Wind turbine nacelle with liquid containment and associated method

Abstract

The present disclosure is related to a nacelle (16) for a wind turbine (10). The nacelle (16) comprises a bottom (160) and a vertical (162) cover. The vertical cover (162) comprises an inner surface (163). The bottom cover (160) at least partially defines a bottom receptacle (180) suitable for retaining liquid, which comprises a bottom surface (182) and a rim (184) arranged along the perimeter. The inner surface (163) of the vertical cover (162) is connected to the bottom receptacle (180) and a first volume (120a) is at least partially defined by the inner surface (163) of the vertical cover (162). Furthermore, the nacelle (16) comprises a channel (150) configured to provide flow communication between the first bottom receptacle (180) and the first volume (120). Related methods are also disclosed.

Description

WIND TURBINE NACELLE WITH LIQUID CONTAINMENT AND ASSOCIATED METHODFIELD

[0001] The present disclosure relates to wind turbine nacelles. More particularly, the present disclosure relates to nacelles comprising liquid containment capabilities. The present disclosure further relates to methods related to a nacelle for a wind turbine.BACKGROUND

[0002] Modern wind turbines are commonly used to supply electricity into the electrical grid. Wind turbines of this kind generally comprise a tower and a rotor arranged on the tower. The rotor, which typically comprises a hub and a plurality of blades, is set into rotation under the influence of the wind on the blades. Said rotation generates a torque that is normally transmitted through a rotor shaft to a generator, either directly ("directly driven" or "gearless") or through the use of a gearbox. This way, the generator produces electricity which can be supplied to the electrical grid.

[0003] Wind turbines have evolved rapidly over the last decades and wind turbine components have been modified to withstand higher loads and adverse weather conditions. Components like the gearbox (if present), the generator, the converter, the transformer, electrical power cables, cooling systems and structures (e.g. bedplate and frames) may be partly or completely housed in a nacelle. The nacelle provides a cover to protect such components from the outside environment, i.e. from precipitation, dust, UV radiation, lightning strikes and other. The nacelle generally sits on top of a yaw bearing, which allows it to rotate to maintain the nacelle and rotor aligned with the wind direction.

[0004] Wind turbine nacelles may comprise a plurality of nacelle covers, which may be assembled to define an interior volume to house the wind turbine components. In particular, a wind turbine nacelle may exhibit a substantially box-like structure and it may comprise a bottom cover, a top cover, a front cover, a rear cover and two lateral covers.

[0005] Large wind turbines need large nacelles to accommodate all the required components. This may be particularly the case in offshore wind turbines, which typically exhibit higher power ratings. Due to limitations in both manufacturing and transportation, nacellecovers may be split into multiple parts or panels. Such panels may be assembled and sealed to form a corresponding cover.

[0006] Nacelle covers generally comprise composite materials and are often manufactured with resin-infused glass fiber composites to meet the requirements with respect to size, internal and external geometry, and weight.

[0007] Some of the components housed in the nacelle may comprise lubricating and / or cooling circuits, which may require use of liquids. Furthermore, in some cases, oil or other potentially contaminant liquids, may be used as the lubricant or the cooling medium. As an example, this may be the case for the cooling circuit of the transformer, the gearbox or the electrical generator.

[0008] Sealing of the nacelle is of paramount importance, especially in offshore installations, wherein any leakage of the mentioned liquids needs to be prevented to preserve the marine environment. Accordingly, wind turbine nacelles are designed with the ability to contain a certain amount of liquid in their bottom covers. To this end, the bottom covers may be provided with liquid receptacles. Thus, in case of a leakage in any of the components housed in the nacelle or in any of the corresponding lubrication or cooling circuits, the leaked fluid can be contained inside the nacelle by the liquid receptacles.

[0009] More particularly, in order to provide improved control and optimum dimensioning, dedicated liquid receptacles may be designed for different regions of the bottom cover. The liquid receptacles may be dimensioned to contain a certain amount of liquid depending, among others, on the specific component housed above the corresponding region of the bottom cover.

[0010] The distribution of components within the nacelle may not be uniform, thus leading to certain regions of the bottom cover being more exposed to potential liquid leakage than others. Accordingly, certain receptacles may be at a higher risk of overflowing. Hence, it is known to define flow channels between adjacent receptacles such that liquid can be redistributed. That is, liquid is allowed to flow from a first liquid receptacle to a second adjacent liquid receptable when a certain liquid level is reached in the first liquid receptacle. In this manner, liquid can be redistributed and different liquid receptacles of the nacelle bottom cover can be used to contain the spilled liquid regardless of the origin of the liquid.

[0011] Nevertheless, existing solutions exhibit some limitations and drawbacks. Among others, existing solutions lack flexibility as the specific positions of the flow channels must be defined while designing the bottom cover of the nacelle. In some cases, connected receptacles may correspond to different panels, which may add significant complexity in the design and assembly process due to the required alignment of different panels. Furthermore, differentbottom covers, often requiring mould modifications, may be needed for slightly different wind turbines, exhibiting slightly different internal distribution of components, or even for wind turbines being retrofitted. Moreover, the existing solutions are limited to enabling connection between adjacent, i.e. neighboring, receptacles. This may also impose restrictions in the distribution of the leaked liquid and in the location of the flow channels.

[0012] The present disclosure provides methods and systems to at least partially overcome some of the aforementioned drawbacks.SUMMARY

[0013] In an aspect of the present disclosure, a nacelle for a wind turbine is provided. The nacelle comprises a substantially horizontal bottom cover and a substantially vertical cover. The substantially vertical cover comprises an inner surface facing an interior of the wind turbine nacelle. The bottom cover at least partially defines a first bottom receptacle suitable for retaining liquid. The first bottom receptacle comprises a substantially horizontal bottom surface and a rim arranged along the perimeter of the bottom surface, the rim extending at least partially in a vertical direction. An inner surface of the vertical cover is connected to the first bottom receptacle and a first volume is, at least partially, defined by the inner surface of the vertical cover. Moreover, the nacelle comprises a channel configured to provide flow communication between the first bottom receptacle and the first volume.

[0014] According to this aspect, a system with increased flexibility is provided for the containment of liquids in a wind turbine nacelle. Thus, the first volume defined after connection of the vertical cover to the bottom receptacle can be used in different manners to increase the versatility of the system as will be shown in more detail below. On the one hand, the defined first volume may increase the overall capacity of the nacelle to contain liquid by providing an additional liquid receptacle, which may be used when the level of a liquid in the first bottom receptacle of the nacelle bottom cover exceeds a predetermined level.

[0015] On the other hand, and as shown in more detail in reference to some of the examples, a plurality of bottom receptacles may be provided in the bottom cover and a plurality of volumes may be defined. Such volumes may be used as a connecting path to enable connection between the different bottom receptacles as shown in more detail in examples of the present disclosure. It is understood that, even if the term volume is used to refer to the volume defined by each of the bottom receptacles, a new volume may result from the combination of the volumes defined by adjacent bottom receptacles.

[0016] In a further aspect of the present disclosure, another nacelle for a wind turbine is provided. The nacelle comprises a substantially horizontal bottom cover and a substantially vertical cover. The substantially vertical cover comprises an inner surface facing an interior of the wind turbine nacelle. The bottom cover at least partially defines a first and second bottom receptacles suitable for retaining liquid, the first and second bottom receptacles comprising a substantially horizontal bottom surface and a rim arranged along the perimeter of the bottom surface. The rim extends at least partially in a vertical direction. Besides, a further volume is defined between the rims of the first and second bottom receptacles and the vertical cover, the further volume being suitable for fluidly connecting the first bottom receptacle with the second bottom receptacle.

[0017] According to this further aspect of the present disclosure, a nacelle with improved liquid containing capabilities is provided. In particular, the provision of a fluid connection via a newly generated volume provides increased versatility and flexibility. Hence, selected bottom receptacles, including non-adjacent bottom receptacles, can be fluidly connected by means of the further volume.

[0018] In an additional aspect, a method is provided. The method comprises providing a vertical cover of a wind turbine nacelle, the vertical cover comprising an inner surface facing, in a mounted state, an interior of the wind turbine nacelle. The method further comprises providing a bottom cover of the wind turbine nacelle, the bottom cover at least partially defining a first bottom receptacle. The first bottom receptacle comprises a substantially horizontal bottom surface and a rim arranged along the perimeter of the bottom surface, the rim extending at least partially in a vertical direction. The method also comprises connecting an inner surface of the vertical cover to the first bottom receptacle. After connection of the vertical cover to the first bottom receptacle, a first volume is at least partially defined by the inner surface of the vertical cover.

[0019] According to this additional aspect, an easy and versatile method may be provided for the manufacture of a nacelle for a wind turbine. In particular, the bottom cover may be molded and it may comprise a plurality of panels. A bottom receptacle may be at least partially defined in the corresponding panels. Fiber reinforced material may be used for the manufacture of the panels. In some examples, a plurality of bottom receptacles may be at least partially defined.

[0020] In an example, the substantially horizontal bottom surface and the rim of the bottom receptacle may be entirely formed by the bottom cover. Specifically, the substantially horizontal bottom surface and the rim may be integrally formed. Hence, they may be molded in a single mould while manufacturing the bottom cover of the nacelle.

[0021] In another example, the substantially horizontal bottom surface and the rim may be manufactured separately, and they may be subsequently connected. In this example, the bottom cover of the nacelle may comprise the substantially horizontal bottom surface whereas the rim may be individually fabricated and subsequently connected.

[0022] In still a further example, the rim may be manufactured in multiple parts. Specifically, a portion of the rim may be connected to the inner surface of the vertical cover and this may be manufactured integrally with the horizontal bottom surface.

