Conical Section Research Articles

Insights into local wall erosion characteristics and prevention measures for cyclone separators

Cyclone separators are separation devices that use the principle of inertia to remove particulate matter from flue gases. The present study mainly focuses on wall erosion in cyclone separators and associated research. The main locations of erosion in gas–solid cyclone separators, including the entrance impact section, cyclone roof corner, vortex finder outer surface, spiral-type erosion strip, and lower cone section, are examined in detail. The main factors influencing wall erosion are discussed, including inlet flow velocity, solid particle properties and loading, geometrical structure, and manufacturing quality. Finally, several practically preventive measures against wall erosion are presented, including adjustment of operating conditions, the use of erosion-resistant materials, optimization of geometrical structures, and the addition of auxiliary devices, all of which are essential for ensuring operational efficiency, equipment reliability, safety, and environmental protection in various industrial applications. This paper aims to provide a basis for further research into erosion in cyclone separators as well as guidance for engineers involved in their industrial applications.

An Algorithm for Producing Fuzzy Implications via Conical Sections

In the present study, a novel parametric family of fuzzy implications is introduced and its properties are examined. The parametric family of implications is produced only via a fuzzy negation. This in turn enables the effortless production of a wide range of implications from which to select the one that best fits a given problem, for example in fuzzy inference systems or fuzzy neural networks. The fuzzy negations that have been selected as a basis for the proposed methodology are strong, i.e., involutions, thus leading, in general, to the generated fuzzy implications possessing many desirable additional properties. We have examined which of these properties hold for the implications produced by our algorithm and under which conditions. Finally, it is demonstrated that the family of implications generated via the proposed methodology generalizes other well-established implications, including the Łukasiewicz implication.

Parametric design of curved hydrocyclone using data points and its separation enhancement mechanism

Based on parametric design of curves using data points, two novel hydrocyclones were designed: Spline-Curved-Cone hydrocyclone (H2) and Expassoc-Curved-Cone hydrocyclone (H3). These designs are improvements on the traditional biconical hydrocyclone (H1). Numerical simulations and experimental validation by PIV measurement were used to investigate the effects of cone section profiles on the flow characteristics and separation efficiency. The results showed both H2 and H3 achieved higher separation efficiency than H1. Specifically, the highest efficiency of H3 increased by 24.71%, and that of H2 increased by 16.22% compared with H1. It was also found the curved design of cone section profile directly affects the tangential velocity distribution and pressure distribution of the flow field inside hydrocyclones. H3 exhibited better flow field stability and highest separation efficiency due to its optimized cone section space and flow structure. This study provides scientific basis and data support for the optimization and industrial application of the cylinder-on-cone hydrocyclones.

Research on Developing Cyclone Coupling Techniques for Heterogeneous Separators with Design Optimization of Hydrocyclone Separators

Abstract: Hydrocyclone separator is a widely used equipment in the field of liquid-solid separation due to its simple structure, convenient operation, and high separation efficiency. This paper provides a comprehensive review of the working principles, application areas, design optimization, and performance evaluation of hydrocyclone separators, while discussing their future development trends. In addition, particular attention has been given to the aspects related to patents in this study.The focus is on analyzing the structural parameters and flow field characteristics of hydrocyclone separators, as well as the different effects on separation efficiency caused by various hydrocyclone structures and adjustments in hydrocyclone size. The research analysis is conducted on the inlet, cylindrical section, overflow pipe section, cone section, hydrocyclone materials, and other parts, taking into account detailed analysis of operational conditions such as inlet flow rate, pressure drop, separation efficiency, and fluid properties. The future development trend of hydraulic hydrocyclone separators lies in refinement, intelligence, multifunctionality, integration, and energy-saving and environmental protection. In the field of liquid-solid separation, the integration of hydrocyclone separation technology and intelligent devices is becoming increasingly important, and future research will focus on developing new hydrocyclone coupling separation techniques to further improve production efficiency and convenience in daily life. The application prospects are broad, and it is expected to bring significant economic and social benefits to society. It also possesses the potential for patent protection.

