Fan assembly

Abstract

A fan assembly comprises a nozzle and an airflow generator. The nozzle comprises a first airflow outlet arrangement extending substantially along a common plane, and a second airflow outlet arrangement extending substantially along the common plane. The first airflow outlet arrangement comprises one or more first outlets. The second airflow outlet arrangement comprises one or more second outlets. The airflow generator is in fluid communication with the one or more first outlets and the one or more second outlets. The first and second airflow outlet arrangements are configured to discharge respective first and second airflows toward one another substantially along the common plane such that the first and second airflows collide at a focus to produce an aggregate airflow. An acute angle is subtended by the first and second airflows from the focus. Other fan assemblies and a nozzle are described.

Description

[0001]FAN ASSEMBLY BACKGROUND Fan assemblies are used to generate and direct an airflow. Nozzles for fan assemblies are used to direct one or more airflows. SUMMARY A first aspect of the present invention provides a fan assembly comprising a nozzle and an airflow generator. The nozzle comprises a first airflow outlet arrangement and a second airflow outlet arrangement. The first airflow outlet arrangement extends substantially along a common plane. The first airflow outlet arrangement comprises one or more first outlets. The second airflow outlet arrangement extends substantially along the common plane. The second airflow outlet arrangement comprises one or more second outlets. The airflow generator is in fluid communication with the one or more first outlets and the one or more second outlets. The first and second airflow outlet arrangements are configured to discharge respective first and second airflows toward one another substantially along the common plane such that the first and second airflows collide at a focus to produce an aggregate airflow. An acute angle is subtended by the first and second airflows from the focus. The acute angle may be measured at the focus and is subtended between at least one of: the first airflow outlet arrangement and the second airflow outlet arrangement; a centroid of the first airflow outlet arrangement and a centroid of the second airflow outlet arrangement; or a centroid of one of the one or more first outlets and a centroid one of the one or more second outlets. The focus may be a centroid of a focal region, wherein the focal region is a region in which the first airflow and the second airflow collide or coalesce to form the aggregate flow. The acute angle may be equal to 180° minus an internal angle between the first airflow outlet arrangement and the second airflow outlet arrangement. The acute angle may be an internal angle between a central axis of the first airflow outlet arrangement and a central axis of the second airflow outlet arrangement. A centroid of the first airflow outlet arrangement is on the central axis of the first airflow outlet arrangement, a centroid of the second airflow outlet arrangement is on the central axis of the second airflow outlet arrangement. The central axis of the first airflow outlet arrangement and the central axis of the second airflow outlet arrangement are both in the common plane. A second aspect of the present invention provides a fan assembly comprising: an airflow generator; a first airflow outlet arrangement elongate along a common plane; and a second airflow outlet arrangement elongate along the common plane. The first and second airflow outlet arrangements are arranged with an obtuse internal angle therebetween. The obtuse internal angle is in the common plane. The first and second airflow outlet arrangements are configured to receive an airflow generated by the airflow generator and to discharge respective first and second airflows toward one another along the common plane such that the first and second airflows collide between the first and second airflow outlets. Collision of the first and second airflows may produce an aggregate airflow. A third aspect of the present invention provides a nozzle for a fan assembly. The nozzle comprises a first airflow outlet arrangement and a second airflow outlet arrangement. The first airflow outlet arrangement extends substantially along a common plane. The first airflow outlet arrangement comprises one or more first outlets. The second airflow outlet arrangement extends substantially along the common plane. The second airflow outlet arrangement comprises one or more second outlets. The first and second airflow outlet arrangements are configured to discharge respective first and second airflows toward one another substantially along the common plane such that the first and second airflows collide at a focus to produce an aggregate airflow. The first and second airflows are supplied by an airflow generator of the fan assembly. An acute angle is subtended by the first and second airflows from the focus. A fourth aspect of the present invention provides a nozzle for a fan assembly. The nozzle comprises: an airflow generator; a first airflow outlet arrangement elongate along a common plane; and a second airflow outlet arrangement elongate along the common plane. The first and second airflow outlet arrangements are arranged with an obtuse internal angle therebetween. The obtuse internal angle is in the common plane. The first and second airflow outlet arrangements are configured to receive an airflow generated by the airflow generator and to discharge respective first and second airflows toward one another along the common plane such that the first and second airflows collide between the first and second airflow outlets. Collision of the first and second airflows may produce an aggregate airflow. The nozzle of the third or fourth aspects of the present invention may form part of the fan assembly of the first aspect of the present invention or the second aspect of the present invention. Using the fan assembly of the first or second aspects of the present invention or the nozzle of the third or fourth aspects of the present invention results in the first airflow and the second airflow colliding in the common plane and forming the aggregate airflow which, for example, can be directed at a user. The following may apply to the first, second, third and / or fourth aspects of the present invention. The first airflow outlet arrangement and the second airflow outlet arrangement extending substantially along the common plane may result in the fan assembly or nozzle being compact and / or space-efficient compared to other fan assemblies or nozzles that generate a comparable airflow. Further, the first airflow outlet arrangement and the second airflow outlet arrangement extending substantially along the common plane may result in the aggregate airflow having an airflow profile of greater width perpendicular to the common plane than other outlet arrangements of a comparable width perpendicular to the common plane. The first airflow outlet arrangement and the second airflow outlet arrangement being elongate on the common plane may result in the fan assembly or nozzle being compact and / or space- efficient compared to other fan assemblies or nozzles that generate a comparable airflow. Providing the first airflow outlet arrangement that is angled to the second airflow outlet arrangement may help to provide a compact solution. Further, the first airflow outlet arrangement and the second airflow outlet arrangement being elongate on the common plane with the obtuse internal angle therebetween may result in the aggregate airflow having an airflow profile of greater width perpendicular to the common plane than other outlet arrangements of a comparable width perpendicular to the common plane. Elongate herein is defined as having a length greater than a width, the width perpendicular to the length, for example, the length being one of: at least 2, at least 5, at least 10, or at least 20 times greater than the width. Elongate along a plane or axis herein is with the length along said plane or axis. The collision of the first airflow and the second airflow may result in the aggregate airflow having the circular, substantially circular, or quasi-circular airflow profile. A circular, substantially circular, or quasi-circular airflow profile may be desirable for applications of the fan assembly or nozzle such as for cooling or heating an object and / or user. An airflow profile herein may be the shape produced by a surface plot of the velocity of the aggregate airflow on a profile plane perpendicular to the common plane, with values below a threshold being removed. In other examples, the airflow profile is the shape produced by a threshold contour of a contour plot of the velocity of the aggregate airflow on the profile plane. The threshold contour is a contour wherein the value of the velocity of the aggregate airflow is the threshold. The threshold may, for example, be in the region from 0.1 to 1.0 metres per second. The threshold may be a threshold wherein velocities below the threshold are ineffective for employing a task for which the fan assembly or nozzle is used, for example, the task being cooling or heating of an object or user. Further, the threshold may be a threshold wherein velocities below the threshold are not reliably due to operation of the fan assembly or nozzle, for example, due to ambient airflow. Further, the threshold may be a threshold wherein velocities below the threshold are not detectable by a user. A circular, substantially circular, or quasi-circular airflow profile may be formed closer to the fan assembly or nozzle than is achieved, for example, by other fan assemblies or nozzles, and may allow a user to be subject to a circular, substantially circular, or quasi-circular airflow profile generated by the fan assembly or nozzle when the object or user is closer to the fan assembly or nozzle than other fan assemblies or nozzles. This may be desirable in confined environments or for a reducing a footprint of the fan assembly or nozzle when in use. In some examples, the first and second airflow outlet arrangements are configured to project air toward a collision axis that is located between the first and second airflow outlet arrangements, and which extends perpendicular to the profile plane and along the common plane. In some examples, the first and second airflow outlet arrangements are arranged along opposing respective arms of a V-shape or a U-shape that lies in the common plane, wherein an interior angle of an apex of the respective V-shape or the U-shape is obtuse. With such an arrangement the collision of the first airflow and the second airflow may result in the aggregate airflow having a circular, substantially circular, or quasi-circular airflow