[0023] The volume defined, at least partially, by the inner surface of the vertical cover may act as a distribution chamber for the leaked liquid, thus enabling either containment of liquid or redistribution to a different location, e.g. to further bottom receptacles.

[0024] Additional objects, advantages and features of embodiments of the present disclosure will become apparent to those skilled in the art upon examination of the description, or may be learned by practice.BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Non-limiting examples of the present disclosure will be described in the following, with reference to the appended drawings, in which:Figure 1 schematically illustrates a perspective view of one example of a wind turbine;Figure 2 illustrates an example of a hub and a nacelle of a wind turbine;Figure 3 schematically illustrates a perspective view of an exterior of a nacelle of a wind turbine comprising several covers;Figure 4 schematically illustrates a perspective view of a bottom cover of a nacelle according to an example;Figure 5 schematically illustrates a perspective view of an area of a bottom cover of a nacelle including a bottom receptacle defining a receptacle according to an example;Figure 6A and 6B schematically illustrate a connection between a vertical cover and a bottom cover of a nacelle according to an example;Figure 7 schematically illustrates another example of a connection between a vertical cover and a bottom cover of a nacelle;Figure 8 schematically illustrates a top-view of a connection between a bottom cover of a nacelle and a vertical cover according to an example;Figure 9 schematically illustrates a perspective view of a connection between a vertical cover and a bottom cover according to still another example;Figures 10A-10C schematically illustrate a perspective view of a portion of a bottom cover of a nacelle (10A), a perspective view of a connection between a bottom cover and a vertical cover of a nacelle (10B), and a schematic top view of such connection according to a further example;Figure 11A and 11 B schematically illustrate a detail of a connection between a bottom cover and a vertical cover in the region of a channel according to an example;Figure 12 shows a flowchart of an example of a method for manufacturing a nacelle of a wind turbine.DETAILED DESCRIPTION OF EXAMPLES

[0026] Reference now will be made in detail to embodiments of the disclosure, one or more examples of which are illustrated in the drawings. Each example is provided by way of explanation, not as a limitation. In fact, it will be apparent to those skilled in the art that various modifications and variations can be made in the present disclosure without departing from the scope or spirit of the teaching. For instance, features illustrated or described as part of one embodiment can be used with another embodiment to yield a still further embodiment. Thus, it is intended that the present disclosure covers such modifications and variations as come within the scope of the appended claims and their equivalents.

[0027] Figure 1 is a perspective view of an example of a wind turbine 10. In the example, the wind turbine 10 is a horizontal-axis wind turbine. Alternatively, the wind turbine 10 may be a vertical-axis wind turbine. In the example, the wind turbine 10 includes a tower 15 that extends from a support system 14 on a ground 12, a nacelle 16 mounted on tower 15, and a rotor 18 that is coupled to nacelle 16. The rotor 18 includes a rotatable hub 20 and at least one rotor blade 22 coupled to and extending outwards from the hub 20. In the example, the rotor 18 has three rotor blades 22. In an alternative embodiment, the rotor 18 includes more or less than three rotor blades 22. The tower 15 may be fabricated from tubular steel to define a cavity (not shown in figure 1) between a support system 14 and the nacelle 16. In an alternative embodiment, the tower 15 is any suitable type of a tower having any suitable height. According to an alternative, the tower can be a hybrid tower comprising a portion made of concrete and a tubular steel portion. Also, the tower can be a partial or full lattice tower.

[0028] The rotor blades 22 are spaced about the hub 20 to facilitate rotating the rotor 18 to enable kinetic energy to be transferred from the wind into usable mechanical energy, andsubsequently, electrical energy. The rotor blades 22 are mated to the hub 20 by coupling a blade root portion 24 to the hub 20 at a plurality of load transfer regions 26. The load transfer regions 26 may have a hub load transfer region and a blade load transfer region (both not shown in figure 1). Loads induced to the rotor blades 22 are transferred to the hub 20 via the load transfer regions 26.

[0029] In examples, the rotor blades 22 may have a length ranging from about 15 meters (m) to about 90 m or more. Rotor blades 22 may have any suitable length that enables the wind turbine 10 to function as described herein. For example, non-limiting examples of blade lengths include 20 m or less, 37 m, 48.7 m, 50.2m, 52.2 m or a length that is greater than 91 m. As wind strikes the rotor blades 22 from a wind direction 28, the rotor 18 is rotated about a rotor axis 30. As the rotor blades 22 are rotated and subjected to centrifugal forces, the rotor blades 22 are also subjected to various forces and moments. As such, the rotor blades 22 may deflect and / or rotate from a neutral, or non-deflected, position to a deflected position.

[0030] Moreover, a pitch angle of the rotor blades 22, i.e., an angle that determines an orientation of the rotor blades 22 with respect to the wind direction, may be changed by a pitch system 32 to control the load and power generated by the wind turbine 10 by adjusting an angular position of at least one rotor blade 22 relative to wind vectors. Pitch axes 34 of rotor blades 22 are shown. During operation of the wind turbine 10, the pitch system 32 may particularly change a pitch angle of the rotor blades 22 such that the angle of attack of (portions of) the rotor blades are reduced, which facilitates reducing a rotational speed and / or facilitates a stall of the rotor 18.

[0031] In the example, a blade pitch of each rotor blade 22 is controlled individually by a wind turbine controller 36 or by a pitch control system 80. Alternatively, the blade pitch for all rotor blades 22 may be controlled simultaneously by said control systems.

[0032] Further, in the example, as the wind direction 28 changes, a yaw direction of the nacelle 16 may be rotated about a yaw axis 38 to position the rotor blades 22 with respect to wind direction 28.

[0033] In the example, the wind turbine controller 36 is shown as being centralized within the nacelle 16, however, the wind turbine controller 36 may be a distributed system throughout the wind turbine 10, on the support system 14, within a wind farm, and / or at a remote-control center. The wind turbine controller 36 includes a processor 40 configured to perform the methods and / or steps described herein. Further, many of the other components described herein include a processor.

[0034] As used herein, the term “processor” is not limited to integrated circuits referred to in the art as a computer, but broadly refers to a controller, a microcontroller, a microcomputer, a programmable logic controller (PLC), an application specific, integrated circuit, and other programmable circuits, and these terms are used interchangeably herein. It should be understood that a processor and / or a control system can also include memory, input channels, and / or output channels.

[0035] Figure 2 is an enlarged sectional view of a portion of the wind turbine 10. In the example, the wind turbine 10 includes the nacelle 16 and the rotor 18 that is rotatably coupled to the nacelle 16. More specifically, the hub 20 of the rotor 18 is rotatably coupled to an electric generator 42 positioned within the nacelle 16 by the main shaft 44, a gearbox 46, a high-speed shaft 48, and a coupling 50. In the example, the main shaft 44 is disposed at least partially coaxial to a longitudinal axis (not shown) of the nacelle 16. A rotation of the main shaft 44 drives the gearbox 46 that subsequently drives the high-speed shaft 48 by translating the relatively slow rotational movement of the rotor 18 and of the main shaft 44 into a relatively fast rotational movement of the high-speed shaft 48. The latter is connected to the generator 42 for generating electrical energy with the help of a coupling 50. Furthermore, a transformer 90 and / or suitable electronics, switches, and / or inverters may be arranged in the nacelle 16 in order to transform electrical energy generated by the generator 42 having a voltage between 400V to 1000 V into electrical energy having medium voltage (10 - 35 KV). Said electrical energy is conducted via power cables from the nacelle 16 into the tower 15.

[0036] The gearbox 46, generator 42 and transformer 90 may be supported by a main support structure frame of the nacelle 16, optionally embodied as a main frame 52. The gearbox 46 may include a gearbox housing that is connected to the main frame 52 by one or more torque arms 103. In the example, the nacelle 16 also includes a main forward support bearing 60 and a main aft support bearing 62. Furthermore, the generator 42 can be mounted to the main frame 52 by decoupling support means 54, in particular in order to prevent vibrations of the generator 42 to be introduced into the main frame 52 and thereby causing a noise emission source.

[0037] Optionally, the main frame 52 is configured to carry the entire load caused by the weight of the rotor 18 and components of the nacelle 16 and by the wind and rotational loads, and furthermore, to introduce these loads into the tower 15 of the wind turbine 10. The rotor shaft 44, generator 42, gearbox 46, high speed shaft 48, coupling 50, and any associated fastening, support, and / or securing device including, but not limited to, support 52, and forward support bearing 60 and aft support bearing 62, are sometimes referred to as a drive train 64.

[0038] In some examples, the wind turbine may be a direct drive wind turbine without gearbox 46. Generator 42 operate at the same rotational speed as the rotor 18 in direct drive wind turbines. They therefore generally have a much larger diameter than generators used in wind turbines having a gearbox 46 for providing a similar amount of power than a wind turbine with a gearbox.

[0039] The nacelle 16 may also include a yaw drive mechanism 56 that may be used to rotate the nacelle 16 and thereby also the rotor 18 about the yaw axis 38 to control the perspective of the rotor blades 22 with respect to the wind direction 28.

[0040] For positioning the nacelle 16 appropriately with respect to the wind direction 28, the nacelle 16 may also include at least one meteorological measurement system 58 which may include a wind vane and anemometer. The meteorological measurement system 58 can provide information to the wind turbine controller 36 that may include wind direction 28 and / or wind speed. In the example, the pitch system 32 is at least partially arranged as a pitch assembly 66 in the hub 20. The pitch assembly 66 includes one or more pitch drive systems 68 and at least one sensor 70. Each pitch drive system 68 is coupled to a respective rotor blade 22 (shown in figure 1) for modulating the pitch angle of a rotor blade 22 along the pitch axis 34. Only one of three pitch drive systems 68 is shown in figure 2.

