WO2000046511A1 - Profils de ventilateur a refroidissement - Google Patents

Profils de ventilateur a refroidissement Download PDF

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Publication number
WO2000046511A1
WO2000046511A1 PCT/US2000/001434 US0001434W WO0046511A1 WO 2000046511 A1 WO2000046511 A1 WO 2000046511A1 US 0001434 W US0001434 W US 0001434W WO 0046511 A1 WO0046511 A1 WO 0046511A1
Authority
WO
WIPO (PCT)
Prior art keywords
blade
airfoil
chord
airfoils
cooling
Prior art date
Application number
PCT/US2000/001434
Other languages
English (en)
Inventor
James L. Tangler
Dan M. Somers
Original Assignee
Midwest Research Institute
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Midwest Research Institute filed Critical Midwest Research Institute
Priority to CA002361801A priority Critical patent/CA2361801A1/fr
Priority to AU29697/00A priority patent/AU746432B2/en
Priority to US09/936,802 priority patent/US6899524B1/en
Priority to EP00908329A priority patent/EP1159530A1/fr
Publication of WO2000046511A1 publication Critical patent/WO2000046511A1/fr

Links

Classifications

    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F04—POSITIVE - DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS FOR LIQUIDS OR ELASTIC FLUIDS
    • F04D—NON-POSITIVE-DISPLACEMENT PUMPS
    • F04D29/00—Details, component parts, or accessories
    • F04D29/26—Rotors specially for elastic fluids
    • F04D29/32—Rotors specially for elastic fluids for axial flow pumps
    • F04D29/38—Blades
    • F04D29/384—Blades characterised by form
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F04—POSITIVE - DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS FOR LIQUIDS OR ELASTIC FLUIDS
    • F04D—NON-POSITIVE-DISPLACEMENT PUMPS
    • F04D29/00—Details, component parts, or accessories
    • F04D29/66—Combating cavitation, whirls, noise, vibration or the like; Balancing
    • F04D29/68—Combating cavitation, whirls, noise, vibration or the like; Balancing by influencing boundary layers
    • F04D29/681—Combating cavitation, whirls, noise, vibration or the like; Balancing by influencing boundary layers especially adapted for elastic fluid pumps
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F05—INDEXING SCHEMES RELATING TO ENGINES OR PUMPS IN VARIOUS SUBCLASSES OF CLASSES F01-F04
    • F05D—INDEXING SCHEME FOR ASPECTS RELATING TO NON-POSITIVE-DISPLACEMENT MACHINES OR ENGINES, GAS-TURBINES OR JET-PROPULSION PLANTS
    • F05D2250/00—Geometry
    • F05D2250/70—Shape
    • F05D2250/74—Shape given by a set or table of xyz-coordinates
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02T—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO TRANSPORTATION
    • Y02T50/00—Aeronautics or air transport
    • Y02T50/60—Efficient propulsion technologies, e.g. for aircraft

