CZ304219B6 - Method of entry of a liquid into a hybrid synthesized current generator and entry mechanism for making the same - Google Patents

Abstract

The invented Method of entry of a liquid into a hybrid synthesized current generator is carried out through the mediation of fluidic diodes (5, 6) such that a fluid from the environment is periodically sucked in through the inlets (7, 8) of the fluidic diodes due to change in the fluid pressure in at least one generator cavity (1, 2), to which both the fluidic diodes (5, 6) are connected by their outputs (10, 11), whereby the fluidic diode inlets (7, 8) are oriented opposite to each another and at the same time, the suction into both the inlets (7, 8) alternates periodically with a simultaneous backflow from both the inlets (7, 8) of the fluidic diodes, where collision (9) of the countercurrent flows of the fluid is created between the inlets (7, 8). The entry mechanism for making the above-described method of entry of a liquid into a hybrid synthesized current generator comprises a pair of fluidic diodes (5, 6), which are connected by their outputs (10, 11) to one or two generator bodies (3, 4), whereby the inlets (7, 8) of the fluidic diodes are oriented counter each another.

Description

A method of introducing a fluid into a hybrid synthesized current generator and an inlet device for carrying out the method

Technical field

The invention relates to the generation of fluid streams in various fields of technology, in particular for cooling hot bodies with a stream of cold fluid or drying wet objects with dry air.

BACKGROUND OF THE INVENTION

A conventional synthesized stream is a flooded fluid stream that is generated by a synthesized stream generator according to U.S. Patent No. 5,758,823. Flooded streams are fluid streams that flow into an environment that has approximately the same material properties, as opposed to diode streams through a free surface, such as Liquid flow outflow to the gas. A special feature of the synthesized stream is zero, the mass of fluid displaced from the generator cavity must equal the mass of the fluid immediately into the aspirated cavity. The sequence of fluid exhaust volumes for each period after discharge turns into a sequence of vortex rings, which produces, under appropriate conditions, a resulting fluid stream called a "synthesized stream" that has a non-zero flow as a result of a fluid stream (such as a stream formed by any conventional means associated with providing a pressure drop across a discharge port, e.g., a discharge from a pressure vessel).

The use of synthesized streams brings a number of advantages. The main advantage is the relative design simplicity of the whole device, since the fluid streams are generated without having to supply the fluid under pressure to the outlet port. Thus, there is no need to use sources of fluid such as a pressure vessel for short-term use and for the continuous operation of any conventional machine such as a compressor, fan, blower, pump, and the like. This brings savings in built-in space, weight and cost. In addition, potential sources of malfunction of the entire device, such as said rotating machines, are thus eliminated. Another significant advantage is that the inlet pipe is eliminated, which in turn brings additional savings in the enclosed space, weight and cost of the device.

Synthesize streams have many possible applications. In particular, it involves the active control of current and / or temperature fields or the separate use of synthesized currents or their systems.

The aim of the active control of the main flow field may be to direct the fluid flow in external aerodynamics, to control the flow field in internal aerodynamics, to intensify the mixing, or to increase the heat and / or mass transfer by controlling the main flow field. The aim of using separate synthesized streams or their assemblies without the main flow field may be to intensify the heat transfer process, respectively. their force action eg for movement control. Synthesized currents are a very promising alternative for many cooling applications, such as high-load components in electronics or cooling turbine blades. For most of these cases, the use of micro-electro-mechanical systems (MEMS) is of great importance - see Carpenter, Pressure-Driven Microfluidics, Artech House, Boston, London, 2007. with a steady, unchanging flow of orders of problematic features over time. An important consequence of the small size and resulting small Reynolds numbers is the laminar or even creeping nature of the flow, where the intensity of heat and mass transfer reaches only small values, as implied by the mechanism of gradient diffusion - as described by Fick's law.

Conventional synthesized streams have a steady-state mean mass flow rate of generator fluid at zero time, and only at a certain distance the fluid flow has a non-zero-time mean

The mass flow component obtained by aspirating the surrounding fluid. In contrast to such conventional cases, the hybrid synthesized stream has a non-zero time-average mass flow component already at the generator outlet. Previously known variants of these generators have been designed either as a single-acting volumetric machine (Trávníček et al., Hybrid synthetic jet and the non-zero-netmass-flux jet, Physics of Fluids, 18 (2006) 081701-1-081701-4), or double-acting (Wang et al., U.S. Patent No. 7,527,086).

The advantage of using a hybrid synthesized current generator is, on the one hand, an increase in the mass flow rate of the fluid through the outlet of the generator itself and, on the other hand, the suction of "fresh" liquid into the generator cavity through the inlet device. The second advantage is justified especially when cooling hot objects such as electronic equipment.

