Centrifugal Fan Research Articles

ПАРАМЕТРИЗАЦИЯ ВЕНТИЛЯТОРНОГО УЗЛА ВНЕШНЕЙ СИСТЕМЫ ОХЛАЖДЕНИЯ ЭЛЕКТРОДВИГАТЕЛЯ

Relevance One of the most important issues in the design of electric machines is the implementation of a cooling system that provides efficient heat removal at low weight and size costs. Maintaining the optimal operating temperature of the active parts of an electric machine is necessary for its efficient and reliable operation, but under conditions of limited weight and size costs, this becomes a difficult engineering task. Air cooling of electric machines still does not lose its relevance due to its simplicity, small weight and size indicators and implementation costs. A key element in air cooling systems is the centrifugal fan, which creates the movement of air masses. Thus, in an air cooling system, the main task is to design a fan that provides the necessary characteristics. Aim of research Aim of the research is to design a fan with backward curved blades based on model parameterization in order to obtain the required performance while maintaining the overall parameters. The required volumetric performance is estimated at 120–200 m3/h depending on the rotational speed. Research methods The study is carried out using three-dimensional numerical computer simulation in the ANSYS CFX software package for computational fluid dynamics. The angles of entry and exit of the air flow from the impeller vary. As a result, 16 different variants of the ratios of the inlet and outlet flow angles were considered. Results As a result of the work, the design of the impeller of the air cooling system of the electric machine was parametrized. As a result of a series of calculations, it was determined that at an angle β2 = 70° for all angles β1 the required performance is provided at 6000 rpm. The most productive solution is the ratio β1 = 30° and β2 = 70°.

A Bayesian Framework of Non-Synchronous Measurements at Coprime Positions for Sound Source Localization With High Resolution

The noise distribution in the mechanical system is tightly connected to the structure design and particular operating conditions. The noise source localization can effectively assist with the operating condition monitoring and noise reduction design of the mechanical device. The performance limitation of the array aperture for lower frequency acoustic localization is broken up by the non-synchronous measurement at coprime positions (CP-NSM), while this method has high uncertainty and requires an efficient adaptive regularization method to solve its corresponding acoustic inverse problem. The algorithms under the Bayesian framework with Student-t priors (variational Bayesian approximation and subspace variational Bayesian) are derived and deployed to solve the acoustic inverse problem in the CP-NSM method, and the results are compared with those obtained by the interior-point method and the alternating direction method of the multipliers algorithm. The proposed Bayesian methods have the advantages of adaptive regularization parameter estimation, which can reduce the influence of various interferences in CP-NSM. At the same time, in addition to using simulations and experiments in the anechoic chambers, the proposed Bayesian algorithms are validated further in real industrial applications. The proposed method is applied to improve the noise reduction design of the centrifugal fan, a mechanical device containing more information from noise sources.

DESIGN AND FABRICATION OF INDOOR AIR PURIFIER & HUMIDIFIER IN FOOD INDUSTRY

In 2021, air pollution has gone beyond all limits. According to the WHO, 7 million people die annually as a result of air pollution. A whopping 91 percent of the world's population is now exposed to air pollution due to its wide distribution. This also implies that the air within your home is contaminated. In order to address this problem, we have developed a small air purifier that employs water as an air filter rather than pricey filters. Additionally, it functions as an air humidifier. The design and development of the next-generation indoor air purifier is the subject of this thesis. The project was carried out using a human-cantered design process, and a patient was the end outcome. The system uses two high performance, low noise centrifugal fans to draw air through a safety mesh. At the bottom of the purifier, there is a water tank through which the air is pushed and subsequently passed. Water catches dust, fungi, germs, and other contaminants, which causes the air it passes through to be automatically cleansed. If you suffer from asthma or another breathing difficulty, you may find a HEPA (sometimes defined as "high-efficiency particulate air," sometimes as "high-energy particulate arresting") air purifier (or a vacuum with a HEPA filter) well worth the investment.

Design of an External Centrifugal Fan for the Cooling System of an Electrical Machine

Air cooling systems for electrical machines still do not lose their relevance. Especially noteworthy here is the aviation industry, in which special attention is paid to the weight and size of all systems, as well as the high density of equipment layout, which can interfere with the implementation of other types of cooling. At such times, only air cooling can be used to ensure the optimum operating temperature of the electrical machine. This article presents a research work on the profiling of blades for an external centrifugal fan of the air-cooling system of an electrical machine. The study is based on 3D numerical calculations using computational fluid dynamics software. Based on the results obtained, a design option was chosen that provides maximum performance.

