A turbine flowmeter

Abstract

The application provides a turbine flowmeter, which comprises a main body, a rotating shaft, a first turbine and a second turbine; an accommodating cavity is formed in the main body; the rotating shaft is located in the accommodating cavity and rotationally connected with the main body; the first turbine and the second turbine are arranged on the rotating shaft respectively, and a preset distance is provided between the first turbine and the second turbine; when fluid flows in the accommodating cavity and sequentially flows through the first turbine and the second turbine, the rotating direction of the first turbine and the rotating direction of the second turbine are the same. The application has the technical effect that the design is reasonable, the viscous resistance loss of the fluid is effectively reduced, and the measurement accuracy is improved.

Description

Technical Field

[0001] This invention belongs to the field of flow measurement technology, and specifically relates to a turbine flow meter. Background Technology

[0002] A turbine flow meter is a commonly used flow measurement instrument. It measures the volumetric flow rate of a fluid by utilizing the relationship between the rotational speed of the turbine and the fluid velocity. In other words, the turbine flow meter uses the relationship between the turbine's rotational speed and the fluid velocity to measure the volumetric flow rate. A sensor converts the rotational speed signal into an electrical signal, which is then processed and displayed by an electronic instrument. Turbine flow meters are widely used in industrial fields due to their advantages such as wide measurement range, high accuracy, and simple structure.

[0003] Existing turbine flow meters handle fluids with both high and low flow rates. At low flow rates, the poor accuracy of the turbine flow meter is partly due to losses caused by fluid viscosity (i.e., viscous resistance loss). Furthermore, as the fluid flow rate decreases, the viscous resistance loss increases exponentially due to the low Reynolds number effect. Therefore, how to compensate for the viscous resistance loss of turbine flow meters has become a pressing technical problem to be solved. Summary of the Invention

[0004] The present invention aims to solve at least one of the technical problems existing in the prior art and provide a new technical solution for turbine flow meters.

[0005] According to one aspect of the present invention, a turbine flow meter is provided, comprising:

[0006] The main body, the interior of which forms a receiving cavity;

[0007] A rotating shaft is located within the receiving cavity and is rotatably connected to the main body;

[0008] A first turbine and a second turbine are respectively disposed on the rotating shaft, and there is a preset distance between the first turbine and the second turbine;

[0009] The fluid velocity, the first turbine speed, and the second turbine speed satisfy the following formula:

[0010]

[0011] In the above formula: Q is the fluid velocity; R is the blade radius of the first turbine or the blade radius of the second turbine; A is the cross-sectional area of ​​the fluid flowing within the containment cavity; β is the relative fluid velocity angle with the axial direction; ω Ι ω is the rotational speed of the first turbine; II' This refers to the rotational speed of the second turbine.

[0012] When fluid flows within the containment cavity and sequentially passes through the first turbine and the second turbine, the rotation direction of the first turbine and the rotation direction of the second turbine are the same.

[0013] Optionally, the flow direction of the fluid within the receiving cavity forms a first preset angle with the blades of the first turbine and a second preset angle with the blades of the second turbine, wherein the first preset angle and the second preset angle are the same.

[0014] Optionally, the first turbine includes a plurality of first blades spaced apart circumferentially; the second turbine includes a plurality of second blades spaced apart circumferentially.

[0015] The exit metal angle of the first blade is the same as that of the second blade.

[0016] Optionally, the number of the first blades and the number of the second blades are different.

[0017] Optionally, the number of the first blades and the number of the second blades differ by 1.

[0018] Optionally, the relative speeds between the first turbine and the second turbine are the same.

[0019] Optionally, the first turbine and the second turbine have the same geometry.

[0020] Optionally, the flow angle of the fluid is the same as the outlet metal angle of the first blade or the outlet metal angle of the second blade.

[0021] Optionally, when fluid flows within the containment cavity and sequentially passes through the first turbine and the second turbine, the first blades and the second blades are staggered.

[0022] One technical advantage of this invention is that:

[0023] In this embodiment, the first turbine and the second turbine are respectively disposed on the rotating shaft, and there is a preset distance between the first turbine and the second turbine. Moreover, when the fluid flows in the receiving cavity and flows through the first turbine and the second turbine in sequence, the rotation direction of the first turbine is the same as that of the second turbine.

