Flow mixer duct for a bleed system

Abstract

A duct for a bleed system of an aircraft, wherein the duct extends from an inlet section to an outlet section along a longitudinal axis, and wherein the duct comprises a continuous piece arranged on and protruding from the internal wall of the duct. The duct is subject to temperature gradients in order to reduce the temperature of the warmest airflow closer to the inner wall rather than rapidly mix the airflow.

Claims

1. A duct for a bleed system of an aircraft, wherein the duct extends at least partially along a longitudinal axis, the duct comprising: an inlet section for entering a fluid flow into the duct; an outlet section, distanced from the inlet section, through which such fluid flow exits the duct; and at least one continuous piece arranged on an internal wall of the duct and protruding therefrom, the at least one continuous piece having: a first end located at a position adjacent to the inlet section and a second end located at a position close to the outlet section, wherein the at least one continuous piece is slantly extended from the first end to the second end along a direction of the longitudinal axis of the duct so that the first and second ends are substantially opposed in transversal cross-section of the duct, wherein the at least one continuous piece has three portions: a first portion starting at the first end of the at least one continuous piece, a second portion, and a third portion ending at the second end of the at least one continuous piece, wherein each of the first portion, the second portion, and the third portion of the at least one continuous piece has a different tilting degree in relation to the longitudinal axis of the duct.

2. The duct according to claim 1, wherein the first and third portions are less tilted in relation to the longitudinal axis of the duct than the second portion.

3. The duct according to claim 1, wherein the first and third portions are substantially parallel to the longitudinal axis of the duct, the second portion forming an angle between 30° and 60° with the longitudinal axis of the duct.

4. The duct according to claim 1, wherein the at least one continuous piece is a substantially elongated thin piece.

5. The duct according to claim 1, wherein the at least one continuous piece is angled with respect to the internal wall of the duct.

6. The duct according to claim 5, wherein an angle between the at least one continuous piece and the internal wall of the duct varies along a path of the at least one continuous piece.

7. The duct according to claim 1, wherein the at least one continuous piece comprises at least two continuous pieces arranged on the internal wall of the duct.

8. The duct according to claim 7, wherein two of the at least two continuous pieces are symmetrically arranged on the internal wall of the duct relative to a middle plane passing through the longitudinal axis from top to bottom of the duct, the first ends of the two continuous pieces being separated a first predetermined distance, and the second ends of the two continuous pieces being separated a second predetermined distance.

9. The duct according to claim 8, wherein the first predetermined distance is greater than the second predetermined distance.

10. The duct according to claim 7, wherein at least two of the at least two continuous pieces are arranged on the internal wall of the duct staggered relative to the axis, each continuous piece starting at a different position along the longitudinal axis.

11. The duct according to claim 1, wherein the duct is substantially cylindrical at least along a portion of the duct.

12. The duct according to claim 11, wherein the at least one continuous piece has a helical profile on the internal wall of the duct.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) These and other characteristics and advantages of the invention will become clearly understood in view of the detailed description of the invention which becomes apparent from a preferred embodiment of the invention, given just as an example and not being limited thereto, with reference to the drawings.

(2) FIGS. 1A-C show an embodiment of a duct according to the invention in front, longitudinal section and rear view, respectively.

(3) FIG. 2 shows an embodiment of a duct according to the invention.

(4) FIGS. 3A-B show the results of CFD analysis performed for the duct according to the embodiment of FIG. 2.

(5) FIG. 4 shows an embodiment of a duct according to the invention.

(6) FIG. 5 shows the results of CFD analysis performed for the duct according to the embodiment of FIG. 4.

(7) FIGS. 6A-C show another embodiment of a duct according to the invention.

(8) FIG. 7 shows the results of CFD analysis performed for the duct according to the embodiment of FIGS. 6A-C.

(9) FIGS. 8A-B show yet another embodiment of a duct according to the invention.

(10) FIG. 9 shows the results of CFD analysis performed for the duct according to the embodiment of FIGS. 8A-B.

(11) FIG. 10 shows an embodiment of an aircraft according to the invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

(12) FIGS. 1A-C show an embodiment of a duct for a bleed system of an aircraft according to the invention. In these figures the duct is shown in front, longitudinal section and rear view, respectively.

