CN117772435A - Self-excitation jet device for jet mode self-adaptive switching and design method thereof - Google Patents
Self-excitation jet device for jet mode self-adaptive switching and design method thereof Download PDFInfo
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Abstract
The invention discloses a jet mode self-adaptive switching self-excitation jet device and a design method thereof, wherein the device comprises: the air guide port, the mixing cavity and the jet port are sequentially positioned on the central axis of the device to form a main flow path; the utility model discloses a static pressure chamber, including the static pressure chamber, the static pressure chamber is equipped with the static pressure chamber and encircles the feedback loop that the static pressure chamber set up respectively, the static pressure chamber is the hollow structure who forms by the static pressure chamber wall ring, it has the static pressure hole of certain number to open on the static pressure chamber wall, just the flexible membrane is all installed to one side that the static pressure chamber wall is close to the axis, wherein: when the pressure of the air inlet of the device is different, the flexible membrane presents different modes of clinging to or keeping away from the wall of the static pressure cavity, and then a sweeping jet flow or a steady jet flow is generated at the jet port for controlling the flow of fluid.
Description
Technical Field
The invention relates to a jet mode self-adaptive switching self-excitation jet device and a design method thereof, belonging to the technical field of flow control.
Background
Current fluid machines are moving toward high aerodynamic loads, and when the fluid machine load increases significantly beyond the current aerodynamic design level, flow separation phenomena are typically caused by high back pressure gradients or shock-boundary layer interference, causing dramatic drop in fluid machine efficiency and even destabilization. Therefore, researchers at home and abroad are always focusing on flow control technology and corresponding flow control devices capable of inhibiting or even eliminating flow separation. The unsteady flow control technique is an advanced flow control technique that produces unsteady excitations that take advantage of flow instabilities that interact with the proposed structure in the separated flow. Related researches show that the same flow control effect is achieved, and the consumption energy of the unsteady flow control technology can be saved by 1-2 orders of magnitude compared with the corresponding unsteady flow control technology, namely the flow control device has the effect of 'four-two jack pulling'.
The self-exciting jet oscillator can be used as an unsteady flow control device. If the inlet and the outlet of the self-excited jet oscillator are respectively connected with a high-pressure gas source and a low-pressure gas source, the self-excited jet oscillator can rely on flow instability to enable the outlet to generate unsteady jet, and the unsteady jet can be used as unsteady excitation required by unsteady flow control. The self-excited jet oscillator has a simple structure and no movable parts, so that the self-excited jet oscillator has a good application prospect.
However, the current self-excited fluidic oscillators have the problem of adaptability under variable operating conditions as passive unsteady flow control devices. During operation, the self-exciting jet oscillator has high internal flow loss due to the periodical oscillation of fluid in the self-exciting jet oscillator. Taking the self-excitation jet oscillator as an example, the self-excitation jet oscillator is applied to the compressor, in non-design working conditions, particularly near stall working conditions, the compressor blades generate great flow loss due to blade back separation, and at the moment, if the self-excitation jet oscillator is used for unsteady flow control, a good control effect is expected to be generated. Although the flow losses inside the self-exciting fluidic oscillator are high, the losses tend to be much smaller than the gains from suppressing flow separation. However, under the design working condition of the compressor, the blades tend to work at a high efficiency point, no flow separation or less flow separation exists, the flow loss of the blades is low, the necessity of flow control does not exist at the moment, but the self-excited jet oscillator is not actively closed, and higher internal flow loss is generated when the self-excited jet oscillator continues to operate, so that the overall performance of the compressor is reduced. Therefore, the conventional self-excitation jet oscillator is used as a passive flow control mode, has no applicability of changing along with the working condition of a passive object, and influences the engineering practicability.
Disclosure of Invention
The invention aims to overcome the defects in the prior art, and provides a jet mode self-adaptive switching self-excitation jet device and a design method thereof, which can be used for inhibiting flow separation on devices such as fluid machinery, an air inlet and exhaust system and the like and improving flow efficiency.
