CFD-Based Structural Optimization of Rotor Cage for High-Efficiency Rotor Classifier

Due to the uneven materials dispersion and high dust concentration in industrial applications of turbo air classifiers, a high-efficiency rotor classifier was designed. Numerical simulations by ANSYS-Fluent 19.0, the effects of rotor cage shape, the number of blades, and the blade profile on the inner flow field, as well as classification performance, were investigated. The simulation results indicated a significant improvement in flow field distribution near the classification surface with the conical rotor cage. Furthermore, there was an average reduction of 10.1% in cut size, as well as a 23.6% increase in classification accuracy. When the number of blades was 36, the flow field distribution between the blades was relatively uniform and a smaller cut size was obtained at a higher classification accuracy. A streamline blade with 52° as the inlet installation angle effectively reduced the impact of the airflow on the blade and eliminated the inertia anti-vortex between blades. The cut size reduction was 4.7–6.3%, with a basically unchanged classification accuracy. The material classification experimental results were in agreement with the simulated results. The discrete phase model (DPM) could well-predict the cut sizes and classification accuracy, but it could not present the fishhook effect. The present study provides theoretical guidance for the structural optimization of an air classifier with a rotor cage.

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Effects of Blade Parameters on the Flow Field and Classification Performance of the Vertical Roller Mill via Numerical Investigations

Mathematical Problems in Engineering ◽

10.1155/2020/3290694 ◽

2020 ◽

Vol 2020 ◽

pp. 1-15

Author(s):

Chang Liu ◽

Zuobing Chen ◽

Weili Zhang ◽

Chenggang Yang ◽

Ya Mao ◽

...

Keyword(s):

Flow Field ◽

Pressure Difference ◽

Continuous Phase ◽

Classification Performance ◽

Field Analysis ◽

Discrete Phase Model ◽

Roller Mill ◽

Discrete Phase ◽

Vertical Roller ◽

Classification Efficiency

The vertical roller mill is an important crushing and grading screening device widely used in many industries. Its classification efficiency and the pressure difference determine the entire producing capacity and power consumption, respectively, which makes them the two key indicators describing the mill performance. Based on the DPM (Discrete Phase Model) and continuous phase coupling model, the flow field characteristics in the vertical roller mill including the velocity and pressure fields and the discrete phase distributions had been analyzed. The influence of blade parameters like the shape, number, and rotating speed on the flow field and classification performance had also been comprehensively explored. The numerical simulations showed that there are vortices in many zones in the mill and the blades are of great significance to the mill performance. The blade IV not only results in high classification efficiency but also reduces effectively the pressure difference in the separator and also the whole machine. The conclusions of the flow field analysis and the blade effects on the classification efficiency and the pressure difference could guide designing and optimizing the equipment structure and the milling process, which is of great importance to obtain better overall performance of the vertical roller mill.

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Aerodynamic Performance Investigation under the Influence of Heavy Rain of a NACA 0012 Airfoil for Wind Turbine Applications

International Review of Mechanical Engineering (IREME) ◽

10.15866/ireme.v6i6.20761 ◽

2012 ◽

Vol 6 (6) ◽

pp. 1228-1235

Author(s):

Eleni C. Douvi ◽

Dionissios P. Margaris

Keyword(s):

Flow Field ◽

Wind Turbine ◽

Heavy Rain ◽

Aerodynamic Characteristics ◽

Aerodynamic Performance ◽

Spherical Particles ◽

Discrete Phase Model ◽

Two Phase ◽

Naca0012 Airfoil ◽

The Impact

The study of the prediction of the flow field and aerodynamic characteristics of a NACA0012 airfoil in simulated heavy rain, using a computational fluid dynamics code is presented. The simulation of rain is accomplished by using the two-phase flow Discrete Phase Model, which is available in the CFD code. Spherical particles are tracked through the two-dimensional, incompressible air flow field over a NACA0012 airfoil, at a simulated rain rate of 1000 mm/h and operating at Reynolds numbers Re=1×106 and Re=3×106. To validate the CFD developed model, the results are compared with well-established and published experimental data, showing good agreement. The aim of the work was to show the behavior of the airfoil at these conditions and to establish a verified solution method. Lift and drag coefficients are computed at various angles of attack in both dry and wet conditions and the results are compared to show the effects of rain at airfoil performance. The impact of rain on wind turbine performance is also analyzed. It is concluded that rain causes degradation of aerodynamic performance, especially lift is decreased and drag is increased.

