One-dimensional pipe network calculation empirical formula setting method

Abstract

A method for setting empirical formulas for one-dimensional pipe network calculation, which relates to the technical field of aero-engine design and manufacturing. To solve the technical problems existing in the prior art, namely, the traditional pipe network calculation model has high complexity and insufficient accuracy in establishing the blade cooling structure, the technical solution provided by the present invention is as follows: A method for setting empirical formulas for one-dimensional pipe network calculation, the method comprising: dividing the blade into a preset number of segments, and defining each segment as a throttling unit; establishing a one-dimensional calculation model according to the throttling unit; simplifying the one-dimensional calculation model; matching corresponding parameters for each throttling unit; and setting a flow resistance empirical formula, a heat transfer coefficient empirical formula and a film hole empirical formula in the one-dimensional calculation model. It can be applied to the design and optimization of the thermal management system of aero-engines.

Description

Technical Field

[0001] It relates to the technical field of aero-engine design and manufacturing. Background Art

[0002] In the field of aero-engine design and manufacturing, during the operation of an aero-engine, it is affected by a high-temperature and high-pressure working environment. To ensure the stable operation of the engine and extend its service life, it is necessary to reasonably control and regulate the temperature inside the engine. The design of the blade cooling structure is a crucial part of the aero-engine thermal management system, which directly affects the temperature distribution of the blade, the cooling effect, and the overall performance of the engine.

[0003] Therefore, the establishment of the pipe network calculation model is a key link; there are some defects in the traditional pipe network calculation model for the establishment of the blade cooling structure, which are mainly reflected in the following aspects:

[0004] High complexity: In the traditional method, when establishing the pipe network calculation model, it is necessary to consider the complexity of the blade cooling structure, involving cumbersome geometric modeling and flow field analysis, making the modeling process complex and time-consuming.

[0005] Insufficient accuracy: When the traditional pipe network calculation model considers the blade cooling structure, the assumptions about fluid flow and heat transfer are too simplified, resulting in low accuracy of the model and difficulty in accurately predicting the cooling effect and the blade temperature distribution. Summary of the Invention

[0006] To solve the technical problems existing in the prior art, namely, the high complexity and insufficient accuracy of the traditional pipe network calculation model in establishing the blade cooling structure, the technical solution provided by the present invention is as follows:

[0007] A method for setting one-dimensional pipe network calculation empirical formulas, the method comprising:

[0008] The step of dividing the blade into a preset number of segments, defining each segment as a throttling unit, and defining nodes;

[0009] The step of numbering the throttling units and nodes, and recording the geometric inlet and outlet relationships between the throttling units and nodes;

[0010] The step of establishing a one-dimensional calculation model according to the geometric inlet and outlet relationships between the throttling units and nodes;

[0011] The step of simplifying the one-dimensional calculation model;

[0012] The step of matching corresponding parameters for each throttling unit;

[0013] The step of setting a flow resistance empirical formula, a heat transfer coefficient empirical formula, and a film hole empirical formula in the one-dimensional calculation model.

[0014] Furthermore, a preferred embodiment is provided, in which the blade is divided into a preset number of segments according to the blade height.

[0015] Furthermore, a preferred embodiment is provided, in which the connection between every two throttling units is defined as a node.

[0016] Furthermore, a preferred embodiment is provided, in which in the step of numbering the throttling units and nodes, the step of numbering the geometric inlets and outlets between each throttling unit and node is further included.

[0017] Furthermore, a preferred embodiment is provided, in which a pipe network diagram including the connection relationships between each throttling unit is drawn through the geometric inlet and outlet relationships between the throttling units and nodes, and a one-dimensional calculation model is established according to the pipe network diagram.

[0018] Furthermore, a preferred embodiment is provided, in which assumptions are made about the internal and external flows and heat transfer of the throttling units in the one-dimensional calculation model to simplify the one-dimensional calculation model.

[0019] Furthermore, a preferred embodiment is provided, in which corresponding lengths, cross-sectional areas, inlet and outlet geometric parameters, and types and size parameters of turbulence structures are matched for each throttling unit.

[0020] Based on the same inventive concept, the present invention further provides a one-dimensional pipe network calculation empirical formula setting device, which includes:

[0021] a module for dividing the blade into a preset number of segments, defining each segment as a throttling unit, and defining nodes;

[0022] a module for numbering the throttling units and nodes and recording the geometric inlet and outlet relationships between the throttling units and nodes;

[0023] a module for establishing a one-dimensional calculation model according to the geometric inlet and outlet relationships between the throttling units and nodes;

[0024] a module for simplifying the one-dimensional calculation model;

[0025] a module for matching corresponding parameters for each throttling unit;

[0026] a module for setting a flow resistance empirical formula, a heat transfer coefficient empirical formula, and a film hole empirical formula in the one-dimensional calculation model.

[0027] Based on the same inventive concept, the present invention further provides a computer storage medium for storing a computer program, and when the computer program is read by a computer, the computer executes the method described above.

[0028] Based on the same inventive concept, the present invention also provides a computer, comprising a processor and a storage medium. When the processor reads the computer program stored in the storage medium, the computer executes the method described above.

[0029] Compared with the prior art, the beneficial effects of the technical solution provided by the present invention are as follows:

[0030] The method for setting the one-dimensional pipe network calculation empirical formula provided by the present invention divides the blade into several segments along the blade height to form throttling units, numbers and records the throttling units, effectively simplifying the modeling process.

