Conical Section Research Articles

Experimental study on the piezo-based energy harvester utilizing the ambient vibrations for smart applications

The proposed energy harvester has novel construction, its performance evaluated through frequency response, force response and power harvested under an optimum load, is presented. This harvester is more suitable for low power applications like IoT devices, Wireless sensor nodes and biomedical implants. The suggested harvester has two sections namely truncated cone and rectangular beam section (TCRB). The analytical model is formulated and natural frequencies are obtained using FEA tool. Simulations for natural frequencies and associated comprehensive parameters are done along with distribution of stress across the piezo patch. The tapered radius ratio of the truncated cone is analysed to obtain the optimal value. The simulated model is fabricated and verified experimentally. The result is compared with uniform cantilever beam harvester. The voltage produced by a TCRB harvester is 56.76 % higher than the harvester with a homogeneous rectangular cantilever beam. The rectangular harvester has a resonant frequency of 52.8 Hz, while the TCRB harvester has 39.4 Hz. Also, the TCRB type piezoelectric vibration energy harvester with optimum taper radius ratio provides greater power, than uniform and trapezoidal cantilever beams. The obtained experimental results match the simulation results, ascertains the validity of the proposed harvester.

Effects of composite structures on internal flow field and particle classification performance of hydrocyclone

ABSTRACT Hydrocyclones are commonly used solid – liquid separation apparatuses extensively adopted in various sorting industries owing to their unique advantages. However, the intrinsic constraints of their structures result in comparatively low-classification precision. Therefore, this study proposes a series of composite-structured hydrocyclones to augment their classification accuracy. Employing computational fluid dynamics techniques, this study provides a numerical analysis of hydrocyclones with varying structures, thus resulting in a series of valuable findings. Initially, the introduction of the composite structures effectively strengthened the centrifugal force in a manner directly proportional to the number of inlets. Internal turbulence provides effective turbulent scouring of the particles, simultaneously offering enhanced flow-field stability. Finally, the cutting ability and classification precision of the composite structures were substantially enhanced compared with those of traditional hydrocyclones. This was most evident in the structures that utilized four inlets, a parabolic cone section, and a thick-walled overflow pipe structure which resulted in superior product quality.

Study on Influence of Core Structure on Catalytic Converter Performance Using CFD

In recent years, as the automotive industry is growing, one of the major hope for future vehicles is to meet emissions regulations. Automobiles pollute the air, and clean-air laws have made Catalytic Converters a legal requirement because they convert harmful pollutants from an engine's exhaust into cleaner emissions. The device works with the principle of a catalyst, something that causes or speeds up a chemical reaction without itself being changed. But the presence of a catalytic converter increases the exhaust back pressure which has an indirect effect on the engine efficiency ie engine efficiency decreases, thus increasing fuel consumption. The performance of a catalytic converter is substantially affected by the flow distribution inside the substrate, a uniform flow distribution can increase its efficiency, lower the pressure drop and optimize engine performance. The flow distribution in a catalytic converter assembly 15 is governed by the geometry configurations of the inlet and outlet cone section, the substrate, and exhaust gas compositions, and therefore a better design of the catalytic converter is very important. This Project deals with the fundamental understanding and study of complex processes taking place involving fluid flow, pressure, and velocity profiles in the catalytic converter using ANSYS WORKBENCH 2022 R1. The main objective of our analysis is to determine the most effective and optimum design of a Catalytic Converter

Research on the Methods for Obtaining Droplet Impingement Characteristics in the Lagrangian Framework

