DE102010017523A1 - Method and mixing device for mixing two fluids and their use - Google Patents

Abstract

The invention relates to a method for mixing two fluids, the method comprising the following steps: forming a flow of a fluid along a flow channel (1), providing a pulsating / oscillating injection stream of another fluid, passing the further fluid through a passive passive cavity structure microfluidic actuator device (2) whose output is coupled to the flow channel (1) via an injection device and which is configured to self-induce the pulsating / oscillating injection current at a pulsation / oscillation frequency, and mixing the fluid and the further fluid by the pulsating / oscillating injection stream of the further fluid is introduced via the injection device into the flow of the fluid transversely to the flow direction of the fluid in the flow channel (1). Furthermore, the use of the method is provided.

Description

The invention relates to technologies in the field of mixing fluids, in particular a method and a mixing device for mixing two fluids and their use.

Background of the invention

Mixing two or more fluids is part of processes in various technology areas. For example, fluids are to be mixed in internal combustion engines before the actual burning.

In the mixing process of the fluids is often the situation that one of the fluids to be mixed flows along a flow channel and another of the fluids to be mixed is introduced into this stream. A so-called "cross-mixing" process is used when a fluid flows along the flow channel and another fluid to be mixed herewith is introduced transversely to the flow direction of the fluid into the flow channel. A "co-flow mixing" process is used when both fluids are introduced in the same direction. However, an arbitrary angle between flow channel and injection direction of the fluid to be mixed can also be generated. The introduction of the further fluid takes place with the aid of an injection device, with which the further fluid is introduced into the flow channel. Investigations have been carried out to optimize the geometric design of injection devices (cf., for example Holdeman et al., Mixing in a Row of Jets with a Confined Crossflow, AIAA Journal, 1977, 15, 243-249 ; Liscinsky et al., Experimental Investigation of Crossflow Jet Mixing in a Rectangular Duct, AIAA Paper 93-20037, 1.993 ; Liscinsky et al., Crossflow Mixing of Noncircular jets, AIAA Paper 95-0732, 1995 ).

To improve the mixing process so-called active controls have been proposed. Investigations concerning the active control of individual injection nozzles in connection with cross-mixing have been carried out ( Johari et al., Penetration and mixing of fully modulated turbulent jets in crossflow, AIAA Journal, American Institute of Aeronautics and Astronautics, 1999, 37, 842-850 ; Eroglu et al., Structure, penetration, and mixing of pulsed jets in crossflow, AIAA journal, 2001, 39, 417-423 ). This demonstrated that the active actuation of individual injection streams can improve the quality of the mixing process.

Summary of the invention

The object of the invention is to provide new technologies for the mixing of fluids, which improve the mixing process qualitatively and in terms of its variability for different applications.

This object is achieved by a method for mixing two fluids according to independent claim 1 and a mixing device for mixing two fluids according to independent claim 5. Furthermore, the use of the method and / or the mixing device according to claim 10 is provided. Advantageous embodiments of the invention are the subject of dependent subclaims.

• – Ausbilden eines Stromes eines Fluids entlang eines Strömungskanals,
• – Bereitstellen eines pulsierenden/oszillierenden Injektionsstromes eines weiteren Fluids, indem das weitere Fluid durch eine Hohlraumstruktur einer passiven mikrofluidischen Aktoreinrichtung geführt wird, deren Ausgang über eine Injektionseinrichtung an den Strömungskanal koppelt und die konfiguriert ist, den pulsierenden/oszillierenden Injektionsstrom mit einer Pulsations-/Oszillationsfrequenz selbstinduzierend zu erzeugen, und
• – Mischen des Fluids und des weiteren Fluids, indem der pulsierende/oszillierende Injektionsstrom des weiteren Fluids über die Injektionseinrichtung in den Strom des Fluids quer zur Strömungsrichtung des Fluids in dem Strömungskanal eingebracht wird.

The invention includes the idea of a method for mixing two fluids, the method comprising the following steps:

• Forming a flow of a fluid along a flow channel,
• - Providing a pulsating / oscillating injection stream of another fluid by the further fluid is passed through a cavity structure of a passive microfluidic actuator means whose output is coupled via an injection device to the flow channel and which is configured, the pulsating / oscillating injection current with a Pulsations- / Oszillationsfrequenz to produce self-inducing, and
• Mixing the fluid and the further fluid by introducing the pulsating / oscillating injection current of the further fluid via the injection device into the flow of the fluid transversely to the flow direction of the fluid in the flow channel.

