The Design of a Large Diameter Axial Flow Fan for Air-Cooled Heat Exchanger Applications

2017 ◽  
Author(s):  
Michael B. Wilkinson ◽  
Johan van der Spuy ◽  
Theodor W. von Backström
Keyword(s):  
Flow Field ◽  
Large Diameter ◽  
Axial Flow ◽  
Pressure Rise ◽  
Design Procedure ◽  
Axial Flow Fan ◽  
Disk Model ◽  
Actuator Disk ◽  
Static Efficiency ◽  
Air Cooled Heat Exchanger

An axial flow fan design methodology is developed to design large diameter, low pressure rise, rotor-only fans for large air-cooled heat exchangers. The procedure aims to design highly efficient axial flow fans that perform well when subjected to off design conditions commonly encountered in air-cooled heat exchangers. The procedure makes use of several optimisation steps in order to achieve this. These steps include optimising the hub-tip ratio, vortex distribution, blading and aerofoil camber distributions in order to attain maximum total-to-static efficiency at the design point. In order to validate the design procedure a 24 ft, 8 bladed axial flow fan is designed to the specifications required for an air-cooled heat exchanger for a concentrated solar power (CSP) plant. The designed fan is numerically evaluated using both a modified version of the actuator disk model and a three dimensional periodic fan blade model. The results of these CFD simulations are used to evaluate the design procedure by comparing the fan performance characteristic data to the design specification and values calculated by the design code. The flow field directly down stream of the fan is also analysed in order to evaluate how closely the numerically predicted flow field matches the designed flow field, as well as determine whether the assumptions made in the design procedure are reasonable. The fan is found to meet the required pressure rise, however the fan total-to-static efficiency is found to be lower than estimated during the design process. The actuator disk model is found to under estimate the power consumption of the fan, however the actuator disk model does provide a reasonable estimate of the exit flow conditions as well as the total-to-static pressure characteristic of the fan.

Performance Testing of an Axial Flow Fan Designed for Air-Cooled Heat Exchanger Applications

2018 ◽  
Vol 141 (5) ◽  
Author(s):  
Michael B. Wilkinson ◽  
Sybrand J. van der Spuy ◽  
Theodor W. von Backström
Keyword(s):  
Experimental Data ◽  
Static Pressure ◽  
Axial Flow ◽  
Pressure Rise ◽  
Test Facility ◽  
Cfd Model ◽  
Blade Angle ◽  
Axial Flow Fan ◽  
Fan Performance ◽  
Static Efficiency

An axial flow fan developed in the previous study is tested in order to characterize its performance. The M-fan, a 7.3152 m diameter rotor only axial flow fan was designed to perform well under the challenging operating conditions encountered in air-cooled heat exchangers. Preliminary computational fluid dynamics (CFD) results obtained using an actuator disk model (ADM) as well as a periodic three dimensional model indicate that the fan meets the specified performance targets, with an expected total-to-static efficiency of 59.4% and a total-to-static pressure rise of 114.7 Pa at the operating point. Experimental tests are performed on the M-fan in order to determine its performance across a full range of flow rates. A range of fan configurations are tested in order to ascertain the effect of tip clearance, blade angle, and hub configuration on fan performance. Due to the lack of a suitable facility for testing a large diameter fan, a scaled 1.542 m diameter model is tested on the ISO 5801 type A fan test facility at Stellenbosch University. A Reynolds-averaged Navier–Stokes CFD model representing the M-fan in the test facility is also developed in order to provide additional insight into the flow field in the vicinity of the fan blades. The results of the CFD model will be validated using the experimental data obtained. Both the CFD results and the experimental data obtained are compared to the initial CFD results for the full scale fan, as obtained in the previous study, by means of fan scaling laws. Experimental data indicate that the M-fan does not meet the pressure requirement set out in the initial study at the design blade setting angle of 34 deg. Under these conditions, the M-fan attains a total-to-static pressure rise of 102.5 Pa and a total-to-static efficiency of 56.4%, running with a tip gap of 2 mm. Increasing the blade angle is shown to be a potential remedy, improving the total-to-static pressure rise and efficiency obtained at the operating point. The M-fan is also shown to be highly sensitive to increasing tip gap, with larger tip gaps substantially reducing fan performance. The losses due to tip gap are also shown to be overestimated by the CFD simulations. Both experimental and numerically obtained results indicate lower fan total-to-static efficiencies than obtained in the initial CFD study. Results indicate that the M-fan is suited to its intended application, however, it should be operated with a smaller tip gap than initially recommended and a larger blade setting angle. Hub configuration is also shown to have an influence on fan performance, potentially improving performance at low flow rates.