[0041] In the example, the pitch assembly 66 includes at least one pitch bearing 72 coupled to hub 20 and to a respective rotor blade 22 (shown in figure 1) for rotating the respective rotor blade 22 about the pitch axis 34. The pitch drive system 68 includes a pitch drive motor 74, a pitch drive gearbox 76, and a pitch drive pinion 78. The pitch drive motor 74 is coupled to the pitch drive gearbox 76 such that the pitch drive motor 74 imparts mechanical force to the pitch drive gearbox 76. The pitch drive gearbox 76 is coupled to the pitch drive pinion 78 such that the pitch drive pinion 78 is rotated by the pitch drive gearbox 76. The pitch bearing 72 is coupled to pitch drive pinion 78 such that the rotation of the pitch drive pinion 78 causes a rotation of the pitch bearing 72.

[0042] Pitch drive system 68 is coupled to the wind turbine controller 36 for adjusting the pitch angle of a rotor blade 22 upon receipt of one or more signals from the wind turbine controller 36. In the example, the pitch drive motor 74 is any suitable motor driven by electrical power and / or a hydraulic system that enables pitch assembly 66 to function as described herein. Alternatively, the pitch assembly 66 may include any suitable structure, configuration, arrangement, and / or components such as, but not limited to, hydraulic cylinders, springs, and / or servomechanisms. In certain embodiments, the pitch drive motor 74 is driven by energy extracted from a rotational inertia of hub 20 and / or a stored energy source (not shown) that supplies energy to components of the wind turbine 10.

[0043] The pitch assembly 66 may also include one or more pitch control systems 80 for controlling the pitch drive system 68 according to control signals from the wind turbine controller 36, in case of specific prioritized situations and / or during rotor 18 overspeed. In the example, the pitch assembly 66 includes at least one pitch control system 80 communicatively coupled to a respective pitch drive system 68 for controlling pitch drive system 68 independently from the wind turbine controller 36. In the example, the pitch control system 80 is coupled to the pitch drive system 68 and to a sensor 70. During normal operation of the wind turbine 10, the wind turbine controller 36 may control the pitch drive system 68 to adjust a pitch angle of rotor blades 22.

[0044] According to an embodiment, a power generator 84, for example comprising a battery and electric capacitors, is arranged at or within the hub 20 and is coupled to the sensor 70, the pitch control system 80, and to the pitch drive system 68 to provide a source of power to these components. In the example, the power generator 84 provides a continuing source of power to the pitch assembly 66 during operation of the wind turbine 10. In an alternative embodiment, power generator 84 provides power to the pitch assembly 66 only during an electrical power loss event of the wind turbine 10. The electrical power loss event may include power grid loss or dip, malfunctioning of an electrical system of the wind turbine 10, and / or failure of the wind turbine controller 36. During the electrical power loss event, the power generator 84 operates to provide electrical power to the pitch assembly 66 such that pitch assembly 66 can operate during the electrical power loss event.

[0045] In the example, the pitch drive system 68, the sensor 70, the pitch control system 80, cables, and the power generator 84 are each positioned in a cavity 86 defined by an inner surface 88 of hub 20. In an alternative embodiment, said components are positioned with respect to an outer roof surface of hub 20 and may be coupled, directly or indirectly, to the outer roof surface.

[0046] Figure 3 is a schematic perspective view of an exterior of a nacelle 16. The nacelle 16 shown in Figure 3 comprises a substantially horizontal bottom cover 160 and a substantially horizontal top cover 164 (not clearly visible in Figure 3). Furthermore, the nacelle 16 comprises vertical covers 162 extending from the bottom cover 160 to the top cover 164. Only the rear cover 162a and one of the lateral covers 162b are visible in Figure 3, but it is understood that the nacelle 16 comprises also a front cover and another lateral cover, which is arranged opposite to the vertical lateral cover 162b shown. The nacelle vertical covers 162 are assembled to define an inner volume wherein multiple wind turbine components are housed.

[0047] The assembled nacelle 16 resembles a box-like structure. The height of the nacelle 16 extends in a substantially vertical, or “z”, direction. The nacelle 16 is also defined by itslength, which extends along the “x” direction, which corresponds to the longitudinal rotor axis 30 of the wind turbine 10. Finally, the width of the nacelle 16 extends in the “y” direction, which is perpendicular to the rotor axis 30 of the wind turbine 10.

[0048] Figure 4 is a perspective view of a nacelle bottom cover 160 according to an example. The bottom cover 160 at least partially defines a plurality of bottom receptacles 180. Actually, in the example shown in Figure 4, the bottom receptacles 180 are entirely defined by the bottom cover 160, i.e. no other part of the nacelle 16 is needed to define the bottom receptacles 180. In other words, the substantially horizontal bottom surface 182 and the rim 184 of the first bottom receptacle 180 may be formed by the bottom cover. Manufacturability and assembly of the nacelle 16 may also be simplified by entirely defining the bottom receptacle 180 in the bottom cover 160. In particular, the substantially horizontal bottom surface 182 and the rim 184 may be integrally formed.

[0049] The bottom cover 160 in this example is split into multiple parts or panels 170. Specifically, three panels 170a, 170b, 170c are depicted which, in the assembled state, may be connected to form the bottom cover 160.

[0050] The connection lines between the different panels 170 may be sealed to prevent leakage or ingress of liquids. In alternative examples, a single piece nacelle bottom cover 160 may be provided. Thus, the plurality of bottom receptacles 180 may still be at least partially defined (in this example entirely defined) by the bottom cover 160, but a single panel may be used. Nevertheless, the use of multiple panels 170 may be preferred for large wind turbines 10, e.g. offshore wind turbines, for which very large nacelles 16 may be needed in order to accommodate all the components. In such case, manufacturability and transportation of such large covers may become difficult. Accordingly, a bottom cover 160 comprising multiple panels 170 may be envisaged. In all cases, the nacelle bottom cover 160 may be manufactured with a fiber reinforced material, e.g. glass fiber, and a mould (or multiple moulds in case of a nacelle bottom cover 160 comprising multiple panels) may be employed for the manufacture.

[0051] Figure 5 provides a schematic view of one of the panels 170 of the bottom cover 160. In this example, a single panel 170 may be used to defined the complete bottom receptacle 180 In other words, a panel 170 may be provided which comprises a single bottom receptacle 180. Nevertheless, in other examples, multiple bottom receptacles 180, which may be configured to contain the liquid of different components arranged above them, may be defined in a single panel 170. In still other examples, multiple panels 170 may be connected to at least partially define a single bottom receptacle 180.

[0052] The bottom receptacle 180 comprises a substantially horizontal bottom surface 182 and a rim 184. The rim 184 is arranged along the perimeter of the bottom surface 182 and it extends, at least partially, in a vertical direction. In this manner, the bottom surface 182 and the rim 184 define a liquid receptacle, which is configured to contain a liquid. In some examples, the bottom surface 182 and the rim 184 may be integrally formed, e.g. by moulding. In other examples, the rim 184 may be manufactured separately and connected to the bottom surface 182. In still further examples, the rim 184 may be at least partially provided by a vertical cover 162.

[0053] The dimensions of the bottom receptacle may be adjusted based on the dimensions of the bottom surface 182 and / or the rim 184. Accordingly, a larger receptacle, with a larger liquid capacity, may be provided by increasing the dimensions of the bottom surface 182 and / or the height of the rim 184.

[0054] As seen in Figure 4, different bottom receptacles 180 may be distributed over the area of the bottom cover 160. More particularly, the position and size of the liquid receptacles 180 may be determined by the physical layout or distribution of the different components arranged within the nacelle 16, e.g. gearbox, generator, power converter, or transformer. Such components may contain different amounts of liquid for, e.g. cooling or lubrication purposes. Accordingly, the bottom receptacles 180 may be arranged underneath corresponding components so as to collect liquid leaked by specific components. Nevertheless, in some cases, redistribution of the liquid among different receptacles may be preferred in order to provide a more uniform distribution of the liquid and / or to prevent accidental overflow in some of the receptacles.

[0055] Furthermore, as also shown in Figure 4, in an example of the present disclosure, some of the bottom receptacles 180 (e.g. bottom receptacle labelled as 180p) may be arranged in a periphery of the bottom cover 160, i.e. they may be defined such that at least a portion of the corresponding rims 184 is defined in the outer perimeter of the bottom cover 160. Accordingly, such bottom receptacles 180p may be connected to at least one of the vertical covers 162 shown in Figure 3. As also shown in Figure 4, some other bottom receptacles 180 may be inner bottom receptacles 180i. Such inner bottom receptacles 180i may be arranged in an inner position of the bottom cover 160, i.e. in a position wherein no portion of the rim 184 is in an outer perimeter of the bottom cover 160. In other words, inner bottom receptacles 180i may not be connected to any of the vertical covers 162 shown in Figure 3. In particular, one or more of the inner bottom receptacles 180i may be surrounded by other bottom receptacles 180.

[0056] Figures 6A and 6B show an example of the present disclosure. In these figures, a first bottom receptacle 180a is depicted. In particular, a schematic perspective view is provided in Figure 6A, whereas a cross-sectional view is provided in Figure 6B.

