Cylinder Hole Research Articles

Research on flow and heat transfer characteristics of supersonic film cooling with different hole-configurations

In order to investigates the flow and heat transfer characteristics under supersonic mainstream conditions among three typical film hole-configurations—cylinder hole (CH), fan-shaped hole (FSH), and laidback fan-shaped hole (LFSH), this study conducted numerical simulation using the ANSYS CFX and based on the assumption of compressible flow. The results indicate that the cooling effectiveness of the CH dramatically decreases as the blowing ratio increases, while FSH and LFSH improves. When the supersonic mainstream encounters the coolant, flow structures such as oblique shock waves, expansion waves, and mixing layers et al., will be generated around the film holes, which have an impact on the flow and heat transfer characteristics. Under the conditions of same blowing ratio, the shock wave intensity of LFSH is significantly lower than the other two holes and the kidney vortices formed by the CH develop further along the mainstream direction. While the strength of the kidney vortices formed by the FSH and the LFSH is weaker. Additionally, the LFSH incurred the least total pressure loss from before the shock wave to after the oblique shock wave. Specifically, at a blowing ratio of 0.8, it achieved a reduction of approximately 20% in total pressure loss compared to the CH.

A Comprehensive Design and Performance Assessment of a Reel-Type Blade Organic Waste Chopper Machine

The global issue of organic waste poses a serious threat to the environment and public health. With the increasing production of organic waste driven by population growth and urbanization, waste management systems worldwide are confronted with inevitable pressures. The decomposition process of organic waste generates methane gas, contributing not only to global climate change through the greenhouse gas effect but also posing risks of air and water pollution. The primary function of organic waste lies in its ability to become a valuable resource through recycling and composting processes. The potential use of organic waste as a source of renewable energy through biogas or biomass production also presents promising prospects. The objective of this research is to design a reel-type chopper machine for more optimal waste processing. The research method employed is engineering, involving non-routine design activities to create something new in both process and form. The results of the study show that the designed reel-type organic waste shredder has dimensions of 800 mm in length, 750 mm in width, and 1042 mm in height. The machine consists of four main components: the frame hopper, shredding cylinder, and discharge hole. The chopper machine has a power of 2.2 kW, a chopper capacity of 1 ton/hour, and a cutting length of 2–5 cm. The advantages of the shredded output from this reel-type chopper machine can accelerate the decomposition and fermentation processes of organic waste. The smaller and uniformly shredded particles provide a larger surface area for the activities of decomposing microorganisms. Additionally, reel-type machines are more efficient in processing materials with high moisture levels, such as wet branches or leaves. By ensuring optimal particle size, reel-type machines also enhance the efficiency of composting, as well as the production of compost briquettes and briquettes fueled by organic waste. Therefore, the role of reel-type organic waste shredder machines is crucial in maximizing the value of organic waste, accelerating the recycling cycle, and effectively reducing environmental impact.

Multi-objective optimisation of heat transfer and structural strength of aero-piston air-cooled engine cylinder based on orthogonal test

Owing to their compact and lightweight structure, air-cooled aviation piston engines are used in general aviation, agriculture, and military fields. To address the kind of engine thermal load problem, this study used a horizontal four-cylinder four-stroke aviation piston air-cooled gasoline engine as the research object. Tested the engine cylinder temperature and pressure under calibrated power conditions, built a one-dimensional simulation model and a fluid–structure interaction simulation model. Four main structural parameters—fin thickness, fin spacing, fin length, and cylinder wall thickness—were considered as factors. Each factors have five levels to construct orthogonal tests to analyse their influence on the cylinder heat transfer and structural strength performance. A range analysis of the orthogonal test showed that the fin thickness had the most significant influence on the thermal stress, while the fin length most significantly influenced the temperature and cylinder hole deformation. A comprehensive frequency analysis method combining intuitive and range analyses is used to determine the optimal combination scheme, and the heat transfer and strength performance of the engine cylinder before and after optimization is compared. The results indicated that the fin thickness and length had the most influence on cylinder performance. After optimisation, the temperature decreased by 3.3 % from 198.3 ℃ to 191.8 ℃, while the thermal stress decreased by 21.9 % from 100.5 MPa to 78.5 MPa. In addition, the cylinder hole deformation decreased by 11 %, from 0.273 mm to 0.243 mm. These research results can provide a reference for the design and optimisation of heat fins of air-cooled aviation piston engines.