The impact of supercooled water droplets is the cause of aircraft icing, and the acquisition of impingement characteristics is the key to icing prediction and the design of ice protection systems. The introduction of water droplet collection efficiency is required to obtain the characteristics for the Lagrangian method. In this work, a traditional flow tube method, a local flow tube method, and a statistical method are established to calculate the local collection efficiency, based on Lagrangian droplet trajectories. Through the numerical simulations of the air–droplet flow field around an NACA 0012 airfoil, the accuracies of the three methods in regard to collection efficiency are verified. Then, these three methods are applied to obtain the results for water droplet trajectories and the collection efficiency of an S-shaped duct, a 2D engine cone section and an icing wind tunnel. The results show that the distributions of water droplet collection efficiency obtained by the three methods are consistent and the three methods are all feasible when the water droplets do not overlap or cross before hitting the aircraft surfaces. When the water droplets are shadowed by upstream surfaces or blown by air injection, the droplet trajectories might overlap or even cross, and the local collection efficiencies obtained by the traditional flow tube method, local flow tube method, and statistical method might differ. The statistical method is relatively accurate. However, not all the droplet impingement characteristics obtained by the three methods are different due to these effects, and the non-crossing of the droplet trajectories is not a necessary condition for the use of the flow tube method. The effects of trajectory crossings are analyzed and discussed in detail in different situations for the three methods. This work is helpful for understanding and accurately calculating the droplet impingement characteristics and is of great significance for simulations of the aircraft icing process and anti/de-icing range.

Experimental study on flow characteristics of ash band in a cyclone separator using HPIV techniques

In a reversed cyclone separator, the ash bands were frequently observed on the wall surface, which were formed by the separated particles and rotated down. Nevertheless, the flow characteristics of the ash bands are rarely measured and discussed in the previous literatures. In this study, the flow characteristics of the ash bands were experimentally investigated by use of the High-speed Particle Image Velocimetry (HPIV) method. The experiments were conducted on a ϕ160mm cyclone at inlet velocity of 12, 16, 20 m/s and inlet concentration of 30, 50, 70, 100 g/m3. The test powders were catalyst and iron powder. The ash band's geometric characteristics, including width, slope angle and pitch, were extracted through advanced image analysis algorithms. Results revealed that the slope angle and pitch of the ash band were different in the cylindrical section and cone section. The width decreased as the ash band moved downwardly. Additionally, the ash band's flow parameters were measured. As the particle movement changed from suspension pattern in the separation space to sliding pattern on the wall surface along the radial, the particle velocities decreased. And the particle velocities further decreased as ash band forming. Particle velocities exhibited non-uniform and fluctuating behavior within the ash band. Notably, the velocities were lower in the central region of the ash band than that at the outer layer. Meanwhile, the particle concentration gradually increased, leading to a particle concentration in the ash band being 450 times higher than the inlet concentration. Along the axial, the ash band averaged velocity initially increased in the cylindrical section and then decreased in the cone section, varied with the inlet velocity, inlet concentration and particle properties such as particle size and density. This study revealed mechanisms behind particle aggregation in cyclone separator and analyzed the dynamic flow characteristics of ash band in detail.

Features of the precessing vortex control in the Francis turbine model via jet injection

The study elucidates the mechanisms involved in actively controlling vortex phenomena within hydraulic turbines, particularly prevalent during partial load operations, leading to severe pressure fluctuations within the draft tube. Employing laser Doppler anemometry alongside acoustic sensors, the research delves into the flow structure and pulsation characteristics within the conical section of a Francis hydraulic turbine model under the influence of supplementary control jets injected through the runner streamline body. It was observed that orientation of the control jet has a discernible effect on reduction in pressure pulsations emanating from the precessing vortex core (PVC). An optimal injection strategy for diminishing pressure fluctuations while maintaining high turbine efficiency is identified. The findings align with earlier theoretical predictions derived from linear stability analysis of flow perturbations.

Study on the Unsteady Flow Characteristics of a Pump Turbine in Pump Mode

Extensive research has been conducted on the performance of pump turbines, particularly focused on understanding the generation mechanism of S-shaped characteristics. However, there has been a lack of research on unsteady flow characteristics in hump characteristics with small guide vane openings. This study focuses on the hump characteristics of a pump turbine in pump mode. The unsteady numerical simulation method is used along with experimental testing to examine the internal flow characteristics and induced pressure fluctuations under pump operating conditions. The results indicate that flow separation occurs in the impeller when the flow rate decreases to the valley operating condition, and recirculation flow occurs near the impeller inlet at the partial flow rate. Moreover, the unstable flow on the positive slope exhibits a low-frequency characteristic of 0.15fn. The pressure fluctuation from the hub to shroud areas of the guide vane region diminishes sequentially. Notably, distinct vortex structures emerge at the draft tube cone section under the valley operating condition. These structures extend toward the elbow section of the draft tube as the flow rate decreases. This phenomenon generates low-frequency pressure fluctuation originating from the primary frequency of the vortex and dean vortex on the surface, located at 0.4 D of the draft tube under conditions of low flow rate.