For efficient suction of the "fresh" unheated fluid, it appears advantageous to use a fluoride diode (Trávníček et al., Hybrid Synthetic Jet as a Non-Zero-Net-Mass-Flux Jet, Physics of Fluids, 18 (2006) 081701-1-081701- 4, Wang et al., US Patent 7,527,086). The use of fluidic diodes to regulate the pulsating movement of fluid without mechanically moving parts is known, for example, in so-called valveless positive displacement pumps (Stemme and Stemme, WO 94/19609; Gerlach, WO 9600849 A1; Foster et al., US 5,876) 187). Another known field is pulsating jet engines (Paris et al., Patent GB 805 543; Quellette, patent application US 2005/0097897). In all these cases, using a conventional non-return valve with mechanically moving parts would reduce the reliability of the entire machine. Efforts to maximize reliability therefore lead to systems without mechanically moving parts.

Although many types of fluidic diodes are currently known (Yastrebova, Fluid diodes, Automatics and Telemechanics 3, 101, 1971; Carpenter, Pressure-Driven Microfluidics, Artech House, Boston, London, 2007), it is not yet known how to optimize a fluidic diode for use in a hybrid synthesized current generator input device. Complicated facts are primarily the requirements of small size and the associated small Reynolds numbers and correspondingly high frequency of fluid pulsations. All variants of hybrid synthesized current generators investigated so far have always been in the form of widening channels (Wang et al., U.S. Patent No. 7,527,086; Trávníček et al., Hybrid Synthetic Jet and the Non-Zero-Netmass-Flux Jet, Physics of Fluids, 18 (2006) 081701-1-081701-4; Travnicek et al., Performance of synthetic jet actuators based on hybrid and double-acting principles, Journal of Visualization, 11 (2008), 221-229).

The transition from a conventional synthesized stream to a hybrid synthesized stream allows for better results in a variety of applications. The inlet device of the hybrid synthesized current generator is a key element for desirably increasing the mass flow of fluid through the generator. Said inlet device periodically sucks and expels the working fluid. The criterion that quantifies the magnitude of the time-average component of the mass flow through the generator is the volume efficiency ε _ν . This is the ratio of the resulting volume of fluid displaced through the generator orifice over the entire period (i.e., the volume dispensed minus the volume aspirated) relative to the total volume pumped into the generator cavity over the entire period. The two limit values are ε _ν = 0 and 1. Zero value is achieved by conventional synthesized current generators, as implied by the law of mass conservation. The value ε _ν = 1 is the ideal value of a pump equipped with an ideally operating non-return valve, which would, however, require mechanically movable components whose use lies entirely outside the scope of the invention. So far, the volumetric efficiency values of the hybrid synthesized jet generators have only reached ε ^ = 0.13 and 0.19, as experimentally evaluated and published (Trávníček et al., Physics of Fluids, 18 (2006) 081701-1-081701-4; Travnicek et al., Performance of synthetic jet actuators based on hybrid and double-acting principles, Journal of Visualization, 11 (2008), 221-229). The volumetric efficiency value quantifies the so-called rectifying effect: a larger amount of fluid flows through the fluidic diode during the suction part of the period in the direction from the environment into the working cavity of the generator than in the opposite direction during extrusion

-2E period 304219 B6. Achieving the desired higher volumetric efficiency values ε _ν is associated with the design of a better input device.

SUMMARY OF THE INVENTION

It is an object of the present invention to overcome or at least alleviate the disadvantage of the prior art, which is the relatively low volumetric efficiency of hybrid synthesized stream generators.

It is an object of the present invention to provide a fluid inlet to the hybrid synthesized flow generator and an inlet device for carrying out the process.

In particular, the present invention relates to a method for introducing fluid into a hybrid synthesized current generator via fluidic diodes, characterized in that ambient fluid is periodically aspirated through the fluidic diode orifice by varying the fluid pressure in at least one cavity of the generator to which both fluidic diodes are connected. their outlets, the fluidic diode orifices facing each other, and the simultaneous aspiration into both fluidic diode orifices alternates periodically with simultaneous backflow from both fluidic diode orifices where a collision of counter-current fluid flows between the orifices.

According to the invention, a fluid inlet method may also be effective in that the fluidic diode outlets are connected to two different generator cavities in which fluid pressure changes periodically and synchronously with the same frequency and the same phase, and so the fluid suction and expulsion periodically and synchronously orifices of fluidic diodes.