[0031] The method for setting the one-dimensional pipe network calculation empirical formula provided by the present invention provides a division method that makes the process of establishing a pipe network calculation model more intuitive and clear, reducing the complexity of modeling.

[0032] The method for setting the one-dimensional pipe network calculation empirical formula provided by the present invention makes reasonable assumptions about the flow and heat transfer inside and outside the throttling unit, and establishes a momentum equation and an energy equation for one-dimensional flow, making the established one-dimensional calculation model more in line with the actual flow situation.

[0033] The method for setting the one-dimensional pipe network calculation empirical formula provided by the present invention further improves the calculation accuracy by specifying the necessary parameters of each throttling unit, such as length, cross-sectional area, inlet and outlet geometric parameters, etc.

[0034] The method for setting the one-dimensional pipe network calculation empirical formula provided by the present invention conducts a more detailed simulation of the heat transfer situation of the cold air flow, considering factors such as heat transfer between the inner and outer walls and the heat conduction direction, making the prediction of the cooling effect more accurate.

[0035] The method for setting the one-dimensional pipe network calculation empirical formula provided by the present invention helps to optimize the design of the blade cooling structure and improve the working efficiency and performance of the aeroengine.

[0036] The method for setting the one-dimensional pipe network calculation empirical formula provided by the present invention can be applied to the design and optimization of the thermal management system of aeroengines. Description of the Drawings

[0037] Figure 1 is the convergence curve for the pipe network pressure balance calculation;

[0038] Figure 2 is the convergence curve for the pipe network temperature balance calculation;

[0039] Figure 3 is the schematic diagram of the positioning method for the hole feature;

[0040] Figure 4 is the schematic diagram of the gas film hole modeling example;

[0041] Figure 5 It is a schematic diagram of the three-dimensional solid model of the blade and the cold air passage. Specific implementation mode

[0042] To make the advantages and beneficial effects of the technical solution provided by the present invention more clearly reflected, the technical solution provided by the present invention will be further described in detail with reference to the accompanying drawings. Specifically:

[0043] Embodiment 1. This embodiment provides a method for setting the empirical formula for one-dimensional pipe network calculation. The method includes:

[0044] The step of dividing the blade into a preset number of segments, defining each segment as a throttling unit, and defining nodes;

[0045] The step of numbering the throttling units and nodes and recording the geometric inlet and outlet relationships between the throttling units and nodes;

[0046] The step of establishing a one-dimensional calculation model according to the geometric inlet and outlet relationships between the throttling units and nodes;

[0047] The step of simplifying the one-dimensional calculation model;

[0048] The step of matching corresponding parameters for each throttling unit;

[0049] The step of setting the flow resistance empirical formula, heat transfer coefficient empirical formula and gas film hole empirical formula in the one-dimensional calculation model.

[0050] Specifically:

[0051] Empirical formula for smooth straight pipe:

[0052] cfs = 0.11 * (68.4 / re + (1.6e-6) / dh) ^ 0.25;

[0053] Where dh is the characteristic scale.

[0054] Where dh is the characteristic scale, equivalent diameter, and length in Re.

[0055] Function: Calculate the friction coefficient of a smooth straight pipe according to the Reynolds number and characteristic scale.

[0056] Detailed description: Calculate the friction coefficient of a smooth straight pipe using the empirical formula according to the preset Reynolds number and characteristic scale.

[0057] According to the given Reynolds number (re) and characteristic scale (dh), calculate the values of the two terms 68.4 / re and (1.6e-6) / dh through the formula.

[0058] Substitute the calculated values of the above two items into the formula and perform the corresponding operations to finally obtain the value of the friction coefficient (cfs).

[0059] This friction coefficient represents the degree of friction during fluid flow in a smooth straight pipe and is one of the important parameters for fluid momentum transfer.

[0060] Empirical formula for a straight pipe with parallel ribs:

[0061] Function: Calculate the friction coefficient of a straight pipe with parallel rib roughness.

[0062] Detailed description: Calculate the friction coefficient of a straight pipe with parallel rib roughness according to preset parameters such as rib pitch, rib height, and rib angle along the flow direction, considering the inclination of the ribs.

[0063] First, according to the given rib pitch (dd) and rib height (ee), calculate the parameters PA, PB, and PC through the formula.

[0064] Then, calculate the parameter xx based on the calculated PA, PB, and PC.

[0065] Next, if the rib angle along the flow direction (alpha) is less than 45 degrees (indicating that the ribs are very inclined), enter a loop and update the value of xx through iterative calculation until a certain convergence condition is met.

[0066] Calculate the roughness Reynolds number (eplus) based on the calculated xx.

[0067] Finally, determine the final friction coefficient (cf) based on the magnitude of the roughness Reynolds number. If the roughness Reynolds number is greater than 35, calculate the friction coefficient using a specific formula; otherwise, approximately use the friction coefficient of a smooth pipe.

[0068] Empirical formula for staggered cylindrical ribs:

[0069] Function: Calculate the friction coefficient of a channel with staggered cylindrical ribs.

[0070] Detailed description: Calculate the friction coefficient of a channel with staggered cylindrical ribs according to preset parameters, including the spacing perpendicular to the flow direction, the spacing along the flow direction, the number of rows, etc., through the formula.

[0071] First, according to the given spacing perpendicular to the flow direction (sn), the spacing along the flow direction (x), and the number of rows (n), calculate the parameter f1 through the formula.

[0072] f1 = (0.25 + 0.118 / (sn / dd - 1)^1.08) * re^-0.16.

[0073] Next, based on the calculated f1, number of columns (nn), channel length (leng), and characteristic scale (dh), the final friction coefficient (cf) is calculated through the formula.