In order to achieve the above purpose, the invention is realized by adopting the following technical scheme:
in a first aspect, the present invention provides a self-exciting fluidic device for adaptive switching of fluidic modes, comprising: the air guide port, the mixing cavity and the jet port are sequentially positioned on the central axis of the device to form a main flow path; the utility model discloses a static pressure chamber, including the static pressure chamber, the static pressure chamber is equipped with the static pressure chamber and encircles the feedback loop that the static pressure chamber set up respectively, the static pressure chamber is the hollow structure who forms by the static pressure chamber wall ring, it has the static pressure hole of certain number to open on the static pressure chamber wall, just the flexible membrane is all installed to one side that the static pressure chamber wall is close to the axis, wherein:
when the device bleed port is given different bleed port pressures, the flexible membrane assumes different modes of clinging to or moving away from the hydrostatic cavity wall, thereby generating a swept or steady jet at the jet port for flow control of the fluid.
Further, the static pressure cavity is filled with a static pressure P 0 The static pressure P 0 A fixed value, or a pressure value associated with an external flow field controlled by the self-exciting fluidic device.
Further, the static pressure of one side of the flexible film far away from the central axis and the static pressure P in the static pressure cavity 0 Equal.
Further, setting the average static pressure of the near-central axis side of the flexible membrane as P 1 When the given pressure of the air entraining port is higher, P is as follows 1 ≥P u When the flexible membrane is in a state of being tightly attached to the wall of the hydrostatic cavity, the jet port generates a sweeping jet flow with a certain frequency, and when the given pressure of the air inlet is lower, P is caused 1 ≤P s When the flexible membrane is far away from the wall of the static pressure cavity, the jet orifice generates fixed positionA constant jet, wherein: p (P) u For the ejector to be in the minimum flow state of the sweeping jet mode, the average static pressure P of the near-central axis side of the flexible membrane u ；P s The average static pressure of the near central axis side of the corresponding flexible membrane is just when the ejector enters a steady jet mode.
Further, the ejector is in a minimum flow state of a sweeping jet mode, and the average static pressure P of the near-central axis side of the flexible membrane 8 u The calculation formula of (2) is as follows:
P u ≈P 0 +F 0 /R 0
wherein F is 0 For the tension of the flexible film in a state of being clung to the wall of the hydrostatic cavity, R 0 Is the average curvature radius of the pressure cavity wall near the central axis.
Further, the calculation formula of the average static pressure of the near central axis side of the corresponding flexible membrane when the ejector just enters the steady jet mode is as follows:
P s ＝P 0 －F c /R c
wherein R is c When the throat width of the flexible film is equal to h, the curvature radius of the flexible film, F c When the throat width of the flexible film is equal to h, the tension of the flexible film is h, and the h is the throat width of the flexible film corresponding to the mode that the ejector enters the steady jet mode.
In a second aspect, the present invention provides a method for designing a self-exciting fluidic device for adaptive switching of fluidic modes according to any one of the preceding claims, comprising:
calculating the average static pressure P of the near-central axis side of the flexible membrane when the flexible membrane is in a state of being clung to the wall of the static pressure cavity and the ejector is in a state of minimum flow of a swept jet mode u ；
Through P u Calculating the tension F of the flexible film in a state of being clung to the wall of the hydrostatic cavity 0 ；
Calculating average static pressure P of the flexible membrane near the central axis when the flexible membrane is far away from the wall of the static pressure cavity and the ejector just enters a steady jet mode s ；
Through P s Calculating the tension F of the flexible film in a state of being far away from the wall of the hydrostatic cavity c ；
By designing the tension F of a given flexible film in two critical states 0 And F c The self-excitation jet device capable of adaptively switching the jet mode is obtained, and the self-excitation jet device can adaptively switch between a steady jet mode and an unsteady jet mode.