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The Study on Numerical Simulation and Experiments of Four Product Hydrocyclone with Double Vortex Finders

Minerals ◽

10.3390/min9010023 ◽

2018 ◽

Vol 9 (1) ◽

pp. 23 ◽

Cited By ~ 2

Author(s):

Yuekan Zhang ◽

Peikun Liu ◽

Lanyue Jiang ◽

Xinghua Yang

Keyword(s):

Flow Field ◽

Field Distribution ◽

Fine Particles ◽

Structural Parameters ◽

Industrial Applications ◽

Medium Size ◽

Operational Parameters ◽

Particle Size Range ◽

Second Stage ◽

Overflow Pipe

A hydrocyclone is an instrument that can effectively separate multi-phase mixtures of particles with different densities or sizes based on centrifugal sedimentation principles. However, conventional hydrocyclones lead to two products only, resulting in an over-wide particle size range that does not meet the requirements of subsequent operations. In this article, a two-stage series, a four product hydrocyclone is proposed. The first stage hydrocyclone is designed to be a coaxial double overflow pipe: under the effect of separation, fine particles are discharged from the internal overflow pipe, while medium-size particles are discharged from external overflow pipe before entering the second stage hydrocyclone for fine sedimentation. In other words, one-stage grading leads to four products, including the first stage underflow, the first stage overflow, the second stage underflow, and the second stage overflow. The effects of structural parameters and operational parameters on flow field distribution in hydrocyclone were investigated via a study of flow field distribution in multi-product hydrocyclones using numerical simulations. The application of four product hydrocyclone in iron recovery shows that the grade and recovery of iron concentrate exceed 65.08% and 86.14%, respectively. This study provides references for understanding the flow field distribution in hydrocyclones and development of multi-product grading instrument in terms of both theory and industrial applications.

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A High-Gain Observer-Based Adaptive Super-Twisting Algorithm for DC-Link Voltage Control of NPC Converters

Energies ◽

10.3390/en13051110 ◽

2020 ◽

Vol 13 (5) ◽

pp. 1110 ◽

Cited By ~ 1

Author(s):

Xiaoning Shen ◽

Jianxing Liu ◽

Abraham Marquez ◽

Wensheng Luo ◽

Jose I. Leon ◽

...

Keyword(s):

Disturbance Rejection ◽

High Efficiency ◽

Dynamic Performance ◽

High Gain ◽

Voltage Regulation ◽

Industrial Applications ◽

High Gain Observer ◽

Twisting Algorithm ◽

The Impact ◽

Fast Dynamic

Acting as an interface between the grid and many energy systems, the active front-end (AFE) has been widely used in a large variety of industrial applications. In this paper, in order to ensure the fast dynamic performance and good disturbance rejection ability of the AFE, a high-gain observer (HGO) plus adaptive super-twisting algorithm (STA) for the three-level neutral-point-clamped (NPC) converter is proposed. Comparing with the conventional PI control strategy, the proposed controller implements the adaptive STA in the voltage regulator to provide a faster transient response. The gains of the adaptive STA keep varying according to the rules being reduced in steady state but increasing in transient conditions. Therefore, the chattering phenomenon is mitigated and the dynamic response is guaranteed. Additionally, to undermine the impact of external disturbances on the dc-link voltage, a high-efficiency HGO is designed in the voltage regulation loop to reject it. Experimental results based on a three-level NPC prototype are given and compared with the conventional PI method to validate the fast dynamic performance and high disturbance rejection ability of the proposed approach.

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Experimental Investigation of the Diffuser Vane Clearance Effect in a Centrifugal Compressor Stage With Adjustable Diffuser Geometry: Part I — Compressor Performance Analysis

Volume 2D: Turbomachinery ◽

10.1115/gt2014-26896 ◽

2014 ◽

Cited By ~ 2

Author(s):

Stefan Ubben ◽

Reinhard Niehuis

Keyword(s):

