius. The maximum value is about 0.04 mm. This result is the basis for modifying the geometry of the surface of the finger hole. The modified geometry of the PPH is obtained by boring the cylindrical surface with a profile modeled by the appropriate spline on the geometric model. The boring axis is offset by 0.02 mm from the PPH axis. Verification modeling showed that the averaged loads on the edge of the model are 143 MPa for the cylindrical and 107 MPa for the modified PPH (-25% for the modified profile).

Experimental and numerical study on the effect mechanism of geometric parameters on jet impingement cooling in a limited space

In order to meet the development needs of the internal cooling structure of gas turbine blades, this paper researches the jet impingement cooling in a limited space. Numerical simulation method is employed to obtain the flow field details and analyze the flow and heat transfer mechanism. The heat transfer coefficient distribution of the target surface is obtained by the transient liquid crystal, which verifies the accuracy of the CFD results. The effects of inlet mass flow rate m˙in, rows of jet holes N, jet hole diameter Dj, jet-to-target distance H/Dj and transverse distance between jet holes S/W are considered. The results show that: The flow and heat transfer characteristics at different m˙in are qualitatively similar. N has a significant effect on the heat transfer coefficient and total pressure difference. With the increase of N, the heat transfer coefficient and the total pressure difference decrease. Dj has obvious effect on heat transfer coefficient and total pressure difference. As Dj increases, both the heat transfer coefficient and the total pressure difference decrease. H/Dj has only a slight effect on the heat transfer coefficient and total pressure difference. When H/Dj increases from 1.2 to 2.2, the heat transfer coefficient increases and the total pressure difference decreases. When H/Dj increases from 2.2 to 3.2, the heat transfer coefficient decreases and the total pressure difference is almost unchanged. The effect of S/W on the heat transfer coefficient and total pressure difference is more obvious than that of H/Dj. The heat transfer coefficient and total pressure difference are the largest when S/W = 0.5. The structure with N = 8，Dj = 24 mm，H/Dj = 2.2，S/W = 0.5 has the best comprehensive heat transfer performance under the range of the boundary condition.

Supercontinuum generation in Ga‐Sb‐S chalcogenide‐based PCF using optofluidic approach

AbstractWe report the design and theoretical study of a Ga‐Sb‐S chalcogenide glass‐based photonic crystal fiber (PCF) structure for mid‐infrared supercontinuum generation. The proposed design is engineered by adjusting the diameter of air holes in the cladding region and pitch, giving us control over the dispersion characteristics of the fiber. The optimized structure design offers the Zero Dispersion Wavelength of 5.2 μm. When pumped with 50 fs secant hyperbolic pulses of peak power 4.9 kW, for a fiber of length 8 mm at pump wavelength of 5 μm, the proposed structure design produces an ultra‐broadband supercontinuum spectrum spanning 1.5–14 μm. Proposed PCF design should be helpful in, biomedical imaging, supercontinuum sources, biosesning, and optical coherence tomography.

Long-term Visual Outcomes in Patients With Idiopathic Macular Hole Surgery.

This study assesses long-term outcomes following surgical repair of idiopathic full-thickness macular holes (FTMHs) in patients with at least 5 years of postoperative follow-up. A retrospective study evaluated patients diagnosed with idiopathic FTMH who received surgical repair at a single tertiary center with at least 5 years of postoperative follow-up. Data collection included demographic and preoperative characteristics along with macular hole structural integrity as determined by spectral-domain optical coherence tomography (OCT). Functional and structural improvement were assessed by collection of visual acuity and findings on OCT at determined time points until 9 years of follow-up. The study comprised 90 eyes of 80 patients with a mean age of 67.2 ± 6.8 years, with an average postoperative follow-up of 80.8 ± 17.4 months (range 54 to 130 months). The mean macular hole diameter was 239.7 µm ± 92.2. Macular hole reoperation occurred in four eyes (4%) at a mean duration of 5.5 ± 6 months (range 0.3 to 13 months). Over the study duration, ellipsoid zone (EZ) integrity was maintained in 67.8% of eyes, with an absence of intraretinal fluid (IRF) in 96% on final OCT. The preoperative mean Early Treatment Diabetic Retinopathy Study (ETDRS) best visual acuity (BVA) of 51 improved to a mean BVA of 76 at 5 years postoperatively, with an average gain of 24 letters at one year that remained stable over 5 years (P < 0.05). Eight years after surgical repair, more than 80% of patients achieved a BVA > 65. Vitreoretinal surgery for idiopathic FTMH resulted in successful hole closure and sustained visual acuity improvement over long-term follow-up. [Ophthalmic Surg Lasers Imaging Retina 2024;55:XX-XX.].

