METHOD FOR IMPROVING CROSSWIND STABILITY OF A PROPELLER DUCT AND A CORRESPONDING APPARATUS, SYSTEM AND COMPUTER READABLE MEDIUM

• US 20150344126A1
• Filed: 01/13/2014
• Published: 12/03/2015
• Est. Priority Date: 01/21/2013
• Status: Abandoned Application

• Current Assignee: Singapore Technologies Aerospace Limited (Government of Singapore)
• Original Assignee: Singapore Technologies Aerospace Limited (Government of Singapore)
• Inventors: CHAN, Keen Ian
• Application Number:
  US14/760,278
• Publication Number:
  US 20150344126A1
• Time in Patent Office: Days
• US Class Current: 1/1
• CPC Class Codes: B64C 11/001 Shrouded propellers
• CPC Class Codes: B64C 27/20 Rotorcraft characterised by having shrouded rotors, e.g. flying platforms
• CPC Class Codes: F15D 1/02 in pipes or conduits

Abstract

Various embodiments provide a method for improving crosswind stability of a propeller duct. The method comprises defining an initial duct section based on a predetermined airfoil section having an initial value of a geometric parameter such that the geometric parameter of a portion of the initial duct section has the initial value. The method also comprises determining fluid flow paths around the initial duct section when subject to a crosswind having a predetermined crosswind speed. The method further comprises varying the initial value of the geometric parameter of the initial duct section to a threshold value which causes separation of fluid flow paths at a windward side of the initial duct section at and above the predetermined crosswind speed to form an improved duct section. Various embodiments provide a corresponding apparatus, system and/or computer readable medium.

Claims

1. A method for improving crosswind stability of a propeller duct, the method comprising:

defining an initial duct section free of added flow controllers based on a predetermined airfoil section having an initial value of a geometric parameter such that the geometric parameter of a portion of the initial duct section has the initial value;

determining fluid flow paths around the initial duct section when subject to a crosswind having a predetermined crosswind speed; and

varying the initial value of the geometric parameter of the initial duct section to a threshold value which causes separation of fluid flow paths at a windward side of the initial duct section at and above the predetermined crosswind speed to form an improved duct section corresponding to the predetermined crosswind speed.

2. The method as claimed in claim 1, wherein the portion of the initial duct section having the initial value of the geometric parameter is a leading edge portion of the initial duct section.

3. The method as claimed in claim 2, wherein a curvature of the leading edge portion of the initial duct section corresponds with a curvature of a leading edge portion of the predetermined airfoil section.

4. The method of claim 1, wherein a leading edge portion of the initial duct section comprises an airfoil portion having the same initial value of the geometric parameter as the predetermined airfoil section.

5. The method of claim 1, wherein determining fluid flow paths around the initial duct section when subject to a crosswind having a predetermined crosswind speed comprises determining a flow field.

6. The method of claim 1, wherein the threshold value causes attached fluid flow paths at the windward side at below the predetermined crosswind speed.

7. The method of claim 1, wherein varying the initial value of the geometric parameter of the initial duct section varies a curvature of a leading edge portion of the initial duct section, and wherein the threshold value defines a specific curvature of the leading edge portion of the initial duct section.

8. The method of claim 7, wherein varying the initial value of the geometric parameter of the initial duct section increases the curvature of the leading edge portion of the initial duct section.

9. The method of claim 6, further comprising determining fluid flow paths around the improved duct section at below the predetermined crosswind speed to determine that fluid flow paths are attached.

10. The method of claim 1, wherein the geometric parameter comprises a measure of curvature.

11. The method of claim 10, wherein the measure of curvature comprises a thickness to chord ratio.

12. The method of claim 1, further comprising measuring the initial value of the geometric parameter of the predetermined airfoil section.

17. A computer readable storage medium having stored thereon computer program code for instructing a computer processor to execute the method of claim 1.

13. An apparatus comprising:

at least one processor; and

at least one memory including computer program code;

the at least one memory and the computer program code configured to, with the at least one processor, cause the apparatus at least to;

define an initial duct section free of added flow controllers based on a predetermined airfoil section having an initial value of a geometric parameter such that the geometric parameter of a portion of the initial duct section has the initial value;

determine fluid flow paths around the initial duct section when subject to a crosswind having a predetermined crosswind speed; and

vary the initial value of the geometric parameter of the initial duct section to a threshold value which causes separation of fluid flow paths at a windward side of the initial duct section at and above the predetermined crosswind speed to form an improved duct section corresponding to the predetermined crosswind speed.

14. The apparatus of claim 13, further comprising a measuring device configured in use to receive geometric data of the predetermined airfoil section, the measuring device being adapted to determine the initial value of the geometric parameter of the predetermined airfoil section based on the received geometric data.

15. A system for improving crosswind stability of a propeller duct, the system comprising:

means for defining an initial duct section free of added flow controllers based on a predetermined airfoil section having an initial value of a geometric parameter such that the geometric parameter of a portion of the initial duct section has the initial value;

means for determining fluid flow paths around the initial duct section when subject to a crosswind having a predetermined crosswind speed; and

means for varying the initial value of the geometric parameter of the initial duct section to a threshold value which causes separation of fluid flow paths at a windward side of the initial duct section at and above the predetermined crosswind speed to form an improved duct section corresponding to the predetermined crosswind speed.

16. The system of claim 15, further comprising means for receiving geometric data of the predetermined airfoil section and determining the initial value of the geometric parameter of the predetermined airfoil section based on the received geometric data.