WO2011149440A2 - Procédé d'amélioration de la réduction de traînée d'écoulement et de la production d'élévation à l'aide d'un dé-turbulateur - Google Patents

Procédé d'amélioration de la réduction de traînée d'écoulement et de la production d'élévation à l'aide d'un dé-turbulateur Download PDF

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Publication number
WO2011149440A2
WO2011149440A2 PCT/US2008/053517 US2008053517W WO2011149440A2 WO 2011149440 A2 WO2011149440 A2 WO 2011149440A2 US 2008053517 W US2008053517 W US 2008053517W WO 2011149440 A2 WO2011149440 A2 WO 2011149440A2
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WIPO (PCT)
Prior art keywords
flow
wing
drag
deturbulator
fcs
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PCT/US2008/053517
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English (en)
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WO2011149440A3 (fr
Inventor
Sumon Kumar Sinha
Sumontro Sinha
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Sinhatech
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Publication of WO2011149440A2 publication Critical patent/WO2011149440A2/fr
Publication of WO2011149440A3 publication Critical patent/WO2011149440A3/fr

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Classifications

    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B64—AIRCRAFT; AVIATION; COSMONAUTICS
    • B64C—AEROPLANES; HELICOPTERS
    • B64C21/00—Influencing air flow over aircraft surfaces by affecting boundary layer flow
    • B64C21/10—Influencing air flow over aircraft surfaces by affecting boundary layer flow using other surface properties, e.g. roughness
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F15—FLUID-PRESSURE ACTUATORS; HYDRAULICS OR PNEUMATICS IN GENERAL
    • F15D—FLUID DYNAMICS, i.e. METHODS OR MEANS FOR INFLUENCING THE FLOW OF GASES OR LIQUIDS
    • F15D1/00—Influencing flow of fluids
    • F15D1/002—Influencing flow of fluids by influencing the boundary layer
    • F15D1/0025—Influencing flow of fluids by influencing the boundary layer using passive means, i.e. without external energy supply
    • F15D1/006—Influencing flow of fluids by influencing the boundary layer using passive means, i.e. without external energy supply comprising moving surfaces, wherein the surface, or at least a portion thereof is moved or deformed by the fluid flow
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F28—HEAT EXCHANGE IN GENERAL
    • F28F—DETAILS OF HEAT-EXCHANGE AND HEAT-TRANSFER APPARATUS, OF GENERAL APPLICATION
    • F28F13/00—Arrangements for modifying heat-transfer, e.g. increasing, decreasing
    • F28F13/06—Arrangements for modifying heat-transfer, e.g. increasing, decreasing by affecting the pattern of flow of the heat-exchange media
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B64—AIRCRAFT; AVIATION; COSMONAUTICS
    • B64C—AEROPLANES; HELICOPTERS
    • B64C2230/00—Boundary layer controls
    • B64C2230/26—Boundary layer controls by using rib lets or hydrophobic surfaces
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F28—HEAT EXCHANGE IN GENERAL
    • F28F—DETAILS OF HEAT-EXCHANGE AND HEAT-TRANSFER APPARATUS, OF GENERAL APPLICATION
    • F28F2215/00—Fins
    • F28F2215/14—Fins in the form of movable or loose fins
    • 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
    • Y02T50/10—Drag reduction