profile closer to the fan assembly or nozzle than for other arrangements. The volumetric flow of the aggregate airflow of some such examples may be greater than the volumetric flow produced by other arrangements. Volumetric flow herein is the volume of air traveling through a measurement surface in a unit of time and may be calculated by integrating the velocity of air over the measurement surface. The measurement surface may be a plane perpendicular to the common plane and / or the collision axis and at a measurement distance. The measurement distance may be a distance from at least one of: the fan assembly, the nozzle, the first airflow outlet arrangement or the second airflow outlet arrangement. For example, the measurement distance may be from 300 to 1000 millimetres from the fan assembly. Velocity values less than a threshold may be ignored when integrating the velocity over the measurement surface. The threshold may be the threshold referred to above. With the first airflow outlet arrangement and the second airflow outlet arrangement configured relative to one another in a V-shape or a U-shape, a peak velocity of the aggregate airflow produced by the fan assembly or nozzle may be greater than a peak velocity of the aggregate airflow produced by other shapes. Peak velocity herein is the maximum of the velocity of the aggregate airflow through the measurement surface. The peak velocity in some examples is less than 80 metres per second, for example, no more than 20 or 10 meters per second. When compared to other arrangements of outlets, the aforementioned V-shape and U-shape have been found to provide a particularly large volumetric flow for the cross-sectional area of the airflow outlet arrangements. Further, the peak velocity was also found to be particularly large for the power input into the fan assembly or nozzle when compared to other arrangements of airflow outlet arrangements. Additionally, the aforementioned V-shape and U-shape each produced an aggregate airflow with a circular, substantially circular, or quasi-circular airflow profile from 300 to 1000 millimetres from the fan assembly or nozzle. In some examples with the first and second airflow outlet arrangements arranged in the aforementioned V-shape or U-shape, an end of the first outlet closest to the second outlet is a fixed distance, for example no more than 100 millimetres, from the apex of the respective V- shape or U-shape, and an end of the second outlet closest to the first outlet a fixed distance, for example no more than 100 millimetres, from the apex of the respective V-shape or U-shape. In some such examples, a circular, substantially circular, or quasi-circular airflow profile may be formed closer to the fan assembly or nozzle than other configuration. Further, the volumetric flow of the aggregate airflow and the peak velocity of the aggregate airflow may be greater than other configurations. In some examples, the first airflow is substantially laminar between the first airflow outlet arrangement and a point of collision with the second airflow. The second airflow is substantially laminar between the second airflow outlet arrangement and the point of collision with the first airflow. The point of collision may be on the collision axis. In some examples, at least one of: the velocity of the first airflow between the first airflow outlet arrangement and the point of collision with the second airflow is less than 80 metres per second, for example no more than 20 or 10 meters per second. The velocity of the second airflow between the second airflow outlet arrangement and the point of collision with the first airflow is less than 80 metres per second, for example no more than 20 or 10 meters per second. The focus may be on the collision axis. The focus may be on the common plane. The focus is, for example, from 5 to 1000 millimetres from the fan assembly. The focus may be a point within, or a centroid of, a focal region, wherein the focal region is a region in which the first airflow and the second airflow collide or coalesce to form the aggregate flow. The focal region may extend along the collision axis. A focal distance is the minimum distance from the fan assembly to the focal region along the collision axis. The focal distance is, for example, from 5 millimetres to 1000 millimetres. The first airflow outlet arrangement and the second airflow outlet arrangement may each extend substantially linearly along the common plane, for example, between respective opposing ends of each of the first and second airflow outlet arrangements. Accordingly, the first and second airflows may be less turbulent than if the first and second airflow outlet arrangements did not extend substantially linearly along the common plane. The first airflow outlet arrangement and the second airflow outlet arrangement may each extend substantially arcuately along the common plane, for example, between respective opposing ends of each of the first and second airflow outlet arrangements. Accordingly, the first and second airflows may be less turbulent than if the first and second airflow outlet arrangements did not each extend substantially arcuately along the common plane. In some examples, the first and second airflow outlet arrangements are configured such that the acute angle is from 10 to 30 degrees (i.e., 10° to 30°). In some such examples, a circular, substantially circular, or quasi-circular airflow profile may be formed closer to the fan assembly or nozzle than when the acute angle is not from 10° to 30°. Further, the aforementioned volumetric flow of the aggregate airflow and peak velocity of the aggregate airflow may be greater than when the acute angle is not from 10° to 30°. In some examples, the first and second airflow outlet arrangements are configured such that the acute angle is from 15° to 20°. In some such examples, a circular, substantially circular, or quasi-circular airflow profile may be formed closer to the fan assembly or nozzle than when the acute angle is not from 15° to 20°. Further, the aforementioned volumetric flow of the aggregate airflow and peak velocity of the aggregate airflow may be greater than when the acute angle is not from 15° to 20°. In some examples, the acute angle is from 16° to 18°. It has been found that such an angle may provide a particularly large volumetric flow of the aggregate airflow and peak velocity of the aggregate airflow produced by the fan assembly or nozzle, as well as a circular, substantially circular, or quasi-circular airflow profile of the aggregate airflow at a distance from 300 to 1000 millimetres from the fan assembly or nozzle. In some examples, the obtuse internal angle is from 150° to 170°. In some such examples, a circular, substantially circular, or quasi-circular airflow profile may be formed closer to the fan assembly or nozzle than when the obtuse internal angle is not from 150° to 170°. Further, the aforementioned volumetric flow of the aggregate airflow and peak velocity of the aggregate airflow may be greater than when the obtuse internal angle is not from 150° to 170°. In some examples, the obtuse internal angle is from 160° to 165°. In some such examples, a circular, substantially circular, or quasi-circular airflow profile may be formed closer to the fan assembly or nozzle than when the obtuse internal angle is not from 160° to 165°. Further, the aforementioned volumetric flow of the aggregate airflow and peak velocity of the aggregate airflow may be greater than when the obtuse internal angle is not from 160° to 165°. In some examples, the obtuse internal angle is from 162° to 164°. It has been found that such an angle may provide a particularly large volumetric flow of the aggregate airflow and peak velocity of the aggregate airflow produced by the fan assembly or nozzle, as well as a circular, substantially circular, or quasi-circular airflow profile at a distance from 300 to 1000 millimetres from the fan assembly or nozzle. In some examples, a central axis of the first airflow outlet arrangement is in the common plane. The central axis of the first airflow outlet arrangement and the collision axis have a first acute internal angle therebetween. A centroid of the first airflow outlet arrangement is on the central axis of the first airflow outlet arrangement. A central axis of the second airflow outlet arrangement is in the common plane. The central axis of the second airflow outlet arrangement and the collision axis have a second acute internal angle therebetween. A centroid of the second airflow outlet arrangement is on the central axis of the second airflow outlet arrangement. The sum of the first acute internal angle and the second acute internal angle may be from 10° to 30°. In some such examples, a circular, substantially circular, or quasi-circular airflow profile may be formed closer to the fan assembly or nozzle than when the second acute internal angle is not from 10° to 30°. Further, the aforementioned volumetric flow of the aggregate airflow and peak velocity of the aggregate airflow may be greater than when the sum of the first acute internal angle and the second acute internal angle is not from 10° to 30. The sum of the first acute internal angle and the second acute internal angle may be from 15° to 20°. Further to the above, it was found that when the sum of the first acute internal angle and the second acute internal angle is from 15° to 20°: volumetric flow of the aggregate airflow and peak velocity of the aggregate airflow may be increased, and a circular, substantially circular, or quasi-circular airflow profile may be formed closer to the fan assembly or nozzle than when the sum of the first acute internal angle and the second acute internal angle is not from 15° to 20°. In some examples, the first acute internal angle and the second acute internal angle are from 16° to 18°. It has been found that some such examples provide a particularly large volumetric flow of the aggregate airflow and peak velocity of the aggregate airflow produced by the fan assembly or nozzle, as well as a circular, substantially circular, or quasi-circular airflow profile at a distance from 300 to 1000 millimetres from the fan assembly or nozzle. At least one of the first acute internal angle or the second acute internal angle may be from 5° to 15°. With such first and / or second acute internal angles, the airflow profile may be substantially centred on the collision axis which may allow prediction of where the peak velocity of the aggregate airflow is, for example, by a user. A difference between the first acute internal angle and the second acute internal angle may be no more than 5°. With a difference between the first acute internal angle and the second acute internal angle no more than 5°, the airflow profile of the aggregate airflow may be substantially centred on the collision