[0057] In this example, an inner surface 163 of the vertical cover 162 may be connected to the rim 184a of the first bottom receptacle 180a at a first connection area 130a. In particular, a horizontally extending end region of the inner surface 163 of the vertical cover 162 may be connected to the rim 184a. The first connection area 130a may extend along a substantially horizontal direction. A protruding portion 186a of the rim 184a may extend vertically beyond the first connection area 130a.

[0058] In this example, the inner surface 163 of the vertical cover 162 may be shaped such that a first volume 120a is defined. In alternative examples, the rim 184a may be shaped such a first volume 120a is defined. Furthermore, a channel 150a is defined in the rim 184a as also shown in Figure 6A. The channel 150a provides flow communication between the first bottom receptacle 180a and the first volume 120a. In an example, the channel 150a may be provided in the protruding portion 186a of the rim 184a.

[0059] According to this example, the position of the channel 150a may be selected independently from the position of the channel in any other bottom receptacles (if present). Furthermore, the channel 150a may be defined in the perimeter area of the nacelle 16, i.e. at a location wherein the bottom cover 160 of the nacelle 16 is connected to the vertical cover 162, thus avoiding potential interference with components arranged within the nacelle 16. Besides, the specific location of the channel 150 may be conveniently optimized to account for e.g. location of the equipment or ease of accessibility. In particular, the channel 150a may be placed at a location facilitating easy inspection by maintenance personnel.

[0060] In an example, the bottom cover 160 may at least partially define a second bottom receptacle 180b. The second bottom receptacle 180b may comprise a substantially horizontal bottom surface 182b and a rim 184b arranged along the perimeter of the bottom surface 182b. The rim 184b may extend at least partially in a vertical direction. Similarly to the first bottom receptacle 180a, the inner surface 163 of the vertical cover 162 may also be connected to the second bottom receptacle 180b and a second volume 120b may be at least partially defined by the inner surface 163 of the vertical cover 162. Furthermore, a channel 150b may be arranged to provide flow communication between the second bottom receptacle 180b and the second volume 120b.

[0061] In particular, in the example shown in Figure 6A, the inner surface 163 of the vertical cover 162 may be connected to the rim 184b of the second bottom receptacle 180b at a secondconnection area 130b. A protruding portion 186b of the rim 184b may extend vertically beyond such second connection area 130b. Besides, the inner surface 163 of the vertical cover 162 and / or the rim 184b of the second bottom receptacle 180b may be shaped such that the second volume 120b may be defined between the inner surface 163 of the vertical cover 162 and the protruding portion 186b of the rim 184b. In particular, in the example shown in Figure 6A, the inner surface 163 of the vertical cover 162 exhibits a curvature to provide such second volume 120b. A channel 150b may also be defined in the rim 184b of the second bottom receptacle 180b to provide flow communication between the second bottom receptacle 180b and the volume 120b defined by the inner surface 163 of the vertical cover 162 and the protruding portions 186b of the rim 184b.

[0062] Moreover, as also shown in Figure 6A, flow communication may be provided between the first 180a and the second 180b bottom receptacles via the first 120a and the second 120b volumes. Accordingly, liquid may be transferred from the first receptacle 180a to the second receptable 180b via the created volumes 120a, 120b (which may also be referred to as a single volume). In this manner, liquid redistribution may be achieved, thus adding controllability on the filling of the different liquid receptacles 180a, 180b.

[0063] The volumes 120a, 120b may serve as an additional liquid receptacle and / or as a guiding flow path. As shown in Figure 6A, the arrangement of the two bottom receptacles 180a, 180b may be such that the two connection areas 130a, 130b may be adjacent to each other, thus giving place to a combined connection area 130. Consequently, the two volumes 120a, 120b may also result in a common volume 120, which may correspond to the combination of the two volumes 120a, 120b. The numerals 130 and 120 may be used to refer to such combined connection area and volume in subsequent figures. In other words, in case of adjacent liquid receptacles, the expression volume may refer to the aggregated volume.

[0064] The connection areas 130a, 130b (or the combined connection area 130 in Figure 6B) exhibit a certain size in a substantially vertical, i.e. “z”, direction and they extend along a substantially horizontal plane. In particular, the vertical cover 162 may be either a lateral cover or a front / rear cover. In the former case, the connection area 130 may extend along a direction substantially parallel to the rotor axis 30 of the wind turbine 10, i.e. it may extend along an “x” direction, as shown in Figure 3. In the latter case, the connection area 130 may extend along a direction substantially perpendicular to the rotor axis 30 of the wind turbine 10, i.e. it may extend along a “y” direction, as shown in Figure 3.

[0065] As depicted in Figures 6A and 6B, the rims 184a, 184b of the bottom receptacles 180a, 180b may comprise protruding portions 186a, 186b that extend vertically beyond the connection areas 130a, 130b. Specifically, the protruding portions 186a, 186b may extendvertically beyond an upper part 135 of the connection areas 130a, 130b. Thus, in this example, the two connection areas 130a, 130b may exhibit a substantially equal size in the vertical direction, such that the upper part of the two connection areas 130a, 130b may coincide in a same upper part 135.

[0066] As shown in the example of Figures 6A and 6B, the bottom receptacles 180a, 180b may be entirely formed by the bottom cover 160. That is, the horizontal surfaces 182a, 182b and the rims 184a, 184b (including the protruding portions 186a, 186b) may be formed by the bottom cover 160. Furthermore, as also shown in Figures 6A and 6B, the rims 184a, 184b may comprise a single part, which may be integrally formed with the corresponding surfaces 182a, 182b.

[0067] In another example, the rims 184a, 184b, or at least a part of the rims 184a, 184b, may be manufactured separately. In particular, the protruding portions 186a, 186b of the rims 184a, 184b may be manufactured separately and they may be connected so as to extend in a substantially vertical direction. Hence, the protruding portions 186a, 186b may be connected and arranged as extensions of the portions of the rims 184a, 184b connected to the inner surface 163 of the vertical cover 162. In this manner, the rims 184a, 184b may comprise a first part connected to the vertical cover 162 in the connection areas 130a, 130b, and a second part extending beyond such connection areas 130a, 130b (or, as already described, the combined connection area 130 in the case shown in Figure 6A).

[0068] As already indicated, the connection areas 130a, 130b (or the combined connection area 130) may extend along a direction in a substantially horizontal plane. Different vertical covers 162 may be used to define the volume 120 shown in Figures 6A and 6B. Thus, the vertical cover 162 may comprise one of the following: a front cover of the nacelle, a rear cover of the nacelle, or a lateral cover of the nacelle. Depending on the vertical cover 162, i.e. either lateral or front / rear cover, the connection areas 130a, 130b may extend along the length or the width of the nacelle 16. The connection may comprise a mechanical fixation with bolts and / or rivets. An adhesive may also be used for the connection of the vertical cover 162 and the rims 184a, 184b. Furthermore, the bottom region of the volumes 120a, 120b, particularly the interface between the inner surface 163 of the vertical cover 162 and the rims 184a, 184b, may be sealed to prevent leakage of liquid to the outside of the nacelle 16. To this end, a sealant may be applied along the whole length of the connection areas 130a, 130b. The connection areas 130a, 130b may extend for a certain minimum width in the vertical direction to ensure proper fixation between the parts. Accordingly, the connection areas 130a, 130b (or the combined connection area 130 in the case of Figure 6A) may define an upper plane or upper part 135.

[0069] The combined volume resulting from the combination of the volumes 120a and 120b in Figure 6A may provide additional volume for the containment of liquids, i.e. it may act as an additional liquid receptacle. In this case, such liquid receptacle may not be associated to any specific component but it may extend in the periphery of the nacelle bottom cover 160 along at least a portion of the length and / or width of the nacelle 16. Accordingly, the volumes 120a, 120b may also act as a guiding path or fluid conveyor, which may be used to redistribute liquids between different bottom receptacles 180, e.g. between the first bottom receptacle 180a and the second bottom receptacle 180b in Figure 6A. or between said bottom receptacles 180a, 180b and further bottom receptacles (not depicted in Figure 6A). In particular, in an example, a further bottom receptacle may be configured as a collector. Accordingly, liquid may be redistributed and collected at a dedicated bottom receptacle, which may be provided at a convenient location to facilitate, e.g. removal of the liquid during maintenance and / or repair operations.

[0070] In examples of the present disclosure, and as already explained with reference to Figure 4, the bottom cover 160 may comprise a plurality of panels 170. Specifically, the bottom cover 160 may at least partially define two bottom receptacles 180 arranged in two different panels 170. The use of multiple panels 170 may be preferred for manufacturability or logistics reasons. Liquid containing components, i.e. components with a risk of liquid leakage, may be distributed over a large area inside the nacelle 16. Accordingly, when using a plurality of panels 170, more than one of such panels 170 may be located underneath a liquid containing component. Therefore, more than one panel 170 may be provided with a bottom receptacle 180 comprising a liquid receptacle.

[0071] In some examples, a configuration like the one depicted in Figures 6A-6B may be arranged in a single vertical cover 162 whereas, in some other cases, such configuration may be replicated in more than one, or even in all, vertical covers 162 of the nacelle 16. In this manner, an increased flexibility and accessibility may be provided.

[0072] The shape of the vertical cover 162 according to an example, especially the shape of the vertical cover 162 at its end region, is schematically shown in the cross-section depicted in Figure 6B. Hence, in this example, the vertical cover 162 may be shaped with a curvature extending outwards from the connection area 130a to define a volume 120a between the inner surface 163 of the vertical cover 162 and the rim 184a.