• – einem Strömungskanal, welcher konfiguriert ist für einen Strom eines Fluids,
• – einer passiven mikrofluidischen Aktoreinrichtung, die mit einer Hohlraumstruktur gebildet ist, wobei die passive mikrofluidische Aktoreinrichtung konfiguriert ist, mittels Strömen eines weiteren Fluids durch die Hohlraumstruktur einen pulsierenden/oszillierenden Injektionsstrom des weiteren Fluids mit einer Pulsations-/Oszillationsfrequenz selbstinduzierend zu erzeugen, und
• – einer Injektionseinrichtung, die an den Ausgang der passiven mikrofluidischen Aktoreinrichtung und den Strömungskanal koppelt und konfiguriert ist, zum Mischen des Fluids und des weiteren Fluids den pulsierenden/oszillierenden Injektionsstrom des weiteren Fluids in den Strom des Fluids quer zur Strömungsrichtung des Fluids in dem Strömungskanal einzubringen.

According to another aspect of the invention, there is provided a mixing apparatus for mixing two fluids, comprising:

• A flow channel configured for a flow of a fluid,
• A passive microfluidic actuator device formed with a cavity structure, wherein the passive microfluidic actuator device is configured to self-induce by pulsing another fluid through the cavity structure to induce a pulsatile / oscillating injection current of the further fluid at a pulsation / oscillation frequency;
• - An injection device which is coupled to the output of the passive microfluidic actuator means and the flow channel and configured for mixing the fluid and the further fluid to introduce the pulsating / oscillating injection current of the further fluid in the flow of fluid transverse to the flow direction of the fluid in the flow channel ,

The method and / or the mixing device can be used in various devices, in particular one Gas combustion engine, a burner of a gas combustion engine, a T-mixer of the chemical industry or a chemical tube reactor. The process can be used in conjunction with liquids or gases. A use in connection with so-called NACH profiles can be provided. AFTER profiles are two-dimensional sections of airfoil wing profiles developed by the National Advisory Committee for Aeronautics for wing design.

According to the invention, a passive microfluidic actuator device is used to self-inducing to provide a pulsating or oscillating injection flow of a fluid, which is then introduced as a pulsating / oscillating fluid flow in another fluid, which is transverse to the flow direction of the other fluid in a flow channel. The microfluidic actuator device is passive in particular in the sense that a movement of elements of the actuator device for generating the pulsating / oscillating injection current is not provided. Rather, the formation of the pulsating / oscillating injection current is self-inducing in a cavity structure of the actuator device, which is flowed through by the admixed fluid. The pulsation / oscillation of the injection current then takes place with a characteristic frequency. In this way, efficient mixing of the fluid from the injection stream into the other fluid flowing in the flow channel is achieved. An individual adaptation of the mixing process for different application situations is possible in particular in that the passive microfluidic actuator device is provided with a cavity structure suitable for the respective application, whereby the generation and provision of the pulsating / oscillating injection current is adapted to the desired application parameters.

The pulsation / oscillation frequency of the pulsating / oscillating injection stream of the further fluid corresponds to a characteristic frequency of the passive microfluidic actuator device. These include in particular so-called acoustic resonance frequencies, which are usually independent of the mass flow through the actuator device. Furthermore, this includes frequencies that arise due to a fluid mechanical feedback, which can also be referred to as fluid mechanical frequencies. The frequency at the outlet of the actuator device is then often dependent on the mass flow through the actuator device. There is then no constancy.

A preferred embodiment of the invention provides that the fluid in the flow channel flows around a flow channel element, on which the injection device is formed. In this case, it may be provided that outlet openings of the injection device are distributed around the surface of the flow channel element around it, so that the further fluid can be introduced into the flow of the fluid flowing around the flow channel element more efficiently. In one embodiment, the flow channel element is provided with a fluidically optimized surface contour.

In an expedient embodiment of the invention it can be provided that the additional fluid is introduced into the flow of the fluid via an arrangement of a plurality of outlet openings of the injection device, wherein the arrangement of the plurality of outlet openings extends substantially transversely to the flow direction of the fluid in the flow channel. The plurality of outlet openings can be distributed in one embodiment over the entire channel width of the flow channel.