Heat transfer evaluation of return-flow impingement cooling considering inclined sidewall and conical return hole

Impingement cooling techniques are extensively utilized on the turbine blade leading edge to mitigate thermal load. This study is an extend of an anti-crossflow return-flow impingement cooling scheme. In this study, the effects of inclined sidewalls and return holes are numerically studied with jet Reynolds number varying from 5,000 to 15,000. Three sidewall schemes (vertical, inward inclined, and outward inclined) and two return hole shapes (constant cross section and conical cross section) are investigated and compared. Numerical results show that by inclining the sidewalls, the interaction and scrape effects from return flow on the sidewalls are changed, causing heat transfer performance and pressure loss vary. To be specific, as the sidewalls are inclined inwards/outwards, the heat transfer is enhanced/weakened accordingly, making a maximum increase by 12.9% and maximum decrease by 14.3% compared to the origin design. The introduction of conical return holes contributes to improving upwards velocity of return flow and subsequently enhancing scraping effects on sidewalls. For case with vertical sidewalls, inward-inclined sidewalls, and outward-inclined sidewalls, the area-averaged Nusselt number is maximum increased by 47.2%, 61.9% and 25.7% with the application of conical return holes.

Self-sustained stable combustion of off-gas from Solid Oxide Fuel Cell in a cone-shaped porous burner with preheaters

A divergent porous medium burner with three embedded preheaters has been numerically studied in this paper. The burner can be used to recover heat from Solid Oxide Fuel Cell for burning extremely low calorific off-gas. The developed burner consists of a conical section filled with porous media in the upper part and three preheaters located downstream through which the fresh mixture recovers heat from exhaust gas. A coupled solution method is used to study the structure of the preheater, and the feasibility of the method is verified. The results show that the burner can use the heat recovered from the exhaust gas to burn mixtures without the need for any external heating. The burner is capable of dealing with extremely low calorific off-gas, it can stabilize the combustion of a mixture with a heating value of 0.908 MJ/kg. The results also show that the mass flow ratio has a great influence on the recovery efficiency. When the mass flow ratio is less than one, the recovery efficiency increases sharply with the increase of mass flow ratio. With the further increase of mass flow ratio, the recovery efficiency decreases. This study provides the guidance for the treatment of low-grade off-gas without additional energy consumption.

The Influence of Structure Optimization on Vortex Suppression and Energy Dissipation in the Draft Tube of Francis Turbine

Under partial load operating conditions, vortex rope generation in the draft tube of a Francis turbine is considered one of the main reasons for hydro unit vibration. In this paper, a Francis turbine HLA551-LJ-43 in the laboratory was taken as a prototype. Numerical simulations of the entire flow passage were carried out. Four different hydro-turbines were chosen to analyze the effect of vortex suppression, which were named the prototype turbine (N-J), the turbine with J-grooves installed on its conical section (W-J), the one with extending runner cone (C), and the one that considered the J-grooves and the extending runner cone at the same time (J+C). Under the part load conditions in which the vortex rope is easily generated (0.4–0.8 times design flow QBEP), the spectrum characteristics of pressure fluctuation, the morphology of vortex rope, and the energy dissipation based on the entropy production theory in the draft tube were studied. The results show that the three optimized structures W-J, C, and J+C could reduce the pressure pulsation in the conical section of the draft tube, weaken the eccentricity of the vortex rope, and decrease the energy losses in the runner and draft tube. It is worth mentioning that the turbine with a J+C optimized structure had the most potent effect on vortex suppression and energy dissipation. Primarily when operating in deep partial load (DPL) conditions, the efficiency of the turbine with a J+C optimized structure was increased by 13.7% compared to the prototype turbine, and the main frequency amplitude of the pressure pulsation in the draft tube was reduced to 32% of the prototype.