[0073] In another example of the disclosure, the rim 184a and, more specifically, the protruding portion 186a of the rim 184a, may be shaped with a curvature extending inwards from the connection area 130a to define a volume 120a between the inner surface 163 of the vertical cover 162 and the rim 184a. In a variant of this example, a panel 170 may be firstmanufactured with a mould so as to define the bottom surface 182 of a bottom receptacle 180. The rim 184, with the desired shape, may be manufactured separately and it may be subsequently connected at the perimeter of the bottom surface 182. In a further variant of this example, the rim 184 may be manufactured in multiple pieces, which may be connected to the bottom surface 182. In still another example, the part of the rim 184 connected to the vertical cover 162 in the connection area 130 may be integrally formed with the bottom surface 182 whereas the protruding portion 186 of the rim 184 may be manufactured separately, and subsequently connected, so as to form the complete rim 184.

[0074] In still further examples, the previous two examples may be combined. Thus, the vertical cover 162 may be shaped with an outwardly extending curvature (as depicted in Figure 6B), and the rim 184 may be shaped with an inwardly extending curvature.

[0075] It is understood that only the connection between the first bottom receptacle 180a and the vertical cover 162 is depicted in Figure 6B for illustrative and clarity purposes. Nevertheless, an equivalent cross-sectional view may be provided for the connection between the second bottom receptacle 180b and the vertical cover 162, or between a further bottom receptacle 180 (not shown) and the vertical cover 162.

[0076] The channel 150a, 150b may be provided with multiple configurations in different examples of the present disclosure. Thus, in an example shown in Figure 7, the channel 150a, 150b may comprise a local depression 155, the local depression comprising a region or reduced height of the rim 184a, 184b. Specifically, the local depression may comprise a cutout of the rim 184a, 184b. In the example shown in Figure 7, the reduced height in the local depression is designated as hc. In this example, the height, hc, of the local depression 155 may define a maximum predetermined volume of liquid that can be contained in the corresponding bottom receptacle 180a, 180b. In other words, liquid contained in the bottom receptacle 180a, 180b may remain in the receptacle until a certain level, defined by the height hc, is reached. When such a height is reached by the liquid, the liquid may flow, via the channel 150a, 150b, to the corresponding volume 120 defined between the inner surface 163 of the vertical cover 162 and the corresponding rims 184a, 184b.

[0077] This may provide an easy and convenient manner to limit the capacity of a certain bottom receptacle. Furthermore, in examples of the disclosure, and as shown in Figures 6A, 6B and 7, the height of the rim 184a, 184b at the local depression 155 may be configured such that the rim 184a, 184b at the local depression 155 is substantially aligned with an upper part 135 of the connection area 130. Such upper part is schematically represented by the line designated with numeral 135 in Figures 6A or 7. Alignment of the local depression 155 with the upper part 135 of the connection area 130 may prevent local accumulation of the overflownliquid in the volume 120. Thus, redistribution of the liquid to other regions of the bottom cover 160, more specifically to other bottom receptacles 180, may be facilitated. Such redistribution of liquid between bottom receptacles 180 is also visible in Figures 6A and 7. As an example, liquid overflowing from a first bottom receptacle 180a may be first transferred to the volume 120 via the channel 150a. From here, at least a portion of said liquid may enter a second bottom receptacle 180b, the another bottom receptacle 180b comprising a corresponding channel 150b.

[0078] In an example of the disclosure, a bottom cover 160 may at least partially define a first 180a and a second 180b bottom receptacles with channels 150a, 150b in the respective rims 184a, 184b. Channels 150a, 150b may comprise a local depression of the corresponding rims 184a, 184b, the local depression comprising a region of reduced height of the corresponding rim 184a, 184b. Even if, in the example depicted in Figure 7, such reduced height is substantially the same for both channels 150a, 150b, other examples may involve that the reduced height of the local depression of the channel 150a of the first bottom receptacle 180a may be different than the reduced height of the channel 150b of the second bottom receptacle 180b. In this manner, different levels of liquids may be allowed in different bottom receptacles 180a, 180b depending on, e.g. the component located at the respective position of the nacelle 16, or other specific needs.

[0079] Also, in some examples, different liquids may be leaked in different areas of the nacelle 16. Some of these liquids may exhibit a higher hazard than others. On the one hand, bottom receptacles 180 arranged in regions with higher risk of leakage of such hazardous liquids may be provided with higher rims 184 and / or higher reduced heights, hc, at the corresponding local depressions 155. In this manner, such liquids may be more effectively contained within such bottom receptacles 180. On the other hand, bottom receptacles 180 arranged in positions wherein not hazardous liquids, e.g. water, are primarily expected, may be provided with lower reduced heights, hc, at the corresponding channels 150.

[0080] In still further examples, at least one of the channels 150 may comprise an orifice 154 instead of a cut-out. Such an example is also depicted in Figure 7 for illustrative purposes. The use of orifices 154 instead of cut-outs may provide improved control and may improve the mechanical behavior of the system. When using orifices 154, similar considerations to those already described with respect to the cut-out may apply. Thus, a height of the orifice, h0, may play an equivalent role to the height, hc, of the local depression 155. As an example, the location and size of the orifice 154 may be selected such that the height, h0, of the bottom part of the orifice 154 corresponds to a certain predetermined liquid level in the corresponding bottom receptacle 180. As also explained with reference to the channels 150 based on a cut-out of the rim 184, different orifices 154, exhibiting different heights, h0, may be used for different bottom receptacles 180, thus allowing a predetermined redistribution of the liquid in the multiple bottom receptacles 180.

[0081] Furthermore, in examples of the disclosure, a further degree of freedom may be provided by means of flow controlling devices, e.g. fill valves. Thus, a flow controlling device (see, e.g. flow controlling device 153 in Figure 7 for the channel 150b of the second bottom receptacle 180b) may be arranged in the channel 150b to control the flow communication between the corresponding liquid receptacle and the volume 120 defined by the inner surface of the vertical cover 162 and the rim 184b. In this manner, a controllable filling of the bottom receptacles may be provided. In examples comprising a plurality of bottom receptacles 180 and a plurality of corresponding channels 150, a flow controlling device may be arranged in some or in all the channels 150.

[0082] Specifically, in nacelles 16 comprising several bottom receptacles 180 to contain liquid, a plurality of such bottom receptacles 180 may be in flow communication to the same volume 120. Such an example is depicted in Figures 6A or 7, in which a first 180a and a second 180b bottom receptacles are in flow communication via a combined volume 120, which results from the combination of the respective volumes 120a, 120b. Nevertheless, such flow communication may be controlled by a valve. In this manner, liquid overflowing from a first bottom receptacle 180a may first reach the volume 120 and may then be distributed, in a convenient manner, to a selected second bottom receptacle 180b (or to a plurality of second bottom receptacles) by means of the flow controlling devices 153. Therefore, a predetermined filling order and / or predetermined filling levels for different bottom receptacles 180 may be obtained.

[0083] Different types of controlling devices may be envisaged in examples of the disclosure. In some variants, a fully controllable valve may be provided. A liquid level sensor may be provided and the valve may be actuated by means of a corresponding actuator. In other examples, a passive controlling device, such as a fill valve comprising a floater, may be employed.

[0084] Figure 8 provides a schematic top view of a section of a nacelle 16 according to an example. In this example, the bottom cover 160 of the nacelle 16 at least partially defines a first 180a and a second 180b bottom receptacles. The first 180a and second 180b bottom receptacles may be adjacent to each other and they may be separated by a separation wall 140. The separation wall 140 may be defined by a portion of the respective rims 184a, 184b. In examples, the separation wall 140 may be substantially perpendicular to the connection areas 130a, 130b. In other examples, the separation wall 140 may exhibit a non-perpendicularorientation. Channels 150a, 150b may be defined in the rims 184a, 184b of the first 180a and second 180b bottom receptacles and they may be located in the vicinity of the separation wall 140. According to this example, a convenient redistribution of liquid between the adjacent bottom receptacles 180a, 180b may be provided. Specifically, by arranging the channels 150a, 150b in the vicinity of the separation wall 140, only a short flow path, via the volume 120, may be required to effectively transfer liquid from one of the bottom receptacles 180a, 180b to the other adjacent bottom receptacle 180a, 180b.

[0085] Figure 9 shows another example of the present disclosure. In this example, a first 180a and a second 180b bottom receptacle may also be provided in an adjacent manner. Similarly to the previous example, a separation wall 140 may be defined by a portion of the corresponding rims 184a, 184b to provide a physical separation between the two bottom receptacles 180a, 180b. A passage 145 may be arranged in the separation wall 140 to provide flow communication between the adjacent bottom receptacles 180a, 180b. In this example, a direct flow communication path may be provided between adjacent bottom receptacles 180a, 180b.

[0086] The at least one passage 145 may be configured to provide flow communication between the bottom receptacles 180a, 180b at a first liquid level, hp, in any of the bottom receptacles 180a, 180b. On the other hand, a channel 150a may be provided in the first bottom receptacle 180a in a similar fashion as described above with reference to other examples. The channel 150a may be configured to provide flow communication with the volume 120 at a second liquid level, hc. Specifically, the first liquid level, hp, may be lower than the second liquid level, hc. In this manner, a preferred sequence, at predetermined liquid levels, may be provided for the redistribution of liquids. Specifically, a first liquid level, hp, may be defined for the redistribution of liquids between the two adjacent bottom receptacles 180a, 180b. Hence, a direct flow redistribution may be provided up until such level is reached. Then, when the liquid level in the corresponding bottom receptacles 180a, 180b exceeds a second predetermined level, as defined by hc, the liquid or liquids may flow to the volume 120 at least partially defined by the inner surface 163 of the vertical cover 162 via the channel 150a defined in the first bottom receptacle 180a. From here, the liquid may be redistributed to other bottom receptacles 180 of the nacelle bottom cover 160. In this manner, for sufficiently modest liquid leakages, the liquid may be entirely contained in the two adjacent bottom receptacles 180a, 180b, thus facilitating further removal and identification of the liquid source. In an example, liquid outflowing from the channel 150a may be directed, via the volume 120, to an especially dedicated bottom receptacle, which may be configured as a liquid collector. The dedicatedbottom receptacle may be arranged in a position suitable for the removal of liquid during maintenance or repair operations.