Comprehensive evaluation on conjugate heat transfer and thermal stress performance of film cooling

Film cooling is a commonly used cooling technology in gas turbines, which could reduce heat load by spreading cooling air. However, it faces the problem of stress concentration in structures with holes. The present work focuses on conjugate heat transfer and thermal stress characteristics for a flat film cooling plate through an experimentally validated numerical approach. It discusses the effect of three geometry factors: inclination angle, compound angle, and ellipticity. An engine case simulation and a laboratory case simulation are compared to validate the analogy principle of conjugate heat transfer and thermal stress analysis derived from theoretical analysis. According to the analogy principle, the laboratory flat plate film cooling cases are set to conduct numerical studies. The maximum Mises stress of the film hole is equal to the product of the reference stress and the stress concentration factor. The reference Mises stress is proportional to the overall cooling effectiveness. The stress concentration factor is mainly related to the geometry of the film hole. Reducing the inclination angle of the film hole from 90° to 30° increases the overall cooling effectiveness and drastically increases the stress concentration factor from 2.7 to 5.5. Based on a cylinder hole with a 30° inclination angle, increasing the compound angle enhances the overall cooling effectiveness and slightly increases the stress concentration factor. Based on a cylinder hole with a 30° inclination angle, increasing the ellipticity increases the overall cooling effectiveness and reduces the stress concentration factor. With the increase of ellipticity from 0 to 4, the stress concentration factor decreases from 5.5 to 2. Elliptical film holes are ideal for future low-stress, high-cooling-efficiency turbine blades to extend the life of cooling vanes.

Comparisons of Overall Performance Among Double-Jet Film Cooling Holes, Cylinder Holes, and Fan-Shaped Holes

Abstract In this paper, the film-cooling effectiveness (η) and heat transfer coefficient (h) of different film hole geometries are investigated, including double-jet film cooling (DJFC) holes, streamwise cylindrical holes, and fan-shaped holes, both experimentally and numerically. Results reveal that when the blowing ratio is less than 1.0, the DJFC holes have the highest η and the highest h, as well as the highest net heat flux reduction (NHFR). However, a higher blowing ratio (>1.0) leads to a quickly decreasing NHFR of DJFC holes. The asymmetric antikidney vortex and the high turbulent kinetic energy (TKE) are dominant in the performance of the DJFC holes. Owing to medium effectiveness and the lowest heat transfer coefficient, the fan-shaped holes possess the highest net heat flux reduction at M = 2.0 although the value is negative. The relatively weak kidney vortex and the low TKE can explain the phenomena. The cylindrical holes have the lowest η and the lowest NHFR due to the kidney vortex and relatively higher TKE.

Experimental Study of Two Rows Hybrid Film Cooling Holes Over Flat Plate Surface Using IR Technology

The study examines the effectiveness of two rows of hybrid film cooling holes over a plate surface using infrared technology and a thermal wind tunnel. The two rows consist of seventeen coolant injection holes, with nine in the first row and eight in the second row. Two cases were studied: case 1 using cylindrical holes and case 2 using hybrid holes. Both cases had the same cross-sectional area with a hydraulic diameter of 5.3 mm and a forward coolant injection angle of 30° in the streamwise direction. Different blowing ratios (mass flows ratio between the coolant and mainstream) were tested at 0.5, 1.0, and 1.5. The study focuses on evaluating the impact of hole shape with various blowing ratios on film cooling effectiveness. In addition, thermal images of the test surface were taken via an infrared camera after reaching a steady state. The results indicated that at a blowing ratio of 0.5, there was a significant enhancement in film efficacy, with a decrease in the test surface temperature of the cylinder and hybrid hole cases by 31.8% and 35.0%, respectively, when compared to a blowing ratio of 1.0 and 1.5, which had a temperature increase. Therefore, the film cooling effectiveness decreased to 30.9% and 32.4%, and 29.5% and 31.7% for the cylinder and hybrid hole cases, respectively. Additionally, the better overall film cooling effectiveness in this study was achieved by the configuration of the hybrid holes at a blowing ratio of 0.5, which resulted in a film cooling effectiveness of 35.0%