[0074] cf = 4 * f1 * nn / leng * dh.

[0075] This friction coefficient represents the degree of friction during fluid flow in a channel with staggered cylindrical ribs and is one of the important parameters for fluid momentum transfer.

[0076] Empirical formula for 90-degree circular bend:

[0077] Function: Calculate the friction coefficient of a 90-degree circular bend channel.

[0078] Detailed description: Based on the channel length and characteristic scale, calculate the friction coefficient of a 90-degree circular bend channel through the formula.

[0079] First, calculate a constant f, whose value is 4.51 divided by 2 and then divided by 4.

[0080] Next, based on the given channel length (leng) and equivalent diameter (dh), calculate the friction coefficient (cf) through the formula, that is, divide f by the ratio of the channel length to the equivalent diameter.

[0081] This friction coefficient represents the degree of friction during fluid flow in a 90-degree circular bend channel and is one of the important parameters for fluid momentum transfer.

[0082] Empirical formula for 90-degree square bend:

[0083] Function: Calculate the friction coefficient of a 90-degree square bend channel.

[0084] Detailed description: Based on the channel length and characteristic scale, calculate the friction coefficient of a 90-degree square bend channel through the formula.

[0085] First, calculate a constant f, whose value is 4.01 divided by 2 and then divided by 4.

[0086] Next, based on the given channel length (leng) and equivalent diameter (dh), calculate the friction coefficient (cf) through the formula, that is, divide f by the ratio of the channel length to the equivalent diameter.

[0087] This friction coefficient represents the degree of friction during fluid flow in a 90-degree square bend channel and is one of the important parameters for fluid momentum transfer.

[0088] Simple deep holes (thickened leading edge) on an infinite flat plate include impingement cooling holes:

[0089] Function: Calculate the friction coefficient of a simple deep hole on an infinite flat plate, considering impingement cooling holes.

[0090] Detailed description: According to the channel length and characteristic scale, calculate the friction coefficient of a simple deep hole on an infinite flat plate by interpolation method, and consider the frictional loss along the way as needed.

[0091] First, divide the channel length (leng) by the equivalent diameter (dh) to obtain the length ratio lde.

[0092] Define an array lde0 of length ratios and a corresponding array f00 of friction coefficients, representing the friction coefficients at different length ratios.

[0093] Calculate the friction coefficient f at the current length ratio by interpolation method (interp11) based on the given arrays of length ratios and friction coefficients.

[0094] Obtain the final friction coefficient cf based on the calculated friction coefficient f and the ratio of the channel length to the equivalent diameter.

[0095] Add the friction coefficient cf to the previously calculated friction coefficient cfs of the smooth straight pipe to obtain the final friction coefficient.

[0096] This process is used to determine the friction coefficient of a simple deep hole on an infinite flat plate under given conditions, considering the influence of the length ratio on the friction coefficient and taking into account the frictional loss along the way when necessary.

[0097] Empirical formula for heat transfer coefficient:

[0098] Function: Calculate the heat transfer coefficient according to parameters such as fluid and wall temperatures, Reynolds number, etc.

[0099] Detailed description: Calculate the heat transfer coefficient by formula according to preset parameters, including fluid temperature, wall temperature, Reynolds number, etc.

[0100] Empirical formula for film holes:

[0101] Function: Calculate the film cooling effectiveness.

[0102] Detailed description: Calculate the film cooling effectiveness according to preset parameters, including distance matrix, blowing ratio matrix, logic matrix, etc.

[0103] Embodiment 2: This embodiment further limits the method for setting the empirical formula for one-dimensional pipe network calculation provided in Embodiment 1, and divides the blade into a preset number of segments according to the blade height.

[0104] Embodiment 3. This embodiment further limits the one-dimensional pipe network calculation empirical formula setting method provided in Embodiment 1, and defines the connection between every two of the throttling units as a node.

[0105] Embodiment 4. This embodiment further limits the one-dimensional pipe network calculation empirical formula setting method provided in Embodiment 1. In the step of numbering the throttling units and nodes, it further includes the step of numbering the geometric inlets and outlets between each throttling unit and node.

[0106] Embodiment 5. This embodiment further limits the one-dimensional pipe network calculation empirical formula setting method provided in Embodiment 1. Through the geometric inlet and outlet relationship between the throttling units and nodes, a pipe network network diagram including the connection relationship between each throttling unit is drawn, and based on the pipe network network diagram, the one-dimensional calculation model is established.

[0107] Embodiment 6. This embodiment further limits the one-dimensional pipe network calculation empirical formula setting method provided in Embodiment 1. Hypotheses are made on the internal and external flow and heat transfer of the throttling units in the one-dimensional calculation model to simplify the one-dimensional calculation model.

[0108] Embodiment 7. This embodiment further limits the one-dimensional pipe network calculation empirical formula setting method provided in Embodiment 1. Corresponding lengths, cross-sectional areas, inlet and outlet geometric parameters, types and size parameters of the flow disturbance structures are matched for each throttling unit.

[0109] Embodiment 8. This embodiment provides a device for setting the one-dimensional pipe network calculation empirical formula. The device includes:

[0110] A module that divides the blade into a preset number of segments, defines each segment as a throttling unit, and defines nodes;

[0111] A module that numbers the throttling units and nodes and records the geometric inlet and outlet relationship between the throttling units and nodes;

[0112] A module that establishes a one-dimensional calculation model according to the geometric inlet and outlet relationship between the throttling units and nodes;

[0113] A module that simplifies the one-dimensional calculation model;

[0114] A module that matches corresponding parameters for each throttling unit;

[0115] A module that sets the flow resistance empirical formula, heat transfer coefficient empirical formula, and air film hole empirical formula in the one-dimensional calculation model.

