A method for detecting the flow area of ​​complex throttling parts

Abstract

The present invention provides a method for detecting the flow area of ​​complex throttling parts, comprising the following steps: the wind provided by the fan passes through a multi-layer rectifier damping net and a rectifier grid to break up the large vortices in the airflow and turn it into a uniform flow field; the airflow after rectification enters the pressure chamber, and the parts to be tested are arranged at the other end of the pressure chamber. During the test, the required pressure in the pressure chamber is set, and the required pressure is graded according to the flow area of ​​the tested parts. When the pressure in the pressure chamber is lower than the required pressure, the input current frequency of the variable frequency motor is increased, thereby increasing the motor and fan speed; when the pressure is higher than the set required pressure, the motor speed is reduced; through the proportional differential integral algorithm, the pressure chamber position is set at a constant pressure value, and the fan speed value is recorded. The obtained flow area needs to be corrected. The present invention realizes the flow area detection of throttling parts with high efficiency, high precision and low energy consumption.

Description

Technical Field

[0001] The present invention relates to a flow area detection method for complex throttling parts. Aiming at the flow area detection needs of complex throttling parts in the aviation, aerospace and other industries, the method realizes efficient, high-precision and low-energy consumption flow area detection of throttling parts, and belongs to the field of detection technology. Background Art

[0002] The turbine is one of the core components of the gas turbine engine power unit. It is a turbine machine that converts the energy of high-temperature, high-pressure combustion gas into kinetic energy and mechanical energy. The high-temperature, high-pressure combustion gas flows from the turbine inlet through the guide blade row and turns and expands, converting the potential energy of the combustion gas into the kinetic energy of the combustion gas. The high-speed combustion gas emits mechanical work through the rotor blades, which can be supplied to the compressor by the gas turbine shaft for air compression. The compressor, combustion chamber and gas turbine constitute the gas generator. The generated combustion gas supplies the power turbine as shaft power output or drives the blades, fans, etc., thus deriving different types of gas turbine engines, including turboshafts, turboprops, turbofans, etc.

[0003] When such aircraft engines and gas turbines are working, the flow capacity of the gas turbine and the power turbine determines the distribution of the expansion ratio of the high-pressure gas since the combustion chamber outlet, and this ratio has a decisive influence on the overall performance of the engine. Therefore, the flow capacity of the turbine is crucial. Generally speaking, the key parts that determine the flow capacity of gas turbines and power turbines are gas turbine and power turbine guides, which are composed of a full ring of blades composed of multiple turbine blades. The throttling position is at the minimum point of the contraction channel composed of adjacent blades. Together with the upper and lower flow channels of the parts, it forms a flow area, see the attachment Figure 2 , Figure 3 Engineering practice shows that due to the irregular shape of the area, its location is difficult to determine, and direct measurement cannot achieve the required accuracy, so other technical approaches must be used.

[0004] At present, the main testing methods for the guided flow area (flow capacity) in China include direct dimension measurement, water flow test, flow function test and other methods.

[0005] Among them, direct size measurement is to directly measure the channel using three-coordinate or optical methods. However, since the throat that affects the energy-saving ability of the part is irregular and its size is very small, engineering practice shows that its accuracy cannot reach the range of ±1%. Due to the large number of guide blades, the measurement efficiency is very low and time-consuming.

[0006] The water flow test builds a large water container and determines the throttling capacity of the parts by the time it takes for the same volume of water to be discharged through the guide. This method cannot meet the accuracy requirements due to the fact that the viscosity of water changes greatly with temperature and the operator's subjective judgment of time.

[0007] The flow function test is the most accurate and widely used test method. This method follows the law of motion similarity in fluid mechanics and simulates the state of airflow in the engine through conversion. During the test bench test, the throttling device is arranged downstream, and the volume flow rate of the airflow passing through is measured by a sonic venturi. The flow function value is calculated by converting it into a mass flow rate and combining it with the measured inlet total temperature and total pressure. The advantage of this method is that the accuracy can reach ±0.7%, which can meet the requirements of engine development, but it also has many disadvantages. This method requires the establishment of an independent test bench and a high-pressure gas source station, with a construction cost of tens of millions. The single test time is long and the test requires many people to participate. Summary of the invention

[0008] In response to the demand for flow area detection of complex throttling parts in the aviation, aerospace and other industries, the present invention proposes a method for detecting the effective flow area of ​​complex throttling parts with high efficiency, rapidness, high precision and low cost, thereby realizing efficient, high-precision and low-energy consumption flow area detection of throttling parts.