(13) The duct extends along a longitudinal axis (z-z′), shown in FIG. 1B in dotted line. According to this embodiment, the duct comprises:

(14) an inlet section (2) for entering a fluid flow into the duct (1);

(15) an outlet section (3) distanced from the inlet section (2), through which such fluid flow exits the duct (1); and

(16) two continuous pieces (4, 5) arranged on the internal wall of the duct and protruding therefrom;

(17) wherein the continuous pieces have a first end (4.1, 5.1) located at a position adjacent to the inlet section (2) and a second end (4.2, 5.2) located at a position close to the outlet section, and

(18) wherein the continuous pieces slantly extend from the first end (4.1, 5.1) to the second end (4.2, 5.2) along the longitudinal axis (z-z′) direction of the duct (1) so that first (4.1, 5.1) and second (4.2, 5.2) ends are substantially opposed in transversal cross-section of the duct (1).

(19) In this embodiment the duct is substantially cylindrical. The two continuous pieces (4, 5) are symmetrically arranged on the internal wall of the duct (1) relative to the axis (z-z′). The first ends (4.1, 5.1) of the continuous pieces (4, 5) are separated a first predetermined distance (d1), and the second ends (4.2, 5.2) of the continuous pieces (4, 5) are separated a second predetermined distance (d2), as visible in FIG. 1C. In this embodiment the first predetermined distance (d1) is smaller than the second predetermined distance (d2). However, in other embodiments the first predetermined distance (d1) may be greater than or equal to the second predetermined distance (d2).

(20) FIG. 1A schematically shows the temperature distribution in the duct (1) at a position upstream the continuous pieces (4, 5). A cold air section and a hot air section are clearly distinguished in the figure, where the cold air section occupies the lower portion of the duct and the hot air section occupies the upper portion of the duct.

(21) It is to be noted that “cold” and “hot” terms are used herein not according to the actual temperature of the air, but because of their relative values. A temperature gradient always has a zone, or end, with less temperature (that is, “cold” air), and an opposite zone, or end, with higher temperature (that is, “hot” air), where temperature in zones therebetween gradually varies from one to other value.

(22) The two symmetrical continuous pieces (4, 5) protruding from the internal wall of the duct (1) guide the bottom cold air towards the top portion of the duct (1) along the internal wall. The cold air guided to the top naturally drives the hot air towards the center of the duct (1), and creates a vortex. The created vortex helps the complete flow mixing at a small distance downstream the continuous pieces (4, 5). This is schematically shown in FIGS. 1B and 1C.

(23) FIGS. 2 and 3A-B show an embodiment of a duct according to the invention in perspective views. In these figures part of the wall of the duct is not represented in order to appreciate the continuous pieces (4, 5) arranged inside the duct.

(24) In this embodiment the duct is substantially cylindrical, the continuous pieces (4, 5) are arranged symmetrically on the internal wall of the duct relative to the axis (z-z′) and have a helical shape.

(25) The continuous pieces (4, 5) protruding from the internal wall of the duct may be either built-in or joined by welding.

(26) FIGS. 3A-B show the results of CFD (Computational Fluid Dynamics) analysis performed for the duct according to the embodiment of FIG. 2. The model was made for a duct having a diameter of 4.5 inch (114.3 cm) and 110 mm of maximum length. The temperature distributions at the inlet section (2) and at the outlet section (3) of the duct (1) are visible in FIGS. 3A-B, respectively. It can be seen that the behavior is as explained in connection with FIGS. 1A-C, with the hot air being pushed away from the duct wall and the vortex starting to mix the airflow.

(27) FIGS. 4 and 5 show another embodiment of a duct according to the invention. This embodiment is a variant of the embodiment of FIGS. 2 and 3A-B, wherein the difference with this embodiment is a greater distance between the first ends (4.1, 5.1) of the continuous pieces (4, 5). This widened distance between the first ends (4.1, 5.1) of the continuous pieces (4, 5) results in reduced effect and pressure loss, as visible in FIG. 5, where the results of a CFD analysis performed for the duct according to the embodiment of FIG. 4 are shown.