[0116] Embodiment 9. This embodiment provides a computer storage medium for storing a computer program. When the computer program is read by a computer, the computer executes the method provided in Embodiment 1.

[0117] Embodiment 10. This embodiment provides a computer, including a processor and a storage medium. When the processor reads the computer program stored in the storage medium, the computer executes the method provided in Embodiment 1.

[0118] Embodiment 11. This embodiment further elaborates and completes the above-provided technical solution in detail. Specifically:

[0119] This embodiment can be applied to the design and manufacturing of aeroengines, especially for the optimized design and performance evaluation of blade cooling structures. By establishing a pipe network calculation model, engineers can more accurately predict the temperature distribution and cooling effect of the blades, thereby optimizing the cooling structure design, improving the working efficiency of the engine, reducing fuel consumption, and increasing the service life of the engine.

[0120] Method for establishing a pipe network calculation model:

[0121] The first step of pipe network calculation is to obtain a pipe network calculation model based on the blade cooling structure. The momentum equation and energy equation of pipe network calculation are established for one-dimensional flow. Therefore, the cold air flow needs to be simplified into a combination of several one-dimensional flows to establish a one-dimensional calculation model. The main steps for establishing a one-dimensional calculation model are as follows:

[0122] 1) Divide the blade into several segments along the blade height. For one flow passage, it is divided into several "throttling units". The connection points of the throttling units are called nodes (sometimes also called chambers). In addition, each hole structure also corresponds to a throttling unit;

[0123] 2) Number each throttling unit and node, and record the numbers of the geometric inlets and outlets of each throttling unit. The geometric inlets and outlets are determined artificially and do not necessarily correspond to the flow inlets and outlets. The flow inlets and outlets need to be determined according to the pipe network calculation;

[0124] 3) Establish the connection relationship of the throttling units to form a one-dimensional calculation model and draw a pipe network network diagram.

[0125] It should be noted that when establishing the throttling unit, the following assumptions are made for the flow and heat transfer inside and outside the unit:

[0126] a) The parameters such as temperature, pressure, and heat transfer coefficient of the cold air inside the unit are uniform;

[0127] b) The stagnation temperature and heat transfer coefficient on the gas side outside the unit are uniform, and the parameters of the inner arc and the back arc can be unequal;

[0128] c) The wall thickness of the inner arc of the unit and the backrest arc takes the average value, and the thermal conductivity takes a fixed value;

[0129] d) Heat is only conducted from the high-temperature side to the low-temperature side of the wall surface, ignoring the heat conduction of the solid between adjacent units and the heat conduction between the solid on the inner arc side and the solid on the back arc side of the unit;

[0130] e) Throttling units such as impact holes, film holes, and pressure balance holes are adiabatically treated;

[0131] f) The external heat transfer coefficient and heat transfer thickness of the middle flow tube at the blade root are not easy to estimate. A constant blade root temperature can be approximately given to roughly simulate the heating situation when the cold air flows through the flow tube.

[0132] It can be seen from the above assumptions that establishing a one-dimensional model greatly simplifies the flow and makes the solution easier; on the other hand, too many assumptions and approximations also restrict the further improvement of the calculation accuracy of the pipe network.

[0133] When establishing the pipe network calculation model, several parameters need to be given for each throttling unit, including: length, equivalent diameter, cross-sectional area, inlet cross-sectional area and inlet radius (relative to the rotation axis), outlet cross-sectional area and outlet radius, the type and related geometric dimensions of the turbulence structure in each flow tube, the inner arc side heat transfer area and the back arc side heat transfer area, the outer heat transfer area on the inner arc side and the back arc side corresponding to each flow tube, the average outer heat transfer coefficient, the average gas stagnation temperature, the average heat conduction wall thickness, as well as the rotational angular velocity, the average thermal conductivity of the blade metal, etc. See the first part of this article: Design process and parameterization method for the pipe network schematic diagram.

[0134] After establishing the pipe network calculation model, the unknowns to be solved include: the pressure and temperature at the nodes, the cold air mass flow rate, flow Re number, and friction resistance coefficient c f at each throttling unit, the inlet and outlet pressure, temperature, total pressure, and total temperature of the throttling unit. When there is heat transfer in the unit, the Nu number, convective heat transfer coefficient of the wall surface, the inner and outer wall temperatures and heat fluxes on the inner arc side and the back arc side also need to be calculated.

[0135] Boundary conditions of the calculation model:

[0136] The boundary conditions of the pipe network calculation model include flow boundary conditions and heat transfer boundary conditions.

[0137] The flow boundary conditions include the pressure and temperature at the cold air inlet, the mainstream pressure and temperature at the outlet of each film hole, the pressure and temperature at the outlet of the trailing split, the pressure and temperature in the outlet chamber of the tip throttle hole, etc. For flow calculations, the temperature does not have to be specified at the outlet. However, there may be a situation where the combustion gas backflows into the cold air passage of the blade during the flow process. That is to say, the outlets of some designs actually become inlets. Therefore, the combustion gas temperature at the cold air outlet must be specified to facilitate the simulation of possible combustion gas backflow. The heat transfer boundary conditions include the average heat transfer coefficient and the combustion gas stagnation temperature on the outer wall surface of each throttle unit with external heat transfer.