[0009] The present invention uses normal temperature air as the medium and a fan as the air source. The energy-saving capacity of the guide is calculated through the direct correlation between the pressure difference before and after the standard orifice plate guide and the fan speed. Tests show that this method has high test efficiency, low test cost and high test accuracy. The specific technical solution is:

[0010] A method for detecting the flow area of ​​complex throttling parts comprises the following steps:

[0011] (1) The variable frequency motor drives the fan to generate a large air volume and provide wind pressure head;

[0012] (2) The wind provided by the fan passes through multiple layers of rectifying damping nets and rectifying grids to break up the large vortices in the airflow, turning it into a flow field with uniform pressure and turbulence;

[0013] After rectification, the airflow enters the pressure chamber, where temperature and pressure probes are arranged to measure the temperature and static pressure value in the pressure chamber;

[0014] The parts to be tested are arranged at the other end of the pressure chamber, and the airflow in the pressure chamber is discharged into the atmosphere through this end;

[0015] During the test, the required pressure in the pressure chamber is set, and the required pressure is graded according to the flow area of ​​the tested part. When the pressure in the pressure chamber is lower than the required pressure, the input current frequency of the variable frequency motor is increased, thereby increasing the motor and fan speed to achieve the purpose of increasing the air volume and pressure; when the pressure is higher than the set required pressure, the motor speed is reduced;

[0016] (3) Use the proportional differential integral algorithm to set the pressure chamber to a constant pressure value. At this time, record the fan speed value.

[0017] The test uses a set of standard orifice plates or other throttling elements with known throttling areas for calibration to obtain the corresponding relationship between pressure, speed and area. The speed value at the set pressure obtained in the test is interpolated to obtain the flow area of ​​the tested part.

[0018] In step (3), the test parameters also include atmospheric pressure, atmospheric temperature, pressure chamber temperature, rectifier front end pressure, gas exhaust temperature, and atmospheric humidity.

[0019] (4) The flow area obtained from the test needs to be corrected. The flow coefficient needs to be corrected. The Reynolds value of the flow field of the test piece needs to be calculated from the test parameters;

[0020] In step (4), the Reynolds number calculation formula is as follows:

[0021] Re=ρvL / μ

[0022] ρ and μ are the fluid density and dynamic viscosity coefficient, v and L are the characteristic velocity and characteristic length of the flow field. Reynolds number physically represents the ratio of the magnitude of inertial force and viscous force. The characteristic length is the orifice plate diameter, and the outlet airflow velocity is calculated by the atmospheric pressure and the constant pressure chamber pressure.

[0023] The flow coefficient is calculated by the Reynolds number, and the effective flow area is obtained by making corrections based on the known physical area of ​​the orifice plate.

[0024] Beneficial effects brought by the technical solution of the present invention:

[0025] The test design of the present invention occupies a small area, has a low investment cost, and is movable;

[0026] The test equipment produced according to the present invention has a high test accuracy of ±0.5% for the flow area of ​​parts;

[0027] The test equipment produced according to the present invention has low test cost, and only one operator is required, which is low in cost;

[0028] The test equipment of the present invention has a wide range of test parts and can be customized according to requirements;

[0029] The equipment produced by the method of the present invention has low maintenance cost. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Figure 1 It is a schematic diagram of the technical solution of the present invention;

[0031] Figure 2 It is a schematic diagram of a typical turbine guide vane, which consists of upper and lower flow channels and a cascade channel composed of blades.

[0032] Figure 3This is a schematic diagram of the airflow passing through the turbine guide vane in the blade cascade cross section. The airflow is accelerated in the blade cascade channel, and the smallest position is the throat. DETAILED DESCRIPTION

[0033] The specific technical solution of the present invention is explained in conjunction with embodiments.

[0034] like Figure 1 As shown, a method for detecting the flow area of ​​complex throttling parts includes the following steps:

[0035] (1) The variable frequency motor drives the fan to generate a large air volume and provide wind pressure head;

[0036] (2) The wind provided by the fan passes through multiple layers of rectifying damping nets and rectifying grids to break up the large vortices in the airflow, turning it into a flow field with uniform pressure and turbulence;

[0037] After rectification, the airflow enters the pressure chamber, where temperature and pressure probes are arranged to measure the temperature and static pressure value in the pressure chamber;

[0038] The parts to be tested are arranged at the other end of the pressure chamber, and the airflow in the pressure chamber is discharged into the atmosphere through this end;

[0039] During the test, the required pressure in the pressure chamber is set, and the required pressure is divided into grades according to the flow area of ​​the tested parts. When the pressure in the pressure chamber is lower than the required pressure, the input current frequency of the variable frequency motor is increased through the programmable logic controller (PLC), thereby increasing the motor and fan speed to achieve the purpose of increasing the air volume and pressure; when the pressure is higher than the set required pressure, the motor speed is reduced.