axis, which may allow prediction of where the peak velocity of the aggregate airflow is, for example, by a user. Further, the airflow profile of the aggregate airflow may be more symmetric than with a difference between the first acute internal angle and the second acute internal angle more than 5°. In some examples, the first acute internal angle and the second acute internal angle are substantially equal. In some such examples the aggregate airflow may be substantially symmetric, for example resulting in the airflow profile being substantially circular. Further, the first acute internal angle and the second acute internal angle being substantially equal may facilitate prediction of where the peak velocity of the aggregate airflow is and / or the direction of the aggregate airflow, for example, by a user. In some examples, the first airflow outlet arrangement comprises a first periphery having a first length and a first width. The first length extends along the common plane and is greater than the first width. The first width extends perpendicular to the common plane. The second airflow outlet arrangement comprises a second periphery having a second length and a second width. The second length extends along the common plane and is greater than the second width. The second width extending perpendicular to the common plane. The first length may be at least 10 times greater than the first width, which may provide a less turbulent first airflow than with the first length not at least 10 times greater than the first width. The first airflow being less turbulent may result in an increase in at least one of the volumetric flow or the peak velocity of the first airflow. Further, the first airflow being less turbulent may result in a circular, substantially circular, or quasi-circular airflow profile of the aggregate airflow being formed at a reduced distance from the fan assembly or nozzle. The second length may be at least 10 times greater than the second width, which may provide a less turbulent second airflow than with the second length not at least 10 times greater than the second width. The second airflow being less turbulent may result in an increase in at least one of the volumetric flow or the peak velocity of the second airflow. Further, the second airflow being less turbulent may result in a circular, substantially circular, or quasi-circular airflow profile of the aggregate airflow being formed at a reduced distance from the fan assembly or nozzle. The first length may be at least 20 times greater than the first width. With the first length at least 20 times greater than the first width, the first airflow may be less turbulent than with the first length not at least 20 times greater than the first width. The second length may be at least 20 times greater than the second width. With the second length at least 20 times greater than the second width the second airflow may be less turbulent than with the second length not at least 20 times greater than the second width. In some examples, a first ratio of the first length to the first width is from 0.75 to 1.25 times a second ratio of the second length to the second width. This may result in the airflow profile of the aggregate airflow being substantially symmetric, for example resulting in the airflow profile being circular, substantially circular, or quasi-circular. Further, the first ratio being from 0.75 to 1.25 times the second ratio may facilitate prediction of where the peak velocity of the aggregate airflow is and / or a direction of the aggregate airflow, for example, by a user. In some examples the first ratio is substantially equal to the second ratio. With the first and second ratio substantially equal the aggregate airflow may be substantially symmetric, for example resulting in the airflow profile of the aggregate airflow being circular, substantially circular, or quasi-circular. Further, the first ratio being substantially equal to the second ratio may facilitate prediction of the location of the peak airflow of the aggregate airflow, for example by a user. The first length may be from 0.75 to 1.25 times the second length. With the first length from 0.75 to 1.25 times the second length, the airflow profile of the aggregate airflow may be substantially centred on the collision axis. Further, the airflow profile of the aggregate airflow may be more symmetric than with the first length not from 0.75 to 1.25 times the second length. The first length may be substantially equal to the second length which may result in the airflow profile of the aggregate airflow being substantially centred on the collision axis and / or the airflow profile being substantially symmetric. The first width may be from 0.75 to 1.25 times the second width. With the first width from 0.75 to 1.25 times the second width, the airflow profile of the aggregate airflow may be substantially centred on the collision axis. Further, the airflow profile of the aggregate airflow may be more symmetric than with the first width not from 0.75 to 1.25 times the second width. The first width may be substantially equal to the second width which may result in the airflow profile being substantially centred on the collision axis and / or the airflow profile being substantially symmetric. In some examples: the first airflow outlet arrangement comprises a first end and a second end, and the second airflow outlet arrangement comprises a third end and a fourth end. A distance from the first end to the third end is less than a distance from the second end to the fourth end. The first length may be a linear distance from the first end to the second end. The second length may be a linear distance from the third end to the fourth end. In some examples, the first airflow and the second airflow at least partially collide at a collision distance at least one of 300 millimetres, 200 millimetres, 100 millimetres, or 50 millimetres from the fan assembly or nozzle. In some examples, the first and second airflows may at least partially collide at a collision distance at least one of 2 times the first length, 2 times the second length, the first length, or the second length from the fan assembly or nozzle. Some such examples result in the aggregate airflow having a circular, substantially circular, or quasi- circular airflow profile closer to the fan assembly or nozzle than with a greater collision distance. The first airflow outlet arrangement may be spaced apart along the common plane from the second airflow outlet arrangement. With the first airflow outlet arrangement spaced apart along the common plane from the second airflow outlet arrangement, the peak velocity and the volumetric flow of the aggregate airflow may be greater than with the first airflow outlet arrangement not spaced apart along the common plane from the second airflow outlet arrangement. With the first airflow outlet arrangement spaced apart along the common plane from the second airflow outlet arrangement, the peak velocity and the volumetric flow of the aggregate airflow may be greater than with the first airflow outlet arrangement and second airflow outlet arrangement being continuous. The first airflow outlet arrangement may be spaced apart from the second airflow outlet arrangement by a fixed distance. The first airflow outlet arrangement being spaced apart from the second airflow outlet arrangement by the fixed distance may result in a fixed value of at least one of: the peak velocity of the aggregate airflow; the volumetric flow of aggregate flow; or the minimum distance from the fan assembly or nozzle at which the aggregate airflow is circular, substantially circular, or quasi-circular. Further, the first airflow outlet arrangement being spaced apart from the second airflow outlet arrangement by the fixed distance may simplify manufacture of the fan assembly or nozzle. The first airflow outlet arrangement may be spaced apart from the second airflow outlet arrangement by a variable distance such that a distance between the focus and the nozzle or fan assembly may be selectively adjusted. Adjustment of the distance of the focus from the nozzle may allow a user of the fan assembly to vary a distance from the fan assembly or nozzle at which a circular, substantially circular, or quasi-circular airflow profile is formed. In some examples, the first airflow outlet arrangement and the second airflow outlet arrangement are continuous. That is, the first and second airflow outlet arrangements may together define a single outlet aperture. In some such examples, the first airflow outlet arrangement and the second airflow outlet arrangement are portions of the same continuous airflow outlet arrangement. Further, in some such examples, a housing defines both the first airflow outlet arrangement and second airflow outlet arrangement. The first airflow outlet arrangement and the second airflow outlet arrangement being continuous may simplify manufacture compared to the first airflow outlet arrangement and the second airflow outlet arrangement being separate. In some examples, the first outlet and the second outlet are continuous and are portions of the same continuous outlet. That is, the first and second outlets may together define a single outlet aperture. The first outlet and the second outlet being continuous may simplify manufacture compared to the first outlet and the second outlet being separate. In some examples, an end of the first airflow outlet arrangement closest to the second airflow outlet arrangement is no more than 200 millimetres from the second airflow outlet arrangement. In some such examples, the end of the first airflow outlet arrangement closest to the second airflow outlet arrangement is no more than 50 millimetres along the common plane from the second airflow outlet arrangement. With an end of the first airflow outlet arrangement closest to the second airflow outlet arrangement no more than 200 millimetres from the second airflow outlet arrangement, a circular, substantially circular, or quasi-circular airflow profile may be formed closer to the fan assembly or nozzle than with an end of the first airflow outlet arrangement closest to the second periphery more than 200 millimetres from the second airflow outlet arrangement. Further, the volumetric flow and the peak velocity may be greater than with an end of the first airflow outlet arrangement closest to the second periphery more than 200 millimetres from the second airflow outlet arrangement. The first airflow outlet arrangement may comprise a plurality of the first outlets; the plurality of the first outlets may be arranged in series along the first length and / or along the common plane. The second airflow outlet arrangement may comprise a plurality of the second outlets; the plurality of the second outlets may be arranged in series along the second length and / or along the common plane. In some examples, each of the first outlets of the plurality of the first outlets and each of the second outlets of the plurality of second outlets is configured to discharge a respective airflow. In some such examples, the airflows discharged by the plurality of the first outlets are parallel, and the airflows discharged by the plurality of second outlets are parallel. Each airflow discharged by a first outlet of the plurality of first outlets collides with a respective airflow discharged by a second outlet of the plurality of second outlets. Each collision has a respective focus, resulting in a plurality of foci. Each focus of the plurality of foci is associated with a respective acute angle subtended by the respective first outlet and second outlet at the focus. In some such examples, the respective acute angles are the same. Further, in some such examples, each focus of the plurality of foci are on the collision axis and extend in a line along the collision axis. The one or more first outlets may each be elongate, for example, along the common plane. When elongate, each one of the one or more first outlets may be referred to as a slot. With the one or more first outlets each being elongate the first airflow may be less turbulent than with the one or more first outlets not being elongate. The one or more second outlets may each be elongate, for example, along the common plane. When elongate, each one of the one or more second outlets may be referred to as a slot. With the one or more second outlets each being elongate the second airflow may be less turbulent than with the one or more second outlets not being elongate. The first airflow outlet arrangement may be elongate, for example, along the common plane. With the first airflow outlet arrangement being elongate the first airflow may be less turbulent than with the one or more first outlets not being elongate. The second airflow outlet arrangement may each be elongate, for example, along the common plane. With the second airflow outlet arrangement being elongate the second airflow may be less turbulent than with the one or more second outlets not being elongate. In some examples, the focus is equidistant to the first and second airflow outlet arrangements. In some such examples, the airflow profile of the aggregate airflow is more symmetric than with the focus not equidistant to the first and second airflow outlet arrangements. In some examples, the first periphery has a third width different from the first width. The third width is: parallel to the first width, perpendicular to the common plane, perpendicular to the first length, and less than the first length. In some such examples the difference between the first and third widths results in the airflow profile of the first airflow being modified, for example to a preferred shape such as a quasi-rectangular shape, which may increase the volumetric flow of the aggregate airflow compared to other shapes and result in a circular, quasi-circular or substantially circular airflow profile of aggregate airflow closer to the fan assembly compared to other shapes. In some examples, the second periphery has a fourth width different from the second width. The fourth width parallel to the second width, perpendicular to the common plane, perpendicular to the second length, and less than the second length. In some such examples the difference between the second and fourth widths results in the airflow profile of the second airflow being modified, for example to a preferred shape such as a quasi-rectangular shape, which may increase the volumetric flow of the aggregate airflow compared to other shape and result in a circular, quasi-circular or substantially circular airflow profile of aggregate airflow closer to the fan assembly compared to other shapes. In some examples, at least one of the shape of the first outlet, the shape of the second outlet, the first width, the second width, the third width, the fourth width, the first length, or the second length is adjustable, for example, by a user. Such adjustment of the length(s) and / or width(s) may change at least one of: the location of the focus or focal region; the focal distance; the velocity of the first airflow, the velocity of the second airflow, the velocity of the aggregate airflow, the volumetric flow of the first airflow, the volumetric flow of the second airflow, the volumetric flow of the aggregate airflow, or the direction of the aggregate airflow. Many methods of adjustment of the length(s) and / or width(s) are envisaged, for example covers which can be selectively placed over portions of the first airflow outlet arrangement or the second airflow outlet arrangement. A maximum width of the first airflow outlet arrangement perpendicular to the first length and the common plane may be substantially equidistant from the first end and the second end. A maximum width of the second airflow outlet arrangement perpendicular to the second length and the common plane may be substantially equidistant from the third end and the fourth end. In some examples, the cross-sectional area of the first periphery is from 0.75 to 1.25 times a cross-sectional area of the second periphery. In some such examples the airflow profile of the aggregate airflow is more symmetric than with the cross-sectional area of the first periphery not from 0.75 to 1.25 times a cross-sectional area of the second periphery. In some such examples the cross-sectional area of the first periphery is substantially equal to the cross- sectional area of the second periphery, which may result in the airflow profile of the aggregate airflow being substantially symmetrical. At least one of the first periphery, the second periphery, the first airflow outlet arrangement or the second airflow outlet arrangement may be rectangular, substantially rectangular, or quasi- rectangular. An airflow outlet arrangement and / or periphery being rectangular, substantially rectangular, or quasi rectangular may result in an airflow from the airflow outlet arrangement being less turbulent than when the airflow outlet arrangement and / or periphery is another shape. A shape of the first airflow outlet arrangement may be substantially the same as a shape of the second airflow outlet arrangement. The shape of the first airflow outlet arrangement being substantially the shape of the second airflow outlet arrangement may result in a more symmetric airflow profile of the aggregate airflow compared to the shape of the first airflow outlet arrangement being substantially different to the shape of the second airflow outlet arrangement. A shape of the first periphery may be substantially the same as a shape of the periphery. The shape of the first periphery being substantially the shape of the second periphery may result in a more symmetric airflow profile of the aggregate airflow compared to the shape of the first periphery being substantially different to the shape of the second periphery. In some examples, the first airflow outlet arrangement and the second airflow outlet arrangement are pivotable relative to one another about a common rotation axis or a respective rotation axis. The common rotation axis or a respective rotation axis is perpendicular to the common plane. Pivoting of the first airflow outlet arrangement and the second airflow outlet arrangement relative to one another and about the common rotation axis or respective rotation axis changes the obtuse internal angle. Such pivoting may allow tailoring of the peak velocity, volumetric flow, and the minimum distance from the fan assembly at which the aggregate airflow is circular, substantially circular, or quasi-circular. So, each of these parameters may be modulable, for example, by a user of the fan assembly or nozzle. In some examples of the first, third, or fourth aspects of the present invention, the nozzle comprises a first nozzle and a second nozzle. The first nozzle comprises the first airflow outlet arrangement. The second nozzle comprises the second airflow outlet arrangement. The first and second nozzles are pivotable relative to one another about a common rotation axis or a respective rotation axis. The common rotation axis and / or the respective rotation axis is perpendicular to the common plane. Pivoting of the first and second nozzles about the common rotation axis or respective rotation axis changes the acute angle. Such pivoting may allow tailoring of the peak velocity, volumetric flow, and the minimum distance from the fan assembly at which the aggregate airflow is circular, substantially circular, or quasi-circular. So, each of these parameters may be modulable, for example, by a user of the fan assembly or nozzle. The first and second nozzles may be independently pivotable about the common rotation axis or respective rotation axis so as to angle the focus and the aggregate airflow. Such pivoting may allow tailoring of the peak velocity, volumetric flow, and the minimum distance from the fan assembly at which the aggregate airflow is circular, substantially circular, or quasi-circular. So, each of these parameters may be modulable, for example, by a user of the fan assembly. Such pivoting may allow the user to direct the aggregate airflow. The first and second nozzles may be proportionately pivotable about the common rotation axis or respective rotation axis, such that pivoting of the first nozzle about the common rotation axis or respective rotation axis by an amount proportionality pivots the second nozzle by the same amount so as to adjust a distance of the focus from the one or more first and second outlets. Such pivoting may allow tailoring of the peak velocity, volumetric flow, and the minimum distance from the fan assembly at which the aggregate airflow is circular, substantially circular, or quasi-circular. So, each of these parameters may be modulable, for example, by a user of the fan assembly. Such pivoting may allow the user to direct the aggregate airflow. In some such examples, the common rotation axis or respective rotation axis intersects, and is perpendicular to, the collision axis, which may result in the centre of the airflow profile of the aggregate airflow remaining substantially centred on the collision axis during pivoting. The common rotation axis or the respective rotation axis may intersect the common plane at any point or respective points on the common plane. In some examples of the first, third, or fourth aspects of the present invention, the fan assembly comprises an actuation system for pivoting the first nozzle and / or second nozzle about said rotation axis. Such actuation of the pivoting of the first nozzle and / or second nozzle about said rotation axis may allow the direction of at least one of the first or second airflows, for example, by a user. The direction of at least one of the