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Flow characterization in mine ventilation fan blade design using CFD

Hassen Anwar Endris

Journal of Sustainable Mining

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2021

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Vol. 20, iss. 3

144--156

EN

In axial ventilation fans, the generation of a uniform flow velocity is desirable for better efficiency. To that end, different fan blade types have been developed to achieve better flow uniformity. This article aimed to characterize the flow distribution and its uniformity in four blade designs, namely constant chord, tapered blade, skewed blade, and tapered skewed blade, using Computational Fluid Dynamics (CFD). The study employs an iterative study where key study decisions are made as the study progresses. The study began with the selection of a blade profile for the study. A comparative study between the NACA seven-digit and four-digit series was conducted and for its higher flow throughput, the four-digit airfoil profile was selected. Next, with 30 and 40° Angle of Attack (AoA), the constant chord blade flow pattern is characterized. At 40° AoA flow disturbance and high-velocity spots were observed establishing the problem statement. Following that, three optimization strategies (tapering, skewing, and taper skewing) were applied in the design, and the flow pattern of each design was studied. Using a dispersion study a flow uniformity comparison between the models conducted. The property trade-off between three key performance indicators: efficiency, flow rate, and flow uniformity studied. The result shows an axial fan having a higher efficiency doesn't necessarily mean it has higher throughput whereas lower flow dispersion relates to the system's higher efficiency. Therefore, it can be concluded that seeking higher efficiency and flow uniformity in the design and development of axial fans comes with system throughput trade-off.

2

CFD simulations for selection of appropriate blade profile for improving energy efficiency in axial flow mine ventilation fans

Panigrahi D. C., Mishra D. P.

Journal of Sustainable Mining

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2014

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Vol. 13, iss. 1

15--21

EN

Purpose This study focuses on one of the key design aspects of mine ventilation fans, i.e. the selection of an appropriate aerofoil blade profile for the fan blades in order to enhance the energy efficiency of axial flow mine ventilation fans, using CFD simulations. Methods Computational simulations were performed on six selected typical aerofoil sections using CFD code ANSYS Fluent 6.3.26 at angles of attack varying from 0 to 21 at an interval of 3 and at Reynolds number Re = 3 × 106, and various aerody-namic parameters, viz. coefficients of lift (Cl) and drag (Cd) as a function of angle of attack (α) were determined to assess the efficiency of the aerofoils. Results The study revealed that the angle of attack has a significant effect on the lift and drag coefficients and stall condition oc-curred at α values of 12 and 15 in most of the aerofoils. Based on the criterion of higher lift to drag ratio (Cl/Cd), a blade profile was chosen as the most efficient one for mine ventilation fans. Practical implications This study forms a basis for selecting appropriate blade profiles for the axial flow fans used for ventilation in mining industry. Originality/ value The application of an appropriate aerofoil blade profile will impart energy efficiency to the mine ventilation fans and thereby result in energy saving in mine ventilation.

3

Badanie charakterystyki przepływu w tunelu aerodynamicznym zasilanego za pomocą wentylatorów osiowych

Bońkowska E., Pietkiewicz P., Miąskowski W., Nalepa K.

Mechanik

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2011

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R. 84, nr 7(CD)

37-44

PL

W artykule została przedstawiona metoda wyznaczania charakterystyki przepływu w tunelu aerodynamicznym za pomocą wentylatorów osiowych. Badanie zostało przeprowadzone po stronie tłoczącej za zwężką Witoszyńskiego przy użyciu termoanemometru elektronicznego. Oprócz analizy empirycznej wykonana została analiza komputerowa w celach porównawczych.

EN

Method of a flow characteristic’s determination in a wind tunnel with the help of axial-flow fans was presented in this paper. Research were carried out on the pressure side, behind the Witoszyński’s orifice using electronic hot-wire anemometer. Apart from the empirical analysis, also computer analysis was conducted with the comparative purpose.

4

Numerical simulation and modification of 3D flow phenomena in an axial flow fan

Elhadi E. E., Keqi W.