Parameters of the airflow when exiting the fan

The purpose study is to substantiate the parameters of the air flow when exiting the casing and the working parts fan. In the course of studies, the pressure and air flow velocity were determined by an improved Pitot-Prandtal tube. In experimental studies, the influence speed fan wheel improved sprayer on the parameters air flow when exiting the window casing and the working part was studied. It was found that the pressure air flow from the window fan casing increases on average from 65 Pa to 152 Pa when the number of revolutions wheel is increased from 800 r/min to 1200 r/min, and 5.5 times when the number of revolutions is increased from 800 r/min to 1600 r/min. The speed air flow coming out window shroud fan depends on the pressure, it was observed that the speed increased by 2.5 times when the pressure in the system increased from 100 to 350 Pa. According to the results studies carried out, in order to ensure high-quality chemical processing with low energy consumption, the number of revolutions centrifugal fan wheel should be equal to 1500 r/min.

V-Belt Fault Detection Using Extended Park Vector Approach (Epva) in Centrifugal Fan Driven by an Induction Motor

V-Belt Fault Detection Using Extended Park Vector Approach (Epva) in Centrifugal Fan Driven by an Induction Motor

효율과 소음을 고려한 원심팬 입구형상의 수치적 최적화

The inlet geometry of the centrifugal fan has been numerically optimized to maximize the fan performance and to minimize the fan noise. For the optimization, a representative sub-model using the periodic boundary condition in the circumferential direction was constructed. The radii of the bell-mouth and the shroud at the inlet of the fan were selected as design variables. The objective functions were the fan efficiency for the fan performance and the turbulent viscosity for the noise metric. The moving reference frame (MRF) formulation was adopted for the flow analysis. The case studies were conducted and the results were analyzed using the response surface method. The optimal shapes for the maximum efficiency, minimum noise, and the combined performance were examined with the actual fan model with casing geometry. Details of the optimization process, the effects of design variables and the final optimization results were summarized in quantitative and qualitative ways.

梳刷气吸复合式亚麻（胡麻）蒴果收获试验台设计与试验

In view of the problem of plant entanglement threshing roller in the process of mechanized flax harvesting, a comb-brush air-suction composite flax capsule harvesting test stand was designed based on the harvesting method of harvesting capsules independently and then breaking the capsules to thresh them. The following four parameters were selected as experimental factors: the shape of comb tooth cross-section, the rotational speed of comb roller, the relative speed of machine travel and the air volume of centrifugal fan. The following four indicators were chosen as the experimental indicators: capsule removal rate, capsule breakage rate, capsule collection rate and plant winding rate. A four-factor and three-level orthogonal test was conducted. The results showed that the optimal combination of test factors was as follows: the shape of comb tooth cross-section was rectangular, the rotational speed of the brush roller was 90 rad/min, the speed of machine travel relative to the plant was 80 mm/s and the air volume of centrifugal fan was 6000 m3/h. Under the condition of better experiment parameters combination, the capsule removal rate was 96.45%, capsule shell breaking rate was 98.79%, capsule collection rate was 95.65% and flax plants winding rate was 2.52%. The comb-brush air-suction composite flax capsule harvesting test bench provided the feasibility scheme for the problem of plant winding thresher roller and capsule collection.

Design and Testing of the Peanut Pod Cleaning Device

Due to the design of peanut harvesters and cleaners, peanut pods are often mixed with soil, gravel, peanut straw, and other impurities. To solve this problem, this study focused on designing a peanut pod cleaning device by integrating a negative pressure centrifugal fan, a hydrometric cleaning sieve, and a reversible long-mesh cleaning sieve. The relative motion of the peanut pod on the sieve was discussed, its stress analyzed, the design parameters of the sieve and fan determined, and the operation of the device was monitored by using sensors, which accurately recorded and adjusted the working parameters. Finally, the key parameters were tested, and the results showed that the design requirements were met at a vibration frequency of 5.5 Hz, a hydrometric cleaning sieve inclination of 15°, a reciprocating long mesh cleaning sieve inclination of 5°, and a fan speed of 1500 rev/min; the mean loss is 2.26%, and the mean impurity is 3.18%. The findings can be used to provide technical support and reference for the development of peanut pod cleaning devices.