Further, the tension F of the flexible film in a state of being tightly attached to the wall of the hydrostatic cavity is calculated 0 Comprises the following steps:
calculating average curvature radius R of static pressure cavity wall near central axis side from jet ejector geometry 0 ；
Given the outlet static pressure of jet orifice and given the static pressure P in static pressure cavity 0 ；
Calculating the average static pressure P of the near-central axis side of the flexible membrane in a mode of clinging to the wall of the static pressure cavity and in a state of the minimum flow of the ejector in a sweeping jet mode in a numerical simulation mode u ；
Calculating the tension F of the flexible film in a state of being clung to the wall of the hydrostatic cavity 0 The formula is as follows:
F 0 ≈(P u －P 0 )×R 0 。
further, the tension F of the flexible film in a state away from the hydrostatic cavity wall is calculated c Comprises the following steps:
given the outlet static pressure of the jet orifice and given the static pressure in the static pressure cavity as P 0 ；
Determining the width h of the flexible film throat corresponding to the mode of the ejector entering the steady jet flow by a numerical simulation mode;
calculating the curvature radius R of the flexible film when the throat width of the flexible film is equal to h c ；
Through a numerical simulation mode, calculating that the flexible membrane is in a state far away from the static pressure cavity wall, and the average static pressure P of the corresponding flexible membrane near the central axis when the throat width is equal to h s ；
Calculating the tension F when the flexible film is in a state of being far away from the wall of the hydrostatic cavity and the throat width is equal to h c The formula is as follows:
F c ＝(P 0 －P s )×R c 。
further, the design method further comprises:
obtaining the corresponding inlet total pressure P when the ejector just enters a steady jet mode and the width of the flexible film throat is equal to h is * And the corresponding inlet total pressure P of the ejector in the minimum flow state of the sweeping jet mode iu *；
When the total pressure P of the inlet of the jet device i * Satisfy P i *<P is * When the ejector enters a steady jet mode;
when the total pressure P of the inlet of the jet device i * Satisfy P iu *<P i * At this time, the ejector enters an unsteady sweep jet mode.
Compared with the prior art, the invention has the beneficial effects that:
the invention provides a jet mode self-adaptive switching self-excitation jet device and a design method thereof, which can adaptively adjust jet modes according to different air-entraining port pressures, thereby solving the problem of low or even negative benefit of split flow control of the existing self-excitation jet device under a variable working condition state and having stronger engineering practicability.
Drawings
FIG. 1 is a schematic diagram of a self-exciting fluidic device with adaptive switching of fluidic modes according to an embodiment of the present invention;
FIG. 2 is a schematic illustration of an apparatus provided by an embodiment of the present invention in a swept jet mode;
FIG. 3 is a schematic view of an apparatus according to an embodiment of the present invention in a steady jet mode.
In the figure: 1. an air inlet; 2. a mixing chamber; 3. a feedback loop; 4. a jet port; 5. a static pressure cavity; 6. a static pressure cavity wall; 7. a static pressure hole; 8. a flexible film.
Detailed Description
The invention is further described below with reference to the accompanying drawings. The following examples are only for more clearly illustrating the technical aspects of the present invention, and are not intended to limit the scope of the present invention.
In the description of the present invention, it should be understood that the terms "center", "longitudinal", "lateral", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", etc. indicate orientations or positional relationships based on the orientations or positional relationships shown in the drawings, are merely for convenience in describing the present invention and simplifying the description, and do not indicate or imply that the devices or elements referred to must have a specific orientation, be configured and operated in a specific orientation, and thus should not be construed as limiting the present invention. Furthermore, the terms "first," "second," and the like, are used for descriptive purposes only and are not to be construed as indicating or implying a relative importance or implicitly indicating the number of technical features indicated. Thus, a feature defining "a first", "a second", etc. may explicitly or implicitly include one or more such feature. In the description of the present invention, unless otherwise indicated, the meaning of "a plurality" is two or more.
In the description of the present invention, it should be noted that, unless explicitly specified and limited otherwise, the terms "mounted," "connected," and "connected" are to be construed broadly, and may be either fixedly connected, detachably connected, or integrally connected, for example; can be mechanically or electrically connected; can be directly connected or indirectly connected through an intermediate medium, and can be communication between two elements. The specific meaning of the above terms in the present invention can be understood by those of ordinary skill in the art in a specific case.
Example 1
The embodiment introduces a jet mode self-adaptive switching self-excitation jet device, which comprises: an air inlet 1, a mixing cavity 2 and a jet orifice 4 which are sequentially positioned on the central axis of the device form a main flow path; the utility model discloses a static pressure chamber, including mixing chamber, static pressure chamber wall, flexible membrane 8 is all installed to the feedback return circuit 3 that is equipped with static pressure chamber 5 and encircles static pressure chamber 5 setting respectively to the mixing chamber both sides, static pressure chamber 5 is by static pressure chamber wall 6 encircle the hollow structure that forms, it has static pressure hole 7 of certain number to open on the static pressure chamber wall 6, just static pressure chamber wall 6 is close to one side of axis all installs flexible membrane 8, wherein:
when the device bleed port 1 is given different bleed port pressures, the flexible membrane 8 assumes different modes against or away from the hydrostatic chamber wall 6, thereby creating a swept or steady jet at the jet port for flow control of the fluid.