A study on the classification performance of water-injection hydrocyclone

Aiming at the problem of fine particles entrainment in the underflow of hydrocyclone during the metal grinding classification process, a water-injection hydrocyclone was proposed to improve the classification efficiency. Through external injection of water on the wall surface of the cone section, the particles settling in the region were loosely graded so that the fine particles settled in the wall surface returned to the inner swirl again, thus reducing their entry into the underflow. Numerical simulation was used to explore the differences in the internal flow field characteristics and separation performance of the hydrocyclone after adding the water-injection structure. Then the industrial tests were conducted on the classification performance of the water-injection hydrocyclone. Numerical results showed that compared with the conventional hydrocyclone, the static pressure, tangential and axial velocity of the fluid inside the water-injection hydrocyclone increased, while the turbulence intensity decreased. The experimental results showed that with the increase of water-injection flow rate, the content of -74 μm particles in the underflow of water-injection hydrocyclone first decreased and then increased, and the comprehensive classification efficiency increased and then decreased accordingly. Compared with the conventional hydrocyclone, the content of -74 μm particles in the underflow of the water-injection hydrocyclone was reduced from 26.34% to 23.95%, and the comprehensive classification efficiency was increased from 69.22% to 73.03%, which mitigated the phenomenon of fine particles entrainment in the underflow.

Internal flow characteristics in the draft tube of a Francis turbine under different working conditions

The Francis turbine stability is impacted significantly by the flow characteristics in its draft tube. In the case of a Francis turbine in a hydropower plant, numerical simulations were undertaken at the maximum and rated heads, respectively, under three output scenarios of 20%, 100%, and 120%. The flow characteristics in the turbine draft tube and the evolution mechanism of flow pattern were assessed, as well as the impact of opening on vortex rope. The results demonstrate that with the increasing of the guide vane opening, a progressive transformation is noted for the random large vortex rope located in the conical section at the draft tube inlet into uniformly distributed one. The opening influences the velocity and pressure greatly, and as the opening enlarges, enhancement of the flow pattern is noted in the draft tube. Meanwhile, as the head increases, the influence scope of the vortex rope becomes larger. This research can reveal the operating conditions not suitable for the Francis turbine, thereby offering guidance for ensuring the stability of power station operation.

Drag Modeling Effects on Simulations of Supersonic Jet-Induced Cratering in a Soil

The impact of the drag model in the simulation of turbulent granular flows is studied using databases here created through simulations of supersonic jet-induced cratering in granular soil. The simulations are based on a previously developed model, which was shown to be hyperbolic, thus permitting the unhindered propagation of pressure waves critical to craters produced by supersonic plumes. The goal is to identify predicted quantities from these simulations that show sufficient differences among simulations performed with different drag models; these quantities would warrant future experimental investigations determining which model is correct. Among all drag models examined, only two models are found applicable to the regime of investigation. Examination of the databases is conducted from the viewpoint of global quantities and detailed quantities. The results show that isocontours and characteristic length scales are minimally affected by the employed drag law. In contrast, azimuthally averaged and root mean square ejecta-related quantities are more sensitive to the drag model employed, but only in the central part of the crater. This sensitivity is much larger for shallow craters having a parabolic cross section than for deep craters having a conical cross section, thus indicating the experimental configuration best suited to experimentally evaluating drag models.

Optical study on spray mixing, flame propagation and jets evolution within visible methanol active pre-chamber for turbulent jet ignition