[0024] Therefore, since the rotation directions of the first and second turbines are the same, and the fluid velocity, the first turbine speed, and the second turbine speed satisfy a corresponding relationship, the turbine flow meter exhibits lower parasitic losses, thus improving measurement accuracy. Simultaneously, the flow rate flowing into the second turbine is very similar to the flow rate flowing out of the first turbine, with a small angle of attack, avoiding large losses associated with fluid flow separation and reducing viscous resistance losses, thereby lowering overall losses and contributing to further improved accuracy. Attached Figure Description

[0025] Figure 1 This is a schematic diagram of the structure of an existing single-turbine turbine flow meter;

[0026] Figure 2 This is a cross-sectional schematic diagram of an existing turbine flow meter with a single turbine structure.

[0027] Figure 3 A schematic diagram of the velocity triangle of an existing turbine flow meter with a single turbine structure;

[0028] Figure 4 A schematic diagram of an existing turbine flow meter with a dual-turbine structure;

[0029] Figure 5 A schematic diagram of the velocity triangle of an existing turbine flow meter with a dual-turbine structure;

[0030] Figure 6 This is a schematic diagram of the structure of a turbine flow meter according to an embodiment of the present invention;

[0031] Figure 7 This is a schematic diagram of the velocity triangle of a turbine flow meter according to an embodiment of the present invention;

[0032] Figure 8 This is a cross-sectional schematic diagram of a turbine flow meter with a dual-turbine structure.

[0033] Figure 9 A schematic diagram of the velocity triangle at BB for an existing turbine flow meter with a dual-turbine structure;

[0034] Figure 10 This is a schematic diagram of the velocity triangle at BB of a turbine flow meter according to an embodiment of the present invention.

[0035] In the diagram: 1. Main body; 101. Receiving cavity; 2. Rotating shaft; 31. First turbine; 32. Second turbine; 33. Third turbine. Detailed Implementation

[0036] Various exemplary embodiments of the present application will now be described in detail with reference to the accompanying drawings. It should be noted that, unless otherwise specifically stated, the relative arrangement, numerical expressions, and values ​​of the components and steps set forth in these embodiments do not limit the scope of the present application.

[0037] The embodiments of this application will now be described in detail. Examples of these embodiments are illustrated in the accompanying drawings, wherein the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain this application, and should not be construed as limiting this application. All other embodiments obtained by those skilled in the art based on the embodiments of this application without inventive effort are within the scope of protection of this application.

[0038] The terms "first" and "second" in the specification and claims of this application may explicitly or implicitly include one or more of the features. In the description of this application, unless otherwise stated, "multiple" means two or more. Furthermore, "and / or" in the specification and claims indicates at least one of the connected objects, and the character " / " generally indicates that the preceding and following objects are in an "or" relationship.

[0039] In the description of this application, it should be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "clockwise", "counterclockwise", "axial", "radial", "circumferential", etc., indicating the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, are only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of this application.

[0040] In the description of this application, it should be noted that, unless otherwise expressly specified and limited, the terms "installation," "connection," and "linking" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection between two components. Those skilled in the art can understand the specific meaning of the above terms in this application based on the specific circumstances.

[0041] According to one aspect of the invention, see Figure 6 , Figure 7 and Figure 10 A turbine flow meter is provided for measuring the flow rate of fluids with high accuracy.

[0042] Specifically, the turbine flow meter includes:

[0043] Body 1, the interior of which forms a receiving cavity 101;

[0044] A rotating shaft 2 is located within the receiving cavity 101 and is rotatably connected to the main body 1.

[0045] A first turbine 31 and a second turbine 32 are respectively disposed on the rotating shaft 2, and there is a preset distance between the first turbine 31 and the second turbine 32;

[0046] The fluid velocity, the first turbine speed, and the second turbine speed satisfy the following formula:

[0047]

[0048] In the above formula: Q is the fluid velocity; R is the blade radius of the first turbine or the blade radius of the second turbine; A is the cross-sectional area of ​​the fluid flowing within the containment cavity; β is the relative fluid velocity angle with the axial direction; ω Ι ω is the rotational speed of the first turbine; II' This refers to the rotational speed of the second turbine.