The essence of an inlet device for carrying out a method of entering a fluid into a hybrid synthesized current generator is that it comprises a pair of fluidic diodes which are connected to one or two generator bodies via fluidic diode outlets, the fluidic diode mouths facing each other.

In particular, it may be advantageous to have an inlet device according to the invention in that the length of the gap between the mouths of the fluidic diodes is greater than the transverse dimension of the mouths.

It may also be expedient to provide an inlet device according to the invention, characterized in that at the mouth of the fluidic diodes, a continuous convex surface having a toroid surface is attached to each other by the recess of a continuous convex surface.

Fluidic diodes have the shape of channels that connect the surrounding environment with the cavity or cavities in the generator body or hybrid synthesized current generators. According to the size of the transverse dimensions of the orifice we distinguish fluidic diodes in the macroscale and the microscale. In embodiments corresponding to the macro scale, typical transverse dimensions are of the order of (10 ° to 10 ^L ) mm, preferably 1 to 20 mm. There are no extraordinary requirements for the fluidic diode material; they just need to be coherent and stiff enough to prevent changes in shape by the flowing fluid. The most commonly used materials are: non-ferrous metal alloys, steel, polymer materials, preferably brass, aluminum alloys, and plexiglass. They are made by conventional production techniques such as machining, forming or casting. In the microscale, typical transverse dimensions are of the order of (KV ² to 10 °) mm, preferably 0.02 to 1 mm; these microfluidic diodes are usually made of a non-metallic material, such as polymeric materials, glass or silicon, so that they can be made in microfluidic by conventional methods such as micro machining, etching, molding, or casting.

The distinction with respect to the prior art consists in the arrangement of a pair of fluidic diodes, which through their channels connect the surrounding environment with one common cavity in the body of the hybrid synthesized current generator and are positioned so that the mouths face each other. Said fluidic diodes periodically aspirate and extrude the working fluid. Doing so

During extrusion, fluid from each fluidic diode flows into the environment in the form of a flooded stream, and the arrangement of the pair of fluidic diodes facing each other causes the pair of counter-rotating flooded currents to interact with each other, i.e. outside the channel.

Some prior art fluidic diodes also utilize the flow distribution of the fluid into two branches and the interaction of the split flow to accomplish their function (e.g., Tesla, U.S. Pat. No. 1,329,559), and some prior art fluid valves utilize counter-flow through two channels to control flow ( Carpenter, Pressure-Driven Microfluidics, Artech House, Boston, London, 2007). However, in neither case has it been the simultaneous discharge of a pair of counter-rotating flooded currents from the environment outside any channel and their mutual collision in the environment without being affected by solid walls.

The main advantages of the invention over the prior art are the increased volumetric efficiency of the entire hybrid synthesized current generator. Another advantage is the possibility to achieve higher frequencies than using conventional fluidic diodes. Conventional fluidic diodes achieve lower frequencies because their rectifying effect is dependent on the development of the flow across the diode, which lasts for a certain period of time. However, the input device of the present invention has a significant portion of the rectifying effect associated with the collision of two counter-current flooded currents in the environment without affecting the solid walls without changing the flow pattern, thus allowing faster function and higher frequencies.

The inlet device according to the invention can be used in all known hybrid synthesized current generator applications, such as flow field and / or temperature field control in external or internal aerodynamics (eg fluid flow direction or boundary layer control in body flow), intensifying mixing, increasing heat transfer (eg cooling of heavily loaded components in electronics or cooling of turbine blades). In all applications, the hybrid synthesized stream with the inlet device of the present invention achieves better results than the prior art because its volumetric efficiency is higher.

The main advantage of the invention over the prior art is the higher volume efficiency, which reaches ε _μ = 0.2 to 0.9. Another advantage is the possibility to achieve higher frequencies which can reach values of the order of up to 10 ¹ kHz. Conventional fluidic diodes inevitably operate at lower frequencies, since their rectifying effect is delayed and occurs only to develop flow throughout their cavity. The input device of the present invention, however, has a significant portion of the rectifying effect associated with the collision of two opposing flooded currents. In this case, the mutual distance collides with currents after the passage of G / 2, that is, after the time response Af ~ 0.5 G / U, where U is the mean flow velocity at the mouth. In the case of channels extending towards the cavity in the generator body, the input response time response corresponds to the time the fluid flows through the entire channel, i.e., At _L ~ cL / U, where c is the coefficient involving the change in channel cross section. For a fluidic diode of the channel type extending towards the cavity in the generator body, c> 1 applies. Thus, the response time ratio of both cases is kt // St _L = (0.5 / c) (G / L). Since c> 1 and G <L, it applies to the ratio / St / St _L <1. And since the frequency is inversely proportional to the time response Af, the input device according to the invention can operate at higher frequencies than conventional diodes.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1a is a diagram of an inlet device for a hybrid synthesized current generator according to the invention with a pair of fluidic diodes and one cavity in the generator body, wherein both fluidic diodes are connected to the housing by their outlets.

