Airflow generator

Abstract

An airflow generator (1) comprising: an electric ducted fan (2) provided with an inlet (3) and an outlet (4), a fluid conduit (5); and an air multiplier (6) for discharging air along a first axis (A), the air multiplier (6) comprising an inlet (8) and an outlet (9), the fluid conduit (5) fluidly connecting the outlet (4) of the ducted fan (2) to the inlet (8) of the air multiplier (6). The air multiplier (6) comprises an aerodynamic profile defined by a cross-sectional profile shape (P) swept along a profile path (PA), where the cross-sectional profile shape (P) comprises an outer wall portion defining an inner space (S) and defining the outlet (9) fluidly connecting the inner space (S) to ambient air. The outer wall portion comprises a circular guide portion (P1) for facing ambient air moved into by an air multiplier (6), an elongated first side portion (P2) extending from the guide portion (P1) towards a tail portion (PT) of the contour shape (P), and an elongated second side portion (P3) extending from the guide portion (P1) towards the tail portion (PT) of the contour shape (P), the first side portion (P2) extends non-overlapping with respect to itself, and wherein the second side portion (P3) extends non-overlapping with respect to itself, and wherein the first side portion comprises a curved end portion (P4) extending along the first axis (A) past a free end (E) of the second side portion (P3).

Description

Technical Field

[0001] This disclosure relates to an airflow generator and an inductive device assembly including such an airflow generator for cooling a heat exchanger disposed outside the inductive device of the inductive device assembly to achieve transformer cooling. Background Technology

[0002] Power transformers are devices used in power grids. They convert voltage and current to transmit and distribute electrical energy. Power transformers involve large currents; therefore, heat generation is unavoidable. This heat is transferred through the oil inside the transformer tank. For the transformer to operate normally, it is important to release this heat into the surrounding environment. A crucial component of oil cooling is achieved by placing external equipment such as radiators and cooler assemblies next to the transformer, through which the transformer oil circulates and is cooled. In existing technology, air cooling of transformers is achieved by using conventional fans, i.e., bladed fans, or by utilizing natural convection. Existing cooling systems using bladed fans typically generate high noise, have complex structures, are heavy, and difficult to maintain. For high-power transformers, natural convection is insufficient for cooling; therefore, forced cooling is required.

[0003] External transformer cooling typically uses one or more radiators located outside the transformer. The radiator allows oil to circulate from the transformer and flow out to the radiator, where heat is dissipated from the oil into the surrounding air. The cooling process usually utilizes natural convection or forced convection to allow ambient air to pass through the radiator.

[0004] This disclosure relates to cooling systems using forced convection. Forced convection is typically achieved using one or more large fans that blow air across or onto a radiator. Cooling efficiency depends on the airflow rate and therefore on the fan power consumption.

[0005] Therefore, the object of this disclosure is to provide a compact and energy-efficient airflow generator for cooling inductive devices, such as transformers or shunt reactors.

[0006] The prior art does not mention the solution proposed in this disclosure.

[0007] US 2012 / 280051 relates to a fan assembly including an annular nozzle and a main airflow system. The nozzle includes an outer wall and an inner wall surrounded by the outer wall, the inner wall defining an orifice with an orifice axis. The nozzle also includes an internal channel located between the inner and outer walls, extending about the orifice axis to receive airflow, and an air outlet located at or towards the front of the nozzle for ejecting the airflow. The nozzle is configured to eject airflow through the air outlet in a direction away from the orifice axis. The air channel 94 is tubular and aligned along the chord C1 of the airfoil. Therefore, its surface is flat, forming a distinct and abrupt transition between the inner surfaces of the sides 70 and 72 and the air channel 94. This document does not mention any alternative, smoother shapes.