[0049] When fluid flows within the containment cavity 101 and sequentially passes through the first turbine 31 and the second turbine 32, the rotation direction of the first turbine 31 and the rotation direction of the second turbine 32 are the same.

[0050] In this embodiment, the first turbine and the second turbine are respectively disposed on the rotating shaft, and there is a preset distance between the first turbine and the second turbine. Moreover, when the fluid flows in the receiving cavity and flows through the first turbine and the second turbine in sequence, the rotation direction of the first turbine is the same as that of the second turbine.

[0051] Therefore, since the rotation directions of the first and second turbines are the same, and the fluid velocity, the first turbine speed, and the second turbine speed satisfy the corresponding relationship (i.e., the formula mentioned above), the turbine flow meter has lower parasitic losses, thus improving measurement accuracy. Simultaneously, the flow rate flowing into the second turbine is very similar to the flow rate flowing out of the first turbine, with a small angle of attack, avoiding large losses associated with fluid flow separation and reducing viscous resistance losses, thereby lowering overall losses and further improving accuracy.

[0052] Optionally, the flow direction of the fluid in the receiving cavity 101 forms a first preset angle with the blades of the first turbine 31 and a second preset angle with the blades of the second turbine 32, wherein the first preset angle and the second preset angle are the same.

[0053] In the above embodiments, since the first preset angle and the second preset angle are the same, this helps to ensure that the first turbine and the second turbine have basically the same losses, so that the flow rate flowing into the second turbine blade is very similar to the flow rate flowing out of the first turbine blade, and the angle of attack is very small, thus avoiding large losses related to flow separation.

[0054] Optionally, the first turbine 31 includes a plurality of first blades spaced apart along the circumferential direction; the second turbine 32 includes a plurality of second blades spaced apart along the circumferential direction.

[0055] The exit metal angle of the first blade is the same as that of the second blade.

[0056] In the above embodiment, the outlet metal angle is the fluid flow direction relative to the turbine blade. It typically deviates from the metal angle, depending on the airfoil lift and viscous losses. This deviation is called the deviation angle in turbomachinery and is usually very small. The outlet metal angles of the first blade and the second blade are the same, which helps to further ensure that the first turbine and the second turbine have essentially the same losses.

[0057] Optionally, the number of the first blades and the number of the second blades are different.

[0058] When both rotors (i.e., the first turbine and the second turbine) rotate in the same direction, the blades of the downstream rotor (second turbine) may be submerged in the wake of the blades of the upstream rotor (first turbine), which will affect the speed of the second turbine's rotor. This resonance may cause intermittent acceleration and deceleration of the downstream rotor, leading to measurement errors. Having different numbers of first and second blades effectively avoids this situation, ensuring the effectiveness of the turbine flowmeter with a dual-turbine structure rotating in the same direction and preventing measurement errors.

[0059] Optionally, the number of the first blades and the number of the second blades differ by 1. This effectively prevents the downstream rotor (second turbine) blades from being submerged in the wake of the upstream rotor (first turbine) blades, thus ensuring the rotor speed of the second turbine.

[0060] Optionally, the relative speeds between the first turbine 31 and the second turbine 32 are the same. This can better reduce the wear and tear on the first and second turbines and better ensure measurement accuracy.

[0061] Optionally, the first turbine 31 and the second turbine 32 have the same geometry. This can better ensure that the losses of the first turbine and the second turbine are the same, which helps to reduce the loss of fluid flowing through the first turbine and the second turbine.

[0062] Optionally, the fluid flow angle is the same as the outlet metal angle of the first blade or the outlet metal angle of the second blade. This helps to ensure that the first turbine and the second turbine have essentially the same losses.

[0063] Optionally, when fluid flows within the containment cavity and sequentially passes through the first turbine 31 and the second turbine 32, the first blades and the second blades are staggered.

[0064] In the above embodiments, it is possible to effectively prevent the downstream rotor (second turbine) blades from being submerged in the wake of the upstream rotor (first turbine) blades, thus ensuring the speed of the second turbine rotor and reducing measurement errors.

[0065] It should be noted that existing turbine flow meters with a single turbine structure, see [link to relevant documentation]. Figures 1 to 3 And existing turbine flow meters with dual-turbine structures, see Figure 4 , Figure 5 as well as Figure 9 Both are widely used, but the latter is more accurate, has a more complex structure, and therefore costs more. Existing turbine flow meters with a single turbine structure typically have a high / low flow ratio of around 10, while existing turbine flow meters with a dual turbine structure typically have a high / low flow ratio of around 100, offering a wider measurement range.