[0138] The heat transfer boundary conditions and the flow boundary conditions at the cold air outlet are obtained through CFD calculations. Before designing the cooling structure, an aerodynamic calculation is performed on the target blade profile. The heat transfer surface of the blade is set as the first type of boundary condition, and a set of data on the pressure, temperature, and heat transfer coefficient on the blade wall can be obtained. Each time the pipe network calculation model is established, interpolation is performed on this set of data through the program to obtain the corresponding boundary conditions of the pipe network calculation model.

[0139] Control equations of the pipe network calculation model and their discrete treatment:

[0140] The control equation set includes the continuity equation, momentum equation, energy equation, and experimental correlation of flow and heat transfer.

[0141] Continuity equation

[0142] The continuity equation set is established at the nodes. That is, for the i-th node (internal node), there is a mass flow balance equation:

[0143]

[0144] In the formula, q ij represents the mass flow rate of the throttle unit from node i to node j. When there is no throttle unit between the two nodes, q ij = 0. For the boundary node with a given flow rate, the equation becomes q bi represents the fluid amount flowing into node i from the outside. For the boundary node with a given pressure, the continuity equation is not established.

[0145] Momentum equation

[0146] The momentum equation is established for the one-dimensional steady flow of the throttle unit, considering factors such as compressibility, variable cross-section, friction, heat transfer, and rotation effect. Its form is:

[0147]

[0148] After the first-order difference treatment and omitting the small quantities, the discretized momentum equation is obtained:

[0149]

[0150] The expressions for each item are: (i represents the inlet parameter, and j represents the outlet parameter)

[0151]

[0152]

[0153]

[0154] L is the pipe length. q ij When q > 0, m = 1, q ij When q < 0, m = -1.

[0155] In the formula, p i , p j , q ij , c f are unknowns, and the friction resistance coefficient c f is obtained from the empirical formula according to the channel geometric parameters and the Re number.

[0156] The general form of the empirical formula for the resistance coefficient is f = f f (Re, x 1 , x 2 ,...), or the friction resistance coefficient is given The conversion relationship between the two is c f = fD h / L.

[0157] Energy equation

[0158] The form of the energy equation at the node is:

[0159]

[0160] The form of the energy equation of the throttling unit is:

[0161]

[0162] U a = U a1 + U a2 is the total equivalent heat transfer coefficient, and U a1 and U a2 are the equivalent heat transfer coefficients of the back arc and the inner arc respectively:

[0163]

[0164] In the above formulas, h represents the heat transfer coefficient, A represents the heat transfer area, and δ represents the heat conduction thickness. The subscript ci represents the inlet parameter of the cold air flow, and cj represents the outlet parameter of the cold air flow. When q ij > 0, T i = Tci ,T j =T cj When q ij <0, T i =T cj ,T j =T ci The subscript 1 represents the back arc, 2 represents the inner arc, g represents the gas side parameter, c represents the cold air side parameter, and λ is the average thermal conductivity of the metal. The heat transfer coefficient h on the cold air side c Calculate it according to the empirical formula. The empirical formula of heat transfer coefficient is generally Nu = f Nu (Re,Pr,x 1 ,x 2 ,...)or (h c =λNu / D h ).

[0165] Pressure balance calculation program

[0166] In the pressure balance calculation, the temperature is given as a known quantity, and the equations to be solved include: node continuity equation, throttling unit momentum equation and throttling unit resistance empirical formula. ij The sign of the term and q ij There is a complex mathematical relationship between flow and resistance coefficient, which makes it difficult to solve. There are many methods to solve nonlinear equations. The previous pipe network calculation program used DFP algorithm, BFGS algorithm and discrete continuation method to solve. If the initial value is not given reasonably, these algorithms may not converge. This also makes it particularly important to give the initial value of the pipe network calculation.

[0167] Computers can solve linear equations quickly and stably, so we can consider transforming the equations in the pressure balance calculation into linear equations, and solve the nonlinear equations by solving the linear equations through multiple iterations. According to the physical characteristics of the pipe network pressure balance calculation, the solution method is as follows:

[0168] Let M ij =A ij , N ij =B ij q ij +C ij c f q ij , then the momentum equation Transformed to p i -p j =N ij q ij -M ij , where N ijis positive when the cross-sectional area change of the throttling unit flow channel is not too drastic, characterizing the resistance of the throttling unit, and there is, N ij = N ji ; M ij The sign of is related to the direction of the centrifugal inertial force in the throttling unit, characterizing the influence of the centrifugal inertial force on the flow, and there is M ij = -M ji . From this, the flow rate q ij can be obtained as the expression:

[0169]

[0170] According to the continuity equation and the momentum equation, a linear equation system with the node pressure as the unknown can be established:

[0171] Hp = d,

[0172] The elements on the diagonal of the matrix H are When there is a throttling unit between nodes i and j, H ij = 1 / N ij , and at other positions, H ij = 0; when node i is a pressure boundary, H ii = 1, H ij = 0.

[0173] The elements in the vector d When node i is a pressure boundary, d i = p bi ; when node i is a flow boundary condition The vector p is the pressure p to be solved i .

[0174] Directly solving the discretized momentum equation can obtain the p i at the nodes, and then the flow rate q ij can be obtained from the momentum equation.

[0175] According to the flow rate q ij and the average temperature (T i + T j ) / 2 of the throttling unit, the flow Reynolds number Re of the unit can be obtained, and then the resistance coefficient c f can be obtained according to the empirical formula. Determine whether the pressure and flow rate obtained in this iteration and the previous iteration converge. If the convergence condition is not met, re-obtain the expression of the flow rate q ij .

