DRAIN MAST OF AN AIRCRAFT

Abstract

A drain mast for draining liquids from an aircraft. The drain mast comprises a tube and further comprises a pipe coupled to the inner longitudinal surface of the tube and configured such that the drained liquid flows from the tube to the pipe. The pipe has an inlet having its longitudinal axis configured to confront the coming airflow for allowing the inlet of the coming airflow into the pipe, and an outlet having its longitudinal axis inclined with respect to the longitudinal axis of the inlet and configured to discharge the airflow flowing through the pipe in a direction inclined with a component perpendicular to the fuselage of the aircraft.

Claims

1. A drain mast for draining liquids from an aircraft, the drain mast comprising a tube comprising: a first end configured to connect to a source of liquids to be drained from the aircraft, a second end configured to discharge said liquids to the atmosphere, an inner longitudinal surface configured to be exposed to the drained liquid, and an outer longitudinal surface, a pipe coupled to the inner longitudinal surface of the tube and configured such that the drained liquid flows from the tube to the pipe, the pipe comprising: an inlet having its longitudinal axis configured to confront with the coming airflow for allowing the inlet of said coming airflow into the pipe, and an outlet having its longitudinal axis inclined with respect to the longitudinal axis of the inlet and configured to discharge the airflow and the drained liquid flowing through the pipe in a direction inclined with a component perpendicular to the fuselage of the aircraft.

2. The drain mast for draining liquids according to claim 1, wherein the pipe further comprises a duct diametrically located in a cross-section of the pipe and having an end coupled to the inner longitudinal surface of the tube such that the drained liquid flows from the tube to the pipe through the duct, the duct further comprising an opening in the side of the duct pointing towards the airflow direction such that the opening and the airflow create a suction effect that sucks the drained liquid from the duct to the pipe.

3. The drain mast for draining liquids according to claim 2, wherein the opening of the duct is located in a center of the cross-section of the pipe.

4. The drain mast for draining liquids according to claim 2, wherein the duct comprises several openings in the side of the duct pointing towards the airflow direction.

5. The drain mast for draining liquids according to claim 1, wherein a longitudinal axis of the tube is configured to be located in an inclined position with respect to the fuselage of the aircraft.

6. The drain mast for draining liquids according to claim 1, wherein the second end of the tube is configured to be located in a plane inclined with respect to the fuselage of the aircraft.

7. The drain mast for draining liquids, according to claim 1, wherein the tube further comprises an internal rim located at its second end connected to the inner surface of the drain mast, the internal rim further comprising an aperture being located at the lowest part of the internal rim for draining the liquid, the internal rim and the aperture being configured such that at the second end the liquid is directed by gravity through the internal rim to the aperture.

8. The drain mast for draining liquids, according to claim 1, further comprising a fairing enclosing the pipe and the second end of the tube and having an aerodynamic shape for reducing drag.

9. The drain mast for draining liquids, according to claim 1, wherein the pipe comprises a first straight part wherein the liquid is released into the pipe and accelerated, a second straight part wherein the accelerated liquid is released to the atmosphere, having the second straight part inclined with respect to the first straight part, and a bent part located in-between the first and the second straight parts.

10. An auxiliary power unit of an aircraft comprising a drain mast according to claim 1.

11. An aircraft comprising a drain mast according to claim 1.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0031] FIGS. 1A and 1B show schematic longitudinal and cross sections of a drain mast of the state of the art showing the behavior of a fluid droplet.

[0032] FIG. 2 shows a schematic longitudinal section of an embodiment of the drain mast.

[0033] FIG. 3 shows a schematic view showing the pipe and duct of the embodiment of FIG. 2.

[0034] FIG. 4 shows a schematic representation of an embodiment of the pipe.

[0035] FIGS. 5 and 6 show schematic representations of a fairing of the embodiment shown in FIG. 2.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0036] FIG. 1A illustrates the basic components of a known drain mast of an APU compartment of an aircraft, the drain mast comprising a tube (1) having a first end (10) connected to the APU compartment and a second end (11) for discharging the liquids to the atmosphere. The APU compartment is usually located in the tail cone of the aircraft close to the fuselage and receives the liquids leaked by the APU. The tube (1) could also be connected to a receptacle or piping of the aircraft intended to drain a fluid.