Numeric Prediction of the Detail Visibility in Industrial X-Ray Computed Tomography by Human Observers

Industrial Computed Tomography (iCT) is applied in industry for flaw detection, flaw evaluation and dimensional measurement. This requires the correct experimental system settings for sufficient visibility and detectability of details and structure elements. This is an essential tool for long term monitoring of the detail sensitivity of CT scanners. The visibility of indications by human observers on a monitor in cross sectional 2D CT-images can be estimated from the square root of the visible flaw area, the Contrast to Noise Ratio (CNR) and the Modulation Transfer Function (MTF). The ASTM guide E 1441 describes a more detailed procedure for the determination of the minimum contrast for the visibility of flaws based on three essential functions for the prediction of the visibility of small circular indications in iCT slice images. This is the Contrast Discrimination Function (CDF), the Modulation Transfer Function (MTF) as described in the latest revision of ASTM E 1695, and the Contrast Detail Diagram (CDD). All these functions analyse the contrast as function of the spatial frequency in digital 2D slice images. The functions do not describe, how to calculate the visibility limit for human observers. The concept for the automated calculation of the visibility limit of circular indications in reconstructed slice images is discussed in this paper. It is finally determined from the intersection point of the MTF with the Contrast Detail Diagram, which is the combination of CDF and MTF, and a physiological factor c. The new measurement procedures for the prediction of the detail visibility by MTF and CDD was tested with test phantoms and be verified by modelling and measurements. A Round Robin test was conducted with more than 10 parties to verify the visibility formula and the procedure for determination of the visibility limit from the combination of these functions. A form factor is considered to compare cylinder holes with pore indications. Conclusions will be reported and recommendations will be given for the determination of the correct physiological factor c.

Upaya Peningkatan Kualitas dengan Menggunakan Analisis Siklus PDCA pada Perusahaan Otomotif

In this era of globalization, the competition in the automotive industry is getting more challenging, and consumer demands are also continually increasing. This is what encourages the automotive industry to make products as perfect as possible, one of which is minimizing the level of defects in their production lines. By reducing defects, the process will flow faster without going through the repair process. But in actuality, there are still defects found in the poses of its production. This research was conducted in the welding process in the automotive industry. This paper aims to identify defects in the welding production process in the automotive industry. Then analyze the most dominant defect, find the root cause, and improve. This study uses the PDCA cycle method. The PDCA cycle is a continuous improvement model consisting of four sequential components, Plan, Do, Check, and Action. The results of this study identified five major defects in the welding process: hole nut not centered, dents, NG stud bolts, NG parts, and non-stick spots. The average defect per month is 110 defects, and the dominant defect is the non-centered nut hole of 63.8 defects (58%). The root cause is when the part setting stopper position is unstable. The improvement made is adding a locator pin cylinder hole nut to stabilize the position. The results of this improvement can reduce welding defects to 58.5 defects per month, and the average defect hole nut is not centered by 3.5 defects (6%). So the PDCA cycle is very effective in efforts to improve product quality.

Design of a New Type of Bowl Plug and Its Disassembling Device

In order to solve the problem that bowl plug and cylinder hole cavity are difficult to disassemble due to interference fit. Through designing a new type of bowl plug and its disassembly device, the disassembly device is connected with the new bowl plug by the matching shaft, and through the fixing of the support plate and the support frame, the bowl plug can be easily disassembled under the action of the automatic traction device, so as to save manpower and improve work efficiency.