Fig. 1b shows the flow direction and the collision of a pair of counter-rotating flooded fluid streams in the surrounding environment, ie outside the channel.

-4GB 304219 B6

Fig. 1c shows the flow direction in the next part of the period when the fluid is sucked into the cavity from the surroundings.

Fig. 2a shows a pair of fluidic diodes in an embodiment where the generator has two cavities in two different bodies and the fluidic diodes are connected by their outlets to a different cavity, flow direction and collision of a pair of countercurrent flooded fluid streams in the surrounding environment.

Fig. 2b shows the flow direction in the next part of the period when the fluid is sucked into the cavities from the surroundings.

Figure 2c shows the dependence of the volume efficiency on the size of the gap G between the diode orifices.

Fig. 3a shows an embodiment where the flowing convex surfaces, the flow direction and the collision of a pair of counter-flowing flooded fluid streams in the environment, i.e. out of the channel, are connected to the mouth of the fluidic diodes.

Fig. 3b shows the flow direction in the next part of the period when the liquid is sucked from the surroundings into the mouth and flows around the convex surfaces.

DETAILED DESCRIPTION OF THE INVENTION

SUMMARY OF THE INVENTION The present invention provides a method for introducing fluid into a hybrid synthesized current generator via fluidic diodes such that the ambient fluid is periodically sucked through the fluidic diode through a fluid pressure change in at least one cavity of the generator to which both fluidic diodes are connected. the mouths of the fluidic diodes face each other and the simultaneous suction into both mouths of the fluidic diodes alternates periodically with the simultaneous backflow from both mouths of the fluidic diodes, where a collision of counter-current fluid flows between the mouths.

According to the invention, it may also be expedient to introduce fluid into the hybrid synthesized current generator via fluidic diodes, such that fluidic diode outlets are connected to two different generator cavities in which fluid pressure changes periodically and synchronously with the same frequency and phase periodically and synchronously sucking and expelling fluid through the mouths of fluidic diodes.

Example 1

A schematic diagram of the hybrid synthesized current input device for carrying out the method of the invention in the first embodiment is shown in Fig. 1a. The inlet means comprises a pair of fluidic diodes 5, 6 having channels in the form of channels which connect the environment with the cavity and in the generator body and which extend towards the cavity. This is an example made on a macro scale, where the transverse dimensions of the fluidic diode orifices 7, 8 are 5 mm. The material used is plexiglass on the generator body 3 and brass on the fluidic diodes 5, 6. The fluidic diode orifices 7, 8 are directed against each other. Said fluidic diodes 5, 6 periodically suck in and out the working fluid between the environment and the cavity of the generator. The use of a pair of fluidic diodes 5, 6 causes the fluid flow to be divided into two parallel branches. During extrusion, fluid flows from each fluidic diode 5, 6 to the environment in the form of a flooded stream, wherein the arrangement of the pair of fluidic diodes 5, 6 through the orifices 7, 8 causes a collision 9 of a pair of opposing flooded fluid streams in the environment. channel as shown in FIG. 1b. This collision causes an increase in pressure loss during discharge. In this connection, it is particularly advantageous if the gap G between the orifices 7, 8 of the fluidic diodes is 1.5 times greater than the dimensions of the orifice 7,

This increases the pressure drop across the outlet. Giant. 1c schematically illustrates the following part of the period when fluid is sucked into the cavity X from the environment.

Example 2

A diagram of another preferred embodiment of an input device for carrying out the method of the present invention is shown in Figures 2a, 2b and 2c. According to this example, the generator has two cavities 1, 2 in two generator bodies 3, 4 and the input device comprises two inlet fluidic diodes 5, 6. Both have the shape of channels that connect the surrounding environment with the generator cavities 1, 2 in the generator bodies 3, 4. which extend towards these cavities. This example is also carried out on a macro scale, where the transverse dimensions of the fluidic orifice 7, 8 have dimensions of 5 mm. The material used is plexiglass on generator bodies 3, 4 and brass for fluidic diodes 5, 6. The fluidic diode orifices 7, 8 are directed against each other, causing a collision 9 of a pair of counter-rotating flooded fluid streams in the surrounding environment, i.e. outside the channel, as Fig. 2a. This collision causes an increase in pressure loss during discharge. In this connection, it is particularly advantageous if the gap G between the fluid mouths 7, 8 is 1.5 times greater than the dimensions of the fluid mouth 7, 8, since this increases the pressure drop at the outlet. Giant. 2b schematically illustrates the following part of the period when fluid is sucked into the generator cavities 1, 2 from the environment. Giant. 2c shows the dependence of volumetric efficiency on the G gap between the 7,8 diode orifices, measured at 355 Hz excitation frequency, with the highest efficiency of 17% being achieved for the G = 7.5 mm gap, ie 1.5 times the transverse dimension of the orifice 7, 8 fluidic diodes.

