Conical Section Research Articles

Static and dynamic performance of a venturi airflow sensor

Venturi-meters have received limited application to the measurement of human airflow. A 3-D printed Venturi airflow sensor (fV) was integrated to a differential pressure sensor for the purpose to document signal quality, dynamic performance during instantaneous flow, and airflow analysis with subsequent calibration for volume measurement. In addition, we assessed these results for potential use in the measurement of human pulmonary ventilation. The fV was developed via drafting software program and 3-D printer (38 mm ID inlet, 12 mm ID constriction, and 23° conical transition sections). The fV was matched to a differential pressure transducer (0–7 kPa input per 0–10 VDC output). The fV was connected in series with a Pneumotachometer (fP) and Turbine airflow sensor (fT), with 1 m length tracheal tubing (ID: 35 mm), separating the devices. Airflow conditions were controlled by an industrial vacuum for constant flow with a manual-operated ball valve connected in series, and a criterion 3 L calibrated syringe for instantaneous flow. Repeated baseline data were collected for signal stability, and to identify the signal-to-noise ratio for signal quality. Airflow estimates and signal quality analysis was performed on repeated constant airflow conditions that spanned the transducer 0–10 VDC output. Repeated syringe manoeuvres that spanned the transducer 0–10 VDC output were used to determine the dynamic performance of the fV. A paired t-test revealed no statistical difference between fV and fP for signal quality across all airflow conditions (p = 0.2028). A paired t-test of dynamic performance data revealed no statistical significance between response times for the fV Vs fP. A calibration method was tested for validation in volume measurements, which resulted in a mean estimate = 3.032 L; CV = 1.14%; n = 83. The fV is easily manufactured with a durable and simple design, making its potential use for ventilation measurement an affordable and reliable technology. These findings provide a reasonable basis to pursue fV technology in applied validation studies, such as inspired and expired ventilation measurement.

Numerical simulation of aerodynamic problems based on adaptive mesh refinement method

Numerical simulation of aerodynamic problems using an algorithm, which identifies shock regions and refines the mesh there using an adaptive mesh refinement method, is performed. The static mesh adaptation method is based on cell partitioning by adding new nodes to cell faces. The method of identification of the shock regions using a pressure and density gradient criterion and its verification are presented. The use and applications of the developed algorithm are illustrated, and supersonic and hypersonic flows with strong shock waves are calculated. The results computed explore the shock-wave structure of the flow, which develops near the nose cone section of a body and determines its aerodynamic performance. The aerodynamic performance of bodies with different nose cone designs, including a body with a spike and a pointed cone with an opposing gas jet injected from the nose section, are evaluated based on the proposed method. The method of static mesh adaptation provides a visually sharper picture of the flow around the body and reduces the numerical error of drag coefficient calculations in comparison with wind tunnel measurements. The results computed on meshes of similar resolution constructed with the adaptation method and automatic mesh generator are compared. The results computed on the adaptive mesh are similar to those computed on the mesh generated automatically, but the adaptive mesh has a smaller number of cells.

Boundary layer measurements over a body of revolution using long-distance particle image velocimetry

This study reports the development and application of long-distance high magnification Particle Image Velocimetry (PIV) to measure the mean and fluctuating velocity components in a turbulent boundary layer over a body of revolution. A 400 mm lens coupled with an extension tube and a novel aperture control mechanism has enabled high resolution images at a working distance of 1.5 m. The body of revolution used in the investigation is representative of a conventional submarine hull without appendages, as per (Joubert, 2006). The flow over the model was measured at a nominal Reynolds number, ReL=4.0 × 106, based on the length of the body. A comparison of single-point statistics from the PIV experiments were found to compare well with pitot probe and hot-wire measurements. Further, the boundary layer thickness and mean streamwise velocity were found to conform closely with a traditional flat plate turbulent boundary layer in the parallel mid-body section of the geometry. However, a comparison of the streamwise and wall-normal Reynolds stresses with Direct Numerical Simulations (DNS) of a turbulent boundary layer on a flat plate with zero pressure gradient indicated lower turbulence levels. This was partly attributed to the spatial averaging evident both in the hot-wire and PIV measurements. We also report that in the tail section of the model, the boundary layer rapidly grows and departs from the flat plate solution due to the conical section and adverse pressure gradient imposed on the flow.