Methanol spray impingement, mixing, flame propagation and jet evolution within the narrow-confined active pre-chamber (APC) with complex walls were experimentally observed by optical method for the first time. The effects of injection pressure and duration was investigated on an actual-geometry optical APC assembled in constant volume combustion chamber (CVC). Exploration on APC internal processes within static environments forms the basis for optimization of APC and analysis of jet formation. Mie scattering coupled with flame natural luminosity imaging were used to record spray mixing and combustion. The results show that in the APC with narrow-confined space, methanol spray undergoes three wall impingements, inducing a tumble that promotes mixing. High injection pressure enhances rapid spray tip penetration, while long injection duration slows methanol diffusion. In longer injection duration cases, the spray tip after the third impingement interferes with subsequent sprays. For higher injection pressure, this interference occurs in the APC cone section due to a larger spray cone angle, whereas for lower pressure, it happens in the APC duct section. Higher injection pressure also causes more spray to impact the APC bottom after the first wall impingement, hindering flame acceleration in the duct section. Irregular flame propagation is observed in the APC cone section due to wider space and uneven mixture conditions, while the convergent geometry from the APC throat to the duct section significantly accelerates flame propagation. The APC jet appears due to the pressure difference between the APC and the main chamber, with the brightness and length of the visible flame jet increasing with APC flame luminosity and pressure difference. A Mach ring structure is observed initially, but the jet velocity decreases as the Mach ring disappears during the APC inner flame extinguishing process. Through this study, the actual spraying and combustion process in APC is experimentally captured and revealed, which are an important contribution for APC optimization and development.

Study of hydrocyclone with flushing water device for sand washing of municipal sludge

Municipal sludge particles with size range between 0.045 and 0.2 mm were difficult to be precisely separated due to fine size distribution and high content of organic matter, resulting in low sand recycling efficiency. In view of the above problems, this paper proposed a flushing water device which was settled at the cone section of conventional hydrocyclone, aiming to utilize the supplementary water to strengthen the shear force field. Comparative test results showed that the organic matter content in the underflow product was significantly reduced after the addition of flushing water. Using the organic matter content and the sand recovery rate as the response index, the prediction models were established by using response surface optimization test. The influence order of different parameters on the response index was apex diameter, flushing device position and flow rate. Finally, an underflow product with organic matter content of 3.96 % and sand recovery rate of 48.03 % was obtained under the conditions of optimized parameter combinations. The research results can contribute to the development of a new method of residual sludge disposal that improves the sand washing efficiency and the cost-effectiveness of sludge treatment.

Analysis and Testing of a Launch-Vehicle-Like Composite Conical–Cylindrical Shell

Launch-vehicle shell structures, which can be composed of both cylindrical and conical sections, are known to be susceptible to buckling due to their large radius-to-thickness ratios. Advancements in composite manufacturing and numerical methods have enabled designers to consider more nontraditional shapes, such as connecting the conical and cylindrical sections with a toroidal transition to create a single-piece conical–cylindrical shell. This single-piece construction eliminates the need for a stiff, heavy interface ring between sections and has the potential to reduce mass. To better understand the buckling behavior of a composite conical–cylindrical shell, a laboratory-scale article was designed, fabricated, and tested. Before the test, a finite element model that included thickness variations and radial imperfections was created. The test article buckled elastically at 251.8 kN, approximately 8.8% higher than the predicted buckling load of 231.4 kN. Because the test article buckled elastically, the buckling test was repeated. The buckling load measured from the second test was within 1% of that from the first test. Continued research on conical–cylindrical structures has the potential to expand the design space for launch-vehicle structures and lead to improved designs and reduced mass.

Design and Analysis of Gas Cyclone with Arc-Shaped Cone Using Bézier Curve for Improved Performance

Abstract The research investigates novel gas cyclone separators with curved conical sections, comparing eight configurations with varying curvature sizes. Gas cyclones are traditionally used as particle separators to remove dust from gas streams, aiming to achieve a dust-free gas flow at the exit pipe while recovering particles to the dust outlet. Computational fluid dynamics (CFD) was employed to model the gas cyclone using the Reynolds stress turbulence model (RSM); the study examines flow fields and pressure losses. It finds that increased curvature correlates with reduced pressure drop. The curved profile is derived from the Bézier curve, characterized by a set of control points determining its shape. This study examines eight cyclone configurations with the intermediate point placed at varying fractions of the main radius: 1/8, 1/4, 3/8, 1/2, 5/8, 3/4, 7/8, and the main radius itself. The investigation focuses on the impact of different conical segment shapes on cyclone performance, highlighting how convex variants outperform others at higher flow rates while concave variants exhibit higher pressure drop. The pressure drop in the convex variant with an intermediate point position equal to the main radius decreased by 50%. These findings suggest the potential of the convex variant in certain operating conditions over traditional designs with improved particle capture efficiency.