[0087] Figures 10A-10C provide a schematic view of a section of nacelle 16 according to a further example. In particular, Figure 10A provides a perspective view of a section of a bottom cover 160 of a nacelle 16 before connection to a vertical cover 162. Figure 10B depicts a perspective view after connection of the nacelle bottom cover 160 and the vertical cover 162. Finally, Figure 10C, provides a schematic top view of the connected bottom cover 160 and vertical cover 162.

[0088] In this example, the bottom cover 160 may at least partially define three bottom receptacles 180a, 180b, 180c, which may be connected to the vertical cover 162. The three bottom receptacles 180a, 180b, 180c may comprise a substantially horizontal bottom surface 182a, 182b, 182c and a rim 184a, 184b, 184c arranged along the perimeter of the bottom surface 182a, 182b, 182c. The rims 184a, 184b, 184c may extend at least partially in a vertical direction. The inner surface 163 of a vertical cover 162 may be connected to the bottom receptacles 180a, 180b, 180c and volumes may be at least partially defined by the inner surface 163 of the vertical cover 162.

[0089] In particular, in the examples shown, the inner surface 163 may be connected to the rims 184a, 184b, 184c of the three bottom receptacles 180a, 180b, 180c at respective connection areas. Furthermore, in this example, a protruding portion of the rims 184a, 184b, 184c may extend vertically beyond the connection areas. Furthermore, in some examples, the inner surface 163 of the vertical cover 162 and / or the rims 184a, 184b, 184c may be shaped such that the volumes may be defined between the inner surface 163 of the vertical cover 162 and the protruding portions of the rims 184a, 184b, 184c.

[0090] As also shown in Figures 10A-10C, one of the three bottom receptacles 180c may be arranged in an intermediate position between the other two bottom receptacles 180a, 180b.

[0091] In a variant of this example, the rims 184a, 184b of the bottoms receptacles 180a, 180b not arranged in the intermediate position may comprise respective channels 150a, 150b to provide flow communication between the respective bottom receptacles 180a, 180b and the volume 120. The bottom receptacle 180c arranged in the intermediate position may not comprise such a channel.

[0092] According to this example, a redistribution of liquid in the nacelle bottom cover 160, via the volume 120, may be provided while bypassing a certain bottom receptacle 180c. Thus, a liquid exceeding a predetermined level in a certain bottom receptacle 180a, 180b may not be redistributed to a certain bottom receptacle 180c, but to a further bottom receptacle 180a,180b. Indeed, by using the volume 120 defined by the inner surface 163 of the vertical cover 162 and the rims 184a, 184b, 184c as a fluid path, liquid overflowing from one bottom receptacle may be conveyed to a second desired bottom receptacle, the second bottom receptacle being separate from the first bottom receptacle.

[0093] This example may be particularly useful to prevent unwanted presence of liquid in specific bottom receptacles 180 or for avoiding mixture of certain liquids. Hence, the area of certain bottom receptacles 180 may be predefined as working areas for maintenance personnel and they may require frequent access. A desire to keep such bottom receptacles 180 substantially free of liquid may exist. Furthermore, certain areas may also exhibit a weaker structure, which may not be designed to withstand additional liquid weight. As an example, liquid may be distributed between a bottom receptacle in a back part of the nacelle and a bottom receptacle in a front part of the nacelle, thus achieving a more balanced weight distribution. As a further example, the area of some bottom receptacles 180 may comprise openings, e.g. hatches or similar apertures, to facilitate access to and from the nacelle 16. Although seals may be applied around said hatches, a desire to minimize the presence of liquids in such areas may also exist. As still another advantage, liquid may be preferably contained and distributed to bottom receptacles 180 offering easy access for subsequent liquid removal, whereas bottom receptacles 180 with difficult access may be avoided and maintained in a substantially dry condition.

[0094] Moreover, different liquids may be used for the components arranged above different bottom receptacles 180. As an example, a certain liquid may be used for the components arranged above the intermediate bottom receptacle 180c in Figure 10C. Such liquid may be different than the liquid used for components arranged above the other two bottom receptacles 180a, 180b. Depending on the nature of such liquids, an interest may exist to prevent mixture of the same. Accordingly, liquid redistribution may be allowed among a first bottom receptacle 180a and a second bottom receptacle 180b, but not with the intermedia bottom receptacle 180c. Thus, the provision of a volume 120, with the ability to extend along the nacelle 16, may constitute a liquid flow path that may allow optimized redistribution of liquid between selected bottom receptacles 180 while bypassing other bottom receptacles 180.

[0095] In an example, the three bottom receptacles 180a, 180b, 180c may be entirely comprised or defined by the bottom cover 160, i.e. the horizontal surfaces 182a, 182b, 182c and the rims 184a, 184b, 184c of the three bottom receptacles 180a, 180b, 180c may be entirely formed by the bottom cover 160.

[0096] As also shown in the example of Figures 10A-10C, the three bottom receptacles 180a, 180b, 180c may be adjacent to each other. The bottom receptacle 180c, arranged in theintermediate position, may be separated from the other bottom receptacles 180a, 180b by corresponding separation walls 140a, 140b defined by the respective rims 184a, 184b, 184c. A passage 145a may be defined in at least one of the separation walls 140a, 140b to provide flow communication between the intermediate bottom receptacle 180c and one of the other bottom receptacles 180a. In other examples, two passages may be defined to provide flow communication between the intermediate bottom receptacle 180c and the other two receptacles 180a, 180b.

[0097] According to this example, increased flexibility may be provided by adjusting the heights of the channels 150a, 150b and the passage 145a. Thus, the passage 145a may be configured to provide flow communication at a first liquid level and the channels 150a, 150b may be configured to provide flow communication between the corresponding bottom receptacles 180a, 180b and the corresponding volumes 120 at a second liquid level. Specifically, the first liquid level may be higher than the second liquid level. Accordingly, liquid may be first distributed between the bottom receptacles 180a, 180b at each side of the intermediate bottom receptacle 180c. The latter may only receive liquid when the level of liquid in the other two bottom receptacles 180a, 180b exceeds a certain, higher, predetermined level. Such example may be useful to prevent unwanted ingress of liquid in the intermediate bottom receptacle 180c, which may only contribute to the distribution of liquids at, e.g. emergency levels defined by the height of the passage 145a.

[0098] In another variant, the height of the passage 145a may be lower than the height of the channels 150a, 150b. In such case, the intermediate bottom receptacle 180c and the other bottom receptacle 180a connected to it via the passage 145a may be first filled up to a certain level. Upon reaching a level defined by the height of the channels 150a, 150b, liquid may be allowed to flow to the volume 120 and, from here, to the other bottom receptacle 180b.

[0099] As still another example of the disclosure, not shown in the figures, a nacelle 16 may comprise a bottom cover 160 at least partially defining three bottom receptacles 180. The three bottom receptacles 180 may be similar to the ones discussed with reference to Figures 10A-10C. Nevertheless, in this example, the three bottom receptacles 180 may comprise a channel 150 providing flow communication between the bottom receptacles 180 and the volumes 120 defined between the inner surface 163 of the vertical cover 162 and the protruding portions of the corresponding rims 184. Hence, the three bottom receptacles 180 may be configured in an equivalent manner to the first 180a and second 180b bottom receptacles depicted in Figures 6A and 7, i.e. the three bottom receptacles 180 may be connected to an inner surface 163 of a vertical cover 162 via corresponding rims 184. Such rims 184 may also exhibit a portion 186 protruding from the connection area 130 to define respective volumes120. Finally, channels 150 may be provided in the extending portions 186 of the rims 184 to provide flow communication between the bottom receptacles 180 and the volumes 120.

[0100] The channels 150 of the three bottom receptacles 180 may comprise a local depression of the corresponding rim 184, the local depression comprising a region of reduced height of the rim. The reduced height of the local depression 155 of two of the three bottom receptacles 180 may be substantially equal to each other and different to the reduced height of the local depression 155 of the third bottom receptacle 180. In this example, a prioritization may be defined between bottom receptacles 180. In other words, liquid may be redistributed between two of the three bottom receptacles 180 as the liquid reaches a certain height in one of those two bottom receptacles 180. But no such liquid may be allowed to penetrate in the receptacle of the third bottom receptacle 180, whose channel may be configured with a higher height. On the other hand, if liquid is spilled in the bottom receptacle 180 with the higher height, no redistribution to the other two bottom receptacles 180 may occur until a certain overflow level, which may be higher than the overflow level for the other two bottom receptacles 180, is reached.