Definitions

  • the present invention relates to a method for using turbulence modifying flow-control devices to reduce drag on streamlined and bluff bodies, increase lift generated by lifting bodies and also increase convective heat transfer between a body and the flow without increasing flow losses.
  • Heat exchangers are used for transferring heat in a variety of systems such as those for manufacturing, heating ventilating and air-conditioning, power generation, and electronic packaging.
  • One goal in the design of a heat exchanger is to maximize the convective heat transfer between a working fluid and a solid wall.
  • One way to do this is by increasing the velocity of the fluid, which enhances the wall convective heat transfer coefficient.
  • the power required to drive the flow is proportional to the square of the velocity. This imposes an upper limit on the maximum allowable velocities in the heat exchanger.
  • Additional augmentation requires modifying the wall boundary layer flow, usually with the help of turbulence promoters, such as baffles or wall roughness elements. This is generally necessary for heat exchange from air streams due to significantly lower heat capacities and thermal conductivities of air compared to water or other commonly used liquid heat transfer media.
  • a method for reducing drag, increasing lift and heat transfer using a dedfturbulating device is disclosed, with the preferred form of the deturbulator being a flexible composite sheet.
  • the flexible composite sheet comprising a membrane, a substrate coupled to the membrane, and a plurality of ridges coupled between the membrane and the substrate, wherein a vibratory motion is induced from the flow to at least one segment of a membrane spanning a distances, wherein the vibratory motion is reflected from at least one segment of the membrane to the flow, and; wherein a reduction in fluctuations is caused in the flow pressure gradient and freestream velocity U at all frequencies except around f, where f ⁇ U/s.
  • the flexible composite sheet can be wrapped around a blunt leading edge of a plate facing an incoming flow of fluid.
  • the flexible composite sheet can also be wrapped around one or more regions of an aerodynamic surface where a flow pressure gradient changes from favorable to adverse.
  • the flexible composite sheet is replaced with a plurality of plates coupled to a substrate, wherein the plurality of plates has edges that interact with a fluid flow similar to a compliant surface.
  • a method of adding a system of small viscous sublayer scale (around 30-80 micron height) backward and /or forward facing steps on the surface of an airfoil or other 2-D or 3-D streamlined aerodynamic body where the backward facing step is in a favorable pressure gradient and forward facing step is in an adverse pressure gradient, so as to speed up the freestream flow over the front portion of the airfoil or body and reduce skin friction drag by creating a marginally separated thin (0.1 to 10 microns) slip layer next to the wall behind the backward facing step and extending a significant distance behind said step.
  • This method reduces the drag and increases lift if the body is a wing.
  • the same method can be applied to a bluff body, such as an automobile to reduce flow separation induced drag by stabilizing the wake flow and making it appear to the flow as a solid streamiling extension of the original body.
  • the gas mileage of a vehicle improves when treated in this manner.
  • FIG. 1 is a diagram of a flexible composite surface (FCS) in accordance with the present invention.
  • FIG. 2 is a diagram of a portion of the FCS of FIG. 1 interacting with a flow of fluid in accordance with the present invention
  • FIG. 3 shows a photograph of a Global-GT3 test aircraft
  • FIG. 4 is a diagram showing the cross-section of the wing of FIG. 3;
  • FIG. 5 shows a photograph of an FCS mounted on the bottom of the wing of FIG. 3;
  • FIG. 6 is a chart showing measured pressure-side boundary-layer velocity profiles at 80% of chord from the leading edge, with and without the FCS;
  • FIG. 7 is a chart showing measured suction-side boundary-layer velocity profiles, with and without the FCS at 80% of chord from the leading edge;
  • FIG. 8 is a chart showing plots of the pressure-side velocity data of FIG. 6 normalized with respect to the measured velocities furthest away from the wall;
  • FIG. 9 is a diagram of an FCS interacting with a flow of fluid in accordance with another embodiment of the present invention.
  • FIG. 10 is a blow-up diagram of a portion of the FCS of FIG. 9 interacting with a flow of fluid in accordance with another embodiment of the present invention.
  • FIG. 1 1 is a diagram an FCS interacting with a flow of fluid in accordance with another embodiment of the present invention
  • FIG. 12 is a diagram of a heat transfer enhancement test apparatus in accordance with another embodiment of the present invention.
  • FIG. 13 is a top-view diagram of a multi-fin heat sink in accordance with another embodiment of the present invention.