Performance Testing of an Axial Flow Fan Designed for Air-Cooled Heat Exchanger Applications

2018 ◽  
Author(s):  
Michael B. Wilkinson ◽  
Johan van der Spuy ◽  
Theodor W. von Backström
Keyword(s):  
Experimental Data ◽  
Static Pressure ◽  
Axial Flow ◽  
Pressure Rise ◽  
Test Facility ◽  
Cfd Model ◽  
Blade Angle ◽  
Axial Flow Fan ◽  
Fan Performance ◽  
Static Efficiency

An axial flow fan developed in previous study is tested in order to characterise its performance. The M-fan, a 7.3152 m diameter rotor only axial flow fan was designed to perform well under the challenging operating conditions encountered in air-cooled heat exchangers. Preliminary CFD results obtained using an actuator disk model as well as a periodic three dimensional model indicate that the fan meets the specified performance targets, with an expected total-to-static efficiency of 59.4 % and a total-to-static pressure rise of 114.7 Pa at the operating point. Experimental tests are performed on the M-fan in order to determine its performance across a full range of flow rates. A range of fan configurations are tested in order to ascertain the effect of tip clearance, blade angle and hub configuration on fan performance. Due to the lack of a suitable facility for testing a large diameter fan, a scaled 1.542 m diameter model is tested on the BS 848 (ISO 5801) type A fan test facility at Stellenbosch University. A RANS CFD model representing the M-fan in the test facility is also developed in order to provide additional insight into the flow field in the vicinity of the fan blades. The results of the CFD model will be validated using the experimental data obtained. Both the CFD results and the experimental data obtained are compared to the initial CFD results for the full scale fan, as obtained in the previous study, by means of fan scaling laws. Experimental data indicates that the M-fan does not meet the pressure requirement set out in the initial study, at the design blade setting angle of 34 degrees. Under these conditions the M-fan attains a total-to-static pressure rise of 102.5 Pa and a total-to-static efficiency of 56.4%, running with a tip gap of 2 mm. Increasing the blade angle is shown to be a potential remedy, improving the total-to-static pressure rise and efficiency obtained at the operating point. The M-fan is also shown to be highly sensitive to increasing tip gap, with larger tip gaps substantially reducing fan performance. The losses due to tip gap are also shown to be overestimated by the CFD simulations. Both experimental and numerically obtained results indicate lower fan total-to-static efficiencies than obtained in the initial CFD study. Results indicate that the M-fan is suited to its intended application, however it should be operated with a smaller tip gap than initially recommended and a larger blade setting angle. Hub configuration is also shown to have an influence on fan performance, potentially improving performance at low flow rates.

Blade Surface Pressure Measurements on a Low Pressure Rise Axial Flow Fan

2020 ◽  
Author(s):  
Johannes Rohwer ◽  
Sybrand J. van der Spuy ◽  
Theodor W. von Backström ◽  
Francois G. Louw
Keyword(s):  
Flow Field ◽  
Flow Rate ◽  
Surface Pressure ◽  
Static Pressure ◽  
Axial Flow ◽  
Pressure Rise ◽  
Test Facility ◽  
Pressure Measurements ◽  
Blade Surface ◽  
Axial Flow Fan