[0008] Another document, US 2012 / 0318393, discloses a flow guide structure for a bladeless fan. The bladeless fan includes a main unit and a flow guide frame. The flow guide frame is connected to the main unit and includes an exhaust section with internal flow channels communicating with a generator. The exhaust section also includes a converging wall, an inner annular compression wall, and an outer annular compression wall extending forward from both ends of the converging wall. From the junction of the converging wall with the inner and outer annular compression walls, the spacing between the inner and outer annular compression walls gradually decreases. The inner and outer annular compression walls also have distal ends forming a front air outlet to expel airflow forward. Unevenness on the surface of the compression walls can cause obstructions and disturbances in the airflow, potentially causing turbulence and turbulence-related problems such as noise.

[0009] EP 4145079 relates to a cooling device for cooling at least one OAEHE in a transformer. The cooling device includes at least one impeller-motor assembly, at least one fluid conduit, and at least one fluid discharge device. The at least one impeller-motor assembly is adapted to supply fluid to the inlet of the at least one fluid discharge device via the at least one fluid conduit, and to allow the fluid to flow through the at least one fluid discharge device and discharge through at least one fluid outlet of the at least one fluid discharge device. The cooling device further includes a funnel. The at least one impeller-motor assembly is located within a housing at least 3 meters away from the at least one fluid discharge device.

[0010] The airflow generator design according to this disclosure minimizes interference and turbulence in the airflow compared to the prior art, thereby reducing potential noise and improving the efficiency of the cooling device. Summary of the Invention

[0011] According to a first aspect of this disclosure, these and other objectives are achieved by an airflow generator as defined in claim 1, with alternative embodiments defined in the dependent claims. This airflow generator is suitable for cooling an oil-air external heat exchanger for an inductively coupled device. The airflow generator includes an electrically driven ducted fan with an inlet and an outlet, fluid conduits; and An air multiplier for discharging air along a first axis, the air multiplier including an inlet and an outlet. A fluid conduit fluidly connects the outlet of a ducted fan to the inlet of the air multiplier. The air multiplier includes an aerodynamic profile defined by a cross-sectional profile shape swept along a profile path. The cross-sectional profile shape includes an outer wall portion defining an internal space and defining the outlet, the outlet fluidly connecting the internal space to ambient air.

[0012] The outer wall portion includes a circular guide portion for facing ambient air entering via the air multiplier, an elongated first side portion extending from the guide portion toward a tail portion of the profile shape, and an elongated second side portion extending from the guide portion toward the tail portion of the profile shape. The first side portion extends non-overlapping with itself. Similarly, the second side portion extends non-overlapping with itself. The first side portion includes a curved end that extends along the first axis through a free end of the second side portion.

[0013] A fan supplies airflow to an air multiplier. The fan's duct-like nature allows it to effectively pressurize fluid channels. By supplying an air multiplier to the airflow generator, a much larger volume of air than the fan can supply is directed to the oil-air heat exchanger. This reduces power consumption compared to conventional fans that use direct airflow (e.g., to oil-air heat exchangers in inductive devices). Furthermore, the fan and air multiplier combination produces lower noise levels than a typical fan, while delivering the same airflow to the heat exchanger.

[0014] During operation, air is thus forced out of the air multiplier's outlet. The ejected air flows along the curved end of the air multiplier. The ejected air accelerates the ambient air and causes it to flow through the air multiplier. Therefore, before the ambient air reaches the tail section of the air multiplier, its circular guide section is struck by the incoming ambient air.

[0015] The degree of non-overlapping extension of each corresponding side is associated with the following technical effect: the corresponding side does not guide airflow back along itself within the internal space of the air multiplier, nor does it introduce an inner edge toward the internal space. The non-overlapping nature of the corresponding side can alternatively be defined by the presence of a free end of a cross-sectional profile shape configured to define the outer edge of the air multiplier.

[0016] This air multiplier design improves energy efficiency, likely due to reduced turbulence inside the hollow air multiplier after the inner edge facing the internal space is omitted. Furthermore, this non-overlapping nature appears to reduce the tendency for foreign particles to accumulate inside the air multiplier, thereby extending its lifespan and reducing maintenance requirements.

[0017] The gap width between the outlet of the air multiplier and the first and second sides can be in the range of 0.1-10 mm.