Definitions

  • This invention relates to the field of cooling-tower fans and specifically to a family of airfoils for use on the blades of such fans.
  • ducted fans are commonly used in the cooling towers of electric utilities to remove heat from the cooling water of heat exchangers. These fans are made up of four to twelve blades which range from 5 to 20 feet (1.5 to 6.1 meters) in length.
  • a standard twelve foot (3.7 meter) blade employing the NACA 63 2 - 615 airfoil from root to tip has been the most commonly used blade in cooling tower applications. This airfoil is 15% cord thick, and it is designed for an operating lift coefficient of 0.6 with a low-drag-range that extends from a lift coefficient of 0.4 to 0.8. It was initially designed in the early 1940's for use in general aviation and has been in use over the past 50 years. As a result, certain prior art design objectives have evolved over the course of these years.
  • T/P thrust-to-power ratio
  • the tip airfoil should be thin enough to provide low drag, but should also provide a maximum lift-to-drag ratio (1/d) at high values of lift coefficient to minimize blade solidity.
  • a fan satisfying the free vortex flow condition has the product of induced inplane swirl velocity and radius being constant along the span of the blade. This causes the radial pressure gradient to balance the centrifugal forces on the fluid and eliminates spanwise (radial) flow and losses due to turbulent mixing.
  • the free-vortex condition dictates the product of local blade chord and lift coefficient. The product of these two parameters results in the necessary radial loading and the resulting fan thrust.
  • the airfoil lift coefficient is derived for known inlet conditions of advance ratio, blade pitch, and twist angle. Therefore, either a value of lift coefficient or chord must be chosen and the other is calculated to provide an optimum combination along the span.
  • the operating lift coefficient is selected to coincide with the airfoil's best 1/d ratio and the product of the lift coefficient and chord are selected in order to design the fan to a specific thrust, for a given diameter and number of blades. Near the hub the blade requires high twist to achieve a positive angle of attack.
  • an object of this invention to provide an airfoil family having an improved aerodynamic performance but which demonstrates a reduced sensitivity to roughness when operating at c, max .
  • Another object of the invention is to provide an airfoil design that allows a lower solidity blade with lower cascade losses, lighter weight and greater cost efficiency.
  • a family of airfoils for a blade of a cooling-tower fan, wherein the blade has a root region and a tip region, the family of airfoils comprises an airfoil in the root region of the blade having a Reynolds number of 500,000, and an airfoil in the tip region of the blade having a Reynolds number of 1,000,000, and wherein each airfoil is characterized by a maximum lift coefficient that is largely insensitive to roughness effects.
  • Figure 1 is a profile of the prior art airfoil, and the airfoil family according to the present invention.
  • the Borst analysis method uses a rigid-wake model in conjunction with a cascade theory to provide a blade-element analysis method able to use two-dimensional airfoil data.
  • ⁇ c, 2cos( ⁇ , - , )[tan ⁇ , - tan ⁇ - 2a,)] K(x)/K( ) infimtv (Eq. 1)
  • ⁇ is the local blade solidity
  • c is the section lift coefficient
  • ⁇ j is the inflow angle
  • ⁇ is the induced angle of attack that results from wake-induced inplane swirl
  • x is the non- dimensional radius
  • K(x) is Theodorson's circulation function.
  • K(x) is a function of the number of blades, the wake advance ratio, and the radial position of the blade.
  • K(j ) ⁇ nfimtv is Theodorson's circulation function for a fan having an infinite number of blades.
  • the values of K(x) can be found using graphs from Borst, which were created using the rigid, helical- wake model of Gray and Wright.
  • ⁇ is the angle between the chord line and the plane of rotation.
  • the equivalent two-dimensional angle of attack can be calculated knowing the induced angle of attack. This method proceeds with the selection of an induced angle of attack that results for wake-induced, inplane swirl. Using this value, the values of ⁇ c, are calculated using Eq. 1, directly, and Eq. 2 to find ⁇ for use with the two-dimensional airfoil data. The value of , is iterated upon until it results in an angle of attack and lift distribution that is compatible with the strength of the rigid-wake model. Equations 3 and 4 are then integrated to solve the blade-element equations for thrust and torque.
  • T' V ⁇ p W 2 Bc(c, cos ⁇ - c d sin ⁇ )(Eq. 3)
  • Q7r 1 /2 p W 2 Bc(c, cos ⁇ + c d cos ⁇ )(Eq. 4)
  • Figure 1 is a profile of the prior art NACA 63 2 - 615 airfoil (10).
  • the upper surface of the airfoil (10) is shown at (12) and the lower surface at (13).
  • the leading edge of the airfoil is at (14) and the trailing edge is at (15).
  • the chord is shown at line (11).
  • the NACA 63 2 - 615 airfoil has a thickness of 15%.
  • Figure 1 is also a profile of the tip airfoil (20), according to the present invention, relative to the prior art NACA 63 2 - 615 airfoil (10).
  • the upper surface of the tip airfoil (20) is shown at (22) and the lower surface at (23).
  • the leading edge of the tip airfoil is at (24) and the trailing edge is at (25).
  • the chord is shown at line (21).
  • the tip airfoil has a thickness of 10% chord.
  • the specific geometric tailoring of the tip airfoil (20) of Figure 1 is given in the form of the following table of coordinates.
  • the x/c values are dimensionless locations along the blade chord line (21). They are given for both the upper (22) and lower (23) surfaces.
  • the y/c values are the dimensionless heights from the chord line (21) to points either on the upper or lower surface.
  • Figure 1 is also a profile of the root airfoil (30), according to the present invention, relative to the prior art NACA 63 2 - 615 airfoil (10).
  • the upper surface of the root airfoil is shown at (32) and the lower surface at (33).
  • the leading edge of the root airfoil is at (34) and the trailing edge is at (35).
  • the root airfoil has a thickness of 14% chord
  • the specific geometric tailoring of the root airfoil (30) of Figure 1 is given in the form of the following table of coordinates.
  • the x/c values are dimensionless locations along the blade chord line (31). They are given for both the upper (32) and lower (33) surfaces.
  • the y/c values are the dimensionless heights from the chord line (31) to points either on the upper or lower surface.
  • Table 1 summarizes the predicted performance characteristics for these new airfoils relative to the baseline prior art NACA 63 2 - 615 airfoil.
  • the tip airfoil has less thickness than the baseline NACA 63 2 - 615 (10% versus 15%). This reduction in thickness results in a lower minimum drag (0.007 versus 0.009). At the design Reynolds number, the tip airfoil also has a higher c, max (1.50 versus 1.256). The root airfoil is slightly thinner than the NACA 63 2 - 615 and has less drag in the root region (0.008 versus 0.010). It also has a larger c, at zero angle of attack and a greater
  • Fan performance was calculated with the tip and the root airfoils using the baseline blade taper and twist geometry for the design thrust of 2000 LB (8900 newton).
  • 2000 LB (8900 newton) thrust is achieved at a geometric pitch angle of 2° versus 0° for the new airfoils.
  • the new airfoils result in a performance gain of 1.5% for the eight-bladed 28-foot (8.534-meter) diameter fan. This gain does not take into account the gain that would be attributable to the airfoil's improved insensitivity to roughness where some measure of improvement is expected.
  • the geometric pitch angle is with respect to the airfoil chord line which differs from a field pitch angle setting that is normally with respect to the lower surface of the airfoil.
  • the field pitch setting is 4° greater than the geometric pitch angle.
  • the new airfoils are designed to operate at a 0.2 higher c, than the baseline
  • NACA 63 2 - 615 airfoil for a given blade pitch angle.
  • One degree of blade pitch is equivalent to 0.1 c,.
  • the advantage of this tradeoff is that less blade chord results in less dimensional blade drag and the higher pitch angle still lies well within the airfoil's low-drag range. It is also predicted that this chord reduction will increase the performance gain to 1.8% at the 2000 LB (8900 newton) design thrust.