An Operator Defined on Hadamard Product Pertaining to Generalized Hurwitz-Lerch Zeta Function with Conical Section

The author’s goal is to highlight the most recent developments in the research on the study of complex-valued functions as seen through an understanding of geometric function theory. Contributions will be required for any aspect of the Hadamard product associated to the generalized Hurwitz-Lerch Zeta function convoluted with the theory of functions that are univalent. In the present investigation, the author focused into the inclusion relations of a few subclasses of the -starlike functions, -uniformly convex functions, and -quasi-convex functions which together make up the generalized Hurwitz-Lerch Zeta function.

A Preliminary Numerical Study on the Performance of Cyclone Separators in Supercritical CO2 Solar Power Plants

A combined approach of computational fluid dynamics, the discrete phase model, and the wall erosion model was used to numerically investigate the hydrodynamics, separation efficiency, and erosion rate in cyclone separators for s-CO2 solar power plants. Moreover, the results were compared with those for air and CO2 as carrier phases. The experimental data from the literature were used to validate the numerical model, and it was observed that the simulated gas velocities and wall erosion rate accurately aligned with the experimental measurements. The numerical results reveal that s-CO2 had the largest tangential velocity compared to the other two media; its area-weighted axial velocity of upward flow was the lowest in the middle part of the cyclone body, and varied considerably in the bottom region of the conical section. The particles were all collected at the bottom surface of air and CO2, but the separation efficiency of s-CO2 was 81.51%, due to the poor distribution of the vortex and short circuit. Finally, the erosion rate distribution and averaged surface erosion rate were also analyzed for the three carrier phases.

Experimental investigation supported by artificial neural networks (ANNs) for predicting the heating performance of a cyclone separator coupled with induction heating coil

This paper proposes a novel dust separation and thermal inactivation system that couples an electromagnetic induction heating coil with a cyclone separator. The idea is aimed at the thermal inactivation of potential microorganisms (viruses and other pathogens) associated with dust-laden gas streams, particularly from road surfaces. The integrated system was tested in an experimental setup as a proof-of-concept investigation at different cyclone-induction heating temperatures of 100–400 °C (373–673 K) and air discharge flow velocities of 5–30 m/s. In addition, the influence of operating parameters such as cyclone heating temperature (as induction heating inputs), inlet air velocity, and heating time on the efficacy of the induction heating process were investigated. The time-averaged temperature measurements along the axial direction (z-down) showed predominant temperature fluctuations in the cylinder and cone sections for all cases, especially when the gas plummets down the cyclone. Temperature was highest in the conical section (z = 525 mm) at 320 °C (593 K) at 5 m/s and lowest in the outlet section (z = 375 mm) at 185 °C, which was expected. The results show that inlet air velocity plays a crucial role in affecting temperature dynamics. Conclusive results indicate that with increasing temperature, pressure drop decreases significantly. Along with the experimental results, multiple regression indices using an Artificial Neural Network (ANN) modeling were used to predict the cyclone’s induction heating performance, showing good prediction quality in terms of the mean square errors (MSE and RMSE) and the correlation coefficient R2: 0.99. The study demonstrates the technical viability of integrating induction heating coil to a cyclone separator for wide temperature applications.