[0018] The gap width can be non-constant along the length of the air multiplier. By varying the gap width along the length of the air booster (i.e., along the extension direction of the profile path), the local velocity of the airflow through the outlet can be adjusted, thereby controlling the overall airflow distribution of the air accelerated by the airflow generator.

[0019] The longitudinal extension length of the curved end past the free end of the second side can be at least five times the gap width.

[0020] The aerodynamic profile can form a closed loop. The closed-loop design enhances the strength of the air multiplier. Furthermore, since the air multiplier has no free ends, the closed-loop design also reduces turbulence.

[0021] The air jet direction at the outlet can form an angle with the air jet direction at the tail section of the air multiplier, said angle being in the range of 5-35 degrees, for example 10-30 degrees.

[0022] According to a second aspect of this disclosure, these and other objectives are achieved by an inductive device apparatus as defined in claim 7. The inductive device apparatus includes an airflow generator as described in any of the preceding alternatives, and an inductive device provided with an external oil-air heat exchanger. The airflow generator is configured to discharge air toward the oil-air heat exchanger.

[0023] Inductive devices equipped with oil-air heat exchangers are known. By providing such inductive devices with the airflow generator claimed in this disclosure, an energy-efficient and compact cooling system for inductive devices is realized.

[0024] Inductive devices can be static inductive devices, such as transformers or shunt reactors.

[0025] Furthermore, according to this disclosure and compared with the prior art, this arrangement provides an effective solution to avoid disturbances in the airflow path, thereby reducing or eliminating turbulence, and providing an improved and efficient cooling arrangement. Attached Figure Description

[0026] Figure 1 A perspective sectional view of an air emission device according to a first embodiment is shown. The cross-sectional cut is vertical, and the air multiplier extends in a circular closed loop, and is therefore not fully shown.

[0027] Figure 2 The same was shown in Figure 1 The cross-sectional profile shape of the air multiplier is shown in the figure.

[0028] Figure 3 The extension range of various outer wall sections of the air multiplier is shown, and these sections are also... Figure 1 and Figure 2 As shown in the image.

[0029] Figure 4 An example of a curve that does not overlap with itself is shown.

[0030] Figure 5 An example of a curve that overlaps with itself is shown.

[0031] Figure 6 An alternative embodiment with a slightly different cross-sectional profile shape α is shown.

[0032] Figure 7 An inductive device apparatus is shown, comprising an airflow generator and an inductive device, the inductive device being provided with an external oil-air heat exchanger cooled by the airflow generator.

[0033] All accompanying drawings are schematic illustrations and are not drawn to scale. Detailed Implementation

[0034] The embodiments of this disclosure will be explained below with reference to the accompanying drawings.

[0035] Figure 1 An airflow generator 1 is shown, comprising an electrically powered ducted fan 2 having an inlet 3 and an outlet 4. The airflow generator 1 also includes a fluid conduit 5 and an air multiplier 6 for discharging air along a first axis A. The air multiplier 6 includes an inlet 8 and an outlet 9. The fluid conduit 5 fluidly connects the outlet 4 of the ducted fan 2 to the inlet 8 of the air multiplier 6. The term "air multiplier" is already used in the prior art and should therefore be known to those skilled in the art. An air multiplier is a nozzle commonly used in bladeless fans. Here, the term "air multiplier" can refer to any type of air exhaust device / nozzle designed to exhaust air through an outlet (typically in the form of one or more elongated slits) such that the air around the exhaust device is agitated by the air discharged from the outlet, the agitated air volume being at least 5-15 times the volume of the air discharged from the outlet. Another term that can be used instead of "air multiplier" is "Coanda effect." (effect) Air multiplier. This air exhaust device can vary greatly in design, but it is usually in the shape of an extruded hollow profile.

[0036] This disclosure relates to a specific design of an air multiplier 6 made based on a specific design of the cross-sectional profile shape of the air multiplier 6.

