CN-122020903-A - Lemniscate flow tube design and three-dimensional numerical calculation method

CN122020903ACN 122020903 ACN122020903 ACN 122020903ACN-122020903-A

Abstract

The invention relates to the field of impeller mechanical part tests and complete machine tests, in particular to a lemniscate flow tube design and three-dimensional numerical calculation method, which comprises the following steps: iteratively calculating the outlet airflow temperature of the flow tube and the outlet airflow density of the flow tube, introducing a flow tube boundary layer correction coefficient, obtaining the diameter of the flow tube through a continuous mass equation, constructing a bell mouth molded surface based on a lemniscate polar coordinate relationship, drawing a size line and an auxiliary line of the flow tube in mechanical design software, constructing a bell mouth near-wall area grid block boundary line through an arc curve, generating flow tube equal-division grids, setting numerical methods and boundary conditions for the flow tube grids, and solving. The lemniscate flow tube design and three-dimensional numerical calculation method provided by the invention are simple and easy to use, have the characteristics of short time, high calculation precision and the like, and can rapidly provide reference for the design of the test scheme of the whole machine or the compressor part of the gas turbine, so that the design risk can be reduced, and the design quality can be improved.

Inventors

DENG QINGFENG
YANG LU
WANG ZHENG
GAO SIHUA
ZHANG ZHOU
HONG QINGSONG

Assignees

中国船舶集团有限公司第七〇三研究所

Dates

Publication Date: 20260512
Application Date: 20260202

Claims (7)

1. A lemniscate flow tube design and three-dimensional numerical calculation method, the method comprising: The method comprises the steps of firstly, assuming the static temperature of the outlet airflow of a flow pipe to be the Mach number of the outlet airflow of the flow pipe, obtaining the airflow speed, and iteratively calculating the temperature of the outlet airflow of the flow pipe and the density of the outlet airflow of the flow pipe through a thermodynamic first law; calculating the obtained flow density of the outlet of the flow tube based on the through flow of the rated working conditions of the whole gas turbine and/or the compressor part, introducing a correction coefficient of the boundary layer of the flow tube based on the obtained flow speed, obtaining the diameter of the flow tube through a continuous mass equation, and rounding; Determining a lemniscate parameter and a polar angle based on the diameter of the flow tube, constructing a bell mouth molded surface based on a lemniscate polar coordinate relationship, drawing a size line and an auxiliary line of the flow tube in mechanical design software through a plurality of grid topological structures of the flow tube, constructing grid block boundary lines of a near-wall area of the bell mouth by using an arc curve, enabling the included angle between the boundary lines of adjacent grid blocks to be maximum and not more than 180 degrees, and enabling the opposite side lengths of the grid blocks to be consistent, thereby completing the design of the lemniscate flow tube; Generating a 1/4 equal division grid of the flow tube through a grid blocking technology, adopting an O-shaped grid in the central area of the flow tube, carrying out local grid encryption on a flow tube button line and a straight tube near-wall area, generating a flow tube whole-circumference grid through rotary replication, and carrying out numerical method and boundary condition setting in a flow tube whole-circumference grid lead-in ANSYSCFX and solving; and fifthly, analyzing the calculation result, calculating the speed distribution of the boundary layer of the section, and verifying the Mach number and the Reynolds number of the airflow at the outlet of the flow tube.
2. The method for designing and calculating three-dimensional values of a lemniscate flow tube according to claim 1, wherein in the first step, the specific air flow velocity is obtained is as follows: ; Wherein V 1 is the outlet air flow speed of the flow pipe, c is the local sound speed, gamma is the gas insulation index, R g is the gas constant, and T 1 is the outlet air flow static temperature of the flow pipe; After the outlet airflow speed of the flow tube is obtained, calculating and solving the outlet airflow temperature of the flow tube through an energy equation of the steady flow of the first law of thermodynamics, wherein the method specifically comprises the following steps: ; wherein: Calculating the outlet airflow temperature of the flow pipe; For the total temperature of the inlet airflow of the flow tube, for the open air inlet condition, Cp is the specific heat at constant pressure at ambient temperature.
3. The method for designing and calculating three-dimensional values of a lemniscate flow tube according to claim 2, wherein the step one further comprises any one of the following iterative judgment settings after obtaining the outlet airflow temperature of the flow tube: Presence of When the number of the organic matters is more than 0.001, Performing iterative calculation; Presence of And stopping iteration when the temperature is less than or equal to 0.001, wherein the calculated outlet airflow temperature of the flow tube is the outlet airflow static temperature of the flow tube.
4. The method for designing and calculating three-dimensional values of a lemniscate flow tube according to claim 1, wherein the calculating step two obtains the flow tube outlet air flow density by calculation specifically comprises: ; wherein: For the total temperature of the inlet airflow of the flow tube, Is the ambient pressure; Static pressure for the outlet airflow of the flow tube; And step two, calculating to obtain the diameter of the flow tube through a continuous mass equation, wherein the method specifically comprises the following steps: ; wherein D is the diameter of the straight pipe section of the flow pipe, G is the rated working condition through-flow of the whole gas turbine or the compressor part, and K G is the correction coefficient of the boundary layer of the flow pipe.
5. The method according to claim 4, wherein the second step is to obtain the flow tube outlet reynolds number by introducing the flow tube outlet aerodynamic viscosity coefficient after obtaining the flow tube diameter, and calculate the displacement thickness circle flow tube diameter when the flow tube outlet reynolds number is in the range of 5×10 5 ～5×10 7 .
6. The method for designing and calculating three-dimensional values of a lemniscate flow tube according to claim 1, wherein in the third step, size lines and auxiliary lines of the flow tube are drawn in mechanical design software based on a multi-block mesh topology structure of the flow tube, including a lemniscate horn mouth line, a straight pipe section line, a far-field opening boundary, an outlet mass flow boundary and a multi-block mesh boundary, and the obtaining of the design size of the lemniscate flow tube is specifically: ; Wherein R is the symmetry center of the lemniscate and corresponds to the straight line distance from the axis datum point of the flow tube to any point on the wall surface of the lemniscate bell mouth, a is the lemniscate shape parameter, Is the angle R with the flow tube axis, i.e., polar angle.
7. The method for designing and calculating the three-dimensional numerical value of the lemniscate flow tube according to claim 1, wherein the third step is to construct a mesh block boundary line of a horn mouth near wall area in a circular arc curve, and the generating process sequentially comprises a surface, a 1/4 body and a whole-circle mesh.