The static pressure cavity 5 is filled with a static pressure P 0 The static pressure P 0 A fixed value, or a pressure value associated with an external flow field controlled by the self-exciting fluidic device.
Static pressure on one side of the flexible membrane 8 far away from the central axis and static pressure P in the static pressure cavity 5 0 Equal. Setting the average static pressure of the near central axis side of the flexible membrane 8 as P 1 When the given pressure of the air inlet 1 is high, P is made to be 1 ≥P u At this time, the flexible membrane 8 is in a state of being tightly attached to the hydrostatic cavity wall 6, the jet orifice 4 generates a sweeping jet with a certain frequency, and when the given pressure of the air introducing port 1 is lower, the pressure P is caused to be 1 ≤P s At this time, the flexible membrane 8 is in a state of being far away from the hydrostatic cavity wall 6, and the jet orifice 4 generates a steady jet, wherein: p (P) u For the jet device to be in the minimum flow state of the sweeping jet mode, the average static pressure P of the near-central axis side of the flexible membrane 8 u ；P s The average static pressure of the corresponding flexible membrane 8 near the central axis when the ejector just enters the steady jet mode is obtained. Wherein:
the ejector is in a minimum flow state of a sweeping jet mode, and the average static pressure P of the near-central axis side of the flexible membrane 8 u The calculation formula of (2) is as follows:
P u ≈P 0 +F 0 /R 0
wherein F is 0 For the tension of the flexible membrane 8 in a state of being tightly attached to the hydrostatic cavity wall 6, R 0 Is the average curvature radius of the pressure cavity wall 6 near the central axis.
The calculation formula of the average static pressure of the near central axis side of the corresponding flexible membrane 8 when the ejector just enters the steady jet mode is as follows:
P s ＝P 0 －F c /R c
wherein R is c When the throat width of the flexible film 8 is equal to h, the curvature radius of the flexible film 8, F c When the throat width of the flexible film 8 is equal to h, the flexible film is stretchedAnd h is the throat width of the flexible membrane 8 corresponding to the fact that the ejector enters a steady jet mode.
The technical principle of the invention is as follows: when the given pressure of the air introducing port 1 is higher, the flexible membrane 8 is in a state of being clung to the wall of the static pressure cavity under the action of the pressure difference on two sides of the flexible membrane, as shown in fig. 2, the inlet air flow is clung to one of the left wall surface or the right wall surface of the mixing cavity 2 due to the coanda effect, the air flow alternately flows along different paths at a certain frequency due to the action of the feedback loop 3, an unsteady sweeping jet, namely a conventional feedback type self-excited jet ejector principle is formed at the jet port 4, and the flow loss in the jet ejector is higher due to the action of fluid oscillation. When the given pressure of the air-introducing port 1 is low, the flexible membrane 8 is in a state away from the wall of the static pressure cavity under the action of the pressure difference on two sides of the flexible membrane, as shown in fig. 3, the fluid in the mixing cavity cannot be alternately selected between the two side wall surfaces through the coanda effect, the jet port generates steady jet flow, and at the moment, the flow loss in the jet device is low due to no fluid oscillation action. In summary, the self-excitation ejector can switch between a high-loss and sweeping jet mode and a low-loss and steady jet mode according to different input pressures, so that the self-excitation ejector can adapt to different flow conditions of a controlled object.
The invention has the beneficial effects that: the invention relates to a jet mode self-adaptive switching self-excitation jet device, which can adaptively adjust jet modes according to different air-entraining port pressures, thereby solving the problems of low and even negative gains of separation flow control under variable working conditions of the existing self-excitation jet device and having stronger engineering practicability.
The description of the above embodiment will be made with reference to a preferred embodiment.
As shown in fig. 1, a jet mode self-adaptive switching self-excitation jet device comprises a gas guiding port 1, a mixing cavity 2, a feedback loop 3, a jet port 4, a static pressure cavity 5, a static pressure cavity wall 6, a static pressure hole 7 and a flexible membrane 8. The bleed port 1, the mixing cavity 2, the feedback loop 3 and the jet port 4 are components of a conventional self-excited jet oscillator with the feedback loop, and can be scaled based on the geometry of the self-excited jet oscillator with the feedback loop according to the flow control required sweep jet flow and frequency of a controlled object (such as a compressor).