Comparative evaluation of image quality between virtual grid and grid portable radiographic systems

Purpose. Virtual Grid (VG) is an image processing technique designed to address scattered radiation from radiographic systems without a physical grid. It aims to eliminate artifacts caused by grid misalignment and enhance radiographic workflow efficiency. We intend to evaluate image quality between Virtual Grid and grid-based radiographic systems across various patient thicknesses. Methods. A Fujifilm Virtual Grid and GE AMX-4 portable radiographic system was used. Image quality was assessed using MTF, NPS, LCR, and CNR. MTF calculations employed an edge-device method with a 0.1 mmCu sheet. For NPS evaluation, uniform images were acquired with multiple 30 × 30 cm solid water blocks (2 cm thick), overlaid in 2 cm increments to simulate patient sizes from 2cm to 40 cm. LCR and CNR were evaluated using a CIRS test plate with 9-hole depths for a hole diameter of 0.375’. The test object was placed on top of the detector then water blocks, while maintaining the same SID, beam quality, and exposure between the units. Visual assessments were conducted by four readers, quantifying perceived hole numbers. The weighted Cohen’s Kappa and Welch’s T-test were utilized for statistical analysis. Results. At 80% MTF, VG exhibited high contrast resolution of 1.1 l p/mm compared to 1.2 l p/mm for the grid system. VG demonstrated lower noise levels across all frequencies for equivalent patient thicknesses. Welch’s T-test indicated no significant differences in LCR (P = 0.31) and CNR (P = 0.34) between the systems. However, qualitative observation demonstrated VG’s better low contrast response for patient sizes ≥10 cm. The average weighted Cohen’s Kappa value was 0.78. Conclusion. This work indicates the Virtual Grid technology can effectively mitigate scattered radiation to improve granularity and low-contrast resolution in an image compared to a grid system. Furthermore, it can potentially reduce patient dose.

Sound absorption properties and mechanism of multi‐layer micro‐perforated nanofiber membrane

AbstractAiming at achieving low‐frequency and broadband sound absorption under the premise of light and thin layers, in this paper, polyvinyl butyral (PVB) nanofiber membranes were micro‐perforated and then combined sequentially to prepare multi‐layer micro‐perforated nanofiber membrane (MPNM) for acoustic noise reduction. It was demonstrated that the multi‐layer MPNM exhibited a high absorption (constantly over 50%) in the frequency of 480–2500 Hz. In addition, the established theoretical model of the sound absorbing coefficient can accurately predict the sound absorption performance of the structure with different layers, which can provide a theoretical foundation for the design of the structure of the nanofibrous membrane acoustic absorber. Based on the proposed acoustic model, the relationships between the absorption properties and the parameters were investigated, and it was found that the effective acoustic absorption frequency range and acoustic absorption coefficient curve of the multi‐layer MPNM were closely related to the size and arrangement of hole diameter, perforation rate, fiber membrane thickness, and cavity depth. Optimization of the structural parameters utilizing algorithms can achieve superior sound absorption performance, with an average absorption coefficient of 0.81 in the frequency of 100–2500 Hz. This study provides a theoretical and experimental basis for the development of low‐frequency sound‐absorbing materials and is of great significance for optimizing the acoustic performance of nanofiber membranes and expanding their applications in various acoustic engineering applications.

Application of a xenopericardial plate for closing a laparostomy in conditions of a purulent-inflammatory process