Centrifugal Compressor ◽

High Efficiency ◽

Negative Impact ◽

Pressure Ratio ◽

Industrial Applications ◽

Flow Measurements ◽

Flow Phenomena ◽

Compressor Performance ◽

Compressor Map ◽

The Impact

The combination of variable speed control and adjustable diffuser vanes offers an attractive design option for centrifugal compressors applied in industrial applications where a wide operating range at high efficiency level and a favorable surge line is required. However, the knowledge about the impact on compressor performance of a diffuser vane clearance between vane and diffuser wall which is mandatory since the diffuser geometry adjustment has to take place during operation, is still not satisfying. This two-part paper summarizes results of investigations performed at the Institute of Jet Propulsion and Turbomachinery at RWTH Aachen with an industrial-like centrifugal compressor, featuring a design pressure ratio of 4 and a design speed of 35200 rpm. Particular attention was directed to the influence of the diffuser clearance on the operating behavior of the entire stage, the pressure recovery in the diffuser and on the diffuser flow by a systematic variation of the parameters diffuser clearance height, diffuser vane angle, radial gap between impeller exit and diffuser inlet, and rotor speed. Compressor map measurements provide a summary of the operating behavior related to diffuser geometry and impeller speed, whereas detailed flow measurements with temperature and pressure probes allow a breakdown of the losses between impeller and diffuser and contribute to a better understanding of relevant flow phenomena. The results presented in Part I show that an one-sided diffuser clearance does not necessarily has a negative impact on the operation and loss behavior of the centrifugal compressor, but instead may contribute to an increased pressure ratio and improved efficiency. The flow phenomena responsible for this detected performance behavior are exposed in Part II [28], where the results of detailed measurements with pressure probes at diffuser exit and Particle Image Velocimetry (PIV) measurements conducted inside the diffuser channel, revealing the complex and unsteady flow leaving the impeller and passing the diffuser channel, are discussed. The experimental results are published as an open CFD testcase “Radiver 2” [26], extending the experimental data base of the testcase “Radiver” published in 2003 by Ziegler [31].

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Effects of Flow Baffles on Flow Profile, Pressure Drop and Classification Performance in Classifiers

Processes ◽

10.3390/pr9071213 ◽

2021 ◽

Vol 9 (7) ◽

pp. 1213

Author(s):

Michael Betz ◽

Marco Gleiss ◽

Hermann Nirschl

Keyword(s):

Pressure Loss ◽

Collection Efficiency ◽

Flow Behavior ◽

Classification Performance ◽

Operating Conditions ◽

Flow Profile ◽

Discrete Phase Model ◽

Operation Conditions ◽

Air Classifier ◽

The Impact

This paper presents a study of the use of flow baffles inside a centrifugal air classifier. An air classifier belongs to the most widely used classification devices in mills in the mineral industry, which is why there is a great interest in optimizing the process flow and pressure loss. Using Computational Fluid Dynamics (CFD), the flow profile in a classifier without and with flow baffles is systematically compared. In the simulations, turbulence effects are modeled with the realizable k–ε model, and the Multiple Reference Frame approach (MRF) is used to represent the rotation of the classifier wheel. The discrete phase model is used to predict the collection efficiency. The effects on the pressure loss and the classification efficiency of the classifier are considered for two operating conditions. In addition, a comparison with experimental data is performed. Firstly, the simulations and experiments show good agreement. Furthermore, the investigations show that the use of flow baffles is suitable for optimizing the flow behavior in the classifier, especially in reducing the pressure loss and therefore energy costs. Moreover, the flow baffles have an impact on the classification performance. The impact depends on the operation conditions, especially the classifier speed. At low classifier speeds, the classifier without flow baffles separates more efficiently; as the speed increases, the classification performance of the classifier with flow baffles improves.

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Numerical Investigation on Flow Field Distribution of Eccentric Compressors Based on Steady and Unsteady CFD Methods

Energies ◽

10.3390/en13226081 ◽

2020 ◽

Vol 13 (22) ◽

pp. 6081

Author(s):

Chao Jiang ◽

Jun Hu ◽

Jiayu Wang ◽

Longteng Cong

Keyword(s):

Flow Field ◽

Field Distribution ◽

Tip Clearance ◽

Flow Coefficient ◽

Characteristic Line ◽

Axial Compressors ◽

Ansys Cfx ◽

Engine Compressor ◽

Computational Fluid Dynamics Cfd ◽

The Impact

The tip clearance has an important effect on the performance of an engine compressor. While the impact of tip clearance on a concentric compressor has been widely explored in previous research, the flow field distribution of an eccentric compressor has only been minimally explored. Both the steady and unsteady computational fluid dynamics (CFD) methods have been widely used in the studies of concentric axial-compressors, and they have similar simulation results in terms of flow field. However, they have been rarely applied to axial-compressors with non-uniform tip clearance to investigate their flow field. In this paper, ANSYS CFX is used as CFD software, and both steady and unsteady CFD methods are applied to study a single rotor of ROTOR67 to investigate the compressor characteristic line and flow field under different eccentricity conditions. The results show that non-uniform tip clearance creates a non-uniform flow field at the inlet and tip regions over the whole operating range. The circumferential position where the flow coefficient and the axial velocity are the smallest occurs at a position close to the maximum tip clearance and is located on the side deviating toward the direction of rotation of the rotor. Compared with steady CFD, unsteady CFD has better predictive capability for the flow field distribution in axial compressors with non-uniform tip clearance.