As shown in FIG. 1, the hydrostatic cavity 5 is a hollow structure formed by encircling the hydrostatic cavity wall 6, and a certain number of hydrostatic holes 7 are formed in the hydrostatic cavity wall 6, and the size and the number of the hydrostatic holes 7 are optimized to ensure the hydrostatic pressure on the far central axis side of the flexible membrane 8 and the hydrostatic pressure P in the hydrostatic cavity 5 0 Can be quickly consistent and ensure that the flexible membrane 8 does not enter the hydrostatic chamber 5. Static pressure P 0 Static pressure P can be induced in association with an external flow field controlled by the self-exciting jet means, e.g. by bleed air 0 Equal to the outlet static pressure of jet port 4 (i.e. jet outlet back pressure).
As shown in FIG. 2, the mean radius of curvature R of the hydrostatic chamber wall 6 on the near-central axis side is calculated from the ejector geometry 0 . The static pressure at the outlet of a given jet orifice 4 and the static pressure in a static pressure cavity 5 are fixed values P in a numerical simulation mode 0 The flexible membrane 8 is calculated to be in a mode of clinging to the hydrostatic cavity wall 6, and the ejector is in a minimum flow state of a swept jet mode (corresponding to the total inlet pressure of P iu * ) Mean static pressure P of flexible membrane 8 near central axis side u . Thereby, the tension F of the flexible film 8 is obtained 0 (against the hydrostatic chamber wall) satisfies: f (F) 0 ≈(P u －P 0 )×R 0 。
As shown in FIG. 3, the throat width h of the flexible membrane 8 corresponding to the mode of the ejector entering the steady jet flow is determined by a numerical simulation mode, and the average static pressure P of the flexible membrane 8 near the central axis side at the moment is calculated s Radius of curvature R of flexible film 8 c Total pressure P of jet inlet is * . Thereby obtaining the tension F of the flexible film c (flexible film throat width h) satisfies: f (F) c ≈(P 0 －P s )×R c 。
By the above steps, the tension F of a given flexible film in two critical states is designed 0 (against the hydrostatic chamber wall) and F c The self-excitation jet device with the jet mode self-adaptive switching can be obtained by the flexible membrane throat width being h, and the device can be self-adaptively used in a steady jet mode and an unsteady jet modeSwitching between modes. Specifically, when the ejector inlet total pressure P i * Satisfy P i *<P is * When the ejector enters a steady jet mode (the flow loss in the ejector is lower), the ejector is suitable for a flow field with low loss and good flow state (such as a design point of a gas compressor); while when the total pressure P of the inlet of the jet device iu *<P i * When the ejector enters an unsteady sweep jet mode (the flow loss in the ejector is higher), the ejector is suitable for acting on a flow field with high loss and poor flow state (such as a near stall point of a compressor).
Example 2
The present embodiment provides a method for designing a self-excited fluidic device for adaptive switching of fluidic modes according to any one of embodiment 1, comprising:
calculating the average static pressure P of the near-central axis side of the flexible membrane when the flexible membrane is in a state of being clung to the wall of the static pressure cavity and the ejector is in a state of minimum flow of a swept jet mode u ；
Through P u Calculating the tension F of the flexible film in a state of being clung to the wall of the hydrostatic cavity 0 ；
Calculating average static pressure P of the flexible membrane near the central axis when the flexible membrane is far away from the wall of the static pressure cavity and the ejector just enters a steady jet mode s ；
Through P s Calculating the tension F of the flexible film in a state of being far away from the wall of the hydrostatic cavity c ；
By designing the tension F of a given flexible film in two critical states 0 And F c The self-excitation jet device capable of adaptively switching the jet mode is obtained, and the self-excitation jet device can adaptively switch between a steady jet mode and an unsteady jet mode.
