US4932612A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Method and apparatus for reducing turbulent skin friction
Assignee: Individual
•
Filing: 1987-10-26
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Granted: 1990-06-12
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Expires: 2007-10-26
Abstract
Abstract A method and apparatus for reducing the skin friction on objects in relative motion to a field of fluid. The areas of relative low speed motion are fixed to align with a series of ridges on the surface of the object. The areas of low speed motion aligned with the ridges are removed by suction from the turbulent boundary layer which results in a reduction of drag on the object. An alternative embodiment injects fluid into areas of relative high speed between the ridges to reduce the shear and the drag caused by it. Selective suction and injection are combined in one apparatus in a second alternative embodiment. A fourth embodiment injects a polymeric solution to reduce drag. A fifth embodiment heats the fluid in specified areas to reduce drag. A sixth embodiment uses a compliant material in specified areas of the surface in contact with flowing fluid to reduce drag.
Inventors
- 👤 Ron F. Blackwelder
- 👤 Mohamed Gad-el-Hak
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-24 16:24
CPC Classifications
B; B64; B64C; B64C21/00; B64C21/02; B64C21/025; B64C21/04; B64C21/06; B64C21/10; B64C2230/00; B64C2230/04; B64C2230/06; B64C2230/10; B64C2230/16; B64C2230/26; Y; Y02; Y02T; Y02T50/00; Y02T50/10
Claims Analysis
Total Claims: 29
Claim 1
Independent Claim
68 words
A method for reducing turbulent skin friction of bodies in relative motion to a field of fluid comprising the steps of: locating localized areas of high and low speed flow in the area adjacent to the outside surface of the bodies; and, fixing said areas of low and high speed flow to a given area on the body; and, removing said areas of low and high speed flow.
Claim 2
Independent Claim
68 words
A method for reducing turbulent skin friction of bodies in relative motion to a field of fluid comprising the steps of: locating localized areas of high and low speed flow in the area adjacent to the outside surface of the bodies; and, fixing said areas of low and high speed flow to a given area on the body; and, removing said areas of low and high speed flow.
Claim 3
Dependent Claim
27 words
The method of claim 1, wherein said removing step is provided by removal of fluid in the low speed area from near the body by selective suction.
Claim 4
Dependent Claim
24 words
The method of claim 1, wherein said removing step is provided by selective injection of fluid into the high speed area near the body.
Claim 5
Dependent Claim
18 words
The method of claim 1, wherein said fixing step is accomplished by addition of ridges to said body.
Claim 6
Dependent Claim
22 words
The method of claim 4, wherein said removing step is provided by removal of fluid in the low speed area by suction.
Claim 7
Dependent Claim
16 words
The method of claim 5, wherein said suction is provided at the peaks of said ridges.
Claim 8
Dependent Claim
25 words
The method of claim 4, wherein said fixing step is provided by addition of ridges parallel to the direction of fluid flow to said body.
Claim 9
Dependent Claim
16 words
The method of claim 7, wherein said injection is provided between the peaks of said ridges.
Claim 10
Dependent Claim
24 words
The method of claim 4 wherein said fixing step is accomplished by heating fluid in the localized area adjacent the apex of said ridges.
Claim 11
Dependent Claim
16 words
The method of claim 9 wherein said heating is accomplished by use of electrical heating elements.
Claim 12
Dependent Claim
24 words
The method of claim 4 wherein said fixing step is accomplished by the injection of a polymeric solution at the apex of said, ridges.
Claim 13
Dependent Claim
25 words
The method of claim 4, wherein the said fixing step is accomplished by the provision of a compliant surface at the apex of said ridges.
Claim 14
Dependent Claim
31 words
The method of claim 4, wherein the fixing step is accomplished by the heating of fluid in the localized area between the apex of said ridges and the fluid is air.
Claim 15
Independent Claim
79 words
An apparatus for reducing drag on objects surrounded by a boundary layer of fluid in relative motion to a field of fluid comprising; fixation means attached to said object for fixing low and high speed areas of fluid flow to preselected areas on said object; and, retardation means attached to said object for retarding the bursting process in the boundary layer of fluid around said object; and, timing means attached to said retardation means to randomly time its application.
Claim 16
Independent Claim
79 words
An apparatus for reducing drag on objects surrounded by a boundary layer of fluid in relative motion to a field of fluid comprising; fixation means attached to said object for fixing low and high speed areas of fluid flow to preselected areas on said object; and, retardation means attached to said object for retarding the bursting process in the boundary layer of fluid around said object; and, timing means attached to said retardation means to randomly time its application.
Claim 17
Dependent Claim
26 words
An apparatus as in claim 14, wherein said fixation means is a series of ridges attached to said object parallel to the direction of fluid flow.
Claim 18
Dependent Claim
14 words
An apparatus as in claim 15, wherein said ridges are circular in cross section.
Claim 19
Dependent Claim
19 words
An apparatus as in claim 14, wherein said retardation means includes a series of slots parallel to said ridges.
Claim 20
Dependent Claim
17 words
An apparatus as in claim 17, wherein said slots are adapted for addition and withdrawal of fluid.
Claim 21
Dependent Claim
28 words
An apparatus as in claim 17, wherein said slots are located on the tops of said ridges and are provided for withdrawal of fluid from said boundary layer.
Claim 22
Dependent Claim
36 words
An apparatus as in claim 17 wherein said slots are so located as to coincide with the location of relative low speed fluid streaks in said boundary layer and remove said streaks when suction is applied.
Claim 23
Dependent Claim
18 words
An apparatus as in claim 17, wherein said slots are located in the valleys created between said ridges.
Claim 24
Dependent Claim
15 words
An apparatus as in claim 21, wherein said slots are adapted for injection of fluid.
Claim 25
Dependent Claim
38 words
An apparatus as in claim 22, wherein said slots are so located as to coincide with the location of areas of relative high speed fluid and destroy said areas when fluid is injected into said high speed areas.
Claim 26
Dependent Claim
103 words
An improved aircraft of the type including two wings attached to an elongated fuselage which is extended in a direction parallel to normal motion of the aircraft in a field of gas with a turbulent boundary layer adjacent to the fuselage, the improvement comprising; a plurality of ridges attached to the fuselage of said aircraft for fixing the area in relative low speed motion in said fluid to a point on said fuselage; and, a plurality of slots parallel to said ridges for adding and withdrawing fluid in said boundary layer for retarding the shedding of said areas in relative low speed motion.
Claim 27
Dependent Claim
103 words
An improved aircraft of the type including two wings attached to an elongated fuselage which is extended in a direction parallel to normal motion of the aircraft in a field of gas with a turbulent boundary layer adjacent to the fuselage, the improvement comprising; a plurality of ridges attached to the fuselage of said aircraft for fixing the area in relative low speed motion in said fluid to a point on said fuselage; and, a plurality of slots parallel to said ridges for adding and withdrawing fluid in said boundary layer for retarding the shedding of said areas in relative low speed motion.
Claim 28
Dependent Claim
31 words
An improved aircraft as in claim 24, further comprising: suction means attached to said slots for withdrawing fluid from said boundary layer in areas immediately above the peaks of said ridges.
Claim 29
Dependent Claim
27 words
An improved aircraft as in claim 24 further comprising injection means attached to said slots for injecting fluid into said boundary layer in areas between said ridges.
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USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1993-06-11 | 1993-12-11 | 1994-06-12 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1997-06-11 | 1997-12-11 | 1998-06-12 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2001-06-11 | 2001-12-11 | 2002-06-12 | $7700.00 | Window Closed / Lapsed |