Flow Survey of a Forward Curved Blades Centrifugal Fan for HVAC Applications

2016 ◽  
Author(s):  
Fabio Breviario ◽  
Dario Brivio ◽  
Lucio Cardillo ◽  
Alessandro Corsini ◽  
Giovanni Delibra
Keyword(s):  
Total Pressure ◽  
Acoustic Emissions ◽  
Pressure Rise ◽  
Leading Edge ◽  
Cost Effective ◽  
Centrifugal Fan ◽  
Centrifugal Fans ◽  
Flow Features ◽  
Curved Blade ◽  
New Generation

The advancements in fan technology are nowadays animated by two major drivers: the legal requirements that impose minimum fan efficiency grades for fans sold within European Union (and soon US and Asia), and the market request for better air performance and lower sound emissions. Within HVAC (Heating, Ventilating and Air Conditioning) applications, centrifugal fans with forward curved blades are widely used due to the higher total pressure rise capability and lower acoustic emissions with respect to more efficient backward curved blades. However the continuous rise of minimum fan efficiency grades pushes the manufacturers to develop a new generation of forward curved centrifugal fans, improving previous design. Here the challenge is not only on aerodynamics, but in the overall production process, as squirrel cage fans are characterised by a cost-effective consolidated technology, based on simple blade geometries and easy series manufacturing. For example, the blades usually have circular camber lines, as results of cut cylinders. Thus, once the number of blades and the angle at the leading edge are selected, the chord and the deflection capability are constrained as well. These concurring aspects led industry to include in the design process new tools, in particular CFD, to analyse the flow features of the current generation of fans in order to understand which phenomena are to be either controlled or exploited to increase efficiency and total pressure rise. Here we present a numerical investigation on a forward curved blade centrifugal fan for HVAC applications, to highlight the flow features inside the impeller and in the critical region of coupling with the volute. The analysis was carried out with OpenFOAM, an open-source library for CFD. Computations were performed with the frozen rotor approach and validated against available experimental data.

Numerical investigations on the effect of volute casing treatment for performance augmentation in a centrifugal fan

2021 ◽  
pp. 095440622110341
Author(s):  
Manjunath L Nilugal ◽  
K Vasudeva Karanth ◽  
Madhwesh N
Keyword(s):  
Total Pressure ◽  
Static Pressure ◽  
Numerical Study ◽  
Pressure Coefficient ◽  
Three Dimensional ◽  
Pressure Rise ◽  
Centrifugal Fan ◽  
Casing Treatment ◽  
Sliding Mesh ◽  
Optimum Configuration

This article presents the effect of volute chamfering on the performance of a forward swept centrifugal fan. The numerical analysis is performed to obtain the performance parameters such as static pressure rise coefficient and total pressure coefficient for various flow coefficients. The chamfer ratio for the volute is optimized parametrically by providing a chamfer on either side of the volute. The influence of the chamfer ratio on the three dimensional flow domain was investigated numerically. The simulation is carried out using Re-Normalisation Group (RNG) k-[Formula: see text] turbulence model. The transient simulation of the fan system is done using standard sliding mesh method available in Fluent. It is found from the analysis that, configuration with chamfer ratio of 4.4 is found be the optimum configuration in terms of better performance characteristics. On an average, this optimum configuration provides improvement of about 6.3% in static pressure rise coefficient when compared to the base model. This optimized chamfer configuration also gives a higher total pressure coefficient of about 3% validating the augmentation in static pressure rise coefficient with respect to the base model. Hence, this numerical study establishes the effectiveness of optimally providing volute chamfer on the overall performance improvement of forward bladed centrifugal fan.

Experimental Study of Flow Inside a Centrifugal Fan Using Magnetic Resonance Velocimetry

2019 ◽  
Author(s):  
Davis W. Hoffman ◽  
Laura Villafañe ◽  
Christopher J. Elkins ◽  
John K. Eaton
Keyword(s):  
Three Dimensional ◽  
Leading Edge ◽  
Suction Side ◽  
Reynolds Numbers ◽  
Centrifugal Fan ◽  
Mean Flow ◽  
Magnetic Resonance Velocimetry ◽  
Flow Features ◽  
Outlet Flow ◽  
The Mean

Abstract Three-dimensional, three-component time-averaged velocity fields have been measured within a low-speed centrifugal fan with forward curved blades. The model investigated is representative of fans commonly used in automotive HVAC applications. The flow was analyzed at two Reynolds numbers for the same ratio of blade rotational speed to outlet flow velocity. The flow patterns inside the volute were found to have weak sensitivity to Reynolds number. A pair of counter-rotating vortices evolve circumferentially within the volute with positive and negative helicity in the upper and lower regions, respectively. Measurements have been further extended to capture phase-resolved flow features by synchronizing the data acquisition with the blade passing frequency. The mean flow field through each blade passage is presented including the jet-wake structure extending from the blade and the separation zone on the suction side of the blade leading edge.