Numerical analysis for film cooling characteristics of trenched hole under the effects of rib-disturbed feed flow and curved surface

Film holes are extensively utilized to protect the blade external surface by ejecting coolant, forming a protective film, and separating the hot gas and blade surface. Trenched holes, caused by the turbine blade coated with thermal barrier, greatly feature better film cooling performance than traditional cylinder holes. In this study, the effects of a rib-disturbed feed flow on the film cooling performance of trenched holes are studied through the numerical method. Two typical rib attacking angles, 45° and 135°, are compared with the blowing ratio increasing from 0.5 to 2.0. The effects of the curved surface (convex and concave) are also included. Numerical results prove that film effectiveness with the coolant fed by the rib-disturbed internal flow is sensitive to the blowing ratio. The rib-turbulated cooling flow entering the film hole is featured with different swirling states; therefore, the interaction between the mainstream and the cooling air of varied swirling state leads to different film coverage and effectiveness. Overall, 135° ribs induce better adiabatic film cooling effectiveness than 45° ribs, with a maximum improvement 34.9% at M = 0.5. Film effectiveness on the convex surface is better than that on flat and concave surfaces. Area-averaged η on convex and concave surfaces is, respectively, 4.7% higher and 6.2% lower than that on the flat surface. Normal pressure gradient established on the convex surface contributes to reducing the turbulence intensity and improving the film lateral coverage.

Effects of particle shape and packing style on ethylene oxidation reaction using particle-resolved CFD simulation

Gaining in-depth insights into the effects of particle shapes and packing style on ethylene oxidation reaction is of paramount industrial importance. In this work, reactor models of five packing structures with different particle shapes and three packing structures with different packing styles are established by employing software Blender and COMSOL Multiphysics to explore how the reaction-diffusion behaviors affect ethylene oxidation process. The reliabilities of rigid body dynamics model and particle-resolved reactor model are verified by comparing simulated and experimental pressure drops and ethylene conversions. In all the five packing structures with laminar flow conditions, the high bed porosity and low total particle surface area for the trilobe packing structure give rise to the lowest pressure drop of 27.8 Pa/m, while the internal voids cutting mode provides the excellent heat transfer capacity for the Raschig ring packing structure and the highest ethylene conversion and thereby the highest bed temperature rise of 25.1 K for the four-hole cylinder packing structure. Based on these analyses, changing the packing style to the bottom-up Raschig ring - four hole cylinder packing structure would be a good strategy for the effectively lowered reactor temperature rise by 4.8 K together with the slightly reduced ethylene conversion.

3D co-culture of macrophages and fibroblasts in a sessile drop array for unveiling the role of macrophages in skin wound-healing

Three-dimensional (3D) heterotypic multicellular spheroid models play important roles in researches of the proliferation and remodeling phases in wound healing. This study aimed to develop a sessile drop array to cultivate 3D spheroids and simulate wound healing stage in vitro using NIH-3T3 fibroblasts and M2-type macrophages. By the aid of the offset of surface tension and gravity, the sessile drop array is able to transfer cell suspensions to spheroids via the superhydrophobic surface of each microwell. Meanwhile, each microwell has a cylinder hole at its bottom that provides adequate oxygen to the spheroid. It demonstrated that the NIH-3T3 fibroblast spheroid and the 3T3 fibroblast/M2-type macrophage heterotypic multicellular spheroid can form and maintain physiological activities within nine days. In order to further investigate the structure without destroying the entire spheroid, we reconstructed its 3D morphology using transparent processing technology and the Z-stack function of confocal microscopy. Additionally, a nano antibody-based 3D immunostaining assay was used to analyze the proliferation and differentiation characteristics of these cells. It found that M2-type macrophages were capable of promoting the differentiation of 3T3 fibroblast spheroid. In this study, a novel, inexpensive platform was constructed for developing spheroids, as well as a 3D immunofluorescence method for investigating the macrophage-associated wound healing microenvironment.