Calculating the tension F of the flexible membrane when the flexible membrane is in a state of clinging to the wall of the hydrostatic cavity 0 Comprises the following steps:
calculating average curvature radius R of static pressure cavity wall near central axis side from jet ejector geometry 0 ；
Given the outlet static pressure of jet orifice and given the static pressure P in static pressure cavity 0 ；
By numerical valueIn a simulation mode, calculating the average static pressure P of the near-central axis side of the flexible membrane under the condition that the flexible membrane is in a mode of clinging to the wall of the static pressure cavity and the ejector is in a minimum flow state of a sweeping jet mode u ；
Calculating the tension F of the flexible film in a state of being clung to the wall of the hydrostatic cavity 0 The formula is as follows:
F 0 ≈(P u －P 0 )×R 0 。
further, the tension F of the flexible film in a state away from the hydrostatic cavity wall is calculated c Comprises the following steps:
given the outlet static pressure of the jet orifice and given the static pressure in the static pressure cavity as P 0 ；
Determining the width h of the flexible film throat corresponding to the mode of the ejector entering the steady jet flow by a numerical simulation mode;
calculating the curvature radius R of the flexible film when the throat width of the flexible film is equal to h c ；
Through a numerical simulation mode, calculating that the flexible membrane is in a state far away from the static pressure cavity wall, and the average static pressure P of the corresponding flexible membrane near the central axis when the throat width is equal to h s ；
Calculating the tension F when the flexible film is in a state of being far away from the wall of the hydrostatic cavity and the throat width is equal to h c The formula is as follows:
F c ＝(P 0 －P s )×R c 。
the design method further comprises the following steps:
obtaining the corresponding inlet total pressure P when the ejector just enters a steady jet mode and the width of the flexible film throat is equal to h is * And the corresponding inlet total pressure P of the ejector in the minimum flow state of the sweeping jet mode iu *；
When the total pressure P of the inlet of the jet device i * Satisfy P i *<P is * When the ejector enters a steady jet mode;
when the total pressure P of the inlet of the jet device i * Satisfy P iu *<P i * At this time, the ejector enters an unsteady sweep jet mode.
The foregoing is merely a preferred embodiment of the present invention, and it should be noted that modifications and variations could be made by those skilled in the art without departing from the technical principles of the present invention, and such modifications and variations should also be regarded as being within the scope of the invention.
Claims (10)
1. A self-exciting fluidic device for adaptively switching fluidic modes, comprising: the air-entraining port (1), the mixing cavity (2) and the jet port (4) are sequentially positioned on the central axis of the device to form a main flow path; the utility model provides a static pressure chamber, including mixing chamber, static pressure chamber (5) and feedback return circuit (3) that encircle static pressure chamber (5) set up are equipped with respectively to the mixing chamber both sides, static pressure chamber (5) are by static pressure chamber wall (6) encircle the hollow structure that forms, it has static pressure hole (7) of certain number to open on static pressure chamber wall (6), just static pressure chamber wall (6) all installs flexible membrane (8) near one side of axis, wherein:
when the device bleed port (1) is given different bleed port pressures, the flexible membrane (8) assumes different modes of clinging to or moving away from the hydrostatic cavity wall (6), thereby generating a swept or steady jet at the jet port for flow control of the fluid.
2. A jet mode self-adaptive switching self-exciting jet device according to claim 1, characterized in that the hydrostatic cavity (5) is filled with a static pressure P 0 The static pressure P 0 A fixed value, or a pressure value associated with an external flow field controlled by the self-exciting fluidic device.
3. A jet mode self-adaptive switching self-excitation jet device according to claim 2, wherein the static pressure of the side of the flexible membrane 8 away from the central axis and the static pressure P in the static pressure cavity 5 0 Equal.
4. A self-exciting jet device for jet mode self-adaptive switching according to claim 3, characterized in that the mean static pressure of the near-central axis side of the flexible membrane (8) is set to P 1 When the given pressure of the bleed air port (1) is high, P is caused to be 1 ≥P u At this time, the flexible membrane (8) is in a state of being tightly attached to the hydrostatic cavity wall (6), the jet orifice (4) generates a sweeping jet flow with a certain frequency, and when the given pressure of the air introducing orifice (1) is lower, P is caused 1 ≤P s At this time, the flexible membrane (8) is in a state of being far away from the hydrostatic cavity wall (6), and the jet orifice (4) generates a steady jet flow, wherein: p (P) u For the jet device to be in the minimum flow state of the sweeping jet mode, the average static pressure P of the near-central axis side of the flexible membrane (8) u ；P s The average static pressure of the corresponding flexible membrane (8) near the central axis when the ejector just enters a steady jet mode.