[0037] like Figure 1As shown, the air multiplier 6 includes an aerodynamic profile defined by a cross-sectional profile shape P swept along a profile path PA. Figure 1 As shown in the cross-sectional view, the air multiplier, symmetrical about the cross-section, forms a closed circular loop. As detailed below, other shapes can be used alternatively, employing closed or open "loops" or other forms. Figure 3 As shown, the cross-sectional profile P includes an outer wall portion defining an internal space S and defining an outlet 9 that fluidly connects the internal space S to ambient air. The outer wall portion includes a circular guide portion P1 for facing the ambient air moving in by the air multiplier 6. The outer wall portion also includes an elongated first side portion P2 extending from the guide portion P1 toward a tail portion PT of the profile P, and an elongated second side portion P3 extending from the guide portion P1 toward the tail portion PT of the profile P. The first side portion P2 extends non-overlapping with itself, and the second side portion P3 also extends non-overlapping with itself. Furthermore, the first side portion P2 includes a curved end portion P4 that extends along the first axis A through the free end E of the second side portion P3. In this exemplary embodiment, the end portion P4 has a substantially convex shape, projecting toward the second side portion P3.

[0038] In use, the air multiplier 6 ejects air from its outlet. The ejected air flows along the curved end P4. This curvature is designed to trigger the Coanda effect during use. The ejected air accelerates the ambient air and causes it to flow through the air multiplier 6. Therefore, the circular guide portion P1 of the air multiplier 6 is struck by the incoming ambient air before it reaches the tail portion PT of the air multiplier 6.

[0039] The degree of non-overlapping extension of each corresponding side portion P2, P3 is associated with the following technical effect: the corresponding side portion does not guide airflow back along the corresponding side portion (itself) within the internal space S of the air multiplier. Another effect is that turbulence in the internal space S is avoided because there is no inner edge facing the internal space S (turbulence would otherwise be formed by said edge). In other words, the non-overlapping nature of the corresponding sides P2, P3 can alternatively be defined by the free ends of the cross-sectional profile shape defining the outer edge of the air multiplier 6.

[0040] Figure 4 and Figure 5 Examples of non-overlapping extensions and overlapping extensions are shown respectively.

[0041] For non-overlapping extensions, the first directional component dx of the curve's curvature direction changes direction / reverses somewhere along the curve's extension. This is in Figure 5 The example shows that the x-axis component dx changes from positive to negative, that is, from right to left in the graph. For Figure 4This is not the case for the non-overlapping extension of the curve, where the component dx in the direction of curvature points to the right throughout the entire extension of the curve shown.

[0042] When studying curves to determine whether they do not overlap with themselves, the so-called x-axis is usually chosen to extend parallel to the direction of air jetting through the outlet of the air multiplier 6.

[0043] The direction of the other axis dy may vary along the extension of the curve under study without affecting whether the curve overlaps with itself.

[0044] In other embodiments, the air emission device may include more than one air multiplier. Furthermore, in other embodiments, the shape of the contour path PA can be shaped in any other suitable manner, such as a straight line, ellipse, spiral, N-gon, etc.

[0045] The air multiplier can be made of any suitable material and formed using any suitable manufacturing method. Typically, the aerodynamic profile of the air multiplier 6 is made of extruded aluminum or extruded plastic. Alternatively, the air multiplier 6 can be produced by molding, such as by injection molding of plastic. The air multiplier 6 may include one or more components joined together to form the air multiplier 6. For example, the open end of a hollow profile, whether extruded or otherwise made, may need to be closed with an end cap or fluidly connected to a fluid conduit to allow air to enter through the open end of the profile.

[0046] like Figure 3 As shown, the gap width W between the outlet 9 of the air multiplier 6 and the first side P2 and the second side P3 can be in the range of 0.1-10 mm. In this embodiment, the gap width is substantially constant, but in other embodiments, the gap width may alternatively be non-constant along the length of the contour path of the air multiplier 6.

[0047] The longitudinal extension length L of the bent end P4 passing through the free end E of the second side P3 is preferably at least five times the gap width W.

[0048] The air jet direction of outlet 9 forms an angle α with the air jet direction of the tail portion of air multiplier 6, said angle α being in the range of 5-35 degrees, for example 10-30 degrees.

