GB2518138A - Ducted fan assembly - Google Patents
Ducted fan assembly Download PDFInfo
- Publication number
- GB2518138A GB2518138A GB1313700.5A GB201313700A GB2518138A GB 2518138 A GB2518138 A GB 2518138A GB 201313700 A GB201313700 A GB 201313700A GB 2518138 A GB2518138 A GB 2518138A
- Authority
- GB
- United Kingdom
- Prior art keywords
- duct
- fan
- ducted fan
- fan assembly
- ducted
- Prior art date
- Legal status (The legal status 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 status listed.)
- Granted
Links
Classifications
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B64—AIRCRAFT; AVIATION; COSMONAUTICS
- B64C—AEROPLANES; HELICOPTERS
- B64C11/00—Propellers, e.g. of ducted type; Features common to propellers and rotors for rotorcraft
- B64C11/001—Shrouded propellers
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B60—VEHICLES IN GENERAL
- B60V—AIR-CUSHION VEHICLES
- B60V1/00—Air-cushion
- B60V1/14—Propulsion; Control thereof
Landscapes
- Engineering & Computer Science (AREA)
- Aviation & Aerospace Engineering (AREA)
- Chemical & Material Sciences (AREA)
- Combustion & Propulsion (AREA)
- Transportation (AREA)
- Mechanical Engineering (AREA)
- Structures Of Non-Positive Displacement Pumps (AREA)
Abstract
A fan and duct assembly for a hovercraft or the like includes a fan 6 which is located immediately in front of the bell mouth 5 of a duct 4. A further duct 1 may be located downstream of the first duct and includes an entrance 2 and exit 3. The fan 6 consists of a housing 7 driven by a motor and with blades 8 extending from the housing. The rear duct 1 may include slats 9 that enable a reversal of airflow through the duct. The assembly may include rudders (11,12, fig 6) to direct the airflow exiting the ducts.
Description
DUCTED FAN ASSEMBLY
FIELD OF THE INVENTION
The present invention relates to a duoted fan assembly. More especially, the invention relates to ducted fan assemblies for propelling land and sea going vehicles such as hovercrafts and for providing a flow of air under pressure for venting purposes. These are just a few examples of uses for ducted fan assemblies, in accordance with this invention, can be employed.
BACKGROUND TO THE INVENTION
Ducted fan assemblies general comprise a fan and a duct which directs a flow of pressurised air. In such assemblies the fan sits within the duct itself in an attempt to ensure that as much air is directed through the duct as possible.
There is a constant need to improve performance of ducted fan assemblies to drive as much air through the duct as possible.
In hovercrafts this is especially important as increased air flow through the duct contributes to an increase in thrust.
Convention currently dictates that as little gap as possible must be provided between the tips of the fan blades and the inner wall of the duct so as to minimise turbulence around the blade tips causing re-direction from the high pressure at the back of the fan to low pressure at the front.
Convention also currently dictates that increased performance and thrust is achieved by increasing the duct diameter or by having two ducted fan assemblies side-by-side.
The fact that the fan has to sit very accurately within the duct causes tolerances in the manufacture of the fan blade design and length to be minimal. In the event that the blades of the fan become bent cr damaged, or that they expand through heat, the fan blades are likely to strike the inside of the duct, causing damage, or potentially blocking the duct thereby restricting the airflow.
Minimum tolerance leads conventional ducted fan assemblies to require precision engineering and manufacture.
Furthermore, manufacturers are often restricted as to the types of material that they may use to make the fan as any material used should be non-expandable in heat and also brittle so as to reduce any damage to the duct should the blades of the fan strike it. This is particularly important in ducted fans used for vehicle tunnels for example.
Through extensive development and testing, the Applicant has found that a surprise affect occurs when the fan is located immediately in front of the entrance of the duct (in this case for a system used on a hovercraft), the effect being an enhanced performance of the ducted fan assembly resulting in significantly increased thrust.
Contrary to conventional teaching, tests have shown that the air is sucked in to the duct at the region of the outer periphery of the fan blades, rather than, as one would expect, air within that region to directed outwardly away from the duct.
Moreover, tests have shown that noise level is reduced and that noise emitted is smoother and more stable. The Applicant believes that noise reduction is as a result of less turbulent air flow at the blade tips.
SUMMARY OF THE INVENTION
In one aspect, the present invention provides a fan and a duct wherein the fan is located immediately in front of the duct.
Preferably the diameter of the fan is greater than the internal diameter of the duct.
Preferably the distance between the fan and the entranoe to the duct is in the range of 02.cm to 13 cm, and preferably still the distance is 0.6 cm.
Preferably at least part of each the side wall has a louvred oonfiguration providing an array of apertures through which air flow can be directed.
Preferably, the louvred formation comprises an array of slats with a surface angled towards the front of the duct.
Preferably, a plurality of rudders are located near to or at the exit of the duct.
Preferably, the rudders are independently controllable so as to direct at least part of the air flow out of the duct through the louvred section.