  • FIG. 14 is a side-view diagram of the multi-fin heat sink of FIG. 13.
  • FIG. 15 is a diagram of a rocket in a wind tunnel, with a backward facing step created by wrapping duct tape behind the nose cone in order to reduce skin friction drag on the rocket body.
  • FIG. 16 is a graph showing the coefficient of drag of the rocket of FIG. 15 with airspeed for the untreated rocket, a cone behind the rocket (Flow Control Device -1 ) and the step of FIG. 15 (Flow Control Device -2).
  • FIG. 17 is a diagram showing the increase in maximum altitude of the rocket of FIG. 15 (Experimental) when launched vertically versus the same for the untreated rocket (Control).
  • FIG. 18 is a diagram showing the reduction in the angle of the attached shock wave on the top of a wedge as compared to the bottom when the wedge is exposed to a supercritical flow from the left to the right and the top leading edge has a backward facing step immediately behind it.
  • FIG. 19a is a section of a streamlined object, such as a wing with a combination of backward and forward facing steps, flow pre-conditioners and deturbulators (FCSD).
  • FCSD flow pre-conditioners and deturbulators
  • FIG. 19b is a diagram depicting the modification of the top surface boundary layer due to the application of deturbulators in accordance to FIG. 19a.
  • FIG. 20a is a diagram showing the change in non-dimensional surface pressures on a Wortmann airfoil model corresponding to the airfoil at a section of the wing of a Standard Cirrus sailplane, 53-inches outboard from the wing root joint due to a combination of backward and forward facing steps and FCSD deturbulator on the upper surface.
  • FIG. 20b is a diagram showing the change in the profile of boundary layer mean velocities and rms-velocity fluctuations at 80% of the chord on the suction surface due to the treatment of FIG. 20a.
  • FIG. 21 a is a diagram showing an increase in lift-to-drag ratio of a prototype Standard Cirrus sailplane whose wings have been treated throughout the span similar to FIG. 20a.
  • FIG. 21 b is a diagram showing reduction in induced drag (CDi) of the prototype Standard Cirrus sailplane due to partial span and full span treatments of FIG 20a.
  • FIG. 22 is a diagram showing a FCSD Deturbulator strip and triangular shaped flow pre-conditioners installed on the top surface of the GT-3 aircraft wing along with a boundary layer mouse shown on the bottom.
  • FIG. 23 is a diagram showing changes due to the treatment of FIG. 22 in the measured upper surface boundary layer velocity profiles of the GT-3 wing at 90% of the chord.
  • FIG. 24 is a diagram showing the reduction in profile drag of a wing section of the GT-3 due to the treatment of FIG. 22.
  • FIG. 25 is a diagram showing the stabilization of the separated flow region behind a bluff object like a road vehicle due to deturbulator treatment.
  • Fig. 26 is a diagram of a model car in a wind tunnel treated with a backward facing step on the top behind the windshield using a piece of duct tape.
  • FIG. 27 is a diagram showing the aerodynamic drag coefficient of the model car of FIG. 26 with a variety of treatment with the deturbulator on the back top as per FIG 25 showing the largest reduction.
  • FIG. 28a is a diagram of a 2000 Nissan Odyssey EX minivan treated with FCSD strips on the top front and rear and on the sides at the rear corners.
  • FIG. 28b is a diagram showing a close up of the upper surface FCSD Deturbulators of FIG. 28a.
  • FIG. 29a is a diagram showing the change in average highway gas mileage of the Hyundai Odyssey due to the treatment of FIGs. 28a and 28b.
  • FIG. 29b is a diagram showing the change in average highway and city combined gas mileage of the Hyundai Odyssey due to the treatment of FIGs. 28a and 28b.
  • Figure 30 presents a 3-view of Std. Cirrus, a 15 meter test bed sail plane.
  • Figure 31 shows a man with the Deturbulator strips mounted on the test Std. Cirrus.
  • Figure 32 shows thee measured airspeed indicator instrument error data.
  • Figure 33 is a chart that represents the flight measured Airspeed System errors.
  • Figure 34 shows the averaged sink-rates measured during the 6 deturbulated-wing test flights.
  • Figure 35 shows their corresponding L/D ratios.
  • Figure 36 shows the averaged sink-rates measured during the selected 3 deturbulated-wing test flights.
  • Figure 37 shows their corresponding L/D ratios.
  • the present invention relates to the use of devices capable of spectrally altering turbulence to reduce flow induced drag, enhance flow induced lift and enhance flow-surface heat transfer without increasing losses.
  • a system and method in accordance with the present invention enhances the transfer of heat in heat exchangers by utilizing a flexible composite surface (FCS).
  • FCS includes a membrane coupled to a substrate and a plurality of ridges coupled between the membrane and the substrate. Vibratory motion from a flow pressure gradient fluctuation is applied to at least one segment of the membrane.