Parametric design of curved hydrocyclone and its optimization based on artificial neural networks prediction

In order to obtain a higher particle separation efficiency, a method of parametric design of the cylinder cone section of curved hydrocyclone based on control points and data points is proposed. The radial diameters were used as input variables to the BP neural network to predict separation performance, which makes it feasible to optimize the profile of the cylinder and cone section of the curved hydrocyclone. The separation efficiency of Bezier-Curved-Cone hydrocyclone (BCCH) designed using control points is up to 69.24 %, and the separation efficiency of Spline-Curved-Cone hydrocyclone (SCCH) designed using data points is up to 73.30 %, both of which are higher than that of the conventional Thew’s class hydrocyclone (with a separation efficiency of 62.43 %). Meanwhile, the pressure drop of BCCH is the lowest among all of the five hydrocyclones. No.10 hydrocyclone was predicted to be the best one with separation efficiency up to 78.41 % using BP neural network, which was experimentally verified. The novel hydrocyclones with curved profile provides new approach to enhancing separation performance, and the research costs can be reduced by using neural network-based performance prediction and optimization.

Performance experiments and pressure drop prediction modelling of an energy-saving cyclone separator

The study proposes a new type of axial-inlet cyclone separator with the smaller cylinder-cone ratio and an expansion tube at the particle exhaust, named energy-saving cyclone separator, which offers several advantages over the traditional tangential inlet cyclone in engineering units. Experimental results demonstrate that the separation efficiency exceeds 83 % for fine particles smaller than 10μm, while the pressure drop is significantly lower than that of the commonly used PV-type tangential inlet cyclone separator, at only 44 % of the PV cyclone separator’s pressure drop. Moreover, the flow fields of energy-saving cyclone separator are measured to analyze its characteristics. It is found that the lower tangential momentum ratio in both the inner and outer swirl zones of energy-saving cyclone separator reduces the dissipation of dynamic swirl pressure at the bottom of the cone section and outlet pipe, resulting in a lower pressure drop. The high proportion of downward axial momentum in the outer swirl section causes the separated large particles to discharge through the dust exhaust, improving the separation efficiency of coarse particles. Furthermore, a model to predict the pressure drop of energy-saving cyclone separator is developed.

The influence of guide vane opening on internal cavitation of Francis turbine

Abstract In response to the theme of national multi energy complementary power grid construction, hydropower stations need to frequently change the opening of active guide vanes. Operation deviates from the rated working condition. And output is adjusted to meet the flexible power demand of users. Cavitation phenomenon as the biggest problem restricting the eccentric operation of Francis turbine. Easily induce cavitation damage to the flow passage components of the unit and shorten the service life of the unit. Therefore, there is a good engineering research background for the cavitation characteristics inside Francis turbines in the process of exploring the variation of guide vane opening. This paper takes a high head Francis turbine as the research object, based on numerical simulation and model test. The results show that the maximum amplitude of the draft tube vortex gradually increases during the process of decreasing the opening. The degree of cavitation is gradually serious, and the streamline distribution of the flow field inside the impeller is uneven. As the opening of the guide vane gradually increases, the vortexof the draft tube gradually decreases. The cavitation degree is weakened, and the streamline distribution inside the impeller is significantly improved. With the increase of the guide vane opening, the low-speed area on the outlet surface of the impeller gradually decreases, resulting in a gradual reduction of the low-speed zone in the straight cone section of the draft tube, a smaller vortex, a weaker cavitation degree. The internal flow distribution of the impeller is significantly improved.

