AIR LAYER DRAG REDUCTION NOZZLE PLATE AND FLAP
An air layer drag reduction nozzle assembly and retrofit insert for marine vessels is disclosed. The disclosure provides an open cavity and a longitudinal engagement area. A fitting frame is removably affixed to the engagement area and defines an opening that receives a nozzle flap. The flap is hingedly coupled to the fitting frame along a lateral axis extending between port and starboard sides, allowing rotation between closed and open positions. In the closed position, the flap reduces hydrodynamic drag when an air lubrication system is inactive. In the open position, the flap guides gaseous flow from a gas flow inlet toward a direction substantially parallel to the hull. The fitting frame is configured for retrofit installation within an existing sea chest cavity such that an outer surface forms a substantially flush transition with the exterior hull surface. Methods for retrofitting marine vessels are also disclosed.
1 . An air layer drag reduction system nozzle assembly, comprising:
a sea chest having an open cavity therein, wherein said sea chest includes a gas flow inlet, and an open lower boundary configured to receive a flow guiding nozzle flap;
a flow guiding nozzle flap, wherein said flap is configured to guide a direction and flow rate of a gaseous flow;
said sea chest having at least one longitudinal engagement area, wherein said at least one longitudinal engagement area is a rigidly fixed semi-circumferential bracket for mounting said flow guiding nozzle flap, wherein said rigidly fixed semi-circumferential bracket is affixed at least semi-circumferentially at a border of said open lower boundary, and wherein said at least one longitudinal engagement area includes a removably affixed at least semi-circumferential fitting frame;
said flow guiding nozzle flap is coupled to said at least one longitudinal engagement area, wherein said flow guiding nozzle flap is coupled to said at least one longitudinal engagement area by said fitting frame; and
wherein said air layer drag reduction system nozzle assembly is operable in a submerged environment.
2 . The air layer drag reduction system nozzle assembly, as recited in claim 1 , wherein an outer boundary of said fitting frame is configured to conform to a geometry of said open lower boundary of said sea chest.
3 . The air layer drag reduction system nozzle assembly, as recited in claim 1 , wherein said fitting frame includes an inner surface defining an opening configured to conform to a complementary geometry of said flow guiding nozzle flap and an outer surface configured to conform to a complementary geometry of said open lower boundary of said sea chest.
4 . The air layer drag reduction system nozzle assembly, as recited in claim 1 , wherein said at least one longitudinal engagement area further includes:
an intermediary plate positioned between said sea chest and said fitting frame; and
said intermediary plate having an outer boundary configured to conform to a geometry of said open lower boundary of said sea chest and an inner open periphery with a boundary configured to couple with said fitting frame.
5 . The air layer drag reduction system nozzle assembly, as recited in claim 4 , wherein said fitting frame includes an inner surface defining an opening configured to conform to a complementary geometry of said flow guiding nozzle flap and an outer surface configured to conform to a complementary geometry of an open inner periphery of said intermediary plate.
6 . The air layer drag reduction system nozzle assembly, as recited in claim 1 , wherein a forward edge of said flow guiding nozzle flap is coupled to an inner surface of a forward portion of said fitting frame by a hinge connection defining a lateral axis extending between a port side and a starboard side of said fitting frame, and wherein said flow guiding nozzle flap is rotatable about said lateral axis between a closed position and an open position.
7 . The air layer drag reduction system nozzle assembly, as recited in claim 1 , wherein said fitting frame forms a closed loop.
8 . The air layer drag reduction system nozzle assembly, as recited in claim 7 , wherein said fitting frame includes a plurality of apertures configured to align with threaded apertures of said at least one longitudinal engagement area.
9 . The air layer drag reduction system nozzle assembly, as recited in claim 8 , further comprising:
a plurality of mounting bolts extending through said apertures, anti-compression washers positioned between said bolts and said fitting frame, and bolt covers configured to cover heads of said mounting bolts, wherein said bolt covers provide a smoothed external surface.
10 . The air layer drag reduction system nozzle assembly, as recited in claim 1 , wherein a top surface of said flow guiding nozzle flap includes a concave curvature configured to direct gaseous flow from said gas flow inlet toward an axial direction parallel to a hull surface.
11 . The air layer drag reduction system nozzle assembly, as recited in claim 1 , wherein said flow guiding nozzle flap includes a plurality of flow channels extending from a forward region to a rear region of said flow guiding nozzle flap, each flow channel defined by an upper surface of said flow guiding nozzle flap, and upward protrusions forming sidewalls.
12 . The air layer drag reduction system nozzle assembly, as recited in claim 1 , further comprising a removable counterweight positioned at a forward upper region of said flow guiding nozzle flap and configured to bias said flow guiding nozzle flap toward a closed position.
13 . The air layer drag reduction system nozzle assembly, as recited in claim 12 , wherein said counterweight comprises a sacrificial anode.
14 . The air layer drag reduction system nozzle assembly, as recited in claim 12 , wherein a rear section of said counterweight includes at least one concave flow channel configured to direct gaseous flow toward flow channels of said flow guiding nozzle flap.