BRIEF DESCRIPTION OF THE DRAWINGS
The invention will now be described by way of example only with reference to the accompanying drawings in which, Figure 1 is perspective of a ducted fan assembly constructed in accordance with the present invention for use with a hovercraft; Figure 2 is a side view of the ducted fan assembly of figure Figure 3 is a front view of the ducted fan assembly; Figure 4 is a rear view of the ducted fan assembly shown on a hoveroraft body; Figure 5 is a rear view of the ducted fan assembly with one rudder tilted; Figure 6 is a rear view of the ducted fan assembly with both rudders tilted; Figure 7 is a front view of the ducted fan assembly with both rudders tilted; Figure 8 is a front view of the ducted fan assembly with one rudder tilted; Figure 9 is a front view of the ducted fan assembly; and Figure 10 is an exploded view of a section of the ducted fan assembly.
DETAILED DESCRIPTION OF THE INVENTION
Figure 1 illustrates a ducted fan assembly constructed in accordance with the invention. Such an assembly is described hereinafter with reference to use with a hovercraft.
As can be seen in this figure, the invention comprises an first annular duct 1 with an entrance 2 and exit 3. A second annular duct 4 of less length that the first duct 1 is provided immediately in front of the first duct 1.
In an alternative embodiment the first and second ducts 1, 4 are formed integral with one another, in a further embodiment only one duct is provided.
The entrance of the second duct 1 is formed as a bell mouth 5.
The bell mouth of the ducts 1, 4 in the embodiment described is not of constant radius whereby the duct increases in diameter towards the opening of the bell mouth. The ducts though may be formed with a constant radius.
Typically, the duct 1 may have an internal diameter of approximately 81 cm and an outer diameter of approximately 99 cm.
An axial fan 6 is positioned immediately in front of bell mouth 5 of the duct 4. The fan 6 consists of a housing 7, driven to rotate by a motor (not shown) and blades 8 extending laterally from the housing 7. The fact the fan 6 is located outside the duct 4, immediately in front of the bell mouth 5, means that the overall fan diameter may be larger than the duct 4. consequently, increased performance is no longer limited solely to the duct size. Moreover, the ducted system would not be compromised or otherwise affected by slight expansion or deformation of the blades 8. This would allow for increased tolerances during the manufacture and design of the fan blades 8. It would also allow for a greater selection of material from which the fan blades 8 can be manufactured allowing for materials that would be more suited for the purpose.
Tests have shown that the optimum distance between the fan housing 7 and the duct entrance 2 is in the range of 0.2 cm to approximately 13 cm, and most preferably around 0.6 cm.
Within this range, it has been observed that, contrary to expectations, air flow into the duct increased resulting in an increase in thrust of approximately 20%. Tn tests, for example, thrust was increased from 851b (38.5kg) 1051b (47.6kg) Preferably the fan housing 7 is as near to the bell mouth 5 of the duct 4 as possible. The fan and bell mouth may be close to the extent that the tips of the blades 8 of the fan 6 touch or brush the outer rim of the bell mouth 5.
As can be seen in figure 2, the side walls of the duct 1 towards the exit are louvred with each slat 9 having an angled or curved surface 10 so that air flow may be reversed and directed through the slats 8 and out of the duct 1 towards the entrance of the duct 1.
Disposed and moveably fixed at the exit of the annular duct 1, are two rudder members 11, 12 (best seen in figures 5 and 6) In use the rudders 11, 12 can be individually controlled to direct part or all of the flow along one side of the duct 1 out of the slats 9.
Figures 3 and 4 show the rudders 11, 12 left open allowing air to pass straight through the exit 3 of the duct.
Figure 5 shows one rudder 11 tilted to olose of half the duct 1 (the right hand side in the figure) Part or full closure of the rudder 11 will cause the hovercraft to turn right.
Figure 6 shows both rudders 11, 12 tilted to close off the entire duct forcing air to flow back through the slats 10 in the reverse direction, causing hovercraft to reverse.
Each rudder 11, 12 is controlled by a controlling means (not shown), for example a rod or cable extending to a foot pedal or hand lever. Control of the pedal or lever causes the associated rudder to open or close independently of the other.
Opening or closing of the rudders forces the airflow to exit via a particular area of the exit portion.
In this way, the ducted fan assembly may be employed, for example, as the propulsion system in a hoveroraft to modulate the hovercraft's speed and direction.
It will be appreciated that the foregoing is merely examples of embodiments and just some examples of their use. The skilled reader will readily understand that modifications can be made thereto without departing from the true scope of the invention.
Claims (8)
- CLAIMS1. A ducted fan assembly comprising a fan and a duct wherein the fan is located immediately in front of the duct.
- 2. A ducted fan assembly according to claim 1, wherein the diameter of the fan is greater than the internal diameter of the duct.
- 3. A ducted fan assembly according to claim 1 or claim 2, wherein the distance between the fan and the entrance to the duct is in the range of 0.2 cm to approximately 13 cm.