first or second airflows may, for example, be oscillated by a controller. The first airflow outlet arrangement may be fixed with respect to the second airflow outlet arrangement. The acute angle, the obtuse angle, the first internal acute angle and / or the second internal acute angle may thus be fixed, which may result in a desired value of at least one of: the peak velocity, the volumetric flow of air from the fan assembly or nozzle, or the minimum distance from the fan assembly or nozzle at which the aggregate airflow is circular, substantially circular, or quasi-circular. Further, the first airflow outlet arrangement being fixed with respect to the second airflow outlet arrangement may simplify manufacture of the fan assembly or nozzle. In some examples of the first, third, or fourth aspects of the present invention, the fan assembly comprises a base structurally supporting the nozzle. The nozzle is moveable relative to the base to change a direction of the aggregate airflow relative to the base. Changing the direction of the aggregate airflow may allow direction of the aggregate airflow by, for example, a user. In some such examples, the movement relative to the base is swivelling about a vertical axis. The vertical axis may be parallel to the common plane and / or on the common plane. In some such examples, the first airflow outlet arrangement and the second airflow outlet arrangement may be movable together relative to the base. The one or more first and second outlets may each have a width of at least one millimetre, which may result in the volumetric flow of the first airflow, the second airflow and / or the aggregate airflow being greater than with the one or more first and second outlets having a width of less than one millimetre. The first airflow outlet arrangement and the second airflow outlet arrangement may each respectively have a width of at least one millimetre, which may result in the volumetric flow of the first airflow, the second airflow and / or the aggregate airflow being greater than with the first airflow outlet arrangement and the second airflow outlet arrangement each respectively having a width of less than one millimetre. The one or more first and second outlets may each respectively have a constant width, which may result in the first airflow, the second airflow and / or the aggregate airflow being less turbulent. The first airflow outlet arrangement and the second airflow outlet arrangement may each respectively have a constant width, which may result in the first airflow, the second airflow and / or the aggregate airflow being less turbulent. The one or more outlets, which may be one or more first outlets and / or one or more second outlets, may have a width (e.g., a constant width) from one millimetre to ten millimetres, for example the width may be at least two millimetres. The one or more first and second outlets may have a width from one millimetre to ten millimetres, which may result in the volumetric flow and / or peak velocity of the first airflow, the second airflow and / or the aggregate airflow being greater than with the one or more first and second outlets having a width outside this range. The first airflow outlet arrangement and the second airflow outlet arrangement may each have a width from one millimetre to ten millimetres, which may result in the volumetric flow of the first airflow, the second airflow and / or the aggregate airflow being greater than with the first airflow outlet arrangement and the second airflow outlet arrangement having a width outside this range. In some examples, the first and second airflow outlet arrangements may have a length that is substantially equal. In some such examples, the aggregate airflow is more symmetrical than with the first and second airflow outlet arrangements having a length that is not substantially equal. Further the volumetric flow and / or peak velocity of the first airflow, the second airflow and / or the aggregate airflow may be greater than with the first and second airflow outlet arrangements having a length that is not substantially equal. The length of the first and second airflow outlet arrangements may be from 50 to 200 millimetres, which may result in the volumetric flow and / or peak velocity of the first airflow, the second airflow and / or the aggregate airflow being greater than with the length of the first and second airflow outlet arrangements not from 50 to 200 millimetres. In some examples, the first and second airflow outlet arrangements may be configured such that the acute angle is used to generate a shape of the aggregate airflow that is generally circular in cross-section. The shape of the aggregate airflow is, for example, downstream of the focus. The generally circular shape of the aggregate airflow may be desirable, for example, for cooling or heating applications. In some examples, the first and second airflow outlet arrangements are configured such that the aggregate airflow is generally circular in cross-section from 300 to 1000 millimetres from the one or more first and second outlets. The shape of the aggregate airflow is, for example, downstream of the focus. The generally circular shape of the aggregate airflow from 300 to 1000 millimetres from the one or more first and second outlets may be desirable, for example, for cooling or heating applications wherein the object or user is from 300 to 1000 millimetres from the one or more first and second outlets. In some examples of the second aspect of the present invention, the fan assembly comprises: a base, a first arm, and a second arm. The first arm comprises the first airflow outlet arrangement. The second arm comprises the second airflow outlet arrangement. The first arm and the second arm are supported by the base. The first arm and the second arm may be pivotable relative to one another about the rotation axis. Such pivoting may allow tailoring of the peak velocity, volumetric flow, and the minimum distance from the fan assembly at which the aggregate airflow is circular, substantially circular, or quasi-circular. So, each of these parameters may be modulable, for example, by a user of the fan assembly. The first arm and the second arm may be pivotable, together and / or independently, relative to the base. Such pivoting may allow the direction of at least one of the first or second airflows, for example, by a user. In some examples, the fan assembly comprises an actuation system. The actuation system is for moving at least one of the first arm or the second arm. The movement of at least one of the arms is relative to at least one of: the other of the first arm and the second arm, or the base. Such actuation of at least one of the arms may allow the direction of at least one of the first airflow, the second airflow, or the aggregate airflow, for example, by a user. In some examples a ratio of an average velocity of the first airflow and an average velocity of the second airflow may be modulated, for example, by modulation of a valve by a user or a controller. In such examples, the modulation of the ratio may result in modulation of the direction of the aggregate airflow. In some examples, the fan assembly comprises: an air inlet, and an air conduit. The air inlet is in fluid communication with the air conduit. The air conduit is configured to direct air from the airflow generator to the first airflow outlet and the second airflow outlet. The airflow generator is configured to generate an airflow from the air inlet to at least one of the first airflow outlet or the second airflow outlet. The air inlet may allow the choice, for example by a user, of where the air for the airflow generator is taken in from. The airflow generator may allow control of the velocity of the first airflow and / or the velocity of the second airflow, which in turn may allow control of the peak velocity and the volumetric flow of the aggregate airflow. The airflow generator may be comprised in the base, which may lower a centre of mass of the fan assembly when the fan assembly is upright compared to a fan assembly in which the airflow generator not comprised in the base, for example, due to the position of the mass of the airflow generator. In some examples, the fan assembly comprises a main body and an attachment. The main body houses the airflow generator. The attachment comprises the first airflow outlet arrangement and the second airflow outlet arrangement. The attachment is releasably attachable to the main body. In such examples the disassembly and assembly of the fan assembly for transport of the fan assembly may be simplified compared to the attachment being permanently attached to the main body. Further, maintenance of the fan assembly (for example by replacement of the base, airflow generator, or the attachment) may be simplified. The attachment being releasably attachable to the main body may allow the use of the main body with multiple attachments which may increase the functionality of the main body, for example, depending on which attachment is attached to the main body. In some examples the fan assembly or nozzle comprises a first airflow generator to provide airflow to the first airflow outlet arrangements and a second airflow generator to provide airflow to the second airflow outlet arrangement. In some examples, the fan assembly or nozzle comprises an entrainment shield. The entrainment shield may reduce the entrainment of ambient air by at least one of the first airflow, the second airflow or the aggregate airflow compared to other configurations. The fan assembly is, for example: a domestic appliance, such as a bladeless fan (e.g., a desktop fan), or a haircare appliance (e.g., a hair drier or styler), or a hand dryer appliance (e.g., the Dyson Airblade (RTM)). The fan assembly may form part of a cooling fan, an air purifier, a heater, an air conditioner, a dehumidifier and / or a humidifier. The nozzle is, for example, for a domestic appliance, such as a bladeless fan (e.g., a desktop fan), or a haircare appliance (e.g., a hair drier or styler), or a hand dryer appliance (e.g., the Dyson Airblade (RTM)). The nozzle may form part of a cooling fan, an air purifier, a heater, an air conditioner, a dehumidifier, and / or a humidifier. The nozzle may be an attachment for the haircare appliance. In any one or more of the aspects, each of the first airflow outlet arrangement and the second airflow outlet arrangement may refer to an extent or distribution of the respective one or more first and second outlets. In any one or more of the aspects, each of the first airflow outlet arrangement and the second airflow outlet arrangement may refer to one or more portions of the nozzle, for example, one or more portions that define the respective one or more first and second outlets. Thus, the term “arrangement” may not be limited to a component (such as a housing) of the nozzle, such that said component may or may not extend substantially along the common plane. The “arrangement” may therefore be the arrangement of portions that define the outlet(s). BRIEF DESCRIPTION OF THE DRAWINGS Figure 1 shows a schematic side view of a first fan assembly according to an example; Figure 2 shows a schematic side cross-section of the first fan assembly of Figure 1; Figure 3 shows a schematic top view of the first fan assembly of Figure 1; Figure 4 shows a schematic front view of the first fan assembly of Figure 1; Figure 5 shows a schematic side view of a second fan assembly according to an example, and shows the second fan assembly in a first configuration and a second configuration; Figures 6 and 7 show schematic example aggregate airflow profiles generated by the second fan assembly of Figure 5 in five different configurations; Figures 8 and 9 show schematic front views of further fan assemblies according to examples; Figure 10 shows a schematic front view of a third fan assembly according to an example, the third fan assembly shown in two different configurations; Figure 11 shows a schematic front view of a fourth fan assembly according to an example; Figure 12 shows a schematic side view of a fifth fan assembly according to an example; and Figure 13 shows a schematic front view of the fifth fan assembly of Figure 12. DETAILED DESCRIPTION Figures 1 to 4 schematically show three views of a fan assembly 100 according to an example. The relative orientations of each view are indicated using cartesian x-, y-, and z- axes. Figures 1 and 2 are on parallel xy-planes; Figure 3 is on an xz-plane; and Figure 4 is on a yz-plane. The Figures are schematic and are not to scale. The fan assembly 100 comprises a nozzle 102 and a base 108. The nozzle 102 comprises a stand 115, a first airflow outlet arrangement 104, and a second airflow outlet arrangement 106. Both the first airflow outlet arrangement 104 and the second airflow outlet arrangement 106 are supported by the stand 115. The first airflow outlet arrangement 104 comprises a first outlet 128 (shown schematically in Figures 2 and 4) defined by a portion of the first airflow outlet arrangement 104. The first outlet 128 extends substantially along a common plane 132. The second airflow outlet arrangement 106 comprises a second outlet 130 (shown schematically in Figures 2 and 4) defined by a portion of the second airflow outlet arrangement 106. The second outlet 130 extends substantially along the common plane 132. The nozzle 102 is arranged so that the first airflow outlet arrangement 104 and the second airflow outlet arrangement 106 are in a V-shape that lies in the common plane 132. An interior angle 111 of an apex of the V-shape, and thus between the first 104 and second 106 airflow outlet arrangements, is obtuse. The apex of the V-shape is within the stand 115. In this example, the interior angle 111 is around 162 degrees (i.e., 162°) and is a fixed angle. The acute angle 120 is equal to 180° minus an interior angle 111. The end of the first airflow outlet arrangement 104 closest to the second airflow outlet arrangement 106 is a fixed distance of 10 millimetres from the apex of the V-shape. The end of the second airflow outlet arrangement 106 closest to the first airflow outlet arrangement 104 is a fixed distance of 10 millimetres from the apex of the V-shape. The first outlet 128 is rectangular in shape, having a first length 134 and a first width 136. The first length 134 is a linear distance along the common plane 132 between a first end 121 and a second, opposing end 123 of the first outlet 128, and is greater than the first width 136. The first width extends perpendicular to the common plane 132. The first length 134 is 100 millimetres and the first width 136 is 8 millimetres. The second outlet 130 is also rectangular in shape, having a second length 138 and a second width 140, and is substantially the same size as the first outlet arrangement 128. The second length 138 is a linear distance along the common plane 132 between a first end 125 and a second, opposing end 127 of the second outlet 130. The second width 140 extends perpendicular to the common plane 132. The second length 138 is 100 millimetres and the second width 140 is 8 millimetres. A first axis 162 is linear from the first airflow outlet arrangement 104 to the focus 114, and a second axis 164 is linear from the second airflow outlet arrangement 106 to the focus 114. An acute angle 120 is subtended by the first airflow 110 and the second airflow 112 from the focus 114. The acute angle 120 is measured at the focus 114 and is subtended between: a centroid 131 of the first airflow outlet arrangement 104 and a centroid 133 of the second airflow outlet arrangement 106. The acute angle 120 is also subtended by the first airflow outlet arrangement 104 and the second airflow outlet arrangement 106 from the focus 114. In this example the acute angle 120 is around 18°. A central axis 117 of the first airflow outlet arrangement 104 is in the common plane 132. The acute angle 120 may comprise a first acute internal angle 122 and a second acute internal angle 124. The first acute internal angle 122 and the second acute internal angle 124 are equal in the use scenario shown in Figures 1 and 2, but in some other scenarios the first acute internal angle and the second acute internal angle are not equal, for example when airflow discharged from the first and second outlet arrangements 104, 106 is unequal in volume and / or velocity. The first acute internal angle 122 is between the central axis 117 of the first airflow outlet arrangement 104 and the collision axis 118. The centroid 131 of the first airflow outlet arrangement 104 is on the central axis 117 of the first airflow outlet arrangement 104. A central axis 119 of the second airflow outlet arrangement 106 is in the common plane 132. The second acute internal angle 124 is between the central axis 119 of the second airflow outlet arrangement 106 and the collision axis 118. The centroid 133 of the second airflow outlet arrangement 106 is on the central axis 119 of the second airflow outlet arrangement 106. In this example both the first acute angle 122 and the second acute internal angle 124 are each around 9°. The first airflow outlet arrangement 104 is spaced apart along the common plane 132 from the second airflow outlet arrangement 106. The base 108 comprises an airflow generator 101, an air inlet 109, a first air conduit 105, and a second air conduit 107. The airflow generator 101 is in fluid communication with the first outlet 128 and the second outlet 130. The air inlet 109 is on a side of the base 108. The first air conduit 105 is housed in the base 108 and connects the airflow generator 101 and the air inlet 109. The second air conduit 107 fluidly connects the airflow generator 101 to the first outlet 128 and the second outlet 130. When in use, the airflow generator 101 generates an airflow from the air inlet 109 to the first airflow outlet 128 and the second airflow outlet 130 via the first air conduit 105 and the second air conduit 107. The first outlet 128 discharges a first portion of the airflow generated by the airflow generator 101 as a first airflow 110 along the common plane 132. The second outlet 130 discharges a second portion of the airflow generated by the airflow generator 101 as a second airflow 112 along the common plane 132. The first airflow 110 and the second airflow 112 collide on a collision axis 118 at a focus 114. The focus 114 is equidistant to the first outlet arrangement 104 and the second airflow outlet arrangement 106. The collision axis 118 is between the first airflow outlet arrangement 104 and the second airflow outlet arrangement 106. The collision axis 118 extends along the common plane 132, is equidistant to the first outlet arrangement 104 and the second airflow outlet arrangement 106, and coincides with the focus 114. The first airflow 110 is substantially laminar from the first outlet 128 to the focus 114. Similarly, the second airflow 112 is substantially laminar from the second outlet 130 to the focus 114. When the first airflow 110 and the second airflow 112 collide they produce an aggregate airflow 116. The fan assembly may be placed on a surface in such a position that the aggregate airflow 116 is directed at a user. The aggregate airflow 116 is shown as a solid line in Figure 2 and is an extension of the dashed line which shows the collision axis 118. Figure 5 shows a schematic side view of a second fan assembly 500 according to another example. The fan assembly 500 is the same as the fan assembly 500 of Figures 1 to 4 with the Figure references increased by 400, except for the following differences. The fan assembly 500 comprises: a first arm 542, and a second arm 544. The first arm 542 comprises the first airflow outlet arrangement. The second arm 544 comprises the second airflow outlet arrangement. The first arm 542 and the second arm 544 are both supported by the base 508. The first arm 542 and the second arm 544 are each pivotable relative to one another (schematically shown by pivoted first arm 542A and pivoted second arm 544A) about a rotation axis 545 to change the obtuse internal angle 520, 520A between them, which modifies the airflow profile of the aggregate airflow. The first arm 542 and second arm 544 are each pivotable between parallel to the stand 515 and perpendicular to the stand 515 but are limited to the obtuse internal angle 520, 520A being obtuse. The dependency of the shape of the airflow profile of the aggregate airflow on the obtuse internal angle is discussed below in relation to Figures 6 and 7. The rotation axis 545 is perpendicular to the common plane. The first arm 542 and the second arm 544 are also pivotable together relative to the base 508, about the rotation axis 545, which changes a direction of the aggregate airflow 516 (schematically shown with redirected aggregate airflow 516B). The fan assembly 500 comprises an actuation system 550 which, upon actuation, moves the first arm 542 and the second arm 544 relative to one another. The first and second arms 542, 544 are otherwise maintained in a selected position by friction. In other examples, the actuation system 550 is omitted and first arm 542 and the second arm 544 are manually movable by a user and otherwise retain their position by friction, relative to one another and the base 508. Figures 6 and 7 show schematic aggregate airflow profiles generated by the fan assembly 500 of Figure 5. The airflow profiles 672, 674, 676, 776, 778, and 780 correspond to different values for the obtuse internal angle and the acute angle. Each airflow profile is schematically shown as a threshold contour of the velocity of the aggregate airflow at a profile plane 686 and 786 perpendicular