[0049] Therefore, as Figure 2 and 3 As shown, the present invention provides mathematically smooth and continuously curved inner guide surfaces for P2 and P3, without any abrupt changes in angle or obstructions. The inner surfaces maintain a continuous curve from the connection point at guide portion P1 to the endpoints of each side portion P2 and P3. The curved end P4 is particularly smooth.

[0050] For all embodiments, any other construction capable of delivering air from the duct fan to the fluid conduit 5 of the air multiplier 6, such as an internal channel within the housing, may be used instead.

[0051] The airflow generator 1 disclosed herein is particularly suitable for supplying airflow to a heat exchanger installed outside an inductive device. Therefore, this disclosure also relates to an inductive device apparatus 10. For example... Figure 7 As shown, the induction device 10 includes an airflow generator 1 and an induction device as described above. The induction device is equipped with an external oil-air heat exchanger 7. The airflow generator 1 is configured to discharge air toward the oil-air heat exchanger 7.

[0052] The oil-air external heat exchanger 7 is external, meaning it is installed outside the induction device, thus enabling it to radiate and conduct heat to the surrounding air. Typically, oil from inside the induction device is pumped through the oil-air heat exchanger 7, whereby the oil carries the heat generated inside the induction device outward to the heat exchanger 7, so that the airflow from the airflow generator 1 cools the heat exchanger 7.

[0053] Figure Labels

Claims

1. An airflow generator (1), comprising: - Electric duct fan (2), the electric duct fan (2) is provided with an inlet (3) and an outlet (4). - Fluid conduit (5); and - An air multiplier (6) for discharging air along a first axis (A), the air multiplier (6) including an inlet (8) and an outlet (9). The fluid conduit (5) is configured to fluidly connect the outlet (4) of the duct fan (2) to the inlet (8) of the air multiplier (6). The air multiplier (6) includes an aerodynamic profile defined by a cross-sectional profile shape (P) swept along a profile path (PA), wherein the cross-sectional profile shape (P) includes an outer wall portion defining an interior space (S) and defining an outlet (9) that fluidly connects the interior space (S) to ambient air. The outer wall portion includes a circular guide portion (P1) for facing the ambient air moving into the air multiplier (6), an elongated first side portion (P2) extending from the guide portion (P1) toward the tail portion (PT) of the contour shape (P), and an elongated second side portion (P3) extending from the guide portion (P1) toward the tail portion (PT) of the contour shape (P), wherein the first side portion (P2) extends non-overlapping with itself, wherein the second side portion (P3) extends non-overlapping with itself, and wherein the first side portion includes a curved end portion (P4) extending along the first axis (A) through the free end (E) of the second side portion (P3).

2. The airflow generator (1) as described in claim 1, wherein, The gap width (W) of the outlet (9) of the air multiplier (6) between the first side (P2) and the second side (P3) is in the range of 0.1-10 mm.

3. The airflow generator (1) as described in claim 2, wherein, The gap width is not constant along the length of the air multiplier (6).

4. The airflow generator (1) as described in any one of claims 2-3, wherein, The longitudinal extension length (L) of the curved end (P4) through the free end (E) of the second side (P3) is at least five times the gap width (W).

5. The airflow generator (1) as described in any one of claims 1-4, wherein, The aerodynamic profile forms a closed loop.

6. The airflow generator (1) as described in any one of claims 1-5, wherein, The air jet direction of the outlet (9) forms an angle (α) with the air jet direction of the tail portion of the air multiplier (6), the angle (α) being in the range of 5-35 degrees, for example 10-30 degrees.

7. An induction device (10) comprising an airflow generator (1) as claimed in any one of claims 1-6, and an induction device provided with an oil-air external heat exchanger (7), wherein the airflow generator (1) is configured to discharge air toward the oil-air heat exchanger (7).

8. The inductive device apparatus as described in claim 7, wherein, The inductive device is a static inductive device.

9. The inductive device apparatus as described in claim 8, wherein, The inductive device is a transformer.

10. The electrical equipment apparatus as claimed in claim 8, wherein, The inductive device is a parallel reactor.

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