Oxide Reduction Treatment with a Thermal Plasma Torch: A Case Study

This article presents the findings of a study on oxide reduction utilizing a novel reducing plasma torch, employing greenhouse gases such as CO2 and CH4 as plasma gases. The primary aim of this investigation is to establish the viability of this approach. The innovative plasma torch was employed to reduce various oxides, including aluminum oxide, iron oxide, and titanium oxide, as well as a mixed oxide composition, employing a CO2/CH4 molar ratio of 1:1 within a spouted bed reactor. Following plasma treatment, X-ray diffraction (XRD) analysis was conducted to examine the metallic phases, notably titanium, iron, and aluminum. SEM–EDS observations were carried out to assess microstructural changes and identify elemental compositions pre- and post-plasma treatment. The results demonstrate that within the conical section of the reactor, titanium oxide experiences partial reduction, resulting in limited titanium production, while aluminum oxide and iron oxides (magnetite and hematite) undergo reduction to yield aluminum and iron, respectively. Thermodynamic calculations, performed using Factsage software version 8.3, were utilized to predict stable-phase formations following plasma treatment for each material.

Designing the Spigot Structure of Hydrocyclones to Reduce Fine Particle Misplacement in Underflow

Hydrocyclones can be used to concentrate the entrained sands in sewage and alleviate the clogging and erosion of the drainage network, but in practical application, there are problems such as low concentrations of underflow and a high content of fine particles, which cause a significant load on the subsequent sand dewatering and recycling. This paper designs five spigot structures of hydrocyclones and investigates the separation performance by numerical simulation, aiming to improve the applicability of hydrocyclones in the sewage treatment process by optimizing the spigot structure. The research results show that a large cone spigot delays the external downward swirling flow and reduces fine particle content in the underflow, but its effective separation space is reduced, and the turbulence in the cone section area is more intensive, which influences the separation accuracy. An elongated spigot has a reduced underflow water distribution; fine particles are more enriched in the internal swirling flow, and the underflow recoveries of 1 μm and 5 μm particles drop by 2.34% and 2.31%. The spigot structure affects the downward fluid and air intake states; complicated spigot structures contribute to increasing the resistance of particle discharge through underflow, alleviating fine particle misplacement.

Numerical simulation investigating the impact of regulated underflow rate on the performance of a cyclone with split flow

A novel cyclone design called enhanced cyclone with split flow (ECSF) incorporates bypass flow and underflow to eliminate or suppress localized secondary flow observed in conventional cyclones. The present study aims to investigate the mechanism of ECSF in suppressing localized secondary flow and explore methods for regulating the bottom flow rate. The turbulent characteristics within the ECSF are obtained using Reynolds stress model, while the trajectory of particles is predicted using discrete phase model to derive the separation performance. The accuracy of the simulation model has been validated through experimental verification. The results demonstrated that the full separation efficiency of ECSF for PM10 and PM2.5 remained above 90 % and 70 %, respectively. Moreover, it exhibited an increasing trend with the rise in the full split ratio, eventually stabilizing at approximately 95 % and 77 %, correspondingly, when the full split ratio reached 20 %. The bypass flow and underflow effectively eliminated or suppressed the upper ash ring and processing vortex core (PVC) phenomenon, respectively. However, the exacerbation of the short-circuit flow phenomenon hindered further improvement in separation efficiency beyond a full diversion ratio of 20 %. When the full split ratio is relatively small, particles may accumulate in the discharge pipe, which can be resolved by introducing auxiliary airflow; however, it is crucial to ensure that the flow rate of auxiliary flow does not exceed 14.29 % of that of feed flow to avoid compromising the separation efficiency. Furthermore, the split flow induces an additional reversed vortex within the ECSF, which extends from the overflow pipe to conical section. Its structural characteristics are influenced by both back pressure of discharge outlet and diameter of underflow pipe. To ensure optimal performance of the ECSF, it is recommended that the underflow pipe diameter should not be smaller than that of the outlet in conical section.