(28) The CFD analysis performed for ducts according to the invention shows the ability to reduce a maximum upstream air temperature from 370° C. to less than 290° C. at the surface of the internal wall of the duct, with a pressure loss comparable to the one caused by deflector devices already used in the state of the art.

(29) FIGS. 6A-C and 7 show another embodiment of a duct (1) according to the invention. FIGS. 6A-B represent the duct (1) in front and longitudinal section views, respectively. In turn, FIG. 6C shows separately a continuous piece (4, 5) to be arranged inside this duct.

(30) In particular, each of the continuous pieces (4, 5) shown in FIGS. 6A-C is formed by three portions:

(31) a first portion (4.3, 5.3) starting at the first end (4.1, 5.1),

(32) a second portion (4.4, 5.4), and

(33) a third portion (4.5, 5.5) ending at the second end (4.2, 5.2).

(34) It can be observed that first (4.3, 5.3) and third (4.5, 5.5) portions have a different tilting in comparison with the second portion (4.4, 5.4), in regard of the angle formed with the longitudinal axis. In particular, both first (4.3, 5.3) and third (4.5, 5.5) portions are substantially parallel in respect to the longitudinal axis (z-z′) of the duct (1).

(35) In a preferred embodiment, the second portion (4.4, 5.4) forms an angle between 30° and 60° with the longitudinal axis (z-z′) of the duct (1).

(36) Furthermore, it can be seen the angle formed with respect to the inner wall of by each section of the continuous piece (4, 5). In particular, for a given side of the continuous piece, the angle formed with the internal wall of the duct passes from an acute angle to obtuse along the path of the continuous piece.

(37) Accordingly, the continuous pieces (4, 5) have a torsion along their respective paths, wherein the torsion of each portion varies with respect to the others but keeping a smooth transition. Details of this can be seen in FIG. 6A.

(38) FIG. 7 shows the results of CFD analysis performed for the duct (1) according to the embodiment of FIG. 5 with a model under the same conditions as explained in FIGS. 2 and 3A-B.

(39) A variant of the embodiment of FIGS. 6A-C and 7 is shown through FIGS. 8A-B and 9, wherein the difference with this embodiment is a greater distance between the first ends (4.1, 5.1) of the continuous pieces (4, 5).

(40) Furthermore, the tilting between first (4.3, 5.3) and second (4.4, 5.4) portions are significantly less pronounced than corresponding portions of FIGS. 6A-C, being indeed the first portion (4.3, 5.3) almost parallel to the longitudinal axis (z-z′) of the duct (1).

(41) As for FIG. 6A, the continuous piece (4, 5) shown in FIG. 8A is angled (different from 90°) with respect to the inner wall of the duct differently for each of its sections. Nevertheless, smooth transitions between portions of a single continuous piece either in path, or in torsion takes place.

(42) FIG. 9 shows the results of CFD analysis performed for the duct (1) according to the embodiment of FIGS. 8A-B with a model under the same conditions as explained in FIGS. 2 and 3A-B.

(43) FIG. 10 shows an embodiment of an aircraft according to the invention. The aircraft comprises a bleed system (not shown) that comprises:

(44) a heat exchanger with a cold side and a hot side, the hot side comprising an inlet and an outlet, and the cold side comprising an inlet and an outlet; and

(45) a duct according to the invention;

(46) wherein the hot side outlet is in fluid communication with the inlet section of the duct.

(47) While at least one exemplary embodiment of the present invention(s) is disclosed herein, it should be understood that modifications, substitutions and alternatives may be apparent to one of ordinary skill in the art and can be made without departing from the scope of this disclosure. This disclosure is intended to cover any adaptations or variations of the exemplary embodiment(s). In addition, in this disclosure, the terms “comprise” or “comprising” do not exclude other elements or steps, the terms “a” or “one” do not exclude a plural number, and the term “or” means either or both. Furthermore, characteristics or steps which have been described may also be used in combination with other characteristics or steps and in any order unless the disclosure or context suggests otherwise. This disclosure hereby incorporates by reference the complete disclosure of any patent or application from which it claims benefit or priority.