Method, device and storage medium for predicting pressure pulsations in a rotating hydraulic machine

Abstract

The application discloses a method, device and storage medium for predicting pressure pulsation in a rotating hydraulic machine. The method comprises the following steps: constructing an internal flow field model of the rotating hydraulic machine, and obtaining Lamb vector divergence of the rotating hydraulic machine, wherein the pressure gradient of each flow passage is denoted as ▽·P, and the turbulent intensity of the internal flow field is denoted as k; obtaining the pressure pulsation intensity coefficient c in the rotating hydraulic machine according to the following formula p , which is used as a standard for evaluating the pressure pulsation in the rotating hydraulic machine. p The method of the application has a reasonable relationship model and high precision. The prediction process is simple, and the pressure pulsation can be predicted by inputting H, ▽·P, k, ▽·L, ρ, v and d to obtain c p , so that the pressure pulsation in the rotating hydraulic machine can be quickly predicted with high precision, and the method has a wide application prospect.

Description

Technical Field

[0001] This invention relates to the field of engineering application technology, and to a method, device and storage medium for predicting pressure pulsations in rotating hydraulic machinery. Background Technology

[0002] The internal flow of hydraulic machinery is a highly complex three-dimensional unsteady, rotating, multi-wall strong shear turbulent flow. When free shear turbulence is subjected to system rotation and strong wall shear, it not only changes the statistical properties and pseudo-order structure of the turbulent field, but also changes the energy transfer mechanism of the turbulent field. This is mainly reflected in its influence on the momentum and energy transport, eddy viscosity distribution, distribution form of turbulent structure, flow stability, and boundary layer stability of coherent structures at different scales and small-scale flows. It has very complex flow characteristics, which affect and determine the dynamic characteristics of hydraulic machinery such as flow-induced vibration and noise caused by turbulent flow.

[0003] The intense pressure pulsations caused by complex turbulence within hydraulic machinery can easily lead to shaft deformation, blade cracks or breakage, and in severe cases, even create hydraulic engineering problems with the system structure, seriously threatening the operational reliability of the hydraulic machinery and its system. Furthermore, the vibration and noise problems caused by intense pressure pulsations have always been a bottleneck issue in the application of hydraulic machinery in various fields. In different working environments, to frequently adapt to different operating conditions and cope with the complex and changing environment, the mutual interference between the impeller and its diffuser components (volute / guide vanes) of key components of hydraulic machinery creates strong fluid excitation, which in turn induces vibration and noise in the hydraulic machinery system. Even more seriously, when the disturbance frequency of unsteady flow is close to the natural frequency of the structure, it can induce structural instability, causing severe acoustic and structural responses, forming flow-acoustic-structure hydraulic resonance, seriously threatening the stability and reliability of the hydraulic machinery and its system.

[0004] Due to the complexity of hydraulic machinery systems, which include rotating, stationary, and piping components, as well as multi-physics coupling problems involving flow, acoustics, and structure, the essence lies in the intensity and characteristic frequency distribution of pressure pulsations generated within the hydraulic machinery. However, the various factors within hydraulic machinery exhibit nonlinear relationships that cannot be decoupled, making it difficult to fundamentally establish an inertial frame between flow and dynamics. Therefore, current methods for addressing the severe vibration and noise problems induced by unsteady fluid excitation in hydraulic machinery typically involve limiting the operating range or sacrificing performance to achieve better vibration and noise characteristics.

[0005] Therefore, in order to effectively control the pressure pulsations caused by complex flow inside hydraulic machinery, rapid assessment of these pulsations is a prerequisite for solving the problem. However, in the engineering field, the prediction and assessment of pressure pulsations typically employ transient numerical calculations and the placement of pressure sensors at openings in the flow-through components for measurement. The former requires enormous computational resources, while the latter involves a series of experimental conditions that must be met. In particular, the measurement of pressure pulsations inside the impeller is technically challenging due to its rotation.

[0006] Therefore, developing a rapid evaluation method for internal pressure pulsation in hydraulic machinery that requires less data processing, is less difficult to implement, and has lower costs is of great practical significance. Summary of the Invention

[0007] Due to the aforementioned deficiencies in existing technologies, this invention provides a rapid assessment method for internal pressure pulsations in hydraulic machinery that has lower data processing requirements, lower implementation difficulty, and lower cost. Specifically, it is a method for rapidly predicting internal pressure pulsations in rotating hydraulic machinery, overcoming the shortcomings of existing methods for predicting internal pressure pulsations in hydraulic machinery, which have high data processing requirements, high implementation difficulty, and high implementation cost.