[0101] A further aspect of examples of the disclosure can be seen in Figures 8 or Figure 10C. Thus, in examples of the disclosure, one or more barriers 125 may be arranged in the volume 120 defined between the inner surface 163 of the vertical cover 162 and the rims 184a, 184b, 184c. In a specific example, the bottom cover 160 may at least partially define a first bottom receptacle 180a and a second bottom receptacle 180b, and the one or more barriers 125 may be arranged in the first 120a and second 120b volumes to delimit a flow path connecting the first 180a and second 180b bottom receptacles via the corresponding volumes 120a, 120b (or, as shown in Figures 8 and 10C, via the combined volume 120 resulting from the combinations of adjacent bottom receptacles 180a, 180b, 180c). The provision of such barriers 125 may result in a partition of the combined volume 120 and it may improve the effectiveness of the liquid redistribution system. Thus, the barriers 125 may facilitate guiding of liquid overflowing from a certain liquid receptacle via the corresponding channel 150. Accordingly, liquid overflowing from a bottom receptacle 180 may not need to fill the whole volume 120 in order to be redistributed to a further bottom receptacle 180. Thus, as shown in, e.g. Figure 8, an optimized flow guiding path between bottom receptacles 180a, 180b may be obtained by properly arranging the barriers 125.

[0102] Furthermore, in examples of the disclosure, the barriers 125 may be easily replaceable, so as to modify the partitions of the volume 120. In this manner, a more flexible system may be provided. In still other examples, the barriers 125 may comprise controllablegates. In these examples, the flow guiding path in the volume 120 may be defined according to real-time requirements.

[0103] Figures 11A and 11 B show a schematic view of another example comprising improved control on the location and distribution of the liquid in the volume 120 formed between an inner surface 163 of the vertical cover 162 and the rims 184. As shown in the top view of Figure 11A, the vertical cover 162, or more specifically, the inner surface 163 of the vertical cover, may be shaped such that local recesses or depressions may be formed in the region intended for receiving and redistributing the liquid. Figure 11 B provides a detailed view of the section “A” highlighted in Figure 11A. Hence, as shown in Figure 11 B, a trough 122 may be defined in the inner surface 163 of the vertical cover 162 to guide or channel the liquid in a more efficient manner.

[0104] In a further example of the present disclosure, the bottom cover 160 may at least partially define an inner bottom receptacle 180i as already described in reference to Figure 4. The inner bottom receptacle 180i may comprise a substantially horizontal bottom surface and a rim arranged along the perimeter of the bottom surface. The rim may extend at least partially in a vertical direction. Thus, the inner bottom receptacle 180i may define a liquid receptacle in an equivalent manner as the other bottom receptacles 180. The inner bottom receptacle 180i may be adjacent to another bottom receptacle 180p and it may not be connected to the vertical cover 162. The another bottom receptacle 180p may be connected to the vertical cover 162 as described with reference to the first 180a bottom receptable (see Figures 6A-6B). In other words, the another bottom receptacle 180p may be connected to an inner surface 163 of the vertical cover 162 and a volume 120 may be formed. In this example, the inner bottom receptacle 180i and the other bottom receptacle 180p may be separated along a separation wall 146 defined by a portion of the respective rims. A passage 147 may be defined in the separation wall to provide flow communication between the another bottom receptacle 180p and the inner bottom receptacle 180i.

[0105] According to this further example, an inner bottom receptacle 180i may also be in flow communication with the volume 120 via another bottom receptacle 180p. In this manner, the inner bottom receptacle 180i may also contribute to the redistribution of liquid in the bottom cover 160 by properly adjusting the height of the passage 147.

[0106] In another aspect of the disclosure, a method 100 is provided as shown in the flowchart of Figure 12.

[0107] The method comprises, at block 102, providing a vertical cover 162 of a wind turbine nacelle 16, the vertical cover comprising an inner surface 163 facing, in a mounted state, an interior of the wind turbine nacelle 16.

[0108] Block 104 comprises providing a bottom cover 160 of the wind turbine nacelle 16, the bottom cover 160 at least partially defining a first bottom receptacle 180a. The first bottom receptacle 180a comprises a substantially horizontal bottom surface 182a and a rim 184a arranged along the perimeter of the bottom surface 182a. The rim 184a extends at least partially in a vertical direction.

[0109] The method 100 also comprises, at block 106, connecting an inner surface 163 of the vertical cover 162 to the first bottom receptacle 180a such that, after connection of the vertical cover 162 to the first bottom receptacle 180a, a first volume 120a is at least partially defined by the inner surface 163 of the vertical cover 162.

[0110] In an example, connecting an inner surface 163 of the vertical cover 162 to the first bottom receptacle 180a may comprise connecting an inner surface 163 of the vertical cover 162 to the rim 184a of the first bottom receptacle 180a along a first connection area 130a. In a variant, after connection of the vertical cover 162 to the rim 184a, a protruding portion of the rim 184a may extend vertically beyond the first connection area 130a and the vertical cover 162 and / or the rim 184a may be shaped such that the first volume 120a may be at least partially defined by the inner surface 163 of the vertical cover 162 and the protruding portion of the rim 184a.

[0111] In a variant of the method 100, the rim 184a may comprise two separate parts: a first part intended for being connected to the inner surface 163 of the vertical cover 162 and a second part being configured as a protruding portion 186a of the rim 184a. In such case, the part configured as the protruding portion 186a may be connected so as to extend vertically beyond the connection area 130a. To this end, such part may be connected to the part acting as the first portion of the rim 184a before connection of the vertical cover 162 to the rims 184a. Alternatively, the part acting as the protruding portion 186a may be connected once the vertical cover 162 is already connected to the corresponding first portion of the rims 184a.

[0112] In an example of the disclosure, the method 100 may comprise providing one or more channels 150a in the rim 184a of the first bottom receptacle 180a before connection of the vertical cover 162 to the bottom receptacle 180a. The channels 150 may be configured to provide flow communication between the first bottom receptacle 180a and the first volume 120a at least defined by the inner surface of the vertical cover 162.

[0113] The channels 150 to evacuate liquid from a certain bottom receptacle 180a may be easily defined. In particular, in examples comprising a plurality of bottom receptacles 180, a channel 150 may be defined for the different bottom receptacles 180 individually, i.e. without any need to align features of different bottom receptacles 180.

[0114] Although the method 100 has been described in relation to a first bottom receptacle 180a, it is understood that the same method 100 may be applied to a plurality of bottom receptacles 180 (if present).

[0115] Thus, in examples comprising multiple bottom receptacles, channels 150 may be provided in selected bottom receptacles 180. The size and position of the channels 150 may also be optimized to ensure liquid does not exceed a certain predetermined level in the corresponding bottom receptacles 180. Thus, by providing an additional volume 120 and a channel 150 connecting the bottom receptacles 180 with said additional volume 120, a controllable overflow strategy may be utilized.

[0116] Furthermore, the channels 150 may be provided in the corresponding rims 184 in an easy and convenient manner. Thus, cut-outs or orifices may be practiced in the rims 184 of individual bottom receptacles 180. The fact that the channel 150 can be defined in a bottom receptacle 180 individually, may avoid the need for complex alignment processes which may be required while defining channels 150 at the interface between two bottom receptacles 180. Besides, not only alignment, but also manufacturing tolerances may be increased. Indeed, according to this example, channels 150, e.g. cut-outs or orifices, may be conveniently carried out at the most convenient positions of a bottom receptacle 180 with no affectation to other bottom receptacles 180.

[0117] In another example of the disclosure, the method 100 may comprise providing one or more channels 150 after connection of the vertical cover 162 and the bottom receptacle 180a. The channels 150a may be configured to provide flow communication between the first bottom receptacle 180a and the volume 120 defined by the inner surface 163 of the vertical cover 162 after connection. Specifically, the method 100 may comprise defining one or more channels 150a after the wine turbine nacelle 16 is installed in an erected wind turbine 10.

[0118] In an example, the substantially horizontal bottom surface 182 and the rim 184 may be integrally formed. In another example, the substantially horizontal bottom surface 182 and the rim 184 may be manufactured separately, and they may be subsequently connected. In this example, the bottom cover 160 of the nacelle 16 may comprise the substantially horizontal bottom surface 182 whereas the rim 184 may be individually fabricated and subsequently connected. In still a further example, the rim 184 may be manufactured inmultiple parts. Specifically, a portion of the rim 184 connected to the inner surface 163 of the vertical cover 162 may be manufactured integrally with the horizontal bottom surface 182. Then, the protruding portion 186 of the rim 184 may be manufactured separately and connected subsequently.

[0119] In still a further variant, the rim 184 or at least the protruding portion 186 of the rim 184 extending beyond the first connection area 130 may be integrally formed with the vertical cover 162. In such case, the rim 184 of the sides of the first bottom receptacle 180a not connected to the vertical cover 162 may exhibit the same height as the rim provided by the vertical cover 162. To this end, either a separate part may be manufactured and connected to such sides or a rim may be integrally formed in such sides with a height substantially equal to the height of the rim provided by the vertical cover. According to this example, the bottom cover 160 may define the first bottom receptacle 180 only partially. Indeed, the definition of the first bottom receptacle 180 in this example may also require the vertical cover 162, which may be used to provide a portion of the rim 184.

[0120] Different wind turbine variants may exhibit different internal arrangement of the components, which may also determine the potential distribution of spilled liquid. Due to the versatility of the proposed methods, the same moulds may be used for the manufacture of bottom covers 160 of different wind turbines 10. Adaptation to different variants may simply require defining different channel 150 positions in individual bottom receptacles 180.

[0121] Due to the flexibility of the proposed disclosure, this example may even comprise formation of the channels 150 in an already installed wind turbine 10. Several advantages may result from such flexibility. In particular, channels 150 may be redefined in an already operating wind turbine 10 if, e.g. certain components of the nacelle 16 are re-arranged or upgraded. Accordingly, the needs for liquid redistribution may be adjusted. Furthermore, definition of channels 150 upon installation of the nacelle 16 may also allow arranging the channels 150 in the most ergonomic positions, i.e. in positions facilitating the tasks of maintenance personnel. Moreover, subsequent adjustments and / or corrections on originally intended liquid redistribution strategies may also be easily carried out.