Example 3

A diagram of another preferred embodiment of the inlet device according to the invention is shown in Figures 3a and 3b. According to this example, the fluidic diode orifices 7, 8 are provided with fluidic diode recesses 12, 13 which suddenly widen the cross-sections of the fluidic diode channel 5, 6. These fluidic diode recesses 12, 13 are followed by continuous convex fluidic diode surfaces 14, 15 which are Each of these continuous convex surfaces 14, 15 has a shape of one quarter of the surface of the toroid or is only slightly different from such a shape, the toroid and here being a spatial formation which results in an imaginary rotation of less a circle - with a small major diameter - about an axis lying in the same plane as this circle, so that the point of the smaller circle furthest from this axis moves along the large major diameter in such an imaginary rotation. Thus, a toroid is defined by its two major diameters. The small major diameter of the toroid is the diameter of the smallest circle, that is, the planar lines with the same radius of curvature everywhere that can be constructed on the surface of the toroid, while the large major diameter is the diameter of the largest circle ever constructed on that surface. Of course, the invention also relates to toroidal surfaces having the shape of a continuous convex surface 14, 15, where instead of circles they are related to a circle with only slightly different closed planar lines, such as ellipses. This example is carried out on a macro scale, where the transverse dimensions of the orifices 7, 8 of the fluidic diodes have both dimensions of 5 mm. The material used is any sufficiently mechanically strong, for example plexiglass on generator bodies 3, 4 and brass for fluidic diodes 5, 6. The fluidic diode orifices 7, 8 are directed against each other, causing a collision 9 of a pair of counter-rotating flooded fluid streams formed in the environment , i.e., out of the channel, through the fluidic diode outlet as shown in FIG. 3a. This collision causes an increase in pressure loss during discharge. The pair of counter-flowing flooded fluid streams is formed at the edge of the recess and does not bypass the convex surfaces 14, 15 of the fluidic diodes. Giant. 3b schematically illustrates the following part of the period in which fluid is sucked from the environment into the fluidic diode orifice 7, 8 and bypasses the convex surfaces 14, 15 of the fluidic diode, which reduces suction pressure losses.

-6GB 304219 B6

Industrial applicability

The method and apparatus of the invention are particularly useful for the purpose of cooling and / or controlling temperature and current fields in the engineering, electrical, chemical and biochemical industries.

Claims (5)

PATENT CLAIMS A method for introducing fluid into a hybrid synthesized current generator via fluidic diodes (5, 6), characterized in that ambient fluid is periodically sucked through the fluidic diode orifice (7, 8) by varying the fluid pressure in the at least one cavity (1,2) ) of a generator on which the two fluidic diodes (5, 6) are connected by fluidic diode outlets (10, 11), the fluidic diode orifices (7, 8) facing each other and simultaneously aspirating into the two orifices (7, 8) alternating periodically with simultaneous backflow from both fluidic diode orifices (7, 8), where opposing fluid streams (9) collide (9) between the orifices (7, 8). Fluid inlet method according to claim 1, characterized in that the fluidic diode outlets (10, 11) are connected to two different generator cavities (1, 2) in which the fluid pressure changes periodically and synchronously with the same frequency and the same phase. and so that the fluid is sucked and discharged periodically and synchronously through the fluid diode orifices (7, 8). An inlet device for carrying out a method of entering a fluid into a hybrid synthesized current generator according to claim 1 or 2, characterized in that it comprises a pair of fluidic diodes (5, 6) connected to the fluidic diode terminals (10, 11) to one or to two generator bodies (3, 4), the fluidic diode orifices (7, 8) facing each other. An inlet device according to claim 3, characterized in that the gap length between the fluidic diode orifices (7, 8) is greater than the transverse dimension of the orifices (7, 8). An inlet device according to claim 3 or 4, characterized in that continuous convex surfaces (14, 15) having each shape of one quarter of the surface of the toroid are connected to the mouth (7, 8) of the fluidic diodes.