An advantageous embodiment of the invention provides that the pulsating / oscillating injection current is generated with a high pulsation / oscillation frequency and introduced into the flow of the fluid, wherein the pulsation / oscillation frequency in air is at least about 100 Hz, preferably at least about 250 Hz , The frequency is fluid-dependent.

Hereinafter, preferred embodiments of the mixing device for mixing two fluids are explained in detail.

Preferably, a development of the invention in this context provides that in the flow channel, a flow channel element is arranged, which is flowed around by the fluid and on which the injection device is formed. The angle of the fluidic injection may have any angle relative to the fluid flowing around.

In an advantageous embodiment of the invention can be provided that the cavity structure of the passive microfluidic actuator device is at least partially formed in the flow channel element.

A development of the invention can provide that the passive microfluidic actuator device is designed to passively self-regulate the pulsation / oscillation frequency of the pulsating / oscillating injection current as a function of the flow rate of the further fluid through the passive microfluidic actuator device. The passive microfluidic actuator device is configured with its cavity structure so that, depending on the flow rate of the other Fluids can set different Pulsations- / Oszillationsfrequenzen that correspond to a characteristic frequency of the passive microfluidic actuator device.

A preferred development of the invention provides that the injection device is formed with an arrangement of a plurality of outlet openings, wherein the arrangement of the plurality of outlet openings extends substantially transversely to the flow direction of the fluid in the flow channel.

Description of preferred embodiments of the invention

In the following, we will explain the invention with reference to preferred embodiments with reference to figures of a drawing. Hereby show:

1 a schematic representation of a mixing device for mixing fluids,

2 a schematic representation of a portion of the mixing device 1 in cross section,

3 a schematic representation of a passive microfluidic actuator device for generating a self-induced oscillating injection current,

4 a schematic representation of a passive microfluidic actuator device for generating a self-induced pulsating injection current,

5 a schematic representation of two so-called T-mixing devices,

6 a schematic representation of a mixing device for mixing fluids, in which a plurality of injection ports are arranged transversely to the flow channel, and

7 a schematic representation of a NACH profile.

1 shows a schematic representation of a mixing device for mixing fluids, in which along a flow channel 1 a first fluid flows along a direction indicated by the arrow I direction. In the flow channel 1 is a flow channel element 2 arranged, at which several injection openings 3 an injection device are formed, through which a second fluid is introduced transversely to the flow direction of the first fluid (see arrow II) as part of a mixing process.

2 shows a schematic representation of a portion of the mixing device 1 along the line AA 'in 1 , It turns out that the injection ports 3 substantially uniformly distributed along the circumference of the flow channel element 2 are formed, whereby substantially on all sides an application and mixing of the second fluid takes place transversely to the flow direction of the first fluid.

3 shows a passive microfluidic actuator device for generating a self-inducing generated oscillating injection current. The fluid to be mixed in via an inlet opening 30 in a cavity structure 31 introduced the microfluidic actuator device, in which self-inducing an oscillating injection flow of the fluid is formed, which via an output port 32 is delivered. The oscillation frequency of the injected injection current corresponds to a resonant frequency of the cavity structure 31 ,

4 shows a schematic representation of another passive microfluidic actuator device for self-induced generation of a pulsating injection current. Via an entrance opening 40 the fluid to be mixed becomes a cavity structure 41 brought in. Via an exit opening 42 Then a self-induced pulsating injection current is delivered.

Microfluidic cavity structures for the self-induced generation of pulsating / oscillating flows of a fluid are known as such in various embodiments, be it in accordance with the 3 and 4 shown embodiments or in another form (see, for example Shakouchi, Jet and Wake Flow Control and their Practical Application, Int. Conf. on jets, wakes and separated flows, 2008 ).

5 shows a schematic representation with two so-called T-mixers, in which along a respective channel current 1 a first fluid flows (into or out of the image plane). Transverse to the flow direction is using a passive microfluidic actuator device 50 For example, the comments in the 3 and 4 is formed accordingly, introduced an oscillating / pulsating injection current.

6 shows a schematic representation of a mixing device for mixing fluids with a flow channel 1 and a passive microfluidic actuator device 60 in which a pulsating / oscillating injection stream of a further fluid is generated self-induced, which then has an arrangement of several outlets 61 is injected into the flow of the first fluid. The multiple outputs 61 the injection device are distributed in the example shown over the entire flow channel width. An oscillation in the plane of the flow direction can be taken into account in order to achieve a better distribution over the height of the channel.