Design and Test of Stripping and Impurity Removal Device for Spring-Tooth Residual Plastic Film Collector

The residual agricultural plastic film in China is not easily recovered due to the thinness and poor mechanical properties of domestic films, and a large amount of plastic film remaining in farmland soil poses a great threat to soil quality and crop production. A spring-tooth residual plastic film collector (SRPFC) is widely used in domestic residual plastic film (RPF) recycling operations. However, there are two major problems in the current SRPFC: the low recovery rate of the residual film (RRRF) caused by the difficulty of film-stripping and the high impurity rate in the film (IRF). In this paper, a stripping and impurity removal device (SIRD) is designed to address the existing problems of SRPFC, which is mainly composed of film-stripping tooth plates (FTP), two wind-collecting hoods, and two centrifugal fans. The motion and force analysis of the RPF in the film-stripping process was carried out, and the arc FTP was determined to be used for film-stripping. The size parameters of the FTP were obtained by establishing the coordinate system to solve the differential equation. By comparing and analyzing the force of RPF in the airflow field of the test bench for suspension speed and the airflow field of the wind-collecting hood, the RPF equivalent particle was established. The discrete phase model (DPM) in Fluent software was used to simulate the movement of the RPF equivalent particle, and the calculated air volume range of the centrifugal fan was 5501.88~6829.92 m3/h. The effects of forward speed, rotating speed of film conveying chain harrow (FCCH), and rotating speed of the centrifugal fan on RRRF and IRF were studied by orthogonal rotary combination experiment. The test results showed that the best combination of machine operation parameters was when the forward speed was 5 km/h, the rotating speed of the FCCH was 235 r/min, and the rotating speed of the centrifugal fan was 1978 r/min. Under these conditions, the RRRF was 92.53%, and the IRF was 9.31%. Field experiments were carried out with the rounded parameters, and the average RRRF was 92.07%, and the average IRF was 9.56% under the parameter combination, indicating that the optimization scheme of the device was feasible.

Numerical and Theoretical Investigation of the Gap Flow in Centrifugal Fans for Design and Off-Design Conditions

Abstract Industrial turbomachines, such as fans and blowers for drying, venting, cooling or conveying tasks, are often used in industrial applications and frequently are large energy consumers. Thus, there is a need for further optimization and efficiency increase. For fans and blowers, gaps between moving parts are unavoidable due to manufacturing tolerances and possible thermal expansion. In this work, the radial gap and axial overlap between the inlet nozzle and the impeller and its impact on the performance characteristics have been investigated, because detailed knowledge of the losses due to the gap is important for the design of more efficient fans. The presented analysis was performed with the Navier–Stokes-solver ansyscfx. After a detailed grid study, the quantitative effect of the gaps on the performance of the centrifugal fan has been investigated by a variation of the radial gap and axial overlap. It was found, that at the best efficiency point (BEP) the efficiency drops between 1 and 6% depending on the gap width and at partial load it might drop fast also depending on the gap width, up to 50–60%. At overload the drop in efficiency is smaller than at partial load, dropping between 1 and 10%, depending on the gap width and the flowrate. In addition, a metamodel based on a dimensional and regression analysis was developed for partial and overload to predict the gap flowrate without additional computational fluid dynamics (CFD) simulations. The prediction accuracy between the CFD results and the dimensional analysis based metamodel is about 5–10%.

Inlet Gap Influence on Low-Frequency Flow Unsteadiness in a Centrifugal Fan

In this study, unsteady low-frequency characteristics in a voluteless low-speed centrifugal fan operating at a high mass flow rate are studied with improved delayed detached eddy simulation (IDDES). This study is motivated by a recent finding that the non-uniformly distributed pressure inside this type of fan could be alleviated by improving the gap geometry. The present simulation results show that the velocity magnitudes of the gap have distinct low and high regions. Intensive turbulent structures are developed in the low-velocity regions and are swept downstream along the intersection between the blade and shroud, on the pressure side of the blade. Eventually, the turbulence gives rise to a high-pressure region near the blade’s trailing edge. This unsteady flow behavior revolves around the fan rotation axis. Additionally, its period is 5% of the fan rotation speed, based on the analysis of the time history of the gap velocity magnitudes and the evolution of the high-pressure region. The same frequency of high pressure was also found in previous experimental measurements. To the authors’ knowledge, this is the first time that the trigger of the gap turbulence, i.e., the unsteady local low velocity, has been determined.