[0176] The advantage of adopting this solution method is that the calculation is stable and it is easy to converge quickly when there is no initial flow field. When there is no initial flow field, for each throttling unit, M ij = 0, N ij = N 0, let N 0 ≈ 10 5 , and it can converge quickly through iteration.

[0177] Figure 1 Figure 1 shows the nodal pressure convergence curve of a primary turbine moving blade pressure balance calculation, and there is no initial field in the calculation. The horizontal axis is the number of iterations, and the vertical axis is the pressure of each node. There are 55 nodes and 57 throttle units in total. The relaxation factor SOR of the calculation is 0.2, and the judgment basis for the completion of the calculation is that the change in pressure at all nodes in two adjacent iterations is less than 0.1 Pa, and the relative change in the flow rate of all throttle units is less than 0.01%. The iteration was carried out for 84 steps, and the calculation time was less than 1 second.

[0178] Temperature balance calculation program:

[0179] The temperature balance calculation calculates the temperatures at the inlets and outlets of each throttle unit in the pipe network according to the energy equation under the conditions of given nodal pressures and flow rates in the pipe network. Compared with the pressure balance calculation, the temperature balance calculation does not need to solve complex non-linear equations, and it is not easy to diverge in the calculation, so the implementation difficulty is relatively small.

[0180] The temperature balance calculation program internally nests the pressure balance calculation program. In each iteration, a pressure balance calculation needs to be carried out according to the temperature distribution of the pipe network obtained in the previous iteration. The first iteration uses a constant temperature T i = T 0 as the initial temperature field, and T 0 is the temperature at the cold air inlet. For the pressure balance calculation in subsequent iterations, the result of the previous pressure balance calculation is used as the initial field to further improve the calculation speed and calculation stability.

[0181] After completing the pressure balance calculation, starting from each cold air inlet, according to the energy equation of the throttle unit, the flow outlet temperatures of each throttle unit are calculated in sequence along the flow direction; for each node, only when the flow outlet temperatures of all throttle units flowing into this node are known, can the temperature of this node be calculated according to the energy equation of the node, and then the throttle unit flowing out of this node can be calculated. After calculating the temperatures of all nodes and throttle units, the convergence is judged according to the nodal temperature difference obtained from two adjacent temperature calculations.

[0182] Figure 2 Figure 2 shows the nodal temperature convergence curve of a primary turbine moving blade temperature balance calculation. The horizontal axis is the number of iterations, and the vertical axis is the pressure of each node. There are 55 nodes and 57 throttle units in total. The relaxation factor SOR of the calculation is 0.8, and the judgment basis for the completion of the calculation is that the change in temperature at all nodes in two adjacent iterations is less than 0.05 K. The iteration was carried out for 7 steps, and the total calculation time was less than 6 seconds.

[0183] After the model design is completed, three-dimensional gas-thermal coupling numerical simulation needs to be applied for verification, which requires solid modeling of the computational domain. The solid modeling of the computational domain of turbine blades is time-consuming and requires a large amount of manual work. Generally speaking, it often takes several weeks or even months to perform solid modeling on a complete air-cooled turbine blade, and it is difficult to control the model accuracy. Sometimes, the model accuracy is too low, resulting in the failure of computational grid generation.

[0184] In order to achieve high-precision and high-speed solid modeling, parametric design needs to be utilized. The parametric design in this embodiment is completed in a self-written program. Therefore, it is necessary to transfer the geometric design data to a solid modeling software (such as UG NX). Using these data, various geometric features can be quickly and accurately generated in the modeling software, and then the solid modeling of some special structures (such as the blade root and tenon of the moving blade, the blade crown of the moving blade, the end wall of the guide vane, etc.) can be completed in UG, that is, the rapid solid modeling of the blade computational domain can be completed.

[0185] For blades with impingement cooling, film cooling, and turbulator ribs, establishing various hole features and rib features will consume a large amount of time because establishing these features requires positioning and modeling on a spatial curved surface (blade profile surface or internal profile surface), and it is relatively difficult to complete this work in solid modeling software. In addition, establishing a serpentine passage of the moving blade that meets the requirements also requires a lot of effort. Therefore, the key point of the data output program of the parametric design for solid modeling lies in the geometric data output of the film holes, impingement holes, parallel turbulator ribs, and the cold air passage of the moving blade.

[0186] For film holes and impingement holes, using the parametric design program, the positioning of the hole structure (such as the dotted line positioning in Figure 3 ) can be conveniently achieved through interpolation, so as to calculate the matrix of geometric coordinate points on the surface of the hole structure. By means of the method of outputting the surface (such as Figure 4 ), these hole feature points can be transferred to the modeling software to realize the rapid modeling of hole features. This method can be used for the solid modeling of impingement cooling holes, compound angle film cooling holes, and film cooling holes with variable cross-section morphology. The time required to generate a row of film holes in UG is about a few minutes. For the modeling of turbulator ribs, a similar method can also be adopted.

[0187] "Topology design" provides convenience for the modeling of the cold air passage of the moving blade. Through the program, the data output of the surface of each unit passage can be realized, and by transferring these data to the solid modeling software in the form of a surface, the cold air passage can be quickly and accurately generated, and then the modeling of other structures can be completed in the solid modeling software. Figure 5 The solid model of the moving blade is given by adopting this method. Using this set of data output and modeling methods, the solid model of the computational domain of the complex cooling structure of the turbine blade can be completed within a few days, and the model accuracy meets the requirements for dividing the computational grid.