  • the membrane reflects the vibratory motion from the at least one of its segments to the flow pressure gradient fluctuation. This sustains fluctuations in the flow pressure gradient only around a pre-selected frequency. This helps sustain a thin layer of re-circulating fluid downstream of the FCS over the solid surface, which exchanges heat with the flow.
  • This thin layer allows efficient heat transfer from the solid surface to the flowing fluid without introducing high frictional forces between the fluid and the wall. This allows heat transfer without increasing the pressure drop in the fluid flow passage.
  • FIG. 1 is a diagram of a flexible composite surface (FCS) 100 in accordance with the present invention.
  • the FCS 100 is also referred to as the SINHA-FCS 100.
  • the FCS includes a flexible membrane 102, which is stretched across an array of strips or ridges 104.
  • the ridges 104 are coupled to a substrate 106.
  • the FCS 100 can be coupled to an aerodynamic body.
  • the FCS 100 is coupled to a surface of a wing 108.
  • the membrane 102 is thinner (e.g., 6 urn) than the substrate base (e.g., 50-100 urn).
  • the membrane 102, the ridges 104, and the substrate 106 form air pockets 1 10 that contribute towards the stiffness and damping governing flexural vibratory motion 1 12 of the membrane 102.
  • the flexural vibratory motion 1 12 is caused by the flow 1 14 of a fluid along the membrane 102.
  • the natural frequency of the flexural vibratory motion 1 12 can be tuned as desired by varying the spacing S between the ridges 104, the size (e.g., thickness) of the air pockets, the tension of the membrane 102, as well as the density and elastic modulus of the membrane material (Sinha et al, 1999).
  • the damping of the membrane 102 can be made to vary with frequency and flexural mode by segmenting the air pockets 1 10 with suitably located shorter ridges.
  • the narrow gap above a short ridge provides an increased resistance to airflow across it.
  • all flexural modes of the membrane requiring such flows in the substrate have larger damping in comparison to modes that do not.
  • One benefit of the FCS 100 is that it controls the frequency and flexural mode passively, i.e., non-powered.
  • the FCS 100 exploits such a dominant interaction mode for manipulating a varying and adverse-pressure gradient (APG) boundary layer flow.
  • APG flows are those where the imposed pressure tends to oppose the flow. In many instances, this leads to boundary layer flow separation, resulting in large increases in turbulence and flow losses.
  • the present invention decreases the boundary layer flow separation and thus decreases overall turbulence and flow losses. As a result of such manipulation, any turbulence in the flow 1 14 is controlled and the transfer of momentum, heat, and mass across the APG boundary layer can be decoupled and changed to obtain desired outcomes.
  • FIG. 2 is a diagram of a portion of the FCS 100 of FIG. 1 interacting with a flow 1 14 of fluid in accordance with the present invention.
  • the FCS 100 can be located over regions of an aerodynamic surface where the flow pressure gradient changes from favorable to adverse. Under such flow conditions, flow induced pressure fluctuations can impart flexural vibratory motion 1 12 to segments of the membrane 102 between adjacent ridges 104. The flexural vibratory motion 1 12 of the membrane segments, in turn, can impart pressure fluctuations to the flow 1 14 at the vibrating frequencies.
  • the exposed surface of the membrane 102 creates a non-zero wall velocity condition for the boundary layer flow at locations where the flow 1 14 is receptive to this condition.
  • the interaction of the flow 1 14 with the flexural vibratory motion 1 12 of the compliant membrane 102 results in the flow 1 14 being forced to a new equilibrium.
  • equation (3) holds irrespective of the source of the perturbations.
  • the discussions thus far have presumed the source to the flexible wall (Sinha, 2001 ).
  • equation (3) also describes how fluctuations in the freestream velocity U can impart oscillations to a compliant wall at x-locations where equation (1 -a) remains valid (Sinha and Zou, 2000). If fluctuations exist in the freestream velocity U, as is normally the case in most external aerodynamic flows, the presence of a compliant wall around the 3p/3x ⁇ 0 location results in partitioning the energy of the fluctuations between the fluid and the wall (Carpenter et al, 2001 ). The degree of partitioning at any instant depends on the temporal phase of the wall oscillation cycle.
  • the vibratory response of the wall also plays a key role in this interaction.
  • the predominant response of the FCS 100 can be expected to be flexural.
  • the maximum displacements and energy storage capacity of the FCS 100 corresponds to the fundamental mode as per the sketch of the deflected membrane in FIGS. 1 and 2. Dissipation can also be expected to be higher for higher modes of flexural vibratory motion, especially if the low ridges constrict the airflow across them.