Investigating the slow light in a 2D heterostructure photonic crystal composed of circular rods and holes in the square lattices

This theoretical work proposed a two-dimensional heterostructure of photonic crystal and investigated it for slow light applications. The structure includes two photonic crystals: circular Ge rods in the air background and circular holes in the Ge background. It is assumed that both of the crystals have square lattices. The band structures of the individual photonic crystals were studied to choose appropriate rod and hole radii to achieve common photonic band gaps. The effect of the possible combinations of the rod and hole radii was investigated on the group indices, bandwidths, and group index-bandwidth products. The optimum rod and hole radii were achieved. Moreover, the effect of displacements of the rods relative to the hole cylinders was studied, and the optimum displacement was calculated to achieve a high group index-bandwidth product value.

Application of the Source Term Method and Fan-Shaped Hole for Cooling Performance Improvement in a High-Pressure Turbine

This study presents the arrangement design of the cooling hole and the application of a fan-shaped hole to improve the cooling performance of the high-pressure turbine. To this end, the first stage nozzle vane of the energy efficient engine (E3) was selected as the base model, and for efficient design, the source term method, called the injection region, was applied for producing the effect of the cooling flow when the RANS analysis was performed. At this time, because the cooling flow rate also changed when the location of the cooling hole changed, a neural network model was constructed to predict the cooling flow rate for the location of the cooling hole. Design optimization was performed to improve the film cooling effectiveness and the temperature uniformity on the vane surface using the streamwise location of the cooling hole as a design variable, and then the cooling performance was investigated by applying several fan-shaped holes instead of cylinder holes on the pressure side. As a result, the final design was obtained, which improved the film cooling effectiveness by 4.1%p and temperature uniformity by 0.7% compared with the base model.

Morphological Characteristics of Hydraulic Flushing under Multifactor Coupling and Its Enlightenment

The shape of the hydraulic flushing hole is an important basis to determine the effective pumping radius. In the design and evaluation of the drilling hole, it is usually equivalent to a cylinder. However, the formation of the shape of the hole is affected by the gravity of coal and rock bulk, the friction of coal and rock, water force, stress, and other factors, so the scientific nature that is equivalent to a cylinder remains to be discussed. In this paper, based on the analysis of the whole process of hydraulic flushing and the formation of the pore shape, gravity, friction, water force, and ground stress of coal and rock bulk are selected as important factors affecting the pore shape, and the parallel Bergmark-Roos equation and PKN model are introduced to establish the BR-PKN equation of the pore shape of hydraulic flushing. MATLAB is used to reproduce the shape of the hydraulic flushing hole, which is a kind of ellipsoid with three different axes. In order to verify the accuracy of the hole shape, the YZD18.5 video imaging logging tool for mine lateral resistivity is used to collect and analyze the shape data of the hydraulic flushing hole, and the hole section is drawn, which is basically consistent with the theoretical derivation of the hydraulic flushing hole shape. COMSOL is used to simulate the hydraulic flushing equivalent of the ellipsoid hole compared with the cylinder hole under the same coal output and extraction time of 90 days. The extraction radius, desorption surface area, and effective extraction volume are 0.95, 0.79, and 1.14 times, respectively, providing a basis for the optimal design of hydraulic flushing.

가스터빈 블레이드 막냉각 홀의 복합 형상 변화 시 열전달 특성 향상에 관한 수치해석적 연구

Recently, film cooling has been continuously studied to increase the efficiency of gas turbines. A turbine inlet temperature increase occurs as a way to improve the efficiency. However, it is essential to improve the cooling performance of the blade surface because of the melting point of the part. In this paper, a side hole shape wherein a general cylinder hole and two auxiliary holes are combined, is proposed to improve the film cooling efficiency, and the blowing ratio was set to 0.4, 0.8, 1.2, and 2.0. When side hole was applied, the vortex interference at the hole entrance occurred less than that of the cylinder hole. That is, the flow rate of the coolant adsorbed to the surface increased to improve the cooling performance. In conclusion, compared to the cylinder hole, the cooling efficiency of the shape to which the side hole was applied was excellent, and in particular, the average area cooling efficiency with spanwisely designed side holes improved by 83%.