5. A self-exciting fluidic device with adaptive switching of fluidic modes according to claim 4, characterized in that the fluidic device is in a state of minimum flow in swept fluidic mode, the mean static pressure P of the flexible membrane (8) near the central axis u The calculation formula of (2) is as follows:
P u ≈P 0 +F 0 /R 0
wherein F is 0 Is the tension of the flexible film (8) in a state of clinging to the hydrostatic cavity wall (6), R 0 Is the average curvature radius of the pressure cavity wall (6) near the central axis.
6. The jet mode self-adaptive switching self-excitation jet device according to claim 4, wherein the calculation formula of the average static pressure of the near-central axis side of the corresponding flexible membrane (8) when the jet device just enters the steady jet mode is as follows:
P s ＝P 0 －F c /R c
wherein R is c When the throat width of the flexible film (8) is equal to h, the curvature radius F of the flexible film (8) c When the throat width of the flexible film (8) is equal to h, the tension of the flexible film, and h is the throat width of the flexible film (8) corresponding to the fact that the ejector just enters a steady jet mode.
7. A method of designing a self-exciting fluidic device for adaptive switching of fluidic modes according to any one of claims 1 to 6, comprising:
calculating the average static pressure P of the near-central axis side of the flexible membrane (8) under the state that the flexible membrane (8) is tightly attached to the static pressure cavity wall (6) and the ejector is in the minimum flow state of the sweeping jet mode u ；
Through P u Calculating the tension F of the flexible film (8) in a state of being clung to the hydrostatic cavity wall (6) 0 ；
Calculating the average static pressure P of the near central axis side of the corresponding flexible membrane (8) when the flexible membrane (8) is far away from the static pressure cavity wall (6) and the ejector just enters a steady jet mode s ；
Through P s Calculating the tension F of the flexible membrane (8) in a state away from the hydrostatic chamber wall (6) c ；
By designing the tension F of a given flexible film in two critical states 0 And F c The self-excitation jet device capable of adaptively switching the jet mode is obtained, and the self-excitation jet device can adaptively switch between a steady jet mode and an unsteady jet mode.
8. The method for designing a self-excited fluidic device with adaptive switching of fluidic modes according to claim 7, wherein the calculation of the tension force F of the flexible membrane (8) in a state of being in close proximity to the hydrostatic chamber wall (6) 0 Comprises the following steps:
calculating average curvature radius R of static pressure cavity wall (6) near central axis side by ejector geometry 0 ；
Given the outlet static pressure of jet orifice (4) and given the static pressure P in static pressure cavity (5) 0 ；
By means of numerical simulation, calculating the average static pressure P of the near-central axis side of the flexible membrane (8) under the condition that the flexible membrane (8) is in a mode of clinging to the static pressure cavity wall (6) and the ejector is in a minimum flow state of a sweeping jet mode u ；
Calculating the tension F of the flexible film (8) in a state of being clung to the hydrostatic cavity wall (6) 0 The formula is as follows:
F 0 ≈(P u －P 0 )×R 0 。
9. according to claim 7The design method of the self-excitation jet device for adaptively switching the jet mode is characterized in that the tension F of the flexible film (8) in a state of being far away from the static pressure cavity wall (6) is calculated c Comprises the following steps:
given the outlet static pressure of the jet orifice (4) and given the static pressure in the static pressure cavity (5) as P 0 ；
Determining the throat width h of the flexible membrane (8) corresponding to the mode of the ejector entering the steady jet flow through a numerical simulation mode;
calculating the curvature radius R of the flexible film (8) when the throat width of the flexible film (8) is equal to h c ；
Through a numerical simulation mode, calculating that the flexible membrane (8) is far away from the static pressure cavity wall (6), and the average static pressure P of the corresponding flexible membrane (8) near the central axis when the throat width is equal to h s ；
Calculating the tension F when the flexible film (8) is far away from the hydrostatic cavity wall (6) and the throat width is equal to h c The formula is as follows:
F c ＝(P 0 －P s )×R c 。
10. the method of designing a self-exciting fluidic device for adaptive switching of fluidic modes according to claim 7, further comprising:
obtaining the corresponding inlet total pressure P when the ejector just enters a steady jet mode and the width of the flexible film throat is equal to h is * And the corresponding inlet total pressure P of the ejector in the minimum flow state of the sweeping jet mode iu *；
When the total pressure P of the inlet of the jet device i * Satisfy P i *<P is * When the ejector enters a steady jet mode;
when the total pressure P of the inlet of the jet device i * Satisfy P iu *<P i * At this time, the ejector enters an unsteady sweep jet mode.
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