Using DEM to investigate how shell liner can induce ball segregation in a ball mill

Sometimes it is desirable to segregate the ball load in a mill so as to allow for the possibility of larger balls dealing with coarser particles at the feed end and finer product being ground more efficiently at the discharge end. The Hardinge mill with cylindrical and conical sections has been used to achieve segregation quite effectively. The cylindrical section tends to retain the biggest balls while the smaller balls drift to the conical section. However, this is a complex design and we use the discrete element method (DEM) model to investigate if simply altering liner configuration on an ordinary cylindrical mill can lead to similar success. The study involves simulating a mill with 4 sections. Each section can be configured with distinct liner profiles. Three ball size classes are tracked for evidence of segregation at 75% and 60% of critical mill rotation speed. The ball distributions in the various segments at the end of 80 mill revolutions suggest that varying axial liner profile configuration can affect ball segregation, particularly for the mill running at 75% of critical speed. The convenience of using computer simulations to avoid costly plant trials is highlighted.

Design Methodology of Conical Section Shape for Supercavitating Vehicles considering Auto-Oscillation Characteristics

Due to the complexity of the cavity/vehicle and oscillation characteristics, streamlined shape integrated design of conventional fully wetted vehicles is not suitable for supercavitating vehicles. In this paper, a set of design criteria is highlighted to optimize the length and streamlined shape of a conical section subjected to realistic design constraints, which integrate the complex characteristics of the cavity/vehicle system under the condition of auto-oscillation of supercavitating vehicles. The auto-oscillation and its time-domain characteristics are determined. By deriving the equation describing the cavity/vehicle relationship and identifying the maximum amplitude of the Euler angle, the cavity/vehicle tangent point criterion is proposed to determine the theoretical optimum value of the length of the conical section. A method of equal cross-sectional area for gas flow is proposed to design the streamlined shape of the conical section. Water tunnel and autonomous flight experiments were carried out to validate the feasibility of the design methodology developed in this work.

Numerical investigation on non-equal section regenerators performance for pulse tube cryocooler

It is always been a research hotspot to improve the overall efficiency of Stirling pulse tube cryocoolers (SPTCs). The regenerator as the vital component directly determines the performance of SPTCs. Therefore, an approach to improve the overall efficiency is provided by improving the performance of the regenerator. The factors for the influence of the three regenerators structure on the overall efficiency are analyzed and discussed by an 8W@80K SPTC Sage model. The simulation results show the optimal overall efficiency of SPTC with three different regenerators structure varies with the compressor PV power input. Moreover, in terms of the overall efficiency, the smaller the regenerator volume is, the higher overall efficiency will be obtained. Specifically, the overall efficiency of a SPTC with the non-equal (variable and conical) section regenerators is increased by 14.7% and 50% respectively compared with the equal (constant) section regenerator, which theoretically proves the feasibility of this method.

CFD simulation of a novel design of square cyclone with dual-inverse cone

The objective of the present study is to propose a novel design to improve the separation efficiency of the conventional square cyclone. For this purpose, the conical section of the conventional square cyclone with single-cone is modified to dual inverse-cone. In addition, the effect of second-cone length on the performance of cyclone is considered. A three-dimensional numerical simulation is done by solving the Reynolds averaged Navier-Stokes equations with the Reynolds Stress Model (RSM) turbulence model and applying the Eulerian-Lagrangian two-phase method. The turbulent dispersion of particles is predicted by the application of the Discrete Random Walk (DRW) model. The numerical results demonstrate that dual inverse-cone square cyclone although produces higher pressure drop but its separation efficiency is higher than the square cyclone with single-cone. This is due to a smaller separation zone and shorter path of particle movements which force the particles exit from the outlet section of the cyclone. Finally, using dual-inverse cone square cyclone reduces the 50% cut size about 10% and 30% for inlet velocities of 12 m/s and 28 m/s, respectively.