[0040] (3) The pressure chamber is set to a constant pressure value through the proportional differential integral (PID) algorithm. At this time, the fan speed value is recorded.

[0041] At the same time, the test parameters mainly include atmospheric pressure, atmospheric temperature, pressure chamber temperature, rectifier front end pressure, gas exhaust temperature, atmospheric humidity, etc.

[0042] The test uses a set of standard orifice plates or other throttling elements with known throttling areas for calibration to obtain the corresponding relationship between pressure, speed and area. The speed value at the set pressure obtained in the test is interpolated to obtain the flow area of ​​the tested part.

[0043] (4) The flow area obtained from the test needs to be corrected. Since the airflow state of different parts under different pressure and atmospheric conditions is different, the flow coefficient needs to be corrected. The Reynolds number of the flow field of the test piece needs to be calculated from the test parameters. The Reynolds number calculation formula is as follows:

[0044] Re=ρvL / μ

[0045] ρ and μ are the fluid density and dynamic viscosity coefficient, v and L are the characteristic velocity and characteristic length of the flow field. Reynolds number physically represents the ratio of the magnitude of inertial force and viscous force. The characteristic length here is the orifice plate diameter, and the outlet airflow velocity is calculated by the atmospheric pressure and the constant pressure chamber pressure.

[0046] The flow coefficient is calculated using the Reynolds number and corrections are made to the known physical area of ​​the orifice to obtain the effective flow area.

Claims

1. A method for detecting the flow area of ​​complex throttling parts, characterized in that: The following steps are involved: (1) The variable frequency motor drives the fan to generate a large air volume and provide wind pressure head; (2) The wind provided by the fan passes through multiple layers of rectifying damping nets and rectifying grids to break up the large vortices in the airflow, turning it into a flow field with uniform pressure and turbulence; After rectification, the airflow enters the pressure chamber, where temperature and pressure probes are arranged to measure the temperature and static pressure value in the pressure chamber; The parts to be tested are arranged at the other end of the pressure chamber, and the air flow in the pressure chamber is discharged into the atmosphere through this end; During the test, the required pressure in the pressure chamber is set, and the required pressure is divided into grades according to the flow area of ​​the tested parts; when the pressure in the pressure chamber is lower than the required pressure, the input current frequency of the variable frequency motor is increased, thereby increasing the motor and fan speed to achieve the purpose of increasing the air volume and pressure; when the pressure is higher than the set required pressure, the motor speed is reduced; (3) Using the proportional differential integral algorithm, the pressure chamber is positioned at a constant pressure value; at this time, the fan speed value is recorded; The test uses a set of standard orifice plates or other throttling elements with known throttling areas for calibration to obtain the corresponding relationship between pressure, speed and area; the speed value at the set pressure obtained in the test is interpolated to obtain the flow area of ​​the tested parts; (4) The flow area obtained from the test needs to be corrected; the flow coefficient needs to be corrected; The Reynolds value of the flow field of the test piece needs to be calculated from the test parameters; The flow coefficient is calculated using the Reynolds number and corrections are made to the known physical area of ​​the orifice to obtain the effective flow area.

2. A method for detecting the flow area of ​​complex throttling parts according to claim 1, characterized in that: In step (3), the test parameters also include atmospheric pressure, atmospheric temperature, pressure chamber temperature, rectifier front end pressure, gas exhaust temperature, and atmospheric humidity.

3. A method for detecting the flow area of ​​complex throttling parts according to claim 1, characterized in that: In step (4), the Reynolds number calculation formula is as follows: Re=ρvL / μ ρ and μ are the fluid density and dynamic viscosity coefficient, v and L are the characteristic velocity and characteristic length of the flow field; the Reynolds number physically represents the ratio of the inertial force and the viscous force level; the characteristic length is the orifice diameter, and the outlet air flow velocity is calculated by the atmospheric pressure and the constant pressure chamber pressure.

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