Improving Productivity of Misaligned Boring of Hydraulic Cylinder Holes with a Rotating Cutter Block Based on Computer Simulation Results

The analysis of existing processing methods was carried out. A series of virtual experiments was performed; based on their results dependences of the height of residual ridges, the temperature on the workpiece surface and the temperature in the cutting zone on the parameters of the processing mode when boring internal holes with a rotating cutter block were constructed based on the results of virtual computer simulation. An optimization model of the boring process was built. The objective function was received. Within the optimization model framework, solutions were obtained that allow, at the highest value of axial feed, to ensure the required surface quality and avoid changes in the physical and mechanical properties of the material.

The Effect of Holes Number in Cylindrical Samples on the Forced Convection Heat Flow

In this article, an experimental examine changed into carried out on the effect of putting side holes in circular cylinders on the forced convection heat transfer process. Three circular cylindrical samples were made of aluminum. Sample No.1 without side holes, sample No.2 with two side holes, and sample No.3 with four side holes. These cylindrical samples were placed after being heated in an air duct (working section) and the position of samples in an air duct are same. Air cross-flow was applied to the cylindrical samples at different velocities while observing their temperature drop. The results showed that heat transfer of the cylindrical sample with four side holes is better than that of other samples at all air flow velocities. Also Nusselt number was calculated after obtained heat transfer coefficient and at Reynolds number range (7435-20697), where it become discovered that Nusselt number will increase with the Reynolds number in all cylindrical samples. Empirical relationships for Nusselt number with Reynolds number and Prandtl number had been get it for the three circular cylinders and liken with relationships of circular cylindrical forms exist in other references. These Empirical relationships given acceptable constants values.

Reliability optimization of process parameters for marine diesel engine block hole system machining using improved PSO

The processing quality of the block hole system affects the working performance of the marine diesel engine block directly. Choosing an appropriate combination of process parameters is a prerequisite to improving the accuracy of the block hole system. Uncertain fluctuations of process parameters during the machining process would affect the process reliability of the block hole system, resulting in an ultra-poor accuracy. For this reason, the RBF method is used to establish the relationship between the verticality of the cylinder hole and process parameters, including cutting speed, depth of cut, and feed rate. The minimum cylinder hole verticality is taken as the goal and the process reliability constraints of the cylinder hole are set based on Monte Carlo, a reliability optimization model of processing parameters for cylinder hole is established in this paper. Meanwhile, an improved particle swarm algorithm was designed to solve the model, and eventually, the global optimal combination of process parameters for the cylinder hole processing of the diesel engine block in the reliability stable region was obtained.

DC Arc Resistance Rise by PMMA Cylinder Ablation with Arc Shrinking in Silica Sand Filling Space

Concerning DC arc quenching phenomenon in silica sand filling space, we have proposed a new method for raising an arc column resistance (rcol) by use of polymer‐material arrangement. This paper reveals physical factors for rcol rise on the bases of experimental results using the following cylinders made of: (i) Quartz (SiO2) and (ii) PMMA ((C5H8O2)n) with various inner diameters ϕ. For ϕ = 2 mm case, rcol measured for a PMMA cylinder arrangement indicated higher rcol at low current region, while almost same rcol around current peak. For ϕ = 3 mm case, rcol for the PMMA cylinder was lower than rcol for the quartz case at high current region, while almost comparable between these conditions at low current region. For ϕ = 5 mm case, rcol were almost same during the arc quenching process. To discuss the effect of the rcol rise, the followings were also performed: (i) observation of cylinders after arc quenching and (ii) calculation of the electron density of SiO2/Cu or PMMA/SiO2 mixture vapors. It is concluded that, at high current region, rcol can increase due to the shrinking of the arc conductive diameter caused by the cylinder hole and the silica sand filled inside the cylinder hole. On the other hand, the admixing of the PMMA ablation vapor increases rcol at low current region in the present experiment. © 2021 Institute of Electrical Engineers of Japan. Published by Wiley Periodicals LLC.