Swirling fluidization in an anoxic membrane bioreactor as an antifouling technique

Scarce attention has been placed on the geometry of anoxic fluidized bed membrane bioreactors (AFMBR) affecting the hydrodynamic pattern inside the reactor and, consequently, on the mechanical cleaning driven by granular carbon (GC) around the membrane. The present work evaluated the application of a swirling fluidization, produced by a tangential inlet in a reactor with hydrocyclone geometry, with the aim to avoid membrane fouling during the performance of a denitrification process. The study includes 3D-hydrodynamic description of the flow and particles fluidization through computation fluid dynamics (CFD), experimentally validated with the particle image velocimetry (PIV) technique. Water shear stress and GC particles momentum acting over the membranes were also assessed, in addition to monitoring filtration and denitrification performance. The conical section showed higher shear stress and particles momentum as compared to the cylindrical zone. Soluble microbial products (SMP) accumulated on the membrane walls with lower shear stress and particles momentum. The operation of the AFMBR was maintained with a continuous permeate flow without any change in suction pressure and the nitrate removal efficiency was above 90% with negligible accumulation of NO2− and N2O in the denitrifying process. This novel reactor configuration could be suitable for the treatment of industrial wastewaters.

Study on a Large-Scale Three-Dimensional Ultrasonic Plastic Welding Vibration System Based on a Quasi-Periodic Phononic Crystal Structure

The uniformity of amplitude distribution and amplitude gain are two main factors affecting the performance of ultrasonic welding vibration system. In order to improve the uniformity of amplitude distribution and amplitude gain of welding surface to enhance the performance of the vibration system, a new design method of a large-scale three-dimensional ultrasonic plastic welding vibration system based on a quasi-periodic phononic crystal structure is proposed. In this method, the composite horn combined with a conical section and a cylindrical section can effectively improve the output amplitude gain of the welding surface. In addition, the method forms a quasi-periodic phononic crystal structure by slotting in a large-scale three-dimensional tool head, and utilizes the band gap property of the structure to effectively suppress lateral vibration of the tool head and improve the amplitude distribution uniformity of the tool head’s welding surface. However, when the size of the tool head is relatively large, the quasi-periodic phononic crystal structure cannot suppress the lateral vibration very well. Therefore, the paper processes fan-shaped slopes on the output surface of the tool head which can further improve the uniformity of the amplitude distribution and amplitude gain. Finally, the simulation analysis and experiments show that the design method can optimize the large-scale three-dimensional ultrasonic plastic welding system, improve the uniformity of the vibration distribution and increase the output amplitude gain of the welding surface.

Automatic fuzzy rules production based on clustering and implication selection

This paper deals with improving the approximation capability of fuzzy systems. Fuzzy negations produced via conical sections are a promising methodology towards better fuzzy implications in fuzzy rules. The linguistic variables and the fuzzy rules are induced automatically following a fuzzy equivalence relation. The uncertainty of linear or nonlinear systems is thus dealt with. In this study, the clustering is optimized without human intervention, but also the best inference mechanism for a particular dataset is prescribed. It has been found that clustering based on fuzzy equivalence relation and fuzzy inference via conical sections leads to remarkably accurate approximations. A fuzzy rule based system with fewer control parameters is proposed. An application on telecom data shows the use of the methodology, its applicability to a real problem and its performance compared to other alternatives in terms of quality.

Dynamic crushing and energy absorption performance of newly designed multitubular structures

Thin-walled shells like square, conical and polygonal sections are preferred in structural applications requiring high performance under impact loadings for their less weight, and excellent energy dissipating ability. In the current research article, Finite element simulations on the buckling behaviour and crashworthiness performance indicators of multitubular structures were executed. The axial impact crushing behaviour of the proposed multitubular tubes was compared with the traditional simple geometrical tubes and the outcomes revealed that multitubular structures absorbed more impact energy than the traditional tubes. The maximum energy absorption capacity that could be attained is with a circle and square with stiffeners multitubular structure.The overall outcomes indicated that multitubular structures are efficient in dissipating impact energy in axial direction and could be employed as energy absorbers in automotive industries.

Investigations on the lateral impact behaviour of combined geometry tubular structures and its effect of cap fillet radius

Thin-walled tubular elements with square, conical and polygonal sections have been effectually employed as impact energy dissipating structures in modern automotive vehicles for their less weight, stable deformation and outstanding energy dissipating ability. In the current research article, finite element simulation on the lateral buckling behavior and influence of crashworthiness performance indicators on the variation of cap fillet radius were executed. Finite element models were developed with ABAQUS/CAE® code to predict the buckling behavior of the proposed tubes under lateral impact force. The lateral impact crushing behavior of the proposed combined geometry tubes was compared with the traditional simple geometry tubes and the outcomes revealed that combined geometry tubes deformed progressively and absorbed better impact energy than the traditional cylindrical tubes. The maximum energy absorption capacity that could be attained is with a circular tube with 30 mm fillet radius.