[0008] To achieve the above objectives, the present invention provides the following technical solution:

[0009] A method for predicting pressure pulsations within rotating hydraulic machinery, comprising the following steps:

[0010] (1) Construct an internal flow field model of the rotating hydraulic machine and obtain the Lamb vector divergence of the rotating hydraulic machine based on the flow field parameters. The pressure gradient of each flow basin The turbulence intensity k of its internal flow field, where , The units of k and k are s^-2, kg / m^2 / s^2, and m^2 / s^2, respectively;

[0011] (2) The pressure pulsation intensity coefficient c in the rotating hydraulic machinery is obtained according to the following formula. p With pressure pulsation intensity coefficient c p As a standard for evaluating the magnitude of pressure pulsation within rotating hydraulic machinery;

[0012]

[0013] Among them, c p Unitless, c0 is the constant for calculating pressure pulsation intensity, unitless, H is the head of the rotating hydraulic machinery, in meters, v is the average flow velocity based on the inlet, in meters per second, d is the impeller outlet diameter, in meters, and ρ is the medium density, in kg / m³.

[0014] Among them, the pressure pulsation intensity coefficient c p The process of obtaining the calculation formula is as follows:

[0015] (1) When solving the RANS equation, the derived variable Lamb vector divergence is added through preprocessing. and pressure gradient ;

[0016] (2) Obtain the seven physical quantities ρ, v, d, H, and H that affect pressure pulsation. ,k, This forms the equation (Eq-1).

[0017] (1)

[0018] (3) Extract three basic physical quantities from the seven physical quantities (three basic physical quantities are usually selected for incompressible flow). Here, ρ, v, and d are selected as basic physical quantities, and their mutual independence is verified, that is, the exponential determinant formed by the system of equations (Eqs-2) is not zero.

[0019] (2)

[0020] Here, L represents the dimension of length, M represents the dimension of mass, and T represents the dimension of time; and the independence of the three selected variables has been calculated and verified.

[0021] (4) The remaining H is composed of three basic physical quantities. ,k, The four π terms are shown in the system of equations (Eqs-3):

[0022] (3)

[0023] (5) According to the principle of dimensional harmony, the exponents of each π term are (Eq-4):

[0024] (4)

[0025] (6) Finally, the dimensionless expression (Eq-5) affecting the intensity of pressure pulsation inside rotating hydraulic machinery is obtained:

[0026] (5)

[0027] (6)

[0028] After rearranging (Eq-5), the dimensionless parameter c, which characterizes the intensity of pressure pulsation within rotating hydraulic machinery, is obtained. pThe expression (Eq-6) uses a pressure pulsation intensity calculation constant c0, which is obtained in advance based on numerical calculation results.

[0029] The method for predicting pressure pulsations within rotating hydraulic machinery of this invention has a simple and reasonable step sequence. Based on the known influence of various factors on pressure pulsations, it uses Buckingham's π theorem for dimensional harmony analysis, thereby rewriting the original numerous variables into fewer dimensionless variables, simplifying the problem. Finally, it constructs variables that have a significant impact on the intensity of pressure pulsations in rotating hydraulic machinery, including the hydraulic machinery's own energy conversion capacity (head (H)) and the pressure gradient of each flow basin (…). ), turbulence intensity (k) of the flow field, and the effect of nonlinearity of the flow field ( The dimensionless physical relationship between the above-mentioned influencing factors was established using medium density (ρ), average flow velocity based on the inlet (v), and rotary impeller outlet diameter (d) as basic physical quantities. The pressure pulsation intensity calculation constant c0 was determined through numerical calculation, thus completing the construction of the calculation formula (the model is scientifically constructed and has high prediction accuracy). The pressure pulsation intensity coefficient c0 was then used as the basis for this calculation. p As a standard for evaluating the magnitude of pressure pulsation within rotating hydraulic machinery, H is input when subsequently estimating pressure pulsation. ,k, ρ, v, d yields c p It can quickly predict the pressure pulsation inside rotating hydraulic machinery with high accuracy, and has great application prospects.

[0030] As a preferred technical solution:

[0031] The method for predicting pressure pulsations within rotating hydraulic machinery as described above, wherein... The calculation formula is as follows:

[0032] ;

[0033] Where u is the flow velocity in m / s and ω is the vorticity in s^-1.