Description

Lemniscate flow tube design and three-dimensional numerical calculation method Technical Field The invention relates to the field of impeller mechanical part tests and complete machine tests, in particular to a lemniscate flow tube design and three-dimensional numerical calculation method. Background The air inlet flow is an important measurement parameter in the test of the whole machine or the compressor part of the gas turbine, represents the running state of the gas turbine or the compressor, and has important significance in the performance evaluation and the state monitoring of the whole machine or the compressor part of the gas turbine. In the performance test of the whole machine or the compressor part of the gas turbine, a method of installing a double-line flow tube at the inlet position of a tester is widely adopted to measure the air mass flow of the whole machine or the compressor part of the gas turbine. When a tester selects a flow tube to perform performance test on the whole gas turbine or a compressor component, two problems are usually encountered, namely whether the diameter and the size of the flow tube are properly selected, and whether the selection position of the pneumatic parameter measurement section is reasonable. The two problems are directly related to the rationality of a test scheme of a whole gas turbine or a compressor part and the accuracy of a test of key performance parameters, and in fact, related research at home and abroad lacks clear and consistent knowledge about the specific application problem of a flow tube, so that a lemniscate flow tube design and a three-dimensional numerical calculation method are needed. Disclosure of Invention Aiming at the technical problems existing in the prior art, the invention provides a lemniscate flow tube design and a three-dimensional numerical calculation method. The technical scheme for solving the technical problems is as follows, a lemniscate flow tube design and three-dimensional numerical calculation method, the method comprises the following steps: The method comprises the steps of firstly, assuming the static temperature of the outlet airflow of a flow pipe to be the Mach number of the outlet airflow of the flow pipe, obtaining the airflow speed, and iteratively calculating the temperature of the outlet airflow of the flow pipe and the density of the outlet airflow of the flow pipe through a thermodynamic first law; calculating the obtained flow density of the outlet of the flow tube based on the through flow of the rated working conditions of the whole gas turbine and/or the compressor part, introducing a correction coefficient of the boundary layer of the flow tube based on the obtained flow speed, obtaining the diameter of the flow tube through a continuous mass equation, and rounding; Determining a lemniscate parameter and a polar angle based on the diameter of the flow tube, constructing a bell mouth molded surface based on a lemniscate polar coordinate relationship, drawing a size line and an auxiliary line of the flow tube in mechanical design software through a plurality of grid topological structures of the flow tube, constructing grid block boundary lines of a near-wall area of the bell mouth by using an arc curve, enabling the included angle between the boundary lines of adjacent grid blocks to be maximum and not more than 180 degrees, and enabling the opposite side lengths of the grid blocks to be consistent, thereby completing the design of the lemniscate flow tube; Generating a 1/4 equal division grid of the flow tube through a grid blocking technology, adopting an O-shaped grid in the central area of the flow tube, carrying out local grid encryption on a flow tube button line and a straight tube near-wall area, generating a flow tube whole-circumference grid through rotary replication, and carrying out numerical method and boundary condition setting in a flow tube whole-circumference grid lead-in ANSYSCFX and solving; and fifthly, analyzing the calculation result, calculating the speed distribution of the boundary layer of the section, and verifying the Mach number and the Reynolds number of the airflow at the outlet of the flow tube. In a preferred embodiment, in the first step, the air flow velocity is obtained specifically as follows: ; Wherein V 1 is the outlet air flow speed of the flow pipe, c is the local sound speed, gamma is the gas insulation index, R g is the gas constant, and T 1 is the outlet air flow static temperature of the flow pipe; the first step is to calculate the temperature of the outlet airflow of the flow pipe through the energy equation of the steady flow of the first law of thermodynamics after the outlet airflow speed V 1 of the flow pipe is obtained The method specifically comprises the following steps: ; wherein: Calculating the outlet airflow temperature of the flow pipe; For the total temperature of the inlet airflow of the flow tube, for the open air inlet condition, Cp is