Coherent Flow Structures Near Tongue Region in a Centrifugal Fan With Forward-Curved Blades

Abstract The unsteady characteristics of the velocity field around the tongue of the volute in a centrifugal fan with forward-curved blades were investigated by time-resolved particle image velocimetry and mode decomposition analysis, i.e., proper orthogonal decomposition (POD) and spectral proper orthogonal decomposition (SPOD). Both POD and SPOD analysis reveal the existence of two types of unsteadiness in the flow field in the volute, one is the large-scale fluctuations at rotation frequency and its high-order harmonics in the main outlet flow, the other is due to the jet–wake structures at blade passing frequency in the cutoff clearance region. Additionally, SPOD analysis reveals a third type of disturbance, which is characterized as strip-like velocity structures at the intermediate frequency. The geometric and dynamic features of these coherent flow structures are inspected by the eigenfunction and their reduced-order reconstruction. In comparison with the POD analysis, the SPOD analysis enables the examination of the spatial pattern of each frequency component due to its dual-orthogonality nature. These structures direct impact the tongue, and thus might be responsible for the generation of strong wall-pressure fluctuation on the nose of the tongue. Due to the frequency mixing limitation of POD analysis, they cannot be easily identified from the leading-order POD modes. Furthermore, the frequency range of these three groups of disturbances, as well as their spatial extension, are determined via SPOD analysis and reduced-order reconstruction.

Investigations concerning the Flow Stabilization of Backward Curved Centrifugal Impellers at Low Flow Rate

For a backward curved centrifugal fan, reducing volume flow rate from design operating point towards part load yields an increase in noise emission together with a reduction of efficiency. The spectral content of the emerging noise emission can be characterized by a subharmonic hump with several harmonics. Based on narrow-band acoustic measurements and numerical Lattice-Boltzmann simulations, a deeper insight is sought after. Downstream unsteady flow patterns are identified to play a central role in this performance deterioration; and geometrical flow stabilization means are investigated.

Effect of motor intrusion on the aerodynamic performances and unsteady characteristics of internal flow of a volute-free centrifugal fan

The volute-free centrifugal fans are widely used in air conditioning and ventilation applications due to their simple configuration and easy maintenance. The motor normally intrudes towards the fan interior from the rear disc to reduce the size and achieve better compatibility. The size and geometry of the motor affects the local flow field, which may have a serious impact on the aerodynamic performances of the fan. In this paper, we numerically investigated the effect of motor intrusion on the performances and internal flow characteristics of the volute-free centrifugal fan at different flow rates. The numerical results reveal that the internal flow field varies with the increasing of motor height at all flow rates. Under large flow rate, the height of motor has more obvious influence on the static pressure and static pressure efficiency of the fan; as the height of motor increases from 0 to 4 H/8, the two values decrease by 82.8% and 49.7%, respectively. The flow is more unstable which are manifested by the intensified velocity and pressure fluctuations. Therefore, the blocking effect of motor cannot be ignored and must be taken into account for the design the volute-free centrifugal fans.

Volute Optimization Based on Self-Adaption Kriging Surrogate Model

Optimizing the volute performance can effectively improve the efficiency of a centrifugal fan by changing the volute geometric parameter, so the self-adaption Kriging surrogate model is used to optimize the volute geometric parameter. Firstly, volute radius Rd, the radius of tongue r, and outlet angle of the volute θ are selected as the optimization parameters of the volute, and latin hypercube sampling is used to configure the initial sample points, the corresponding three-dimensional aerodynamic model under each sample point configuration is constructed. CFD software is used to simulate the aerodynamic efficiency and total pressure of the centrifugal fan under each initial sample point configuration. Secondly, the Kriging surrogate model of initial sample point configuration parameters, aerodynamic efficiency, and total pressure of volute is constructed, and sample points are added by expectation improvement (EI) method to improve the fitting accuracy of Kriging surrogate model. Finally, the high-precision Kriging surrogate model is used as the fitness function of NSGA-II algorithm to find the Pareto optimal solution under multiobjective optimization, and the optimization target are aero dynamical efficiency and total pressure. The rationality of the above method is verified by optimizing the 9–19.4A type centrifugal fan volute. The efficiency of the optimized fan under working conditions is increased by 1%, and the total pressure under working conditions is not reduced. The optimized volute can effectively improve the overall performance of the centrifugal fan. This study is helpful to promote the application of numerical optimization design method in the volute of centrifugal fan. It provides reference for the optimization design of high-performance centrifugal fan.