  • the FCS 100 constrains turbulent fluctuations to a narrower band. This "customized turbulence" can be expected to be less dissipative.
  • the fundamental natural frequency for flexural vibratory motions 1 12 of the membrane 102 has no bearing on the flow-membrane interaction frequency f, as long as they are sufficiently apart. If the two coincide, the amplitude of the oscillating membrane 102 increases, thereby enhancing non-linear dynamic effects. This can trigger other modes of oscillation of the membrane 102, thereby increasing energy losses and broadening the spectrum of flow fluctuations.
  • the FCS 100 then begins to behave as a broad-spectrum turbulator, promoting much larger losses through rapid buildup of turbulent skin friction.
  • FCS 100 control of boundary layer flows in general, including applications to aircraft wings.
  • the FCS 100 can be applied to an aircraft wing to achieve drag reduction.
  • FIG. 3 shows a photograph of a Global-GT3 test aircraft 140 (manufactured by Global Aircraft Inc., Starkville, MS), which is instrumented for wing-bottom measurements.
  • the aircraft 140 has a wing 150, which is used for the wing drag flight tests.
  • the wing 150 has a starboard flap 152.
  • Pressure transducer array 154 is mounted on top of the wing 150.
  • FIG. 4 is a diagram showing the cross-section of the wing 150 of FIG. 3.
  • the wing 150 is an NLF-0414F natural laminar-flow airfoil wing.
  • the flow pressure gradient changes from slightly favorable to adverse around 65-75% of the chord on both the top (suction) and bottom (pressure) surfaces of this airfoil.
  • FIG. 5 shows a photograph of a SINHA-FCS 100 mounted on the bottom of the wing 150 of FIG. 3, along with the boundary layer mouse 160 used to measure boundary layer velocity profiles. This arrangement is just below the outboard end of the taped section of the starboard flap 152 of FIG. 3.
  • the FCS 100 is a 300-mm spanwise and 50-mm chordwise section.
  • a wing-flap joint 162 runs over the mouse 160.
  • FIG. 7 is a chart showing measured suction-side boundary-layer velocity profiles, with and without the SINHA-FCS at 80% of chord from the leading edge.
  • the difference between Clean-Wing-1 and Clean-Wing-2 profiles shows test uncertainties.
  • FIG. 7 shows a similar behavior for the suction side of the wing, resulting in 18-20% reduction in drag.
  • the two "Clean-Wing" profiles
  • FIG. 8 is a chart showing plots of the pressure-side velocity data of FIG. 6 normalized with respect to the measured velocities furthest away from the wall.
  • the profiles for the wing with FCS are normalized with respect to ⁇ * values before and after FCS application. This isolates the change in the shape of the velocity profile.
  • FIG. 9 is a diagram of an FCS 200 interacting with a flow of fluid in accordance with an embodiment of the present invention.
  • This embodiment consists of thin plates 202 staggered at a shallow angle and sandwiched between compliant porous elastomeric layers 204 having visco-elastic properties.
  • This assembly is imbedded in a substrate 206, which can be affixed to a body over which an adverse-pressure-gradient flow 208 takes place.
  • FIG. 10 is a blow-up diagram of a portion of the FCS 200 of FIG. 9 interacting with a flow of fluid in accordance with another embodiment of the present invention.
  • the tips 220 of the plates 202 are exposed to a locally varying pressure gradient, changing from favorable upstream to adverse downstream.
  • the tips 220 will experience flow- induced oscillations, since the flow pressure gradient exactly over it will be zero.
  • the flow 208 will separate downstream of the tips 220 entrapping a small vortex 222. Due to the damping provided by the compliant layers 204, most of the turbulent kinetic energy imparted to the plates 202 will be dissipated.
  • the vortex 222 should extend just up to the tip 220 of the plate 202 immediately downstream.
  • a larger vortex 222 will cause full-blown flow separation with an accompanying large increase in form or pressure drag.
  • a small vortex 222 due to excessive entrainment in the shear layer 224, will increase the skin friction drag.
  • a reduction in skin friction occurs due to the reversed flow next to the surface of the plates 202 caused by the vortex 222.
  • the choice of the compliant porous elastomeric layer has to be such that its damping increases significantly for oscillation frequencies greater than 2f.
  • FIG. 1 1 is a diagram of an FCS 250 interacting with a flow of fluid in accordance with another embodiment of the present invention.
  • the plates 202 have a curved profile giving and form a fish-scale pattern.
  • counter-rotating longitudinal vortices 252 can be generated that can assist in drawing the shear layer closer to the surface of the plates 202 by enhancing mixing.
  • FIG. 12 is a diagram of a heat transfer enhancement test apparatus 300 in accordance with another embodiment of the present invention.