[0066] In this application, the velocity triangles of existing turbine flow meters with single turbine structures, existing turbine flow meters with dual turbine structures, and the turbine flow meter provided in the embodiments of this application are analyzed to understand why the turbine flow meter provided in the embodiments of this application has higher accuracy.

[0067] In the following analysis, we use the methods and notation accepted in the field of turbomachinery, and use the concept of the velocity triangle to describe the relationship between the turbine rotor and the volumetric flow rate. Here, we colloquially refer to the turbine as the rotor, blade, or cascade commonly found in turbine literature.

[0068] Flow velocity includes both the absolute flow velocity seen in a fixed reference frame and the relative flow velocity seen from the turbine blades. It is the relative speed that drives the turbine's motion. All variables in this analysis are based on standard SI units. The letters in the following formulas are annotated as follows:

[0069] ω: Turbine speed;

[0070] R: The radius of the blade measured from the center of rotation;

[0071] T: Torque exerted by the fluid medium on the turbine cascade;

[0072] The work done by the turbine on the fluid flow per unit mass flow rate;

[0073] V: Fluid velocity in the absolute coordinate system;

[0074] V x : The axial component of V, using the subscript x;

[0075] V t The tangential component of V, using the subscript t;

[0076] W: Flow velocity relative to the turbine cascade;

[0077] U: Tangential wheel speed, equal to radius R multiplied by rotational speed w;

[0078] α: Absolute fluid velocity angle relative to the axial direction;

[0079] β: The relative fluid velocity angle between the fluid and the axial direction;

[0080] 1: Represents a flow station that is a single or first turbine cascade inlet;

[0081] 2: A flow station representing a single or first turbine cascade outlet;

[0082] 3: Represents the flow station at the inlet of the second counter-rotating turbine cascade;

[0083] 4: Represents the flow station at the outlet of the second counter-rotating turbine cascade;

[0084] 3': Represents the flow station at the inlet of the second cascaded turbines rotating in the same direction;

[0085] 4': Represents the flow station at the outlet of the second cascaded turbines rotating in the same direction.

[0086] For existing turbine flow meters with a single turbine structure, Figure 2 The cross-section of a single turbine. Figure 3 The velocity triangles are for the upstream and downstream sides of the turbine blade. For simplicity, without losing the generality of the principle, we study the cylindrical plane at height AA in the blade, unfolding it into a two-dimensional plane to obtain the velocity triangles, see [link to relevant documentation]. Figure 4 .

[0087] Using a well-known theorem in turbomachinery, the fluid medium applied to the turbine can be described by the following "Euler turbine" equation:

[0088]

[0089] Assuming the turbine cross-sectional radius is constant in the current model, and that R, the turbine inlet tangential velocity, and the outlet tangential velocity are the same, then:

[0090] U1=U2=ωR (2)

[0091] In the current analysis, the fluid enters the turbine cascade axially, and the absolute tangential velocity component of station 1 is zero. Therefore:

[0092] V 1t =0 (3)

[0093]

[0094] In the above formula, Q is the volumetric flow rate entering the turbine; A is the cross-sectional area of ​​the fluid flowing within the containment cavity.

[0095] For simplicity, without sacrificing the general applicability of the current analysis, we will assume that the flow cross-sectional area A remains constant upon entering and leaving the turbine cascade. Therefore, the axial component of the absolute fluid velocity at the turbine outlet should be equal to the axial component at the turbine outlet, and thus:

[0096]

[0097] The direction of the volumetric flow relative to the turbine blades typically deviates from the metal flow angle, depending on the airfoil lift and viscous losses. This deviation, known as the deviation angle in turbomachinery, is usually small. For simplicity, without losing the generality of the basic principles derived from this analysis, we assume that the flow angle is the same as the metal flow angle at the turbine blade exit. Therefore, V 2x V 2t The following relationship is formed between ω, R, and β:

[0098]

[0099] Combining equations (1) to (6), we get:

[0100]

[0101] For a turbine operating at a stable speed and steady state, the fluid action on the turbine is equal to the resistance encountered by the turbine during rotation. The work exerted by the fluid on the turbine is equal to external losses, including airfoil friction losses, bearing friction, and the rotation of the fluid action surface with the turbine. For a system with absolutely no losses, then:

[0102]

[0103] Then equation 7 becomes:

[0104]

[0105] or,

[0106]

[0107] As can be seen, there is a well-known linear relationship between volumetric flow rate and turbine speed. This is generally true, especially when the flow velocity is high and the Reynolds number is very high.