to the common plane. The profile plane 686 and 786 is 400 millimetres from the fan assembly. Each of the threshold contours 672, 674, 676, 776, 778, and 780 indicates where on the profile plane the airflow velocity is 0.4 metres per second. Velocities above 0.4 metres per second are enclosed by each threshold contour, and velocities below 0.4 metres per second are not enclosed by each threshold contour. The threshold contours 672, 674, and 676 of Figure 6 correspond to a first, a second and a third sets of values of the obtuse internal angle and the acute angle. A first polar axis 682 is formed by the intersection of the common plane and the profile plane 6586. A second polar axis 684 intersects the first polar axis 682, is perpendicular to the first polar axis 682, and is parallel to the profile plane 686. The first threshold contour 672 corresponds to the acute angle being 30° and the obtuse internal angle being 150°. The first threshold contour 672 is a “peanut shape” Cassini oval that is elongated along the first polar axis 682 and perpendicular to the common plane 682, along which the first outlet and the second outlets are elongate. Both foci of the first threshold contour 672 are on the second polar axis 684 and are equidistant from the first polar axis 682. The second threshold contour 674 corresponds to the acute angle being 25° and the obtuse internal angle being 155°. The second threshold contour 674 is a “peanut shape” Cassini oval. Both foci of the second threshold contour 674 are on the second polar axis 684 and are equidistant from the first polar axis 682. The width of the second threshold contour 684 along the first polar axis 682 is more than the width of the first threshold contour 672 along the first polar axis 682. The third threshold contour 676 corresponds to the acute angle being 17° and the obtuse internal angle being 163°. The third threshold contour 676 is a circle with a centroid at the intersection of the first polar axis 682 and the second polar axis 684. The diameter of the third threshold contour 676 is greater than the width of the second threshold contour 684 along the first polar axis 682. The threshold contours 776, 778, and 780 of Figure 7 correspond to the third, a fourth and a fifth sets of values of the obtuse internal angle and the acute angle. Similarly to Figure 6, a first polar axis 782 is formed by the intersection of the common plane and the profile plane 786, and a second polar axis 784 intersects the first polar axis 782, is perpendicular to the first polar axis 782, and is parallel to the profile plane 786. The third threshold contour 776 is the same as the third threshold contour 676 of Figure 6 described above. The fourth threshold contour 778 corresponds to the acute angle being 10° and the obtuse internal angle being 170°. The fourth threshold contour 778 is a “peanut shape” Cassini oval. Both foci of the fourth threshold contour 778 are on the first polar axis 782 and are equidistant from the second polar axis 784. The diameter of the third threshold contour 776 is greater than the width of the fourth threshold contour 778 along the second polar axis 784. The fifth threshold contour 780 corresponds to the acute angle being 5° and the obtuse internal angle being 175°. The fifth threshold contour 780 is a “peanut shape” Cassini oval that is elongated along the first polar axis 782. Both foci of the fifth threshold contour 780 are on the first polar axis 782 and are equidistant from the second polar axis 784. The width of the fourth threshold contour 778 along the second polar axis 784 is less than the width of the fifth threshold contour 780 along the second polar axis 784. It was found that a circular, quasi-circular, or substantially circular airflow profile of the aggregate airflow may be achieved at the profile plane with the acute angle being from 18° to 16° and the obtuse internal angle being from 162° to 164°. Figure 8 shows a schematic front view of a further fan assembly 800 according to an example. The fan assembly 800 is the same as the fan assembly 100 of Figures 1 to 4 with the Figure references increased by 700, except for the following differences. The first outlet 828 has a first periphery that is an ellipse. The second outlet 830 has a second periphery that is an ellipse. The first periphery has a first length 834, a first width 836, and a third width 858 less than the first width 836. The first width 836 and the third width 858 are: parallel with each other, perpendicular to the first length 834, and less than the first length 834. The second periphery has a second length 838, a second width 840, and a fourth width 860 less than the second width 840. The second width 840 and the fourth width 860 are: parallel with each other, perpendicular to the second length 838, and less than the second length 838. The first width 836 and the second width 840 are 10 millimetres; the third width 858 and the fourth width 860 are 7 millimetres; the first length 834 and the second length 838 are 50 millimetres. The first periphery and the second periphery are substantially the same shape; however, in other examples, the first and second peripheries may be different shapes. Figure 9 shows a schematic front view of a further fan assembly 900 according to an example. The fan assembly 900 is the same as the fan assembly 100 of Figures 1 to 4 with the Figure references increased by 800, except for the following differences. The first airflow outlet arrangement 904 comprises eight first outlets 928 arranged linearly along the common plane 932 defined by portions of the first airflow outlet arrangement 904. The second airflow outlet arrangement 906 comprises eight second outlets 930 arranged linearly along the common plane 932 defined by portions of the second airflow outlet arrangement 906. In this example, each outlet 928, 930 is a circular aperture and are each of the same diameter of 2mm. It will be appreciated that, in other examples, a different number or shape of outlets 928, 930 may be provided. The fan assembly 900 comprises an entrainment shield 992. The entrainment shield 992 is attached to the to the stand 915 on an opposite side of the stand 915 to the first airflow outlet arrangement 904 and the second airflow outlet arrangement. It will be appreciated that, in other examples, other positions, sizes, and shapes of the entrainment shield are envisaged. Figure 10 shows a schematic front view of a further fan assembly 1000A and 1000B according to an example in two configurations. The fan assembly 1000A and 1000B is the same as the fan assembly 100 of Figures 1 to 4 with the Figure references increased by 900, except for the following. The nozzle 1002 is rotatable, by an actuation system 1090 at the base 1008, between a first configuration (shown by fan assembly 1000A) and a second configuration (shown by fan assembly 1000B) relative to the base 108 about a rotation axis 1062 (the rotation schematically shown with curved solid black arrow 1013). Rotation 1013 of the nozzle 1002 about the rotation axis 1062 changes a direction of the aggregate airflow relative to the base 1008. In other examples, the nozzle 1002 is manually movable by a user and the position of the nozzle 1002 is otherwise retained, for example by friction, relative to the base 1008. Figure 11 shows a schematic side view of a further fan assembly 1100 according to an example, the side view parallel to the common plane described above. The fan assembly 1100 is the same as the fan assembly 100 of Figures 1 to 4 with the Figure references increased by 1000, except for the following differences. The first airflow outlet arrangement 1104 and the second airflow outlet arrangement 1106 each extend arcuately along the common plane (rather than linearly as they do in Figures 1 to 4). The first airflow outlet arrangement 1104 and the second airflow outlet arrangement 1106 are in a U-shape arrangement. An acute angle 1120 is subtended by the first airflow outlet arrangement 1104 and the second airflow outlet arrangement 1106 from the focus 1114. Other shapes of the airflow outlet arrangements are envisaged, in other examples the airflow outlet arrangements may be different same shapes from each other. An acute angle 1120 is subtended by the first airflow outlet arrangement 1104 and the second airflow outlet arrangement 1106 from the focus 1114. The acute angle 1120 is measured at the focus 1114 and is subtended between a centroid 1131 of the first airflow outlet arrangement 1104 and a centroid 1133 of the second airflow outlet arrangement 1106. Figure 12 shows a schematic side view of a further fan assembly 2100 according to an example, the side view parallel to the common plane described above. Figure 13 shows a schematic front view of the fan assembly 2100 of Figure 12. The relative orientations of each view are indicated using cartesian x-, y-, and z- axes. Figures 12 is on an xy-plane and Figure 13 is on a yz-plane. The Figures are schematic and are not to scale. The fan assembly 2100 is the same as the fan assembly 1100 of Figure 11 with the Figure references increased by 1000, except for the following differences. The first airflow outlet arrangement 2104 and the second airflow outlet arrangement 2106 are continuous and are portions of the same continuous airflow outlet arrangement. A housing defines both the first airflow outlet arrangement 2104 and second airflow outlet arrangement 2106. The first outlet and the second outlet are continuous and are portions of the same continuous outlet 2198 as defined by a portion of each of the first airflow outlet arrangement 2104 and the first airflow outlet arrangement 2106. For each of the fan assemblies described above the airflow generator comprises a motor and an impeller; however, other airflow generators are envisaged. Each of the fan assemblies above comprise a battery for providing electrical power to the airflow generator; however, other means of providing electrical power to the airflow generator are envisaged, such as mains power via a mains power cable, or auxiliary power (power taken auxiliary from another electronic device, such as a computing device) via an auxiliary cable. Further, the fan assembly may comprise a port for delivery of electrical current to the battery. The fan assembly, the main body, or the nozzle may comprise at least one of a handle, a bucket handle, a carry handle, or a recess handle. It is to be understood that any feature described in relation to any one example may be used alone, or in combination with other features described, and may also be used in combination with one or more features of any other of the examples, or any combination of any other of the examples. Furthermore, equivalents and modifications not described above may also be employed without departing from the scope of the accompanying claims.