- 4. A ducted fan assembly according to claim 3, wherein the distance between the fan and the duct is 0.6 cm.
- 5. A ducted fan assembly according to any one of claims 1 to 4, wherein at least part of each the side wall has a lcuvred configuration providing an array of apertures through which air flow can be directed.
- 6. A ducted fan according to claim 5, wherein the louvred formation comprises an array of slats with a surface angled towards the front of the duct.
- 7. A ducted fan assembly as described in Claim 6, wherein a plurality of rudders are located near to or at the exit of the duct.
- 8. A ducted fan assembly as described in Claim 7, wherein the rudders are independently controllable so as to direct at least part of the air flow out of the duct through the louvred section.
Priority Applications (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
PCT/GB2014/000278 WO2015001290A1 (en) | 2013-07-05 | 2014-07-07 | Assembly of a duct and a fan for hovercraft or aircraft propulsion |
Applications Claiming Priority (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
GBGB1312139.7A GB201312139D0 (en) | 2013-07-05 | 2013-07-05 | Ducted fan assembly |
Publications (3)
Publication Number | Publication Date |
---|---|
GB201313700D0 GB201313700D0 (en) | 2013-09-11 |
GB2518138A true GB2518138A (en) | 2015-03-18 |
GB2518138B GB2518138B (en) | 2019-08-21 |
Family
ID=49033427
Family Applications (2)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
GBGB1312139.7A Ceased GB201312139D0 (en) | 2013-07-05 | 2013-07-05 | Ducted fan assembly |
GB1313700.5A Expired - Fee Related GB2518138B (en) | 2013-07-05 | 2013-07-31 | Ducted fan assembly |
Family Applications Before (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
GBGB1312139.7A Ceased GB201312139D0 (en) | 2013-07-05 | 2013-07-05 | Ducted fan assembly |
Country Status (2)
Country | Link |
---|---|
GB (2) | GB201312139D0 (en) |
WO (1) | WO2015001290A1 (en) |
Citations (5)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
GB389288A (en) * | 1931-04-16 | 1933-03-16 | Luigi Stipa | Propeller arrangement for aeroplanes and the like |
GB578005A (en) * | 1941-10-28 | 1946-06-12 | Fritz Albert Max Heppner | Improvements in and relating to jet propulsion plant |
GB2058222A (en) * | 1979-09-10 | 1981-04-08 | Do Gpkexi Komplex Mekh Shakht | Propulsion installation of air-cushion transport vehicle |
GB2145774A (en) * | 1983-08-31 | 1985-04-03 | Dowty Rotol Ltd | Bladed rotors and ducts associated therewith |
GB2389826A (en) * | 2002-06-22 | 2003-12-24 | John Edward Randell | Craft propulsion |
Family Cites Families (4)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
GB386355A (en) * | 1930-09-01 | 1933-01-19 | Luigi Stipa | Improvements in propellers for aeroplanes and the like |
US1963715A (en) * | 1932-11-29 | 1934-06-19 | Francesco Pandolfi | Cylindrical flying ship |
FR2759971B1 (en) * | 1997-02-21 | 1999-07-16 | Christian Hugues | TRAINE REDUCTION |
US7559191B2 (en) * | 2004-09-17 | 2009-07-14 | Aurora Flight Sciences Corporation | Ducted spinner for engine cooling |
-
2013
- 2013-07-05 GB GBGB1312139.7A patent/GB201312139D0/en not_active Ceased
- 2013-07-31 GB GB1313700.5A patent/GB2518138B/en not_active Expired - Fee Related
-
2014
- 2014-07-07 WO PCT/GB2014/000278 patent/WO2015001290A1/en active Application Filing
Patent Citations (5)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
GB389288A (en) * | 1931-04-16 | 1933-03-16 | Luigi Stipa | Propeller arrangement for aeroplanes and the like |
GB578005A (en) * | 1941-10-28 | 1946-06-12 | Fritz Albert Max Heppner | Improvements in and relating to jet propulsion plant |
GB2058222A (en) * | 1979-09-10 | 1981-04-08 | Do Gpkexi Komplex Mekh Shakht | Propulsion installation of air-cushion transport vehicle |
GB2145774A (en) * | 1983-08-31 | 1985-04-03 | Dowty Rotol Ltd | Bladed rotors and ducts associated therewith |
GB2389826A (en) * | 2002-06-22 | 2003-12-24 | John Edward Randell | Craft propulsion |
Also Published As
Publication number | Publication date |
---|---|
GB201312139D0 (en) | 2013-08-21 |
GB201313700D0 (en) | 2013-09-11 |
WO2015001290A1 (en) | 2015-01-08 |
GB2518138B (en) | 2019-08-21 |
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Legal Events
Date | Code | Title | Description |
---|---|---|---|
PCNP | Patent ceased through non-payment of renewal fee |
Effective date: 20191121 |