[0108] In reality, losses are never zero, especially at low Reynolds numbers where they can become substantial at lower flow rates. Over the years, considerable effort has been made to eliminate the effects of these losses, with significant success achieved through methods such as using two counter-rotating turbines to counteract the effects and still using Equation X to achieve greater accuracy.

[0109] Here, we apply the same analysis as above to the counter-rotating dual-rotating turbine flow meter, such as... Figure 4 As shown. Here, the upstream rotor and downstream rotor are respectively turbine I (i.e., the first turbine 31) and II (i.e., the third turbine 33). The velocity triangle is as follows. Figure 5 As shown.

[0110] It should be noted that the formula above applies to turbine I and remains unchanged. For turbine II, note that V 3t and V 4t With different directions or signs, we obtain the following sequence of equations:

[0111]

[0112] U3=U4=ω II R (12)

[0113]

[0114]

[0115] Similarly, assuming that the flow angle of turbine II is the same as the outflow angle of the turbine blades, then V 2x V 2t ω ΙΙ R and β II The following relationship is formed between them:

[0116]

[0117] Combining equations (11) to (15), we get:

[0118]

[0119] We further assume that turbine I and turbine II have the same geometric dimensions, where β I and β II If the blade exit angle β is the same and the losses of the two rotors are basically the same, then:

[0120]

[0121] therefore:

[0122]

[0123]

[0124] As expected, there is the same linear relationship between flow rate and turbine speed, with turbine I and turbine II being mirror images of each other.

[0125] We assume that the losses are finite, but the losses of the first turbine 31 and the third turbine 33 are the same, that is:

[0126]

[0127] Combining formula (7) (for turbine I) and formula (16), then:

[0128]

[0129] Through several algebraic operations, we derived the following relationship between the flow velocity Q and the rotor speed of turbine I and turbine II:

[0130]

[0131] or,

[0132]

[0133] or,

[0134]

[0135] A detailed examination of equations (22), (23), and (24) shows that the correlation between Q and the rotational speed of the second rotor rotating in the opposite direction is better than that of the first rotor, but it is not perfectly linear. Some literature concludes that the reverse ratio cancels out the losses on both rotors, and that Q and ω2 form a perfectly linear relationship. This shows that the conclusion is incorrect.

[0136] In the embodiments of this application, Figure 6 This is a schematic diagram of the structure of a turbine flow meter according to an embodiment of the present invention; Figure 7 This is a schematic diagram of the velocity triangle of a turbine flow meter according to an embodiment of the present invention.

[0137] See Figure 7 The equations are in the following order, where turbine II' represents the second rotor rotating in the same direction (i.e., the second turbine), then:

[0138]

[0139] U 3' =U 4' =ω II' R (26)

[0140]

[0141]

[0142]

[0143] Combining equations (25) to (29), we obtain:

[0144]

[0145] We again assume that turbine I and turbine II' have the same geometric dimensions, where β I and β II If the blade exit angle β (i.e., the exit metal angle) is the same, and the losses of both rotors are zero, then:

[0146]

[0147] Then we get:

[0148]

[0149] We again assume that the losses are finite, but the losses of both rotors are the same, that is:

[0150]

[0151] Combining equations (7) and (30), we get:

[0152]

[0153] Through algebraic simplification, we derive the relationship between flow velocity and turbine speed:

[0154]

[0155] When two turbines rotate in the same direction, the downstream turbine blades may be submerged in the wake of the first rotor blades, affecting the speed of the second rotor. This resonance can cause intermittent acceleration and deceleration of the downstream rotor, leading to measurement errors. To avoid this, turbines I and II' can have different numbers of blades, for example, differing by 1. This ensures that the upstream and downstream turbine blades never perfectly align. For viscous management, the configuration of each turbine can be further optimized by changing the cascade, chord, and chord pitch. The details of this implementation do not affect the intent of the invention and will not be further explored here.