Claims

Claims 1. A fan assembly comprising: a nozzle comprising: a first airflow outlet arrangement extending substantially along a common plane, the first airflow outlet arrangement comprising one or more first outlets; a second airflow outlet arrangement extending substantially along the common plane, the second airflow outlet arrangement comprising one or more second outlets; and an airflow generator in fluid communication with the one or more first outlets and the one or more second outlets; wherein the first and second airflow outlet arrangements are configured to discharge respective first and second airflows toward one another substantially along the common plane such that the first and second airflows collide at a focus to produce an aggregate airflow, wherein an acute angle is subtended by the first and second airflows from the focus.

2. The fan assembly according to claim 1, wherein the first airflow outlet arrangement and the second airflow outlet arrangement each extend substantially linearly along the common plane.

3. The fan assembly according to claim 1 or claim 2, wherein at least notionally extending the first and second airflow outlet arrangements along the common plane enables a V-shape or a U-shape to be formed, wherein an interior angle of the apex of the respective V-shape or U- shape is obtuse.

4. The fan assembly according to any preceding claim, wherein the first and second airflow outlet arrangements are configured such that the acute angle is from 10 to 30 degrees.

5. The fan assembly according to claim 4, wherein the first and second airflow outlet arrangements are configured such that the acute angle is from 15 to 20 degrees.

6. The fan assembly according to any preceding claim, wherein the first airflow outlet arrangement is spaced apart along the common plane from the second airflow outlet arrangement.

7. The fan assembly according to claim 6, wherein the first airflow outlet arrangement is selectively spaced apart from the second airflow outlet arrangement by a distance that is variable to adjust a distance of the focus from the nozzle.

8. The fan assembly according to claim 6 or claim 7, wherein the first airflow outlet arrangement is spaced apart from the second airflow outlet arrangement by a distance no more than 200 millimetres.

9. The fan assembly according to any preceding claim, wherein each of the one or more first outlets is elongate.

10. The fan assembly according to any preceding claim, wherein each of the one or more second outlets is elongate.

11. The fan assembly according to any preceding claim, wherein at least one of the first or second airflow outlet arrangements comprises a plurality of outlets.

12. The fan assembly according to any preceding claim, wherein the nozzle comprises: a first nozzle comprising the first airflow outlet arrangement; and a second nozzle comprising the second airflow outlet arrangement; wherein the first and second nozzles are pivotable relative to one another about a common rotation axis or a respective rotation axis, wherein said rotation axis is perpendicular to the common plane and pivoting of the first and second nozzles about said rotation axis changes the acute angle.

13. The fan assembly according claim 12, wherein the first and second nozzles are independently pivotable about said rotation axis so as to angle the focus and the aggregate airflow.

14. The fan assembly according claim 12 or claim 13, wherein the first and second nozzles are proportionately pivotable about said rotation axis, such that pivoting of the first nozzle about the rotation axis by an amount proportionality pivots the second nozzle by the same amount so as to adjust a distance of the focus from the one or more first and second outlets.

15. The fan assembly according to any one of claim 12 to claim 14, comprising an actuation system for pivoting the first nozzle and / or second nozzle about said rotation axis.

16. The fan assembly according to any one of claims 1 to claim 11, wherein the first and second airflow outlet arrangements are fixed in position relative to one another.

17. The fan assembly according to any preceding claim, comprising a base structurally supporting the nozzle, wherein the nozzle is moveable relative to the base to change a direction of the aggregate airflow relative to the base.

18. The fan assembly according to claim 17, wherein the airflow generator is disposed in the base.

19. The fan assembly according to any preceding claim, wherein the one or more first and second outlets each have a width of at least 1 millimetre.

20. The fan assembly according to claim 19, wherein the one or more first and second outlets each have a width from 1 millimetre to 10 millimetres.

21. The fan assembly according to any preceding claim, wherein the first and second airflow outlet arrangements have a length that is substantially equal.

22. The fan assembly according to claim 21, wherein the length of the first and second airflow outlet arrangements is from 50 to 200 millimetres.

23. The fan assembly according to any preceding claim, wherein the first and second airflow outlet arrangements are configured such that the acute angle is used to generate a shape of the aggregate airflow that is generally circular in cross-section.

24. The fan assembly according to any preceding claim, wherein the first and second airflow outlet arrangements are configured such that the aggregate airflow is generally circular in cross-section from 400 to 800 millimetres from the one or more first and second outlets.

25. A nozzle for a fan assembly, the nozzle comprising: a first airflow outlet arrangement extending substantially along a common plane, the first airflow outlet arrangement comprising one or more first outlets; and a second airflow outlet arrangement extending substantially along the common plane, the second airflow outlet arrangement comprising one or more second outlets; wherein the first and second airflow outlet arrangements are configured to discharge respective first and second airflows supplied by an airflow generator of the fan assembly toward one another substantially along the common plane such that the first and second airflows collide at a focus to produce an aggregate airflow, wherein an acute angle is subtended by the first and second airflows from the focus.

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