Abstract Fan performance characteristic tests of axial flow fans provide information on the global flow field, based on stable inlet flow field distribution. More information is often required on the local flow distribution existing in the vicinity of the fan blades under installed conditions. A 1.542 m diameter scale model of an axial flow fan, termed the M-Fan is tested in an ISO 5801, type A, test facility. The M-fan was specifically designed for low-pressure, high flow rate application in air-cooled or hybrid condensers. The scaled version of the M-fan was designed to have a fan static pressure rise of 116.7 Pa at a flow rate of 14.2 m3/s. Two specially constructed M-Fan blades are manufactured to conduct blade surface pressure measurements on the blades. The fan blades are equipped with 2 mm diameter tubes that run down the length of the fan blades in order to convey the measured pressure. Piezo-resistive pressure transducers, located on the hub of the fan, measure the static pressure distribution on the blades and the data is transferred to a stationary computer using a wireless telemetry setup. The blade pressure measurement setup is re-commissioned from a previous research project and its performance is qualified by testing and comparing to experimental results obtained on the B2a-fan. Excellent correlation to previous results is obtained. The experimental M-fan results are compared against results from a periodic numerical CFD model of a fan blade modelled in an ISO 5801, Type A test facility configuration. The experimental tests and numerical model correlate well with each other. The experimental blade surface pressure measurements have a minimum Pearson correlation to the numerically determined values of 0.932 (maximum 0.971).

Design Aspects for Large Diameter, Low Speed Axial Flow Fan for Wind Tunnel Application

2017 ◽  
Author(s):  
Shubham Kesharwani ◽  
Chetan S. Mistry ◽  
Subhransu Roy ◽  
Arnab Roy ◽  
Kalyan P. Sinhamahapatra
Keyword(s):  
Wind Tunnel ◽  
Design Methodology ◽  
Computational Analysis ◽  
Large Diameter ◽  
Axial Flow ◽  
Pressure Rise ◽  
Axial Flow Fan ◽  
Low Speed ◽  
Line Analysis ◽  
Selection Of

A large diameter, low speed axial flow fan has been designed to drive the Centre for Railway Research (CRR) wind tunnel at IIT Kharagpur. Total pressure rise of 1400 Pa is required from the fan at the design mass flow rate of 420 kg/s. The outer diameter of the fan is 4 m with 0.6 hub to tip ratio. The present paper discusses the design methodology and computational analysis of wind tunnel fan. The design methodology includes a preliminary mean line analysis using the fundamental governing equations and CFX inbuilt design module. Subsequently, detailed computational analysis of the rotors was carried out using ANSYS CFX®. Based on the results obtained from the CFX analysis, the mean line analysis was modified to achieve the desired performance of the rotor. Parametric study was undertaken with different blade number combination, axial spacing, blade chord length, location of maximum thickness, leading edge profile, etc. The selection of number of blades for rotor and stator is an important aspect for such fan design in terms of cost, utility installation and noise. For low background noise in wind tunnel higher number of blades with suitable combination was selected for the fan ensuring the tone noise (produced by interaction of rotor and stator) is generated at attenuable frequencies. The blade angles, chord lengths, blade camber were optimized for good aerodynamic performance in terms of blade loading, wake thickness, hub-tip pressure profile, overall efficiency and pressure rise. It is strongly believed that discussed design aspects in terms of selection of various geometrical parameters for wind tunnel fan will give useful guidelines for future design of a low speed, large diameter fan of such capacity.

URANS Simulation of an Appended Hull During Steady Turn With Propeller Represented by an Actuator Disk Model

2011 ◽  
Author(s):  
Charles M. Dai ◽  
Ronald W. Miller
Keyword(s):  
Flow Field ◽  
Cross Flow ◽  
Field Measurements ◽  
Navier Stokes ◽  
Experimental Measurements ◽  
Complex Flow ◽  
Ship Maneuvering ◽  
Disk Model ◽  
Actuator Disk ◽  
Propeller Wake