[0156] Co-rotating configurations exhibit lower parasitic losses compared to counter-rotating configurations, thus improving measurement accuracy. Here, we consider the loss mechanism near the blade root or turbine hub, i.e., the BB portion, such as... Figure 8 As shown. For this analysis, Figure 8 A cross-sectional schematic diagram of a turbine flow meter with a dual-turbine structure, which can represent a dual-turbine structure rotating in opposite directions and a dual-turbine structure rotating in the same direction.

[0157] Because the BB segment is very close to the inner rotating hub and immersed in the boundary layer, the axial velocity is very low due to viscous effects. This introduces a higher relative flow angle, β1. This high angle of attack can lead to localized flow separation, introducing turbulent drag and flow blockage. Figure 9 As shown, this effect is particularly pronounced in the counter-rotating turbine II, which is related to the counter-rotating effect, where the relative speed between the two turbines is twice that of a single turbine.

[0158] However, see Figure 10 For a co-rotating configuration, the relative velocities between turbines I and II' are the same. The relative motion is simply the difference in their rotor velocities. Therefore, the flow rate into the blades of turbine II' is very similar to the flow rate out of the blades of turbine I, with a small angle of attack, thus avoiding the large losses associated with flow separation. Further comparison of relative flow velocities W3 and W... 3' This indicates that a higher reverse rotation velocity at the blade inlet also leads to higher losses, with a loss level of 2.

[0159] Our conclusion is that turbine flow meters with a co-rotating dual-turbine structure are more accurate than those with a counter-rotating dual-turbine structure, representing a significant advancement in the state-of-the-art technology in this field.

[0160] It is understood that the above embodiments are merely exemplary implementations used to illustrate the principles of the present invention, and the present invention is not limited thereto. For those skilled in the art, various modifications and improvements can be made without departing from the spirit and essence of the present invention, and these modifications and improvements are also considered to be within the scope of protection of the present invention.

Claims

1. A turbine flow meter, characterized in that, include: The main body, the interior of which forms a receiving cavity; A rotating shaft is located within the receiving cavity and is rotatably connected to the main body; A first turbine and a second turbine are respectively disposed on the rotating shaft, and there is a preset distance between the first turbine and the second turbine; The fluid velocity, the first turbine speed, and the second turbine speed satisfy the following formula: In the above formula: The fluid velocity; The blade radius of the first turbine or the blade radius of the second turbine; This represents the cross-sectional area of ​​the fluid flowing within the cavity; The relative fluid velocity angle between the fluid and the axial direction; This refers to the rotational speed of the first turbine. This refers to the rotational speed of the second turbine. When fluid flows within the containment cavity and sequentially passes through the first turbine and the second turbine, the rotation direction of the first turbine and the rotation direction of the second turbine are the same.

2. The turbine flow meter according to claim 1, characterized in that, The fluid flows within the containment cavity at a first preset angle to the blades of the first turbine and at a second preset angle to the blades of the second turbine, the first preset angle and the second preset angle being the same.

3. The turbine flow meter according to claim 1, characterized in that, The first turbine includes a plurality of first blades spaced apart along the circumferential direction; the second turbine includes a plurality of second blades spaced apart along the circumferential direction. The exit metal angle of the first blade is the same as that of the second blade.

4. The turbine flow meter according to claim 3, characterized in that, The number of the first blades is different from the number of the second blades.

5. The turbine flow meter according to claim 4, characterized in that, The number of the first leaf and the number of the second leaf differ by 1.

6. The turbine flow meter according to claim 1, characterized in that, The relative speeds between the first turbine and the second turbine are the same.

7. The turbine flow meter according to claim 4, characterized in that, The first turbine and the second turbine have the same geometry.

8. The turbine flow meter according to claim 3, characterized in that, The fluid flow angle is the same as the exit metal angle of the first blade.

9. The turbine flow meter according to claim 3, characterized in that, The flow angle of the fluid is the same as the exit metal angle of the second blade.

10. The turbine flow meter according to claim 9, characterized in that, When fluid flows within the containment cavity and sequentially passes through the first turbine and the second turbine, the first blades and the second blades are staggered.

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