  • the heat transfer enhancement test apparatus 300 includes an FCS 302, which is wrapped around the leading edges of heat exchanger fins 304 and 306.
  • the heat exchanger fins 304 and 306 are 250 mm wide.
  • a 3-m/s approach velocity of ambient atmospheric air 308 through a 12.5- mm wide fin passage was used while the upper heat exchanger fin 304 was heated or cooled.
  • the heat transfer coefficients were deduced from direct measurement of fin surface heat flux and air temperatures.
  • the passage pressure drop is between the ambient air and exit of the passage.
  • Application of the FCS 302 was seen to reduce the pressure drop by about 32% while increasing fin surface heat transfer coefficients between 43% and 127%.
  • the FCS 302 achieves this by destroying the similarity of temperature and velocity profiles (i.e., Reynolds analogy) through the sustenance of a thin vortex 310, through turbulence spectrum modification, near the fin surface. Heat flows easily across this vortex, which also allows the main flow through the passage to proceed unabated as compared to the clean fin surface.
  • the following illustrates heat transfer characteristics with and without the FCS 302.
  • FIG. 13 is a top-view diagram of a multi-fin heat sink 350 in accordance with another embodiment of the present invention.
  • the multi-fin heat sink 350 includes an FCS 352, which is wrapped around heat exchanger fins 354.
  • the heat exchanger fins 354 are coupled to a base 356. In operation, heat transfer from the fins to a fluid, or vice-versa, is enhanced, while reducing the fin-passage pressure drop in the fluid.
  • FIG. 14 is a side-view diagram of the multi-fin heat sink 350 of FIG. 13.
  • the FCS-enhanced fins 354 can be configured into a multi-fin heat exchanger in a variety of ways.
  • the fins can be staggered as shown in FIG. 13.
  • the fins 354 can form a plurality of flow passages.
  • the flow passages can be parallel.
  • the principal flow through the flow passages can also have a component parallel to the local gravitational field thereby creating a compact natural convection surface.
  • the FCS can be coupled to fins on a heat pipe, fins on a tube carrying a hot or cold heat transfer fluid, or to the leading edge of one or more blades of a fan.
  • Skin friction drag can be reduced by lifting the boundary layer off the wall by a small amount using a backward facing step to intentionally promote separation behind it, as demonstrated by a 70- ⁇ thick duct tape wrapped around a model rocket immediately behind its nose cone (Fig 15).
  • the coefficient of drag C D deduced from the total pressure difference between the front and rear of the rocket measured by the averaging drag rake in Fig 15 is shown in Fig 16.
  • the reduction in drag increases the maximum altitude of the rocket when it is launched (Fig 17).
  • the reduction in skin friction behind the step can also be used to reduce drag in supersonic flows as demonstrated by the reduced angle of the shock waves at the leading edge of a wedge in an analogous situation of free surface water flow (Fig 18).
  • deturbulator is a surface mounted device that interacts with the flow boundary by means such as passive or active flow-induced compliant wall motion (Fig 1 ), flow induced motion of nano-fibers or other forms of surface mounted compliant or porous structures, electromagnetic forces, motion of trapped vortices due to modified surface texture or geometry or other types of turbulent kinetic energy dissipation or turbulence spectrum modifiers.
  • Fig 19a shows the integration of a FCSD with backward and forward facing steps
  • the forward facing step enhances the formation of the separated flow behind the forward facing step by preventing the thin layer of nearly stagnant fluid near the wall from sliding downstream.
  • the FCSD by itself has been known to create stable thin layers of separated flow in adverse pressure gradients typical in the aft regions of streamlined objects (Sinha 2001 ) resulting in lowering skin friction without increasing form drag as shown in Fig 19b.
  • This effect is extended to favorable pressure gradient regions typical in the forward section of streamlined objects. As a result skin friction is reduced across almost the entire surface of a streamlined object.
  • the increase in lift means that the wing has to fly at a lower angle of attack at a given airspeed, reducing the forward component of the resultant pressure induced force. This reduces the lift-induced drag (commonly referred to as induced drag) of the wing. Since increase in lift occurs along with reduced drag (including skin friction, form drag and induced drag), the lift to drag ratio of the airfoil section and entire wing increase. This was demonstrated during inflight sink rate measurements of the Standard Cirrus sailplane, whose wings were subject to the treatment described above over extended regions of the span (Fig 21 a).
  • Fig 22 shows an installation of FPC and FCSD on the top surface of the GT-3 aircraft (Fig 3) wing.