15 . An air layer drag reduction nozzle insert, comprising:
a fitting frame configured to be removably affixed within an open lower boundary of a sea chest, said fitting frame having an outer surface configured to conform to a complementary geometry of said open lower boundary and an inner surface defining an opening;
a flow guiding nozzle flap positioned within said opening of said fitting frame;
a hinge connection coupling a forward edge of said flow guiding nozzle flap to an inner surface of a forward portion of said fitting frame along a lateral axis extending between a port side and a starboard side of said fitting frame; and
wherein said flow guiding nozzle flap is rotatable about said lateral axis between a closed position and an open position.
16 . The air layer drag reduction nozzle insert, as recited in claim 15 , wherein said fitting frame includes an inner surface defining an opening configured to conform to a complementary geometry of said flow guiding nozzle flap and an outer surface configured to conform to a complementary geometry of said open lower boundary of said sea chest or an intermediary plate.
17 . The air layer drag reduction nozzle insert, as recited in claim 15 , wherein said fitting frame includes an inner surface defining an opening configured to conform to a complementary geometry of said flow guiding nozzle flap and an outer surface configured to conform to a complementary geometry of an open inner periphery of said intermediary plate.
18 . The air layer drag reduction nozzle insert, as recited in claim 15 , wherein said fitting frame forms a closed loop.
19 . The air layer drag reduction nozzle insert, as recited in claim 15 , wherein said fitting frame includes a plurality of apertures configured for mounting said fitting frame to a sea chest or an intermediary plate.
20 . The air layer drag reduction nozzle insert, as recited in claim 19 , further comprising:
a plurality of mounting bolts extending through said apertures, anti-compression washers positioned between said bolts and said fitting frame, and bolt covers configured to cover heads of said mounting bolts, wherein said bolt covers provide a smoothed external surface.
21 . The air layer drag reduction nozzle insert, as recited in claim 15 , wherein a top surface of said flow guiding nozzle flap includes a concave curvature configured to direct a gaseous flow toward an axial direction parallel to a hull surface.
22 . The air layer drag reduction nozzle insert, as recited in claim 15 , wherein said flow guiding nozzle flap includes a plurality of flow channels extending from a forward region to a rear region of said flow guiding nozzle flap, each flow channel defined by an upper surface of said flow guiding nozzle flap, and upward protrusions forming sidewalls.
23 . The air layer drag reduction nozzle insert, as recited in claim 15 , further comprising a removable counterweight positioned at a forward upper region of said flow guiding nozzle flap and configured to bias said flow guiding nozzle flap toward a closed position.
24 . The air layer drag reduction nozzle insert, as recited in claim 23 , wherein a rear section of said counterweight includes at least one concave flow channel configured to direct gaseous flow toward flow channels of said flow guiding nozzle flap.
25 . The air layer drag reduction nozzle insert, as recited in claim 15 , wherein said fitting frame includes a depth configured to position said flow guiding nozzle flap within a sea chest cavity such that an outer surface of said fitting frame forms a substantially flush transition with an outer hull surface of a marine vessel when installed.
26 . A method for retrofitting a marine vessel with an air layer drag reduction nozzle insert, comprising:
providing a nozzle insert, wherein said nozzle insert comprises:
a fitting frame configured to be removably affixed within an open lower boundary of a sea chest, said fitting frame having an outer surface configured to conform to a complementary geometry of said open lower boundary and an inner surface defining an opening;
a flow guiding nozzle flap positioned within said opening of said fitting frame; and
a hinge connection coupling a forward edge of said flow guiding nozzle flap to an inner surface of a forward portion of said fitting frame along a lateral axis extending between a port side and a starboard side of said fitting frame, wherein said flow guiding nozzle flap is rotatable about said lateral axis between a closed position and an open position.
27 . The method for retrofitting a marine vessel with an air layer drag reduction nozzle insert, as recited in claim 26 , further comprising:
removing at least one structure obstructing access to a cavity of said sea chest, thereby exposing said cavity, wherein said cavity provides geometric space configured to receive said nozzle insert.
28 . The method for retrofitting a marine vessel with an air layer drag reduction nozzle insert, as recited in claim 27 , further comprising:
inserting said fitting frame into said cavity of said sea chest such that said fitting frame is positioned within said open lower boundary of said sea chest.
29 . The method for retrofitting a marine vessel with an air layer drag reduction nozzle insert, as recited in claim 28 , further comprising:
securing said fitting frame within said open lower boundary of said sea chest by inserting mounting bolts through apertures of said fitting frame, positioning anti-compression washers between said mounting bolts and said fitting frame, and covering heads of said mounting bolts with bolt covers such that an outer surface of said fitting frame forms a substantially flush transition with an exterior surface of a hull of said marine vessel.
30 . The method for retrofitting a marine vessel with an air layer drag reduction nozzle insert, as recited in claim 26 , wherein said flow guiding nozzle flap of said step of providing a nozzle insert, further includes:
a hinge connection coupling a forward edge of said flow guiding nozzle flap to an inner surface of a forward portion of said fitting frame along a lateral axis extending between a port side and a starboard side of said fitting frame;
a top surface having a concave curvature configured to direct a gaseous flow toward an axial direction parallel to a hull surface;
a plurality of flow channels extending from a forward region to a rear region of said flow guiding nozzle flap, each flow channel defined by an upper surface of said flow guiding nozzle flap and upward protrusions forming sidewalls; and
a removable counterweight positioned at a forward upper region of said flow guiding nozzle flap and configured to bias said flow guiding nozzle flap toward a closed position.