TASK Quarterly : scientific bulletin of Academic Computer Centre in Gdansk

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2003

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Vol. 7, No 2

199-213

EN

This work aims to study and analyze the behavior of flow in an axial flow fan using numerical simulation based on solving Reynolds-averaged Navier-Stokes equations coupled with a modified Spalart-Allaras turbulence model. In the present work, different flow phenomena occuring in an axial flow fan were presented and interpreted at different design conditions and at different regions, with special concern to the rotor exit and stator regions. Large vortices and reverse flow at the stator suction side were observed under high loading conditions. These are mainly due to radial and centrifugal effects in the fluid due to a decreasing flow rate. To avoid this type of flow, the stator flow pattern has been modified using a new stator blade. This blade was designed by changing the stator stagger angle by 10o in the radial direction. This study indicates that the flow in the modified stator region behaves well and gives better performance than that obtained when using a baseline stator, especially under high loading conditions. This study also indicates that the stator stagger angle has a significant effect on modifying the fan performance.

5

Zastosowanie zmodyfikowanego prawa powinowactwa do wyznaczania parametrów pracy dwustopniowego wentylatora osiowego w procesie regulacji z wykorzystaniem zmiany obrotów wirników

Gałaj J.

Przegląd Mechaniczny

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2003

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nr 5

20-26

PL

Celem niniejszej pracy jest przeanalizowanie możliwości dostosowania prawa powinowactwa charakterystyk ciśnienia dla wentylatorów osiowych poprzez ustalenie jak najprostszej zależności funkcyjnej na wykładnik potęgi, którego wartośc standardowo jest równa 2.

6

Zastosowanie zmodyfikowanego prawa powinowactwa do przeliczania charakterystyk ciśnieniowych dwustopniowego wentylatora osiowego przy różnych prędkościach obrotowych wirników

Gałaj J.

Przegląd Mechaniczny

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2003

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nr 3

22-28

7

Charakterystyki osiowego wentylatora dwustopniowego przy różnych kątach ustawienia łopatek wirnika a prawa powinowactwa

Gałaj J.

Przegląd Mechaniczny

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2000

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nr 19-20

32-35

PL

Publikacja jest kontynuacją artykułu autora poświęconego analizie możliwości zastosowania praw powinowactwa do wyznaczania charakterystyk osiowego wentylatora dwustopniowego przy różnych prędkościach obrotowych wirnika. Tematem artykułu jest sprawdzenie zgodności charakterystyk ciśnienia i mocy wentylatora przy różnych kątach ustawienia łopatek wirnika z prawami powinowactwa.

8

Charakterystyki dwustopniowego wentylatora osiowego przy różnych prędkościach obrotowych wirnika a prawa powinowactwa

Gałaj J.

Przegląd Mechaniczny

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2000

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nr 17-18

27-32

EN

This article is the third item in the series devoted to the characteristics of an axial-flow two-stage fan. A check is presented on the conformity of pressure and power characteristics of the fan at different rotational speeds with the laws of affinity. The comparison is based on the analytical form of the characteristics obtained from investigations of an actual fan expressed by means of multinomial quadratic functions.

9

Analityczna postać charakterystyk dwustopniowego wentylatora osiowego dla różnych kątów ustawienia łopatek wirnika

Gałaj J.

Przegląd Mechaniczny

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2000

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nr 15

15-19

PL

Przedstawiono i omówiono analityczne charakterystyki pracy dwustopniowego wentylatora osiowego przy różnych kątach ustawienia łopatek wirnika, celem tak przedstawionych charakterystyk było uproszczenie ich analizy, której efektem jest sformułowanie odpowiednich wniosków dla konstruktorów wentylatorów, przy aproksymacji otrzymanych w wyniku badań punktów pomiarowych posłużono się procedurą wykorzystującą metodę zapewniającą najmniejszy błąd średniokwadratowy.

EN

Analytical performance characteristics of a two-stage axial-flow fan at various rotor blade-angle settings. Such a presentation of the characteristics simplified their analysis which gave valuable information for the designers of fans. When approximating the measurement points obtained from investigations use was msde of the procedure based on the method ensuring the last mean square error.

10

Analityczna postać charakterystyk dwustopniowego wentylatora osiowego dla różnych prędkości obrotowych wirnika

Gałaj J.

Przegląd Mechaniczny

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2000

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nr 13

19-23

EN

Analytical form of the basic characteristics of a two-stage axial-flow fan for several various rotational speed of the rotor. The characteristics were obtained through an approximation of measurement points by polynomial second order or third order functions permitting to achieve the required accuracy with the application of the criterion of a minimum mean square deviation.