Teaching Math through Art: a didactic sequence proposal with scripts for the construction of conics by the string art technique

The interdisciplinary studies in the teaching of mathematics through art makes this articulation a source that generates comprehensive and significant knowledge for both areas, with the possibility of exploring playfulness and creativity for educational purposes. In this context, the string art technique (which consists of building different figures as a result of the orderly manipulation of strings on points fixed on a solid surface) is shown as a potential didactic resource for the development of methodologies that can improve aspects of teaching and learning of geometric figures and their properties, such as conical sections (little explored in relation to other geometric shapes). The exploration of the technique can help the teacher in the teaching process of Analytical Geometry, through dynamic classes using manipulative materials, with the possibility of obtaining better learning results. In this sense, the present work explores the context of interdisciplinary between Mathematics and Arts and proposes a didactic sequence directed to the teaching of conic sections in High School, with string art. The didactic sequence evidences a methodology oriented to the participation of students as active in the construction of their own knowledge, based on the guidelines for the construction of geometric figures by the mediator teacher. In the professional perspective, the objective of the didactic sequence (product of this work) is to help the teacher in the construction of new teaching methodologies that contribute to improve the student's knowledge about conics, in order to obtain satisfactory results in the teaching of Geometry and overcome difficulties observed in classroom practice.

Numerical study on the wall wear of hydrocyclones and experimental verification

Because hydrocyclone wall wear affects the separation performance and causes production accidents, in this paper, a combination of numerical simulation and experimental study is used to investigate the wear of various components of the hydrocyclone. The wear degree of each hydrocyclone component is from large to small for the underflow orifice, cone, inlet annular region, roof, and column. The simulation results show that at the roof of the hydrocyclone, the wear phenomena are distributed in the outer circumference of the circle and increase with radius in the radial direction. At the inlet annular region, the main wear is caused by particle impact, and the most serious part is between 30° and 60° azimuth. In the column section, the main wear is scouring wear, and the wear trajectory is distributed in the form of a spiral belt. In the cone section,the wear rate is larger as it is closer to the underflow orifice, and reaches the maximum near the underflow orifice. The experiment results show that the morphology of the wear in each part is highly consistent with the simulated results, and the wear rate is slightly different in numerical value. The roof and column sections have roughly the same wear rate, the inlet annular region and upper cone section have similar wear rates, about 3.9 times that of the column section. The underflow orifice have the largest wear rate, about 4 times that of the upper cone section and 1.7 times that of the lower cone section.

Numerical investigation of filtering cyclones using response surface methodology and CFD simulation approaches

The cyclone separator pressure drop depends on the geometry and the operating conditions. Alternative equipment to decrease pressure drop is the filtering device. In this paper, the effect of inlet height, inlet flow rate, and conical section permeability about the filtering cyclone performance (Euler number) is studied through CFD simulations. The experimental and numerical results indicate that the turbulence model Large-Eddy Simulations (LES) reasonably predict the pressure drop in high swirling flows in filtering cyclones. CFD simulations suggest the Euler number increase with the increase of inlet height and decrease with the increase of flow rate and permeability. However, there is an interaction between the permeability with the other two variables. Therefore, this study suggests that CFD models can be used as instruments to evaluate same structural and operational variables in the filtering cyclone performance.

Experimental investigation of residence time and axial velocity of 6.0 cm graphite pebbles in a cold-flow pebble bed reactor using radioisotope-based technique

Understanding pebble flow characteristics and residence time distribution is essential for reactor design, fuel burnup estimations, and safety analysis of High-Temperature Gas-Cooled Pebble Bed Reactors. However, due to the complex nature of the dense granular flow, pebble flow remains inadequately understood and challenging to study through experiments. In this work, a three-dimensional experimental pebble-bed setup was developed to investigate pebble flow behavior in pebble-bed reactors. For the first time, 6.0 cm graphite pebbles were utilized, and features such as one pebble at a time discharge mode and continuous pebble recirculation were incorporated. The overall and zonal residence time distributions and the zonal-averaged axial velocity were investigated using a radioisotope-based residence time distribution (RTD) technique. The results showed that the overall residence time increases as the radius of the initial seeding position increases, but with a higher increase rate at the wall compared to the center region. The zonal residence time findings indicated a uniform profile in the upper section of the bed, except near the wall. However, non-uniformity in the radial profile increased in the lower sections, with the greatest variation occurring in the conical section. The axial velocity of the pebbles was found to be small and nearly uniform in the upper section of the bed. In the lower section, however, the velocity increased significantly for the center-region pebbles compared to those at the wall, resulting in a pronounced non-uniform radial profile. Moreover, a consistent hexagonal arrangement of pebbles was observed across the entire container wall after recirculating several bed inventories, which is worth further investigation.