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Experimental Investigation of the Diffuser Vane Clearance Effect in a Centrifugal Compressor Stage With Adjustable Diffuser Geometry: Part II — Detailed Flow Analysis

Volume 2D: Turbomachinery ◽

10.1115/gt2014-27175 ◽

2014 ◽

Cited By ~ 3

Author(s):

Stefan Ubben ◽

Reinhard Niehuis

Keyword(s):

High Efficiency ◽

Negative Impact ◽

Pressure Ratio ◽

Flow Analysis ◽

Industrial Applications ◽

Characteristic Line ◽

Stall Margin ◽

Clearance Flow ◽

Geometry Parameter ◽

The Impact

The combination of variable speed control and adjustable diffuser vanes offers an attractive design option for centrifugal compressors applied in industrial applications where a wide operating range at high efficiency level and a favorable surge line is required. However, the knowledge about the impact on compressor performance of a diffuser vane clearance between vane and diffuser wall which is mandatory since the diffuser geometry adjustment has to take place during operation, is still not satisfying. The results of characteristic line and probe measurements presented in Part I [18] of this two-part paper showed that an one-sided diffuser clearance not necessarily need to lead to a negative impact on compressor operating behavior but is able to contribute to an increase in flow range, stall margin, pressure ratio and efficiency, as long as the diffuser passage is broad enough with respect to the clearance height. In order to reveal the relevant flow phenomena, in Part II the results of detailed measurements of the pressure distribution at diffuser exit and Particle Image Velocimetry (PIV) measurements inside the diffuser channel performed at three clearance configurations and three diffuser angles at a fixed radial gap are discussed. It was found, that for defined diffuser configurations the clearance flow amplifies the diffuser throat vortex capable to reduce the loading of the highly loaded vane pressure side and to support a more homogenous diffuser flow. It turned out that the coaction of the geometry parameter diffuser vane angle and diffuser clearance height is of particular importance. The experimental results are published as an open CFD testcase “Radiver 2” [17], extending the experimental data base of the testcase “Radiver” published in 2003 by Ziegler [24].

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Piezoelectric β-polymorph formation of new textiles by surface modification with coating process based on interfacial interaction on the conformational variation of poly (vinylidene fluoride) (PVDF) chains

The European Physical Journal Applied Physics ◽

10.1051/epjap/2020200158 ◽

2020 ◽

Vol 91 (3) ◽

pp. 31301

Author(s):

Nabil Chakhchaoui ◽

Rida Farhan ◽

Meriem Boutaldat ◽

Marwane Rouway ◽

Adil Eddiai ◽

...

Keyword(s):

High Efficiency ◽

Vinylidene Fluoride ◽

Research Work ◽

Research Area ◽

Interfacial Interaction ◽

Tetraethyl Orthosilicate ◽

Poly Vinylidene Fluoride ◽

Carbon Nanofillers ◽

The Impact ◽

Advanced Applications

Novel textiles have received a lot of attention from researchers in the last decade due to some of their unique features. The introduction of intelligent materials into textile structures offers an opportunity to develop multifunctional textiles, such as sensing, reacting, conducting electricity and performing energy conversion operations. In this research work nanocomposite-based highly piezoelectric and electroactive β-phase new textile has been developed using the pad-dry-cure method. The deposition of poly (vinylidene fluoride) (PVDF) − carbon nanofillers (CNF) − tetraethyl orthosilicate (TEOS), Si(OCH2CH3)4 was acquired on a treated textile substrate using coating technique followed by evaporation to transform the passive (non-functional) textile into a dynamic textile with an enhanced piezoelectric β-phase. The aim of the study is the investigation of the impact the coating of textile via piezoelectric nanocomposites based PVDF-CNF (by optimizing piezoelectric crystalline phase). The chemical composition of CT/PVDF-CNC-TEOS textile was detected by qualitative elemental analysis (SEM/EDX). The added of 0.5% of CNF during the process provides material textiles with a piezoelectric β-phase of up to 50% has been measured by FTIR experiments. These results indicated that CNF has high efficiency in transforming the phase α introduced in the unloaded PVDF, to the β-phase in the case of nanocomposites. Consequently, this fabricated new textile exhibits glorious piezoelectric β-phase even with relatively low coating content of PVDF-CNF-TEOS. The study demonstrates that the pad-dry-cure method can potentially be used for the development of piezoelectric nanocomposite-coated wearable new textiles for sensors and energy harvesting applications. We believe that our study may inspire the research area for future advanced applications.

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