  • Fig 23 shows the measured velocity profiles at 90% chord.
  • Fig 24 shows the reduction in profile drag of the NLF-0414F airfoil section of this wing due to combined upper and lower surface treatment with FPC-FCSD.
  • deturbulators similar to the FCS in Fig- 1 can also be used to streamline road vehicles (Fig 25) and other bluff or partially streamlined objects whose functionality precludes the addition of boattails or other shapes for further streamlining. Enhancing turbulence in the flow over such objects, such as through dimples on golf balls, can reduce drag to a certain extent by reducing the size of the wake but cannot eliminate it altogether.
  • Fig 26 shows a backward facing step behind the windshield and a FCSD just upstream of the rear windshield of a model vehicle in the wind tunnel.
  • Fig 27 shows the reduction in drag due to the various combinations of step and FCSD at a Re of 0.4-million.
  • Fig 28a and Fig 28b shows the same treatment on a 2000 Honda Odyssey EX minivan. Due to larger Re (about 8 million), the front step has been replaced with FCSD on the prototype minivan.
  • Fig 29a measured improvement in highway gas mileage and Fig 29b shows an increase in overall mileage resulting from the treatment of Fig 28a and Fig 28b.
  • the present invention provides numerous benefits. For example, it can enhance heat transfer in a variety of applications while minimizing or lowering the drop in flow pressure, or reduce aircraft wing drag or make fans more efficient and quiet.
  • a passive electrical mode is to be used comprising imbedded interconnected electrodes.
  • Figure 30 presents a 3-view of Std. Cirrus, a 15 meter test bed sail plane.
  • the wing surface distribution is a full length, spanwise mounted, strip of very thin and flat, silvered Mylar hollow tubing that is about 50 mm (1 .98 inches) wide. Mounted on the wing top surfaces at about .65 chord distance from the wing leading edge, it is designed to filter out small turbulence waves in the wing's boundary layer by a process called dynamic flow control.
  • the wing forward leading edges were treated with a proprietary coating, designed to improve the wing airflow boundary layer characteristics.
  • the Std. Cirrus airspeed system uses a fuselage nose pitot tube that is located in the cockpit ventilation air inlet. Small vent holes on the fuselage sides below the wing serve as its static sources. First we checked the pilot and static system lines for leaks, and repaired a small one. Then, while inside the hangar and out of the wind, the sailplane's Winter airspeed indicator was calibrated by carefully comparing its readings to our calibrated reference ASI meter. The errors that were measured for the sailplane's Winter ASI were relatively low, less than about 2 knots over our entire planned flight test range. Those measured
  • the Figure 33 chart presents the flight measured Airspeed System errors. In that figure it is assumed that the airspeed indicator has no errors, and that the errors shown would be those using a perfect ASI.
  • the Std. Cirrus's airspeed system measured errors were small at relatively low airspeeds, but increased almost linearly to about 7 kts at 100 kts indicated airspeed. In general, the test data measurements show that the Std. Cirrus is actually flying considerably slower than the indicated airspeed, but only when flying at airspeeds above 50 kts.
  • deturbulators showed a slightly higher drag than with the clean wings.
  • Cirrus best glide performance from about 33.5:1 at 44 kts, to about 38:1 at 46 kts; an improvement of about 13% in L/Dmax.
  • These numbers are again derived from a 4 th order trend-line drawn through the less-scattered test data points.
  • the many- point averaged deturbulated wing test data at 48 kts still shows a well-above trend-line L/D point of almost 40:1 , an improvement of about 18% over that of the clean-wing data.
  • the above-90 kt data with the deturbulators still showed a slightly higher drag than with the clean wings.
  • chordwise waviness measurements were performed of our test Std. Cirrus's wing top and bottom surfaces at 14 spanwise stations along each wing panel. The magnitudes of wing's surface waves were quite nominal, averaging only about .0044 inches peak-to-peak. That is relatively good, especially considering the sailplane's age. Only on the outer wing panel did our measurements much exceed that value. Those waviness measurements are for peak-to-peak magnitudes -from valleys to peaks.
  • the new Deturbulator could be is a really significant drag-reducing aerodynamic invention since the development of the now-common laminar-flow airfoils that were developed some 65 years ago. Its small size and lightweight make it easy to apply on a sailplane wing. Its location on a sailplane wing may be critical, and if similar performance improvements can be achieved with the many types of high performance sailplanes.
  • a Deturbulator layout for an aircraft as follows:
  • FCSD4/FPC Flow Pre-conditioners