Numerical study on heat transfer and thermal stress of the upper cone membrane wall in radiant syngas cooler

The high temperature syngas induced from the entrained-flow gasifier contains a large amount of sensible heat, which can be efficiently recovered by radiant syngas cooler (RSC). In this work, the membrane wall models of the upper cone section in the RSC are established. The heat transfer characteristics between membrane wall and syngas are explored by numerical simulation under different operating conditions, and the thermal stress distribution on the membrane wall surface is calculated by the fluid-structure coupling method. The results show that the inner surface of the fin is partially overheated and the maximum stress exceeds the allowable stress of the material when there is no protection for the membrane wall. The increase of inlet syngas temperature and flow rate will enhance heat transfer of the upper cone membrane wall, and the effect of the inlet syngas temperature is more obvious. After the application of the silicon carbide refractory, the surface temperature of the membrane wall, especially the temperature of the wide fin parts, is greatly reduced. Moreover, the membrane wall is slightly deformed and warped due to the temperature difference between the two sides of the membrane wall.

Analysis of Mathematical Literacy on Students’ Metacognition in Conic Section Material

Mathematical literacy is one of the components that use mathematical concepts and applies them to an everyday situation. Mathematical literacy helps people to identify and understand the role that mathematics plays in the world, and to make the well-founded judgments and decisions required in life by constructive, engaged, and reflective citizens. By contrast, not everybody acquires sufficiently. This study aims to describe the ability of mathematical literacy especially geometry literacy in terms of student metacognition on conic section material. The problems in this study were: 1) How is the ability of mathematical literacy in terms of student metacognition on conic section material 2) What types of mistakes do students make in solving the problem of cone section and 3) What factors cause students to make mistakes in solving conic section question. This research is a qualitative descriptive study. The subjects in this study were 36 mathematics education students who took courses in Analytical Geometry. The data collected using observation, written test, and interview. Before the researcher conducted the analysis, the researcher examined the validity of the data using validity and reliability tests in order to obtain valid data. Furthermore, the valid data were analysed descriptively through identification, grouping, clarification, explanation and conclusion.

Effect of leakage and blockage on the acoustic behavior of particle filters

The effects of leakage and blockage on the acoustic performance of particle filters have been examined by using one-dimensional acoustic analysis and experimental methods. First, the transfer matrix of a filter system connected to inlet and outlet pipes with conical sections is measured using a two-load method. Then, the transfer matrix of a particle filter only is extracted from the experiments by applying inverse matrices of the conical sections. In the analytical approaches, the one-dimensional acoustic model for the leakage between the filter and the housing is developed. The predicted transmission loss shows a good agreement with the experimental results. Compared to the baseline, the leakage between the filter and housing increases transmission loss at a certain frequency and its harmonics. In addition, the transmission loss for the system with a partially blocked filter is measured. The blockage of the filter also increases the transmission loss at higher frequencies. For the simplicity of experiments to identify the leakage and blockage, the reflection coefficients at the inlet of the filter system have been measured using two different downstream conditions: open pipe and highly absorptive terminations. The experiments show that with highly absorptive terminations, it is easier to see the difference between the baseline and the defects.

Developing the complex method for flow investigation in a hydro-turbine model using laser anemometry and video recording

The complex technique using laser and video equipment in test conditions at the setups of the Laboratory of water turbines of the Leningrad Metal Plant has been developed to conduct laser measurements of velocity fields and video recording of cavitation phenomena based on the integration of the laser systems (“LAD - 0xx" and “Track-07 S”), created at the Kutateladze Institute of Thermophysics SB RAS (IT SB RAS) and JSC “IOIT.” The Doppler anemometer allowed to achieve experimental distribution of the circumferential, axial, and radial velocity components at each point along the radius of the suction tube cone section of test experimental setup which has give information about vortex structure in suction turbine. The developed PTV method is described. The investigation of cavitation behind the turbine blade at test setup at velocities of 8-10 m/s is presented.

Performance evaluation of a tangential cyclone separator with additional inlets on the cone section

This study installed additional inlets on the cone section of a tangential cyclone separator and examined its effect on collection efficiency and pressure drop. When aerosol was injected through the additional inlets and clean air was injected into the original inlet, the cut-off size of particles decreased, compared to that when injecting aerosol through the original inlet. However, it was revealed that there was an optimal flowrate through the additional inlets to enhance the cyclone separator's performance. Meanwhile, injecting aerosol through not only the additional inlets but also the original inlet separated a higher flowrate of aerosol while demonstrating a similar level of collection efficiency and pressure drop compared to those of the reference cyclone separator. Therefore, installing additional inlets to the cone section of a conventional tangential cyclone separator is expected to process a higher flowrate of aerosol than the separator with similar performance, thereby increasing cost effectiveness.