Forward Sweep in a Four-Stage High-Speed Axial Compressor

2006 ◽  
Author(s):  
Michael Braun ◽  
Joerg R. Seume
Keyword(s):  
Total Pressure ◽  
High Speed ◽  
Axial Compressor ◽  
Pressure Rise ◽  
Leading Edge ◽  
Third Stage ◽  
Mach Number Distribution ◽  
Design Speed ◽  
End Wall ◽  
Operating Points

The present paper provides a comparison of a CDA-bladed four-stage high-speed axial compressor and a configuration in which the first three rows are replaced with forward swept blades and vanes. The blades are designed with sweep from mid-span to tip, the vanes from mid-span to the hub. The non-swept portion of the leading edge is kept radial and identical to the CDA blading. The overall performance of the compressor with both configurations is measured at five engine speeds. The flow fields of each rotor and stator at two operating points (“Design Point” and “Near Stall”) of both configurations are investigated at the design speed. On the suction and the pressure side of the third stage vane, static surface pressures are measured to determine the local Mach number distribution and to identify zones of separation. Multistage CFD-computations are carried out for both configurations. The numerical and experimental results of both configurations are compared and show the effect of sweep on the operating map of the compressor from choke to stall: Sweep reduces corner stall and the end-wall losses at high aerodynamic loads. It is shown that the reduction of separation due to sweep leads to an increase of total pressure rise towards lower mass flow so that the present swept compressor achieves higher total pressure ratios at and near the stall limit. An analysis along streamlines suggests that the performance of the compressor could have been improved further by a more uniform total pressure distribution in the front stages and a better match of the sweep in stages 2 and 3.

scholarly journals Investigation of Unsteady Flow Phenomena in a Counterrotating Ducted Propfan

1998 ◽  
Author(s):  
L. Wallscheid ◽  
F. Eulitz ◽  
R. Heinecke
Keyword(s):  
Unsteady Flow ◽  
Total Pressure ◽  
Pressure Rise ◽  
Leading Edge ◽  
Pressure Waves ◽  
Pressure Measurements ◽  
Numerical Investigations ◽  
Downstream Effects ◽  
Flow Phenomena ◽  
Unsteady Simulation

Experimental and numerical investigations on a counterrotating propfan (CRISP) have been carried out to study unsteady flow phenomena generated by the interaction of the two rotors. This paper focuses mainly on the downstream effects of rotor 1 on rotor 2. Therefore unsteady Laser-2-Focus, unsteady total pressure measurements and an unsteady simulation have been carried out. The total pressure measurements behind the rotors show variations of the absolute total pressure outside the wake regions up to 30 percent of the average total pressure rise. Some of these are caused by the interaction of the rotor 1-generated wakes with the leading edge of rotor 2. The others may result from the pressure waves generated by the reflection of the rotor 2-shockwaves by the blades of rotor 1.

Aerodynamic Performance Prediction of Centrifugal Fan With Forward Curved Blades

2012 ◽  
Author(s):  
Jiří Polanský ◽  
Roman Gášpár
Keyword(s):  
Numerical Study ◽  
Pressure Coefficient ◽  
Aerodynamic Characteristics ◽  
Centrifugal Fan ◽  
Centrifugal Stage ◽  
Squirrel Cage ◽  
Centrifugal Fans ◽  
Curved Blade ◽  
3D Unsteady Flow ◽  
Spiral Casing

The paper deals with a numerical study of complex 3D unsteady flow in the impeller and spiral casing of the forward curved blade of the centrifugal stage. Aerodynamic characteristics of eight different geometrical configurations of the impeller for squirrel cage and high pressure centrifugal fans are investigated. The CFD codes ANSYS 13 and OpenFoam are applied. In this study impact of the blade geometry to compressor characteristic is investigated and possibilities of efficiency, pressure coefficient and working range increasing of centrifugal fan are presented.

MODELING AND MULTI-OBJECTIVE OPTIMIZATION OF FORWARD-CURVED BLADE CENTRIFUGAL FANS USING CFD AND NEURAL NETWORKS

2011 ◽  
Vol 35 (1) ◽  
pp. 63-79 ◽  
Author(s):  
Abolfazl Khalkhali ◽  
Mehdi Farajpoor ◽  
Hamed Safikhani
Keyword(s):  
Neural Networks ◽  
Second Step ◽  
Group Method ◽  
Centrifugal Fan ◽  
Multi Objective Optimization ◽  
Multi Objective ◽  
Design Variables ◽  
Conflicting Objectives ◽  
Centrifugal Fans ◽  
Curved Blade

In the present study, multi-objective optimization of Forward-Curved (FC) blade centrifugal fans is performed in three steps. In the first step, Head rise (HR) and the Head loss (HL) in a set of FC centrifugal fan is numerically investigated using commercial software NUMECA. Two meta-models based on the evolved group method of data handling (GMDH) type neural networks are obtained, in the second step, for modeling of HR and HL with respect to geometrical design variables. Finally, using the obtained polynomial neural networks, multi-objective genetic algorithms are used for Pareto based optimization of FC centrifugal fans considering two conflicting objectives, HR and HL.