[0122] This written description uses examples to disclose the teaching, including the preferred embodiments, and also to enable any person skilled in the art to practice the teaching, including making and using any devices or systems and performing any incorporated methods. The patentable scope is defined by the claims, and may include other examples that occur to those skilled in the art. Such other examples are intended to be within the scope of the claims if they have structural elements that do not differ from the literal language of the claims, or if they include equivalent structural elements with insubstantial differences from theliteral languages of the claims. Aspects from the various embodiments described, as well as other known equivalents for each such aspects, can be mixed and matched by one of ordinary skill in the art to construct additional embodiments and techniques in accordance with principles of this application. If reference signs related to drawings are placed in parentheses in a claim, they are solely for attempting to increase the intelligibility of the claim, and shall not be construed as limiting the scope of the claim.

Claims

CLAIMS1. A nacelle (16) for a wind turbine (10), the nacelle (16) comprising a substantially horizontal bottom cover (160) and a substantially vertical cover (162), the substantially vertical cover (162) comprising an inner surface (163) facing an interior of the wind turbine nacelle (16); the bottom cover (160) at least partially defining a first bottom receptacle suitable for retaining liquid (180a); the first bottom receptacle (180a) comprising a substantially horizontal bottom surface (182a) and a rim (184a) arranged along a perimeter of the bottom surface (182a), the rim (184a) extending at least partially in a vertical direction; the inner surface (163) of the vertical cover (162) being connected to the first bottom receptacle (180a); a first volume (120a) being at least partially defined by the inner surface (163) of the vertical cover (162), and the nacelle (16) further comprising a channel (150a) to provide flow communication between the first bottom receptacle (180a) and the first volume (120a).

2. The nacelle (16) of claim 1 , wherein the inner surface (163) of the vertical cover (162) is connected to the rim (184a) of the first bottom receptacle (180a) at a first connection area (130a), the first connection area (130a) extending along a substantially horizontal direction, a protruding portion of the rim (184a) extending vertically beyond the first connection area (130a), the inner surface (163) of the vertical cover (162) and / or the rim (184a) being shaped such that the first volume (120a) is at least partially defined between the inner surface (163) of the vertical cover (162) and the protruding portion of the rim (184); and further wherein the channel (150a) is provided in the rim (184a).

3. The nacelle (16) of any of claims 1 or 2, wherein the substantially horizontal bottom surface (182a) and the rim (184a) of the first bottom receptacle (180a) are formed by the bottom cover (160).

4. The nacelle (16) of any previous claim, wherein the channel (150a) comprises a local depression (155) of the rim (184a), the local depression (155) comprising a region of reduced height of the rim (184a).

5. The nacelle (16) of any of claims 2 to 4, wherein the vertical cover (162) is shaped with a curvature extending outwards from the first connection area (130a) to define the first volume (120a) and / or the rim (184a) is shaped with a curvature extending inwards from the first connection area (130a) to define the first volume (120).

6. The nacelle (16) of any of claims 2 to 5, the bottom cover (160) at least partially defining a second bottom receptacle (180b), the second bottom receptacle (180b) comprising a substantially horizontal bottom surface (182b) and a rim (184b) arranged along a perimeter of the bottom surface (182b), the rim (184b) extending at least partially in a vertical direction; the inner surface (163) of the vertical cover (162) being connected to the rim (184b) of the second bottom receptacle (180b) at a second connection area (130b), the second connection area (130b) extending along a substantially horizontal direction; a protruding portion (186b) of the rim (184b) of the second bottom receptacle (180b) extending vertically beyond the second connection area (130b); the inner surface (163) of the vertical cover (162) and / or the rim (184b) of the second bottom receptacle (180b) being shaped such that a second volume (120b) is defined between the inner surface (163) of the vertical cover (162) and the protruding portions of the rim (184b); a channel (150b) being provided in the rim (184b) of the second bottom receptacle (180b), the channel (150b) providing flow communication between the second bottom receptacle (180b) and the second volume (120b); wherein flow communication is provided between the first (180a) and the second (180b) bottom receptacles via the first (120a) and second (120b) volumes defined between the inner surface (163) of the vertical cover (162) and the protruding portions (186a, 186b) of the corresponding rims (184a, 184b).

7. The nacelle (16) of claim 6, wherein the channels (150a, 150b) provided in the rims (184a, 184b) of the first (180a) and the second (180b) bottom receptacles comprise a local depression (155) of the corresponding rim (184a, 184b), the local depression (155) comprising a region of reduced height of the corresponding rim (184a, 184b).

8. The nacelle (16) of claim 6 or 7, wherein the first (180a) and the second (180b) bottom receptacles are adjacent to each other, the first (180a) and the second (180b) bottom receptacles being separated along a separation wall (140) defined by a portion of the respective rims (184a, 184b), and further wherein the channels (150a, 150b) provided in the rims (184a, 184b) of the first (180a) and the second (180b) bottom receptacles are located in the vicinity of the separation wall (140).

9. The nacelle (16) of any of claims 6 to 8, the bottom cover (160) at least partially defining a third bottom receptacle (180c), the third bottom receptacle (180c) comprising a substantially horizontal bottom surface (182c) and a rim (184c) arranged along a perimeter of the bottom surface (182c), the rim (184c) extending at least partially in a vertical direction; the inner surface (163) of the vertical cover (162) being connected to the rim (184c) of the third bottom receptacle (180c) at a third connection area (130c), the third connection area (130c) extending along a substantially horizontal direction; a protruding portion (186c) of the rim (184c) of the third bottom receptacle (180c) extending vertically beyond the third connection area (130c); the inner surface (163) of the vertical cover (162) and / or the rim (184c) of the third bottom receptacle (180c) being shaped such that a third volume (120c) is defined between the inner surface (163) of the vertical cover (162) and the protruding portion of the rim (184c); and the third bottom receptacle (180c) being arranged in an intermediate position between the first (180a) and the second (180b) bottom receptacles.

10. The nacelle (16) of claim 9, the third bottom receptacle (180c) being adjacent to the first (180a) and the second (180b) bottom receptacles, the third bottom receptacle (180c) being separated from the first (180a) and second (180b) bottom receptacles by corresponding separation walls (140a, 140b) defined by the respective rims (184a, 184b, 184c), wherein apassage (145a) is provided in at least one of the separation walls (140a, 140b) to provide flow communication between the third bottom receptacle (180c) and the first (180a) and / or the second (180b) bottom receptacle.

11. The nacelle (16) of claim 10, wherein the at least one passage (145a) is configured to provide flow communication at a first liquid level, and the channels (150a, 150b) of the first (180a) and second (180b) bottom receptacles are configured to provide flow communication between the corresponding bottom receptacles (180a, 180b) and the corresponding volumes (120a, 120b) between the inner surface (163) of the vertical cover (162) and the rims (184a, 184b) at a second liquid level, specifically, wherein the first liquid level is higher than the second liquid level.

12. The nacelle (16) of any previous claim, the bottom cover (160) at least partially defining an inner bottom receptacle (180i), the inner bottom receptacle (180i) comprising a substantially horizontal bottom surface (182) and a rim (184) arranged along a perimeter of the bottom surface (182), the rim (184) extending at least partially in a vertical direction; the inner bottom receptacle (180i) being adjacent to the first bottom receptacle (180a) and not being connected to the vertical cover (162); the first (180a) and the inner (180i) bottom receptacles being separated along a separation wall (146) defined by portions of the respective rims (184i, 184a); and a passage (147) being provided in the separation wall (146) to provide flow communication between the first bottom receptacle (180a) and the inner bottom receptacle (180i).

13. A method comprising: providing a vertical cover (162) of a wind turbine nacelle (16), the vertical cover (162) comprising an inner surface (163) facing, in a mounted state, an interior of the wind turbine nacelle (16); providing a bottom cover (160) of the wind turbine nacelle (16), the bottom cover (160) at least partially defining a first bottom receptacle (180a);the first bottom receptacle (180a) comprising a substantially horizontal bottom surface (182a) and a rim (184a) arranged along a perimeter of the bottom surface (182a), the rim (184a) extending at least partially in a vertical direction; connecting an inner surface (163) of the vertical cover (162) to the first bottom receptacle (180a), wherein after connection of the vertical cover (162) to the first bottom receptacle (180a), a first volume (120a) is at least partially defined by the inner surface (163) of the vertical cover (162).

14. The method of claim 13, wherein connecting an inner surface (163) of the vertical cover (162) to the first bottom receptacle (180a) comprises connecting an inner surface (163) of the vertical cover (162) to the rim (184a) of the first bottom receptacle (180a) along a first connection area (130a), and wherein after connection of the vertical cover (162) to the rim (184a), a protruding portion of the rim (184a) extends vertically beyond the first connection area (130a), and further wherein the vertical cover (162) and / or the rim (184a) are shaped such that the first volume (120a) is at least partially defined by the inner surface (163) of the vertical cover (162) and the protruding portion of the rim (184a).

15. The method of claim 14, comprising providing one or more channels (150) in the rim (184a) of the first bottom receptacle (180a) before connection of the vertical cover (162) and the rim (184a), the channels (150) being configured to provide flow communication between the first bottom receptacle (180a) and the first volume (120a), or providing one or more channels (150) in the rim (184a) of the first bottom receptacle (180a) after connection of the vertical cover (162) and the rim (184a), the channels (150) being configured to provide flow communication between the first bottom receptacle (180a) and the first volume (120a), specifically providing one or more channels (150) after installation of the wind turbine nacelle (16) in a wind turbine (10).

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