This paper reports on the comparison between computational simulations and experimental measurements of a surface vessel in steady turning conditions. The primary purpose of these efforts is to support the development of physics-based high fidelity maneuvering simulation tools by providing accurate and reliable hydrodynamic data with relevance to maneuvering performances. Reynolds Averaged Unsteady Navier Stokes Solver (URANS): CFDSHIPIOWA was used to perform simulations for validation purposes and for better understanding of the fundamental flow physics of a hull under maneuvering conditions. The Propeller effects were simulated using the actuator disk model included in CFDShip-Iowa. The actuator disk model prescribes a circumferential averaged body force with axial and tangential components. No propeller generated side forces are accounted for in the model. This paper examines the effects of actuator disk model on the overall fidelity of a RANS based ship maneuvering simulations. Both experiments and simulations provide physical insights into the complex flow interactions between the hull and various appendages, the rudders and the propellers. The experimental effort consists of flow field measurements using Stereo Particle-Image Velocimetry (SPIV) in the stern region of the model and force and moment measurements on the whole ship and on ship components such as the bilge keels, the rudders, and the propellers. Comparisons between simulations and experimental measurements were made for velocity distributions at different transverse planes along the ship axis and different forces components for hull, appendages and rudders. The actuator disk model does not predict any propeller generated side forces in the code and they need to be taken into account when comparing hull and appendages generated side forces in the simulations. The simulations were compared with experimental results and they both demonstrate the cross flow effect on the transverse forces and the propeller slip streams generated by the propellers during steady turning conditions. The hull forces (include hull, bilge keels, skeg, shafting and strut) predictions were better for large turning circle case as compared with smaller turning circle. Despite flow field simulations appear to capture gross flow features qualitatively; detailed examinations of flow distributions reveal discrepancies in predictions of propeller wake locations and secondary flow structures. The qualitative comparisons for the rudders forces also reveal large discrepancies and it was shown that the primary cause of discrepancies is due to poor predictions of velocity inflow at the rudder plane.

Numerical Research on Flow Field Characteristics within the Slipstream of a Propeller

2012 ◽  
Vol 224 ◽  
pp. 55-60
Author(s):  
Zhong Zhe Duan ◽  
Pei Qing Liu ◽  
Li Chuan Ma
Keyword(s):  
Flow Field ◽  
Three Dimensional ◽  
Scientific Basis ◽  
Disk Model ◽  
Actuator Disk ◽  
Numerical Result ◽  
Light Load ◽  
Strip Theory ◽  
Flow Field Characteristics ◽  
Numerical Research

Numerical research on three dimensional flow field of a propeller and actuator disk model have been made. Under design conditions (headway 66.889m/s, revolving velocity 2575rpm）, the Slipstream flow field after Propeller is solved by RANS equations with structure mesh. Chosen 12 million mesh through verification of reliability analysis. The numerical result consists of the flow field and vortex field in the propeller slipstream. With comparison to the calculation result of standard strip theory and actuator disk model, it is shown that for light load propeller with the side small contraction of slipstream, in the slipstream cross section after 0.6R away from downstream of propeller rotation plane, the axial, circular and radial induced velocity coefficient by Prandtl’s blade tip corrected standard strip theory result; three dimensional flows numerical simulation and actuator disk model are well consistent. It verified the correctness of standard strip theory and also provided scientific basis for the correction of actuator disk model

scholarly journals Recessed Casing Treatment Effects on Fan Performance and Flow Field

1995 ◽  
Author(s):  
C. S. Kang ◽  
A. B. McKenzie ◽  
R. L. Elder
Keyword(s):  
Flow Field ◽  
Axial Flow ◽  
Pressure Rise ◽  
Operating Efficiency ◽  
Flow Measurements ◽  
Blade Loading ◽  
Stall Margin ◽  
Casing Treatment ◽  
Stall Margin Improvement ◽  
Blade Tip

An experimental investigation to examine the influence of the vaned recess casing treatment on stall margin, operating efficiency and the flow field of a low speed axial flow fan with aerospace type blade loading is presented. Different geometrical designs of the vaned passages were examined. The best configuration resulted in a stall margin improvement of 67%, a significantly higher pressure rise in the stall region and insignificant change in peak efficiency. Detailed 3-D flow measurements in the endwall region and in the casing recess were carried out with a slanted hot-wire, providing some insight to the operation of the device. The results revealed that the stall margin improvement was largely due to the removal of flow from the blade tip to the recess, and the elimination of the growth of the stall region at the tip, which occurs at stall in the solid casing build.

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