Measurements of the Mean Flow Velocity and Velocity Fluctuations at the Exit of an FC Centrifugal Fan Rotor

1981 ◽  
Vol 103 (2) ◽  
pp. 393-399 ◽  
Author(s):  
D. Raj ◽  
W. B. Swim
Keyword(s):  
Three Dimensional ◽  
Leading Edge ◽  
Flow Region ◽  
Centrifugal Fan ◽  
Mean Flow ◽  
Suction Surface ◽  
Inlet Flow ◽  
Design Changes ◽  
Centrifugal Fans ◽  
Visualization Techniques

The flow from a small forward curved fan rotor was studied to provide guidance for fan design. The single width fan had a 0.23 m rotor containing 48 blades. It is typical of the centrifugal fans used in small air-conditioning units. Visualization techniques and hot wire measurements showed the rotor flow to be highly turbulent and strongly three-dimensional. The inlet flow was found to fill only 3/4 of the blade span. The shroud end of the rotor was an inactive or separated region. A jet-wake pattern occurred at the blade exit in the active flow region. The inlet flow separated at the leading edge of the blade suction surface. Design changes are offered to improve the performance of FC fans.

Noise reduction mechanisms for the inclined leading edge vaned diffuser in a centrifugal fan

2017 ◽  
Vol 231 (1) ◽  
pp. 68-83 ◽  
Author(s):  
Gong Wu Qi ◽  
Zhang Wei
Keyword(s):  
Noise Reduction ◽  
Pressure Fluctuation ◽  
Numerical Study ◽  
Second Harmonic ◽  
Leading Edge ◽  
Centrifugal Fan ◽  
Fan Noise ◽  
Vaned Diffuser ◽  
Reduction Mechanisms ◽  
Centrifugal Fans

An experimental and numerical study to explore the noise reduction mechanism for the inclined leading edge vaned diffuser in centrifugal fans is described. Inclined leading edge vaned diffuser is useful in improving fan performance, increasing operating range, and reducing fan noise. The generation of fan noise is related to the pressure fluctuation on the diffuser vane surface, particularly the leading edge. Numerical results show that pressure fluctuation on the inclined leading edge vaned diffuser surface remarkably decreases, unlike that of the original diffuser. The pressure fluctuation is dominated by the components at the blade passing frequency and its second harmonic.

Experimental Study of Flow Inside a Centrifugal Fan Using Magnetic Resonance Velocimetry

2020 ◽  
Vol 142 (4) ◽  
Author(s):  
Davis W. Hoffman ◽  
Laura Villafañe ◽  
Christopher J. Elkins ◽  
John K. Eaton
Keyword(s):  
Three Dimensional ◽  
Leading Edge ◽  
Suction Side ◽  
Reynolds Numbers ◽  
Centrifugal Fan ◽  
Mean Flow ◽  
Magnetic Resonance Velocimetry ◽  
Flow Features ◽  
Outlet Flow ◽  
The Mean

Abstract Three-dimensional (3D), three-component time-averaged velocity fields have been measured within a low-speed centrifugal fan with forward curved (FC) blades. The model investigated is representative of fans commonly used in automotive applications. The flow was analyzed at two Reynolds numbers for the same ratio of blade rotational speed to outlet flow velocity. The flow patterns inside the volute were found to have weak sensitivity to Reynolds number. A pair of counter-rotating vortices evolves circumferentially within the volute with positive and negative helicity in the upper and lower regions, respectively. Measurements have been further extended to capture phase-resolved flow features by synchronizing the data acquisition with the blade passing frequency. The mean flow field through each blade passage is presented including the jet-wake structure extending from the blade and the separation zone on the suction side of the blade leading edge.

Improvement of Centrifugal Fan on Noise With Inducer

2003 ◽  
Author(s):  
Hidechito Hayashi ◽  
Yoshio Kodama ◽  
Kazuo Ogino
Keyword(s):  
Boundary Layer ◽  
Flow Rate ◽  
Total Pressure ◽  
Radial Direction ◽  
Pressure Rise ◽  
Leakage Flow ◽  
Centrifugal Fan ◽  
Noise Performance ◽  
Noise Characteristics ◽  
Inlet Angle

We improved the centrifugal fan for the noise and fluid performance. The fan has the inducer that is unified to the main blade. The geometry of the inducer was obtained with the tuft method and is unique. The fluid turns from axis- to radial-direction in the inducer. The inlet angle and the chord length of the inducer vary in span position. The aerodynamic and noise characteristics of the impeller with inducer have been compared to one without inducer. The total pressure and the efficiency of the impeller with inducer are increased about 20% and 5% in all flow rate. Because the pressure rise occurs in the inducer. And the pressure loss at the inlet of the blade becomes very small. The influence of the leakage flow between the shroud and the bellmouth is restricted near the front shroud, and then the separation of the boundary layer is controlled. The wake width of the main blade becomes fairly small. The specific noise level, which presents the noise performance of the fan, can be reduced about 2–4dB in wide flow rate.

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