Two-Way Blade Modeling Method for Structural Redesign of Compressor Blades

Over the past few years, stringent environmental requirements and the need for increased overall efficiency have forced designers to bring turbomachine components closer to their operating limits. To address lifespan issues, costly redesign operations are thus unavoidable. These operations face many roadblocks, especially when they are triggered by nonlinear phenomena for which there exists no design guidelines. For aircraft engine blades, the handling of nonlinear structural interactions is a major challenge. This works proposes a proof of concept for the redesign of compressor blades undergoing structural contact interactions at the blade-tip/casing interface. The redesign process involves the modeling of an existing input blade, followed by a shape update based on an iterative optimization algorithm. A two-way modeling method is proposed to parameterize the input blade and generate a computer-aided design model from blade parameters describing several conical blade sections. The fidelity of the parameterized blade with respect to the input blade is assessed for the NASA blades rotor 37 and rotor 67. A high fidelity is observed with respect to geometric and dynamic characteristics. The modeling method is fully compatible with an iterative redesign process: it is applied to the redesign of rotor 37 to increase its robustness to contact interactions.

Design and Analysis of Ultrasonic Composite Transducer with a Quarter-wave Taper Transition Horn

Based on the electromechanical equivalent circuit theory, equations related to the resonance frequency and the magnifying coefficient of a quarter-wave vibrator and a quarter-wave taper transition horn were deduced, respectively. A series of 3D models of ultrasonic composite transducers with various conical section length was also established. To reveal the influences of the conical section length and the prestressed bolt on the dynamic characteristics (resonance frequency, amplitude, displacement node, and the maximum equivalent stress) of the models and the design accuracy, finite element (FE) analyses were carried out. The results show that the addition of prestressed bolt increases the resonance frequency and causes the displacement node on the center axis to move towards the small cylindrical section. As the conical section length rises, the increment of resonance frequency reduces and tends to a stable value of 360 Hz while the displacement of the node on the center axis becomes lager and gradually approaches 1.5 mm. Furthermore, the amplitude of the output terminal is stable at 16.18 μm under 220 V peak-topeak (77.8 VRMS) sinusoidal potential excitation. After that, a prototype was fabricated and validated experiments were conducted. The experimental results are consistent with that of theory and simulations. It provides theoretical basis for the design and optimization of small-size, large-amplitude, and high-power composite transducers.

A simplified finite element method for failure analysis in adhesive-bonded nozzle diffuser of solid rocket motors

The adhesive bond between the nozzle diffuser shell and the insulation layer of solid rocket motors (SRM) is widely used due to its lightweight, simple design, and easy operation. The mechanism of adhesive-bonded failure between them is a concern for designers. In this paper, a simplified finite element method for failure analysis in the adhesive-bonded nozzle diffuser of SRM is proposed. In the method, the diffuser shell, insulation layer, and adhesive between them are considered elastic. The maximum Von Mises stress failure criterion is assumed to be suitable for the adhesive. The adhesive-bonded failure is simulated by using the user subroutine VUSDFLD in the commercial Finite Element Analysis software ABAQUS. The method is verified to be simple but effective based on the comparison with experimental results. The adhesive-bonded failure process under external load can be well simulated, and the critical external load of adhesive-bonded failure can be accurately predicted. In addition, the method is utilized to study the failure of the nozzle diffuser with several kinds of original debonding. It is suggested that the original axial debonding ratio should be less than 60%, and the circumferential debonding angle should be smaller than 30° in the conical section of the nozzle diffuser.