Quantification of bell-shaped size selectivity in shrimp trawl fisheries using square mesh panels and a sorting cone after a Nordmøre grid.

Shrimp trawlers in the Barents Sea use a Nordmøre sorting grid ahead of a small-mesh codend to avoid bycatch while catching shrimps efficiently. However, small fish can still pass through the grid to enter the codend, which increases their risk of being retained. In this study, we quantified the selectivity of a standard Nordmøre grid used together with one of two different codend designs, namely a diamond mesh codend with square mesh panels and a codend with a square mesh sorting cone section, for deep-water shrimp (Pandalus borealis), redfish (Sebastes spp.), and American plaice (Hippoglossoides platessoides). For the first time, the selective properties of these two alternative designs were estimated and compared to those of a Nordmøre grid used together with a 35-mm diamond mesh codend, which is the compulsory gear used in the fishery today. With this traditional codend, the size selectivity of both bycatch species showed the expected characteristic bell-shaped size selection pattern, with low retention probability of very small fish and bigger fish but with high retention probability of certain sizes of juveniles. Using the square mesh sorting cone significantly reduced the maximum retention risk of redfish. The maximum retention with the diamond mesh codend with square mesh panels was estimated to be 14% lower than that of the traditional codend, but the difference was not statistically significant. The two alternative codend designs did not result in any significant reduction in bycatch of American plaice.

Design and experimental investigation on longitudinal-torsional composite horn considering the incident angle of ultrasonic wave

The composite vibration mode type of ultrasonic horn has been widely employed in ultrasonic vibration drilling. In order to explore the effect of the incident angle of the ultrasonic wave on longitudinal-torsional composite (LTC) horn, the reason for the mode-conversion and the vibrational characteristics of such horn firstly were analyzed on the basis of elastic wave-field theory. Then, a 3D model was developed with helical slots with different angle set in the conical section of the composite horn, and the vibration modal of the output end face of the horn was analyzed using the finite element analysis (FEA) method. It was found that the incident angle of ultrasonic wave exhibited a significant influence on the vibration modal at the output end face of the horn. The torsional vibration and the longitudinal vibration were changed significantly at the output end face of the horn when the incident angle was 47.6° and 67.2°, and the measured amplitude ratio of the torsional vibration to the longitudinal vibration in the former was improved by 4.9 times than that in the latter. Simultaneously, in both cases, the error of resonant frequency between the measurement and the simulation value reached 1.9% and 1.3%, respectively. It was observed from the ultrasonic vibration drilling test that the higher the amplitude ratio of the torsional vibration to the longitudinal vibration (AT/AL), the more the average drilling force was reduced and the better machined quality could be obtained. The results of this study should be well considered for further reference when designing longitudinal-torsional composite horn with different materials in ultrasonic vibration drilling.

CPFD simulation of petcoke and SRF co–firing in a full–scale cement calciner

Computational particle fluid dynamics (CPFD) simulation is carried out to study the effect of petcoke and solid recovered fuel (SRF) co–firing in a full–scale cement calciner. The simulations are conducted using the Multi–Phase Particle–In–Cell (MP–PIC) approach with the Barracuda Virtual Reactor® 17.3.1 solver. The results from the CPFD simulation are compared with extensive field measurements of gas temperature and composition at several points in different calciner cross–sections. In the simulation, the SRF particles are divided into three components of plastic, biomass, and inert. The plastic particles go through drying, melting and decomposition while the conversion of biomass particles involves drying, devolatilization, and char oxidation. The predicted concentrations of O2 and CO2 are in good agreement with the measurements, while the gas temperature is overpredicted, especially in the lower calciner vessel. However, the trends of changes in the gas temperature are well–captured. The converted fuel fraction and calcination factor are predicted with an acceptable degree of accuracy. The simulation results show that large biomass particles in SRF tend to leave the calciner without complete conversion. Furthermore, a recirculation pattern for SRF particles is observed in the lower calciner vessel and the conical section, leading to high conversion degree of this fuel.