[0037] As can be seen in FIGS. 1A and 1B, the distribution of the airflow in the outer surface (14) of the tube (1) opposite to the surface facing the coming airflow promotes the adherence of the droplets of liquid to the outer surface (14) of the tube (1) such that the droplet runs over the outer surface (14) as it is depicted in FIG. 1B. As previously stated, another option is that the drop or drops are firstly released to the atmosphere but afterwards adhered again to the fuselage by the airflow.

[0038] FIG. 2 shows an embodiment of the invention in which the drain mast has the tube (1) comprising: [0039] a first end (10) connected to the compartment of the aircraft, [0040] a second end (11) for discharging the liquids to the atmosphere and additionally this second end (11) could be configured for being located in a plane inclined with respect to the fuselage, [0041] an inner longitudinal surface (13) configured for being exposed to the drained liquid, and [0042] an outer longitudinal surface (14),

[0043] The pipe (4) comprises an inlet (5) allowing the entrance of the coming airflow and an outlet (9) that has its longitudinal axis inclined with respect to the longitudinal axis of the inlet (5).

[0044] The depicted embodiment also comprises a duct (6) located diametrically with respect to the pipe (4) and having an end coupled to the inner longitudinal surface (13) of the tube (1) such that the drained liquid flows from the tube (1) to the duct (6). The duct (6) further comprises an opening (7) in the side of the duct (6) pointing towards the airflow direction or, what is the same, the opening (7) is located in the face of the duct (6) opposite to the face of the duct (6) facing the incoming flow.

[0045] FIG. 3 shows that the opening (7) of the duct (6) is located in the center of the cross-section of the pipe (4), wherein the maximum speed for the airflow is obtained, although the opening (7) could be located in a different location or the duct (6) can comprise several openings (7) in the face of the duct (6) that is located opposite to the incoming airflow, or, in the worst case, even not having a duct (6) and therefore the tube (1) directly discharging to the pipe (4).

[0046] More specifically, FIG. 4 shows an embodiment wherein the pipe (4) comprises a first straight part (20) in which the drops are released into the pipe (4) and accelerated and a second straight part (21) in which the drops are finally released to the atmosphere with an inclination with respect to the first straight part (20). The pipe (4) also comprises a bended part (22) located in between the first and the second straight parts (20, 21). The first part (20) has to be long enough to provide enough speed to the drops, obtaining a quick acceleration of them. More specifically the length of the first part (20) of the pipe (4) is between 5-22 mm to fully develop the spray.

[0047] The spray is accelerated along the first part (20) of the pipe (4), due to the small size of the droplets and the coming airflow, the inertia forces has less effect and therefore the pipe (4) can be bended avoiding in such a way a possible adherence of the spray to the inner walls of the pipe (4).

[0048] To lead the liquid coming from the walls of the tube (1) to the pipe (4) or to duct (6) are several solutions, one is to incline the tube (1) rearwards then forcing to fall down the fluid onto the inner front face of the tube (1) and run down by gravity through this face. In this case, the longitudinal axis of the tube (1) is located in an inclined position with respect to the fuselage of the aircraft.

[0049] Another embodiment is that the second end (11) of the tube (1) further comprises: [0050] an internal rim (2) located at its second end (11) connected to the inner surface (13) of the tube (1) and configured for being located in a plane inclined with respect to the horizontal plane of the fuselage, the internal rim (2) further comprising an aperture (3) being located at the lowest part of the internal rim (2) for draining the liquid, [0051] the internal rim (2) and the aperture (3) being configured such that at the second end (11) the liquid is directed by gravity through the internal rim (2) to the aperture (3).

[0052] The internal rim (2) can be located in a tube (1) having a chamfered end (11) the rim (2) being located following the profile of the chamfered end (11) or it can be located in a tube (1) with a straight end being the rim (2) in a plane inclined with respect to the fuselage.

[0053] Therefore, drops approaching the open end runs by gravity over the internal rim (2) and are guided to the second end (11) thanks to its inclination and thus to the inclination of the internal rim (2) connected to the second end (11).

[0054] The drain mast also comprises a fairing (8) having an aerodynamic shape to reduce drag, the fairing (8) surrounds the pipe (4) and the end of the tube (1). The faring (8) comprises two orifices, the inlet (3) and the outlet (9) of the pipe (4).

[0055] 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.