[0188] The above further describes the technical solutions provided by the present invention through several specific embodiments to highlight the advantages and beneficial effects of the technical solutions provided by the present invention. However, the several specific embodiments described above are not used as a limitation to the present invention. Any reasonable modifications and improvements to the present invention, combinations of embodiments, equivalent replacements, etc. within the spirit and principle of the present invention shall be included within the protection scope of the present invention.

[0189] In the description of this specification, it is only a preferred embodiment of the present invention, and the scope of rights of the present invention cannot be limited thereby; in addition, the description with reference to terms such as "one embodiment", "some embodiments", "example", "specific example", or "some examples" means that the specific features, structures, materials, or characteristics described in connection with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials, or characteristics described can be combined in any one or N embodiments or examples in a suitable manner. In addition, without contradiction, those skilled in the art can combine and combine the different embodiments or examples described in this specification and the features of different embodiments or examples. In addition, the terms "first" and "second" are only used for descriptive purposes and cannot be understood as indicating or implying relative importance or implicitly specifying the quantity of the indicated technical features. Thus, the features defined with "first" and "second" may explicitly or implicitly include at least one of these features. In the description of the present invention, the meaning of "N" is at least two, such as two, three, etc., unless otherwise specifically defined. Any process or method description represented in a flowchart or otherwise described herein can be understood to represent a module, segment, or portion of code including one or more N executable instructions for implementing a customized logical function or process, and the scope of the preferred embodiments of the present invention includes additional implementations, where the functions may be executed in a manner that is not shown or discussed in sequence, including in a substantially simultaneous manner or in a reverse order according to the functions involved, which should be understood by those skilled in the art to which the embodiments of the present invention belong. The logic and / or steps represented in a flowchart or otherwise described herein, for example, can be considered a sequenced list of executable instructions for implementing a logical function, which can be specifically implemented in any computer-readable medium for use by an instruction execution system, apparatus, or device (such as a computer-based system, a system including a processor, or other systems that can fetch and execute instructions from the instruction execution system, apparatus, or device), or in connection with these instruction execution systems, apparatus, or devices. For the purposes of this specification, a "computer-readable medium" can be any device that can contain, store, communicate, propagate, or transport a program for use by or in connection with an instruction execution system, apparatus, or device. More specific examples (non-exhaustive list) of computer-readable media include the following: an electrical connection portion (electronic device) having one or N wirings, a portable computer diskette (magnetic device), a random access memory (RAM), a read-only memory (ROM), an erasable programmable read-only memory (EPROM or flash memory), an optical fiber device, and a portable compact disc read-only memory (CDROM).In addition, the computer-readable medium can even be paper or other suitable media on which the program can be printed, because the program can be obtained electronically, for example, by optically scanning the paper or other media, followed by editing, interpretation, or other suitable processing if necessary, and then storing it in a computer memory. It should be understood that the various parts of the present invention can be implemented by hardware, software, firmware, or a combination thereof. In the above embodiments, the N steps or methods can be implemented by software or firmware stored in a memory and executed by a suitable instruction execution system. For example, if implemented in hardware, as in another embodiment, any one or a combination of the following techniques well known in the art can be used: discrete logic circuits having logic gate circuits for implementing logical functions on data signals, application specific integrated circuits having appropriate combinational logic gate circuits, programmable gate arrays (PGAs), field programmable gate arrays (FPGAs), and the like.

[0190] Those of ordinary skill in the art can understand that all or part of the steps carried by the methods of the above embodiments can be completed by instructing relevant hardware through a program. The program can be stored in a computer-readable storage medium. When the program is executed, it includes one or a combination of the steps of the method embodiments. In addition, in each of the embodiments of the present invention, the functional units can be integrated into one processing module, or each unit can exist physically alone, or two or more units can be integrated into one module. The above integrated module can be implemented in the form of hardware or in the form of a software functional module. When the above integrated module is implemented in the form of a software functional module and sold or used as an independent product, it can also be stored in a computer-readable storage medium.