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  • Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • General Engineering & Computer Science (AREA)
  • Structures Of Non-Positive Displacement Pumps (AREA)

Abstract

L'invention concerne un ensemble de profils (20, 30) pour une ailette, présentant une base et un haut, d'un ventilateur à refroidissement. L'ensemble de profils comprend un profil (30) au niveau de la base de l'ailette ayant un nombre Reynolds de 500.000 et un profil (20) au haut de l'ailette ayant un nombre Reynolds de 1.000.000. Chaque profil est caractérisé par un coefficient d'élévation maximum qui est quasiment insensible aux effets d'irrégularité.
PCT/US2000/001434 1999-02-08 2000-01-21 Profils de ventilateur a refroidissement WO2000046511A1 (fr)

Priority Applications (4)

Application Number Priority Date Filing Date Title
CA002361801A CA2361801A1 (fr) 1999-02-08 2000-01-21 Profils de ventilateur a refroidissement
AU29697/00A AU746432B2 (en) 1999-02-08 2000-01-21 Cooling-tower fan airfoils
US09/936,802 US6899524B1 (en) 1999-02-08 2000-01-21 Cooling-tower fan airfoils
EP00908329A EP1159530A1 (fr) 1999-02-08 2000-01-21 Profils d'aube pour ventilateur de tour de refroidissement

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
US11898599P 1999-02-08 1999-02-08
US60/118,985 1999-02-08

Publications (1)

Publication Number Publication Date
WO2000046511A1 true WO2000046511A1 (fr) 2000-08-10

Family

ID=22381957

Family Applications (1)

Application Number Title Priority Date Filing Date
PCT/US2000/001434 WO2000046511A1 (fr) 1999-02-08 2000-01-21 Profils de ventilateur a refroidissement

Country Status (4)

Country Link
EP (1) EP1159530A1 (fr)
AU (1) AU746432B2 (fr)
CA (1) CA2361801A1 (fr)
WO (1) WO2000046511A1 (fr)

Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4776513A (en) * 1985-05-28 1988-10-11 Navistar International Transportation Corp. Double seal thermostat
US4911612A (en) * 1988-02-05 1990-03-27 Office National D'etudes Et De Recherches Aerospatiales Sections for shrouded propeller blade
US5417548A (en) * 1994-01-14 1995-05-23 Midwest Research Institute Root region airfoil for wind turbine
US5562420A (en) * 1994-03-14 1996-10-08 Midwest Research Institute Airfoils for wind turbine
US6039541A (en) * 1998-04-07 2000-03-21 University Of Central Florida High efficiency ceiling fan

Patent Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4776513A (en) * 1985-05-28 1988-10-11 Navistar International Transportation Corp. Double seal thermostat
US4911612A (en) * 1988-02-05 1990-03-27 Office National D'etudes Et De Recherches Aerospatiales Sections for shrouded propeller blade
US5417548A (en) * 1994-01-14 1995-05-23 Midwest Research Institute Root region airfoil for wind turbine
US5562420A (en) * 1994-03-14 1996-10-08 Midwest Research Institute Airfoils for wind turbine
US6039541A (en) * 1998-04-07 2000-03-21 University Of Central Florida High efficiency ceiling fan

Non-Patent Citations (1)

* Cited by examiner, † Cited by third party
Title
TANGLER J. L. ET. AL.: "NREL Airfoil Families for HAWTs", NATIONAL RENEWABLE ENERGY LABORATORY REPORT., January 1995 (1995-01-01), XP002928902 *

Also Published As

Publication number Publication date
CA2361801A1 (fr) 2000-08-10
AU2969700A (en) 2000-08-25
EP1159530A1 (fr) 2001-12-05
AU746432B2 (en) 2002-05-02

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