The aim of the study is to study the morphological changes in tissue in the laparostomy area when it is closed with a xenopericardial plate under conditions of an active purulent-inflammatory process. Material and methods. Analysis of data from patients at the Penza regional clinical hospital named after. N.N. Burdenko, with diseases of the abdominal organs, complicated by diffuse purulent peritonitis. During treatment, xenopericardial plates with perforations in a checkerboard pattern were used (hole diameter 0.5 cm). Disinfection of the material was carried out with a sterile solution of furacilin. Using the standard hematoxylin and eosin staining protocol, as well as alternative staining methods according to Van Gieson and Weigert, light-optical examination of stained sections was carried out at a magnification of 40–400 times. Results. In 8 out of 9 patients participating in the study, a favorable course of the inflammatory process was observed; on the 21st day after laparotomy, the symptoms of peritonitis were eliminated, the surgical wound was sutured. In one case, progression of local and general signs of peritonitis was observed within two weeks. After replacing the xenopericardial plate, the course of changes in the surgical wound was favorable. On day 21, the laparotomy wound was also sutured. Repeated examination of the biomaterial one year and two months after implantation of the xenopericardial plate into the anterior abdominal wall did not reveal signs of inflammation. Conclusions. The xenopericardium performed well in conditions of purulent inflammation and in most cases was not subject to melting. In the long term, biointegration of the xenopericardium into its own connective tissue occurred.

Effect of web holes on web crippling capacity of rectangular hollow steel sections under two flange loadings

This paper presents experimental and numerical investigations on web crippling behavior of hot rolled rectangular hollow section (RHS) with web holes. A total of 20 rectangular hollow sections, subjected to interior-two-flange (ITF) and end-two-flange (ETF) loading conditions undergoing web crippling, were experimentally tested. The experimental program was designed to obtain web crippling of specimen having slenderness (h/t) value of 21.32, by varying size and offset distance of web holes under two flange loading conditions. Finite element models of experimentally tested beams were developed, and results of finite element analysis showed good agreement with experimental results. A parametric study was then conducted using finite element analysis on different cross section sizes, to demonstrate the effect of size and position of web holes on web crippling capacity of rectangular hollow sections. It was demonstrated that ratio of diameter of web hole to the depth of flat portion of web (a/h) and ratio of offset distance of web hole to the flat portion of web (x/h) are the primary parameters affecting the web crippling strength. Design recommendations in the form of reduction factors for both loading conditions are proposed, that are conservative to both experimental and finite element results. To assess the reliability level of design recommendations, reliability analyses were undertaken.

The investigation of double wall cooling configuration with spherical cavity

Double wall cooling is an efficient cooling method for turbine blade. Commonly used double wall cooling configurations contains a cubic cavity between two walls. Chaos flow flied in the cavity impedes heat transfer. In this research, a new spherical cavity was proposed, traditional cubic cavity was replaced by several spherical cavities, film hole located on the top of spherical cavity, and impact hole located at the button of spherical cavity. Adjacent spherical cavities were connected by channel. Different spherical cavities were established and numerical simulation was used to check their performance. The influence of blowing ratio, channel, film hole diameter, spherical cavity diameter was analyzed. The performance of cavities was also compared with common double wall cooling configurations. According to the result, when blowing ratio was 0.3, spherical cavity increased cooling effectiveness by 45.6% maximumly compared to common configurations. As for coolant consumption, spherical cavity needs less coolant than common configurations to achieve the same cooling effectiveness. What's more, film hole located at −45° position was benefit for cooling, and cooling effectiveness would increase further when spherical cavity diameter was enlarged.

面向小粒蔬菜种子的气吸排种器排种性能试验

Vegetable precision planting agronomy is suitable for my country's current vegetable planting system, and the air-suction vegetable precision planter is currently the most important work tool in my country. This paper designs a kind of air-absorbing vegetable precision sower for the problems of small vegetable seeds with small grains, poor mobility and high difficulty in achieving uniform sowing of small seeds. First, Fluent software is used to simulate and analyze the flow field of the air chamber in the seed metering device, and the pressure and velocity of the fluid in the air chamber are analyzed. Through the comparison of the pressure distribution cloud chart and the velocity distribution cloud chart, the influence of different apertures, holes, vacuum degree, and gas chamber depth on the flow field of the gas chamber is analyzed. The air suction seed discharger test bench was set up and orthogonal test was carried out, and the test results showed that the optimal parameter combination was 3.5 kPa vacuum degree of the air chamber, 2.4 mm diameter of the type hole, and 18 r/min rotational speed of the seed discharging disk. The high-speed photographic test was carried out under the optimal parameter combination, and the results showed that leakage of suction, adsorption of 1 seed, and adsorption of multiple seeds appeared in the process of suction, and it is important for the development of the air suction precision machine for small seeded vegetables with better performance. The results showed that the phenomenon of leakage, adsorption of 1 seed and adsorption of multiple seeds occurred in the process of seed suction, which provided a reference basis for the development of a better performance of the air-absorption precision planter for small seeds.