Claims

1. A method for setting an empirical formula for one-dimensional pipe network calculation, characterized in that: The method comprises: dividing the blade into a preset number of segments, defining each segment as a throttling unit, and defining the steps of the nodes; The step of numbering the throttling units and nodes and recording the geometric import and export relationships between the throttling units and nodes; A step of establishing a one-dimensional calculation model according to the geometric import and export relationship between the throttling unit and the node; A step of simplifying the one-dimensional calculation model; A step of matching corresponding parameters for each of the throttling units; In the one-dimensional calculation model, a step of setting an empirical formula for flow resistance, an empirical formula for heat transfer coefficient and an empirical formula for air film pores; Smooth straight pipe empirical formula: cfs=0.11*(68.4 / re+(1.6e-6) / dh)^0.25; Where dh is the characteristic scale, expressed as the length in equivalent diameter Re; Calculate the friction coefficient of a smooth straight pipe based on the Reynolds number and characteristic scale; According to the preset Reynolds number and characteristic scale, the friction coefficient of the smooth straight pipe is calculated using the empirical formula; According to the given Reynolds number re and characteristic scale dh, the values ​​of 68.4 / re and 1.6e-6 / dh are calculated by the formula; Substitute the calculated values ​​of the above two items into the formula and perform corresponding operations to finally obtain the value of the friction coefficient cfs; This friction coefficient represents the degree of friction when the fluid flows in a smooth straight tube and is one of the important parameters for fluid momentum transfer. The empirical formula of parallel rib rough straight pipe is used to calculate the friction coefficient of the straight pipe with parallel rib roughness; The friction coefficient of the parallel rib rough straight pipe is calculated based on the preset rib spacing, rib height and rib angle along the flow direction, taking into account the inclination of the ribs. According to the given rib spacing dd and rib height ee, the parameters PA, PB and PC are calculated by formula; according to the calculated PA, PB and PC, the parameter xx is calculated; if the angle between the ribs and the flow direction is less than 45 degrees, a loop is entered to update the value of xx through iterative calculation until a certain convergence condition is met; Calculate the roughness Reynolds number According to the size of the roughness Reynolds number, the final friction coefficient cf is determined. If the roughness Reynolds number is greater than 35, the friction coefficient is calculated using the formula, otherwise the friction coefficient of the smooth tube is approximately used; The empirical formula of staggered cylindrical ribs is used to calculate the friction coefficient of the channel with staggered cylindrical ribs; According to the preset parameters, including the spacing perpendicular to the flow direction, the spacing along the flow direction, and the number of columns, the friction coefficient of the cross-row cylindrical rib channel is calculated by a formula; According to the given spacing sn perpendicular to the flow direction, spacing x along the flow direction and number of columns n, the parameter f1 is calculated by the formula; f1=(0.25+0.118 / (sn / dd-1)^1.08)*re^-0.16; According to the calculated f1, number of columns n, channel length leng and characteristic scale dh, the final friction coefficient cf is calculated by the formula: cf = 4*f1*nn / leng*dh; This friction coefficient represents the degree of friction when the fluid flows in a channel with cross-stacked cylindrical ribs, and is one of the important parameters for fluid momentum transfer. The empirical formula for 90-degree circular turning is used to calculate the friction coefficient of the 90-degree circular turning channel; according to the channel length and characteristic scale, the friction coefficient of the 90-degree circular turning channel is calculated by the formula, and a constant f is calculated, whose value is 4.51 divided by 2 and then divided by 4. According to the given channel length leng and characteristic scale dh, the friction coefficient cf is calculated by the formula, that is, f is divided by the ratio of the channel length to the equivalent diameter; This friction coefficient represents the degree of friction when the fluid flows in a 90-degree circular bend channel and is one of the important parameters for fluid momentum transfer. The empirical formula for 90-degree square turn is used to calculate the friction coefficient of the 90-degree square turn channel; according to the channel length and characteristic scale, the friction coefficient of the 90-degree square turn channel is calculated by the formula, and a constant f is calculated, whose value is 4.01 divided by 2 and then divided by 4. According to the given channel length leng and characteristic scale dh, the friction coefficient cf is calculated by the formula, that is, f is divided by the ratio of the channel length to the equivalent diameter; The thickened front edge of a simple deep hole on an infinite plate includes an impact cooling hole. The impact cooling hole needs to be considered when calculating the friction coefficient of the simple deep hole on the infinite plate. The friction coefficient of the simple deep hole on the infinite plate is calculated by the interpolation method based on the channel length and characteristic scale, and the loss along the way is considered as needed. Divide the channel length leng by the characteristic scale dh to get the length ratio lde, define a length ratio array lde0 and a corresponding friction coefficient array f00 to represent the friction coefficients at different length ratios, and calculate the friction coefficient f at the current length ratio based on the given length ratio array and friction coefficient array through the interpolation method interp11; According to the calculated friction coefficient f and the ratio of the channel length to the equivalent diameter, the final friction coefficient cf is obtained; Add the friction coefficient cf to the previously calculated friction coefficient cfs of the smooth straight pipe to get the final friction coefficient; This procedure is used to determine the friction coefficient of a simple deep hole in an infinite plate under given conditions, taking into account the effect of the length ratio on the friction coefficient and taking into account the losses along the way; The empirical formula of heat transfer coefficient is used to calculate the heat transfer coefficient based on the fluid and wall temperature and Reynolds number parameters; The heat transfer coefficient is calculated using a formula based on preset parameters, including fluid temperature, wall temperature, and Reynolds number.

2. The method for setting the one-dimensional pipe network calculation empirical formula according to claim 1, characterized in that: The blade is divided into a preset number of segments according to the blade height.

3. The method for setting the one-dimensional pipe network calculation empirical formula according to claim 1, characterized in that: A connection point between every two throttling units is defined as a node.

4. The method for setting the one-dimensional pipe network calculation empirical formula according to claim 1, characterized in that: The step of numbering the throttling units and nodes also includes the step of numbering the geometric entrances and exits between each of the throttling units and nodes.

5. The method for setting the one-dimensional pipe network calculation empirical formula according to claim 1, characterized in that: Through the geometric import and export relationship between the throttling units and the nodes, a pipe network diagram including the connection relationship between each of the throttling units is drawn, and the one-dimensional calculation model is established based on the pipe network diagram.

6. The method for setting the one-dimensional pipe network calculation empirical formula according to claim 1, characterized in that: Assumptions are made on the internal and external flows and heat exchange of the throttling unit in the one-dimensional calculation model to simplify the one-dimensional calculation model.

7. The method for setting the one-dimensional pipe network calculation empirical formula according to claim 1, characterized in that: The corresponding length, cross-sectional area, inlet and outlet geometric parameters, type and size parameters of the spoiler structure are matched to each of the throttling units.

8. A computer storage medium for storing a computer program, characterized in that: When the computer program is read by a computer, the computer executes the method of claim 1 .

9. A computer, comprising a processor and a storage medium, characterized in that: When the processor reads the computer program stored in the storage medium, the computer executes the method of claim 1 .

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