Research on a New Type of Self-adaptive and High-efficiency Umbrella Dryer

The new adaptive and high-efficiency umbrella dryer dries the wet umbrella during the rotation and translation process through the upper and lower conveyor belts. The detection module collects parameters such as the diameter of the umbrella surface structure, and by controlling the wind pressure, wind temperature, and tracking the transmission position of the umbrella surface through the adaptive blowing port, the umbrella surface can be dried efficiently. The air outlet of the umbrella dryer faces the road surface of the shopping mall to ensure the drying of the road surface and realize the "one wind and two uses" of the centrifugal fan. The whole device has high air-drying efficiency and short waiting time for customers. the umbrella air-drying device runs through the transition space between the inner and outer doors of large shopping malls and supermarkets. When consumers enter, they place the umbrella on the conveyor belt of the device, and then they can directly walk into the inner door of the mall to take out the dried umbrella. The whole set of devices is efficient and intelligent, ensuring that consumers do not need to stay and waiting in the case of high traffic in shopping malls, improving consumers' shopping comfort, greatly reducing the use of umbrella bags, and preventing white pollution.

Study of the Effect of Throttling on the Success of Starting a Line-Start Permanent Magnet Motor Driving a Centrifugal Fan

Direct-on-line synchronous motors are a good alternative to induction motors in fluid machinery drives due to their greater energy efficiency but have the significant disadvantage of limiting the maximum moment of inertia of the loading mechanism to ensure their successful and reliable start-up. This disadvantage is critical in centrifugal fans with a massive steel impeller. In this article, using a mathematical model, the dynamics of starting and synchronizing a permanent magnet synchronous motor fed directly from the mains as part of a fan drive are studied. The simulation results show the possibility of increasing the maximum moment of inertia of the load at the successful start-up of a direct-on-line synchronous motor by adjusting the hydraulic part of the fan pipeline by means of throttling. The conclusions of this paper can be used when selecting an electric motor to drive industrial fans and can contribute to wider use of energy-efficient synchronous motors with direct start-up from the mains.

Inlet Gap Effect on Tonal Noise Generated from a Voluteless Centrifugal Fan

In this study, three voluteless centrifugal fans are compared for their aeroacoustic performances. The tonal noise is predicted by coupling the IDDES with Formulation 1A of Farassat. The sources of the tonal noise at the blade passing frequency (BPF) are identified. It is found that the sources are related to the fan inlet gap, which introduces higher velocity intensities and turbulent fluctuations interacting with the blade leading edge. By redesigning the gap, the tonal noise at the BPF is reduced effectively.

Evaluation of the Wear-Resistant Plate Performance on Different Locations over the Flow Path of a Large-Sized Heavy-Duty Centrifugal Fan

In industrial applications such as chemical plants, cement factories, and glassmakers, large-sized centrifugal fans are commonly used for dust-laden flow processing. In many cases, the contamination is due to solid particles responsible for fouling and erosion issues. Erosion induces the reduction of mechanical resistance and, at the same time, the modification of the geometry and the surface characteristics of the internal flow path. The process works according to the characteristics of the erodent particles, such as dimension and hardness, which have to be coupled with the mechanical properties of the substrate, like hardness and roughness level. In addition to this, the intensity of the erosion depends on the dynamic characteristics of particles, especially velocity and impact angle. For these reasons, erosion-related issues are difficult predict and reduce. In an attempt to preserve the structural integrity of the internal walls, wear-resistant plates are positioned where the impacting contaminants are supposed to be more detrimental. In the present work, a combined experimental and numerical approach is proposed to evaluate the proper setup of wear-resistance plates over the flow path of a large-sized centrifugal fan. The results show how different regions (rotating and stationary walls) are subjected to different impact behavior, determining that the design of the position of the wear-resistant plate is not straightforward. Suggestions related to reducing the erosion intensity are reported, highlighting the possibility of designing the best compromise between erosion, performance, and costs.