OPTIMIZATION TO INCREASE ENERGY EFFICIENCY OF A SIROCCO CENTRIFUGAL FAN USING COMPUTATIONAL FLUID DYNAMICS (CFD)

This paper presents a numerical and experimental study on the aerodynamic performance of Sirocco centrifugal fans seeking an increase in energy efficiency. Numerical simulations are performed by the Finite-Volume Method commercial code ANSYS Fluent. Characteristics such as flow rate at the outlet, consumed power and sound pressure levels emitted by centrifugal fans with the original model of 16 blades and the optimized models of 16 and 14 blades are compared. Numerical calculations are performed by the continuity equation, the Reynolds Averaged Navier- Stokes (RANS) equations and the k-ω SST turbulence model. The quality of the mesh is evaluated for three different mesh densities. Results demonstrate that it was possible to obtain an increase of flow rate up to 22.7%, and reductions in the noise levels without increasing the consumption of the electric motor

Experimental design of a low noise centrifugal fan

The effect of various design parameters on broadband noise generation by centrifugal fans has been studied. The parameters varied included: blade type, radial and axial inlet clearance, scroll development angle, scroll development length and cutoff clearance. Scaling laws for pressure, flow and noise were applied to allow the A-weighted sound power levels of different fans to be compared at the same operating points. That approach has allowed an optimum low noise fan design to be identified. To extend the usefulness of that design, a semi-empirical procedure for predicting the broadband sound power spectrum of any member of a family of geometrically similar centrifugal fans has also been developed. The prediction procedure allows the calculation of 1/3-octave band sound power levels based on a measurement of the sound power radiated by a single member of the fan family. By the use of the prediction procedure, it is straightforward to identify optimally quiet fans that satisfy a range of pumping requirements

Analysis and Development of Fan Noise Prediction Methodology

A widespread industrial application of centrifugal fans has been found in literature. The centrifugal fans have been widely adopted by domestic, industrial applications and electronic industries due to their large capacity of mass flow and their compactness. It has pointed out that many machines having a moderate efficiency and low aero-acoustic performances are still in operation and could certainly be improved by making use of todays technology

Real-time stall detection of centrifugal fan based on the analysis of symmetrized dot pattern and wavelet packet transform

This paper presents a novel stall detection method based on symmetrized dot pattern (SDP) analysis, which detects the starting point of rotating stall timely and accurately during operations of centrifugal fans. To demonstrate the proposed method, experiments were first performed on a G4-73 No. 8D centrifugal fan to measure the aerodynamic pressure signals of the air flow inside the fan during the gradual development of rotating stall. Then, the SDP technique was used to analyze the pressure signals and extract the time-domain characteristics of the pressure signal during the gradual development of rotation stall. Finally, a comprehensive autocorrelation coefficient was defined and employed as the index for real-time stall detection. In addition, to verify the accuracy of detection results, the tested signals were also analyzed off-line by wavelet transform to detect the actual starting point of rotating stall. The comparison results show that the stall detection method based on the symmetrized dot pattern (SDP) analysis can accurately detect the starting point of rotating stall in centrifugal fans within a short period of 0.05 s

Термическая конвективная печь для обработки лифтовых труб с реверсивным движением теплоносителя

Разработана схема конвективной циркуляционной печи с полным циклом теплообмена (нагрев, выдержка и охлаждение) для термообработки удлиненных изделий, работающей в режиме периодического изменения направления движения теплоносителя на противоположное (реверсивное движение теплоносителя). Для интенсификации процесса охлаждения изделий за счет эффективного подвода и удаления охладителя из рабочего пространства таких печей применяются реверсивные устройства в составе двух центробежных вентиляторов, один из которых работает в режиме аэродинамического запирания охладителя. Представлены экспериментальные регулировочные характеристики реверсивных устройств, собранных на базе различных типов центробежных вентиляторов. Полученные данные могут быть использованы при разработке конвективных циркуляционных печей с полным циклом теплообмена.The scheme of the convective circulation furnace with a full cycle of heat exchange for heat treatment of elongated shape products, operating in the mode of periodic change the direction of flow to the opposite. To intensify the process of cooling products through effective supply and remove the coolant from the working area such furnaces used reversing flow devices, consisting of two centrifugal fans, one of which operates on a aerodynamic locking device. Shows the experimental control characteristics reversing flow devices assembled on the basis of various types of centrifugal fans. The data obtained can be used in the development of convection furnaces circulating of heat exchange with the full cycle

Typical uses of NASTRAN in a petrochemical industry

NASTRAN was principally used to perform failure analysis and redesign process equipment. It was also employed in the evaluation of vendor designs and proposed design modifications to existing process equipment. Stress analysis of forced draft fans, distillation trays, metal stacks, jacketed pipes, heat exchangers, large centrifugal fans, and agitator support structures are described

A Comparison of Propeller and Centrifugal Fans for Circulating the Air in a Wind Tunnel

The tests described in this paper afford a direct comparison of the efficiency and smoothness of flow obtained with propeller fan and multiblade centrifugal fan drives in the same wind tunnel. The propeller fan was found to be superior to the centrifugal fan in that the efficiency was about twice as great, and the flow much smoother

Tonal Noise of Voluteless Centrifugal Fan Generated by Turbulence Stemming from Upstream Inlet Gap

Volutes for radial-flow turbomachines (e.g., centrifugal fans and pumps) are spiral funnel-shaped casings that house rotors. Their function is to guide the flow from rotors to outlets and maintain constant flow speeds. Under specific conditions, however, volutes are removed (termed voluteless) to reduce flow losses and noise. In this paper, a generic voluteless centrifugal fan is investigated for the tonal noise generation at an off-design operation point. In contrast to typical tonal noise sources induced by the fan blades, we find out that another predominant source is the turbulence stemming from the clearance gap between the fan front shroud and the inlet duct. The turbulence evolves along with the front shroud and is swept downstream to interact with the top side of the blade leading edge. An obvious additional tone is observed at\ua0273 Hz other than the blade passing frequency (BPF0) and relevant harmonic frequencies. By coarsening the mesh resolution near the inlet gap and front shroud in the simulations, we artificially deactivate the gap turbulence. Consequently, the tone at\ua0273 Hz disappears completely. The finding indicates that the interaction between the gap turbulence and blades accounts for the tone. As the gap turbulence exists near the front shroud, this rotating wall introduces rotational momentum into the turbulence due to skin friction. Hence, this tonal interaction frequency is smaller than\ua0BPF0 with a decrement of the fan rotation frequency. To the authors\u27 knowledge, this is the first time that voluteless centrifugal fans are studied for the gap-turbulence noise generation