[0034] The process of obtaining the calculation formula is as follows:

[0035] For rotating hydraulic machinery, pressure pulsation is mainly affected by three factors: (1) the rotational frequency formed by the asymmetry of the flow center in the rotating impeller. Therefore, this component is mainly affected by the non-uniformity of the flow in the impeller, and the non-uniformity of the flow can be measured by the strength of the pressure gradient; (2) the blade frequency in the stationary component, that is, the disturbance of the flow in the downstream guide vane by the upstream rotating impeller blade, also known as dynamic-static interference. Therefore, the strength of this effect is mainly affected by the pressure gradient at the trailing edge of the impeller blade; (3) the influence of flow nonlinearity. After any disturbance (Eq-7) enters the nonlinear term of the equation (the second term on the left side of (Eq-8), under the promotion of nonlinearity, a high-power harmonic component is formed. Then, the influence of the non-uniformity of the flow field on the pressure pulsation field under the action of nonlinearity can be measured by the Lamb vector divergence (Eq-11).

[0036] (7)

[0037] (8)

[0038] The Navier-Stokes equations for the motion of incompressible viscous fluids have a particularly important equivalent form, the Lamb form (Eq-9):

[0039] (9)

[0040] The nonlinear convection term of the flow can be represented by (Eq-7) This indicates that any single-valued, continuous, and bounded vector field in space can be decomposed into a potential vector field and a rotational vector field. Therefore, by performing curl operations on both sides of the incompressible control equation (Eq-9) and neglecting terms that contribute zero to vorticity changes, we can obtain the incompressible flow vorticity transport equation (Eq-10):

[0041] (10)

[0042] The Lamb vector divergence is (Eq-11):

[0043] (11)

[0044] Combining the turbulence governing equations and vorticity transport equations, as well as Hamman's research results on Lamb vector divergence, it can be seen that the Lamb vector divergence... It can reflect the interaction between the high strain rate region and the mean field of a turbulent field. In the above text, P represents pressure, with the unit being Pa.

[0045] The present invention also provides a computer device, the computer device comprising:

[0046] At least one processor; and,

[0047] A memory communicatively connected to the at least one processor; wherein,

[0048] The memory stores computer-readable instructions, and when the processor executes the computer-readable instructions, it implements the method for predicting pressure pulsations within rotating hydraulic machinery as described above.

[0049] Furthermore, the present invention also provides a computer-readable storage medium storing computer-readable instructions, which, when executed by a processor, implement the method for predicting pressure pulsations within a rotating hydraulic machine as described above.

[0050] The above technical solution is only one feasible technical solution of the present invention. The scope of protection of the present invention is not limited thereto. Those skilled in the art can reasonably adjust the specific design according to actual needs.

[0051] The above invention has the following advantages or beneficial effects:

[0052] (1) The method for predicting pressure pulsations within rotating hydraulic machinery of the present invention constructs the head (H), pressure gradient of each flow domain (H), and pressure gradient of each flow domain. ), turbulence intensity (k) of the flow field, and the effect of nonlinearity of the flow field ( The medium density (ρ), the average inlet velocity (v), and the outlet diameter of the rotating impeller (d) are related to the pressure pulsation intensity coefficient c within the rotating hydraulic machinery. p The dimensionless physical relationship between the standard for evaluating the magnitude of pressure pulsation in rotating hydraulic machinery proposed in this application and the model is reasonably constructed and has high accuracy.

[0053] (2) The method for predicting pressure pulsations in rotating hydraulic machinery according to the present invention has a simple prediction process. When predicting pressure pulsations, H is input. ,k, ρ, v, d yields c p It can quickly predict the pressure pulsation inside rotating hydraulic machinery with high accuracy, and has great application prospects. Attached Figure Description

[0054] The invention, its features, shape, and advantages will become more apparent from the following detailed description of non-limiting embodiments with reference to the accompanying drawings. Like reference numerals denote like parts throughout the drawings. The drawings are not drawn to scale; the emphasis is on illustrating the gist of the invention.

[0055] Figure 1 This is a step diagram of the method for predicting pressure pulsation in rotating hydraulic machinery according to the present invention.

[0056] Figure 2This is a schematic diagram of the computer device in Example 2. Detailed Implementation

[0057] The structure of the present invention will be further described below with reference to the accompanying drawings and specific embodiments, but this is not intended to limit the present invention.