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  • Engineering & Computer Science (AREA)
  • Physics & Mathematics (AREA)
  • Mechanical Engineering (AREA)
  • General Engineering & Computer Science (AREA)
  • Fluid Mechanics (AREA)
  • Thermal Sciences (AREA)
  • Aviation & Aerospace Engineering (AREA)
  • Aerodynamic Tests, Hydrodynamic Tests, Wind Tunnels, And Water Tanks (AREA)
  • Turbine Rotor Nozzle Sealing (AREA)

Abstract

Le nouveau dé-turbulateur peut être une invention aérodynamique réduisant la traînée de façon vraiment importante depuis le développement des surfaces portantes à écoulement laminaire désormais courantes qui ont été développées il y a 65 ans. Sa petite taille et sa légèreté lui permettent de facilement s'appliquer sur une aile de planeur. Sa position sur une aile de planeur peut être essentielle, et si des améliorations de performances similaires peuvent être réalisées grâce aux nombreux types de planeurs aux performances élevées.
PCT/US2008/053517 2007-08-02 2008-02-08 Procédé d'amélioration de la réduction de traînée d'écoulement et de la production d'élévation à l'aide d'un dé-turbulateur WO2011149440A2 (fr)

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US60/888,860 2007-08-02

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Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US9586464B2 (en) 2015-03-31 2017-03-07 Nissan North America, Inc. Vehicle sunroof wind deflector
WO2019203907A1 (fr) * 2018-04-18 2019-10-24 Avakian Manuel S Système de traitement et de distribution d'eau pour unités de dialyse
WO2021201811A3 (fr) * 2020-12-22 2021-12-23 Msg Teknoloji̇ Li̇mi̇ted Şi̇rketi̇ Surface portante partiellement flexible formée avec un matériau souple à base de silicone

Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2001050215A (ja) * 1999-08-11 2001-02-23 浩伸 ▲黒▼川 カルマン渦低減体
JP2005532209A (ja) * 2002-04-18 2005-10-27 エアバス ドイッチュラント ゲゼルシャフト ミット ベシュレンクテル ハフツング 層流システムのための穿孔スキン構造
WO2006105174A2 (fr) * 2005-03-29 2006-10-05 Sinhatech Procede permettant de reduire la trainee et d'accroitre la portance grace a l'ecoulement d'un fluide sur des objets solides

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2001050215A (ja) * 1999-08-11 2001-02-23 浩伸 ▲黒▼川 カルマン渦低減体
JP2005532209A (ja) * 2002-04-18 2005-10-27 エアバス ドイッチュラント ゲゼルシャフト ミット ベシュレンクテル ハフツング 層流システムのための穿孔スキン構造
WO2006105174A2 (fr) * 2005-03-29 2006-10-05 Sinhatech Procede permettant de reduire la trainee et d'accroitre la portance grace a l'ecoulement d'un fluide sur des objets solides

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US9586464B2 (en) 2015-03-31 2017-03-07 Nissan North America, Inc. Vehicle sunroof wind deflector
WO2019203907A1 (fr) * 2018-04-18 2019-10-24 Avakian Manuel S Système de traitement et de distribution d'eau pour unités de dialyse
WO2021201811A3 (fr) * 2020-12-22 2021-12-23 Msg Teknoloji̇ Li̇mi̇ted Şi̇rketi̇ Surface portante partiellement flexible formée avec un matériau souple à base de silicone

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