Numerical Study of the Internal Fluid Dynamics of Draft Tube in Seawater Pumped Storage Hydropower Plant

Pumped storage hydropower plants are renewable energy systems that are effective in saving energy and solving electricity peak-on shortage. Seawater pumped storage hydropower plants are a novel type of pumped storage hydropower plant specifically supplying electric power for ocean islands with the support of solar energy and wind energy. Compared with traditional pumped storage hydropower plants that are constructed on the mainland, seawater pumped storage hydropower plants should take the influence of the complex marine environment, such as extreme waves and winds, into consideration. Taking the characteristics of waves near islands in the East China Sea as an example, we explored the transient hydraulic characteristics in the draft tube of a pump turbine under wave disturbance using a sliding grid interface and the detached eddy simulation (DES) turbulence model. By analyzing the characteristics of unsteady flow in the draft tube, the vortex characteristics under the Q criterion, the frequency characteristics of the pressure pulsation, the evolution law of the internal fluid, and the propagation law of the pressure pulsation were explored. For the situation without wave disturbance, an obvious eccentric vortex in the straight cone section of the draft tube was observed in the case where the opening of the guide vane was small. With the increase in the opening of the guide vane, the eccentric vortex gradually dissipated. For the situation with wave disturbance, the main frequency of the draft tube equaled the frequency of the wave disturbance, the maximum pressure pulsation at the selected monitoring points increased 5 to 15 times, and the superposition of the wave pressure pulsation signals and the draft tube pressure pulsation produced more low-frequency, high-amplitude pressure pulsation signals. Even though the pressure pulsation frequency spectrum varied a lot, the frequency domain of the pressure pulsation without wave disturbance still existed. In addition, the wave disturbance merely varied with the pressure of the draft tube. The influence of wave disturbance on the pressure distribution in the draft tube was relatively small. The results can provide a reference for the operation of seawater pumped storage hydropower plants.

Critical distribution state of droplets dispersed in oil subjected to electric and centrifugal fields

Oil-water emulsions are extensively produced in industry, which may affect subsequent work or bring about environmental problems. Hence, it is necessary to demulsify and dewater it first. A coupling unit based on high-voltage electric and swirl centrifugal fields is adopted to satisfy emulsion demulsification and dewatering. The droplet size distribution is closely related to the separation performance of the coupling unit, while the droplet size distribution changes dynamically due to coalescence and breakage of the droplets. Droplets possess corresponding distribution under different coupling conditions, and the droplets size distribution may have a specific critical distribution state, in which the separation efficiency of the coupling unit reaches the optimal. Therefore, a numerical model is established to study the critical distribution state under double-field coupling in this study. The influence of coupling conditions on the droplet size distribution is studied to obtain the critical state of droplet size distribution, and the relationship between the critical state and the inlet droplet diameter is investigated. The results show that the critical state exists, and its distribution is as follows: there is a stable region with the maximum diameter gradient within 15 µm from the tail of the large cone section to the front of the small cone section (z = 700–760 mm) of the coupling unit; in the cross sections of the small cone section Z = 660–690 mm, the distribution of droplets volume fraction are almost identical, and the droplet diameter with the largest volume fraction is close to the median diameter. Moreover, the above critical state also exists for different inlet droplet diameters.

Performance analysis of cyclone separators with bulged conical segment using large-eddy simulation

The present study proposes and investigates the performance of novel cyclone separators with bulged conical sections. For this, the curved profile replaces the straight cone wall while using the two fixed ends of the former – the resulting cyclone model resembles the shape of a pot. Five different cyclone configurations with a curvature radius equal to 1.5, 1.25, 1.0, 0.75, and 0.5 m are considered. Advanced closure large-eddy simulation (LES) has been used for numerical simulations to evaluate the mean and fluctuating flow field, collection efficiency, and pressure losses. Conclusive results indicate that the pressure drop and the collection efficiency decrease with an increasing curvature size. Since the proposed model has a larger separation space to accumulate more solid particles than the conventional design, it can be potentially utilized as the pre-separators.