[0058] Example 1

[0059] A method for predicting pressure pulsations within rotating hydraulic machinery, the steps of which are as follows: Figure 1 As shown:

[0060] (1) Construct an internal flow field model of the rotating hydraulic machine and obtain the Lamb vector divergence of the rotating hydraulic machine based on the flow field parameters. The pressure gradient of each flow basin The turbulence intensity k of its internal flow field, where , The units of k and k are s^-2, kg / m^2 / s^2, and m^2 / s^2, respectively;

[0061] in The calculation formula is as follows:

[0062] ;

[0063] Where u is the flow velocity in m / s and ω is the vorticity in s^-1;

[0064] (2) The pressure pulsation intensity coefficient c in the rotating hydraulic machinery is obtained according to the following formula. p With pressure pulsation intensity coefficient c p As a standard for evaluating the magnitude of pressure pulsation within rotating hydraulic machinery;

[0065]

[0066] Among them, c p Unitless, c0 is the pressure pulsation intensity calculation constant (which is obtained in advance based on numerical calculation results), unitless, H is the head of the rotating hydraulic machinery, in meters, v is the average flow velocity based on the inlet, in meters per second, d is the impeller outlet diameter, in meters, and ρ is the medium density, in kg / m³.

[0067] Example 2

[0068] A computer device such as Figure 2 As shown, it includes: at least one processor and a memory communicatively connected to at least one processor;

[0069] The memory stores computer-readable instructions, and when the processor executes the computer-readable instructions, it implements the method for predicting pressure pulsations inside rotating hydraulic machinery as described in Example 1.

[0070] Example 3

[0071] A computer-readable storage medium storing computer-readable instructions, which, when executed by a processor, implement the method for predicting pressure pulsations within a rotating hydraulic machine as described in Example 1.

[0072] The method for predicting pressure pulsations within rotating hydraulic machinery, as verified by this invention, constructs the head (H), pressure gradient of each flow domain, and pressure gradient of each flow domain. ), turbulence intensity (k) of the flow field, and the effect of nonlinearity of the flow field ( The medium density (ρ), the average inlet velocity (v), and the outlet diameter of the rotating impeller (d) are related to the pressure pulsation intensity coefficient c within the rotating hydraulic machinery. p The dimensionless physical relationship between the standard for evaluating the magnitude of pressure pulsations within rotating hydraulic machinery proposed in this application and the model itself is well-constructed and highly accurate; the prediction process is simple, requiring only the input of H when predicting pressure pulsations. ,k, ρ, v, d yields c p It can quickly predict the pressure pulsation inside rotating hydraulic machinery with high accuracy, and has great application prospects.

[0073] Those skilled in the art should understand that variations can be implemented by combining existing technology with the above embodiments, which will not be elaborated here. Such variations do not affect the essence of the present invention, and will not be elaborated here either.

[0074] The preferred embodiments of the present invention have been described above. It should be understood that the present invention is not limited to the specific embodiments described above, and the devices and structures not described in detail should be understood as being implemented in a conventional manner in the art. Any person skilled in the art can make many possible variations and modifications to the technical solutions of the present invention using the methods and techniques disclosed above, or modify them into equivalent embodiments with equivalent changes, without departing from the scope of the present invention. This does not affect the essential content of the present invention. Therefore, any simple modifications, equivalent changes, and modifications made to the above embodiments based on the technical essence of the present invention without departing from the content of the present invention's technical solutions still fall within the protection scope of the present invention.

Claims

1. A method for predicting pressure pulsations within rotating hydraulic machinery, characterized in that: The steps are as follows: (1) Construct an internal flow field model of the rotating hydraulic machine and obtain the Lamb vector divergence of the rotating hydraulic machine based on the flow field parameters. The pressure gradient of each flow basin The turbulence intensity k of its internal flow field, where , The units of k and k are s^-2, kg / m^2 / s^2, and m^2 / s^2, respectively; (2) The pressure pulsation intensity coefficient c in the rotating hydraulic machinery is obtained according to the following formula. p With pressure pulsation intensity coefficient c p As a standard for evaluating the magnitude of pressure pulsation within rotating hydraulic machinery; ， Among them, c p Unitless, c0 is the constant for calculating pressure pulsation intensity, unitless, H is the head of the rotating hydraulic machinery, in meters, v is the average flow velocity based on the inlet, in meters per second, d is the impeller outlet diameter, in meters, and ρ is the medium density, in kg / m³. The The calculation formula is as follows: ； Where u is the flow velocity in m / s and ω is the vorticity in s^-1.

2. A computer device, characterized in that, The computer device includes: At least one processor; and, A memory communicatively connected to the at least one processor; wherein, The memory stores computer-readable instructions, and when the processor executes the computer-readable instructions, it implements the method for predicting pressure pulsations within rotating hydraulic machinery as described in claim 1.

3. A computer-readable storage medium, characterized in that, The computer-readable storage medium stores computer-readable instructions, which, when executed by a processor, implement the method for predicting pressure pulsations within a rotating hydraulic machine as described in claim 1.

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