7 shows a schematic representation of a NACH profile 70 , which is used for example in swirl burners. At the post profile 70 are actuator devices 71 . 72 installed to improve the mixture.

The features of the invention disclosed in the foregoing description, the claims and the figures may be of importance both individually and in any combination for the realization of the invention in its various embodiments.

QUOTES INCLUDE IN THE DESCRIPTION

This list of the documents listed by the applicant has been generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Cited non-patent literature

• Holdeman et al., Mixing in a Row of Jets with Confined Crossflow, AIAA Journal, 1977, 15, 243-249 [0003]
• Liscinsky et al., Experimental Investigation of Crossflow Jet Mixing in a Rectangular Duct, AIAA Paper 93-20037, 1.993 [0003]
• Liscinsky et al., Crossflow Mixing of Noncircular jets, AIAA Paper 95-0732, 1995 [0003]
• Johari et al., Penetration and mixing of fully modulated turbulent jets in crossflow, AIAA Journal, American Institute of Aeronautics and Astronautics, 1999, 37, 842-850 [0004]
• Eroglu et al., Structure, penetration, and mixing of pulsed jets in crossflow, AIAA journal, 2001, 39, 417-423 [0004]
• Shakouchi, Jet and Wake Flow Control and their Practical Application, Int. Conf. on Jets, Wakes and Separated Flows, 2008 [0032]

Claims (10)

A method of mixing two fluids, the method comprising the steps of: - forming a flow of a fluid along a flow channel ( 1 ), - providing a pulsating / oscillating injection stream of a further fluid, by passing the further fluid through a cavity structure of a passive microfluidic actuator device ( 2 ) whose output via an injection device to the flow channel ( 1 ) and is configured to self-induce the pulsating / oscillating injection stream at a pulsating / oscillating frequency, and - mixing the fluid and the further fluid by transducing the pulsing / oscillating injection stream of the further fluid into the stream of fluid across the injector to the flow direction of the fluid in the flow channel ( 1 ) is introduced. Method according to claim 1, characterized in that the fluid in the flow channel ( 1 ) a flow channel element ( 3 ) flows around, on which the injection device is formed. The method of claim 1 or 2, characterized in that the further fluid is introduced via an arrangement of a plurality of outlet openings of the injection device in the flow of the fluid, wherein the arrangement of the plurality of outlet openings substantially transversely to the flow direction of the fluid in the flow channel ( 1 ). Method according to at least one of the preceding claims, characterized in that the pulsating / oscillating injection current is generated with a high pulsation / oscillation frequency and introduced into the flow of the fluid, wherein the pulsation / oscillation frequency in air at least about 100 Hz, preferably at least about 250 Hz. Mixing device for mixing two fluids, comprising: - a flow channel ( 1 ), which is configured for a flow of a fluid, - a passive microfluidic actuator device ( 2 ) formed with a cavity structure, wherein the passive microfluidic actuator device is configured to self-induce a pulsating / oscillating injection current of the further fluid having a pulsation / oscillation frequency by means of flowing another fluid through the cavity structure, and 3 ) connected to the output of the passive microfluidic actuator device ( 2 ) and the flow channel ( 1 ) is coupled and configured for mixing the fluid and the further fluid, the pulsating / oscillating injection current of the further fluid into the flow of the fluid transversely to the flow direction of the fluid in the flow channel ( 1 ). Apparatus according to claim 5, characterized in that in the flow channel ( 1 ) a flow channel element ( 3 ) is arranged, which is flowed around by the fluid and on which the injection device ( 3 ) is formed. Apparatus according to claim 6, characterized in that the cavity structure of the passive microfluidic actuator device ( 2 ) at least partially in the flow channel element ( 3 ) is formed. Device according to at least one of claims 5 to 7, characterized in that the passive microfluidic actuator device, the pulsation / oscillation frequency of the pulsating / oscillating injection current in dependence on the flow rate of the further fluid through the passive microfluidic actuator device ( 2 ) passively self-regulating. Device according to at least one of claims 5 to 8, characterized in that the injection device is formed with an arrangement of a plurality of outlet openings, wherein the arrangement of the plurality of outlet openings substantially transversely to the flow direction of the fluid in the flow channel ( 1 ). Use of a method for mixing two fluids according to at least one of claims 1 to 4 and / or a mixing device for mixing two fluids according to at least one of claims 5 to 9 in a device from the following group of devices: gas combustion machine, burner of a gas combustion machine, Chemical industry T-mixer or chemical tube reactor.

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