An IGV loss test calculation method and an IGV loss and inlet flow calibration method

Abstract

The present application relates to a kind of IGV loss calculation method and application, specifically to a kind of IGV loss test calculation method and the calibration method of IGV loss and import flow, for solving the problem that only relying on experience estimation IGV loss in prior art leads to big error, lack of test data support.This application sets up flow measuring device in the front end of import pipeline, sets up first parameter measuring device before IGV, flow measuring device after, sets up second parameter measuring device in the annular cavity wall surface after IGV, before impeller import;IGV import total pressure and total temperature are calculated by measurement value, by obtaining import flow, combined with measured static pressure, based on isentropic adiabatic flow and continuity principle, calculate IGV after total pressure, and then obtain IGV loss.This application further determines average loss coefficient A by multi-condition test fitting, obtains loss model.This application realizes the accurate test of IGV loss, can provide basis for the basic level performance calculation of not having IGV or the performance prediction of having IGV, reduces test number, saves cost.

Description

Technical Field

[0001] This invention relates to an IGV loss calculation method and its application, specifically to an IGV loss test and calculation method and a calibration method for IGV loss and inlet flow rate. Background Technology

[0002] IGV (Inlet Guide Vane) is a crucial regulating component in centrifugal compressors. When user system processes change, the centrifugal compressor needs to adjust its operating conditions to match user demands. The IGV adjusts the inlet flow rate and pre-swirl by rotating the guide vane angle, thereby shifting the operating point and regulating the performance of the centrifugal compressor. It is a key means of enabling variable-condition operation of centrifugal compressors. Accurately understanding the pressure loss characteristics of the IGV in the basic stage design and overall design of centrifugal compressors is of great significance for optimizing compressor efficiency and guiding on-site operation and adjustment.

[0003] Currently, existing research on IGVs mainly focuses on optimizing the structure of the blades themselves. For example, Chinese patent CN108291485A discloses a method for optimizing the performance of inlet guide vanes and corresponding products. This method improves the IGV blade's performance by incorporating structural improvements such as twisting, bending, surface textures, sealing features, tip leakage reduction features, vanes, or internal channels. These improvements reduce the pressure loss of the IGV blade itself, decrease secondary flow, and improve flow stability. This technical solution provides multiple improvement ideas for the structural design of IGV blades and can reduce the pressure loss of the IGV itself to a certain extent.

[0004] However, in the engineering applications of centrifugal compressors, in addition to the structural design of the IGV blades themselves, accurately assessing the loss characteristics of the IGV under actual operating conditions is equally crucial. On the one hand, the actual loss of the IGV depends not only on the blade structure itself, but also on various factors such as incoming flow conditions, machine Mach number, guide vane opening, and matching of upstream and downstream pipelines. Optimizing the blade structure cannot completely replace the accurate measurement of actual operating losses. On the other hand, when centrifugal compressors are running in the field, the IGV often needs to be adjusted according to the actual operating conditions. If the quantitative relationship between IGV losses and flow rate, machine Mach number, and guide vane angle can be accurately grasped, reliable experimental data can be provided to support the performance prediction and operation optimization of centrifugal compressors.

[0005] Currently, the commonly used method for calculating IGV losses is estimation based on actual on-site operating data. This method can be used to estimate losses at the fully open IGV guide vane angle, but the calculation deviation is relatively large, especially when the guide vane angle is small. This estimation method lacks reliable experimental data support, which means that during the centrifugal compressor product design stage, when the basic stage test includes IGV but the product structural design does not, or vice versa, designers cannot accurately know the impact of IGV losses on the overall performance and can only rely on experience and limited data for rough estimation. This uncertainty often causes the centrifugal compressor to deviate from its high-efficiency point in the field, necessitating adjustments to the centrifugal compressor performance to meet user process requirements, thus sacrificing the operating efficiency of the centrifugal compressor and failing to achieve the design goals of high efficiency and energy saving. Summary of the Invention

[0006] The purpose of this invention is to solve the technical problems of large errors and lack of experimental data support caused by relying solely on experience to estimate IGV loss in the existing technology, and to provide an IGV loss test and calculation method and a calibration method for IGV loss and inlet flow rate.

[0007] To achieve the above objectives, the technical solution provided by this invention is as follows:

[0008] An IGV loss test calculation method for testing the IGV loss of a centrifugal compressor, characterized by the following steps:

[0009] S1. A flow measurement device is installed at the front end of the inlet pipe of the centrifugal compressor under test. A first parameter measurement device is installed before the IGV of the centrifugal compressor under test and after the flow measurement device. A second parameter measurement device is installed after the IGV of the centrifugal compressor under test and before the impeller inlet.

[0010] S2. Obtain the inlet pipe flow rate Q of the centrifugal compressor under test through the flow measurement device. m ;

[0011] S3. Measure the static pressure P of the airflow before the centrifugal compressor IGV under test using the first parameter measuring device. 3s Based on the airflow temperature T3, the total pressure P at the IGV inlet is calculated. 1st and total temperature T 1st ;

[0012] S4. Measure the static pressure P after the IGV and before the impeller inlet of the centrifugal compressor under test using the second parameter measuring device. 0s ;

[0013] S5. Based on the principles of isentropic adiabatic flow and continuity, and the inlet pipe flow rate Q... m Total temperature T at the IGV inlet1st The static pressure P measured by the second parameter measuring device 0s Calculate the total pressure P after the IGV of the centrifugal compressor under test and before the impeller inlet. 0st ;

[0014] S6. Based on the total pressure P at the IGV inlet obtained in step S3... 1st The total pressure P obtained in step S5 after the IGV of the centrifugal compressor under test and before the impeller inlet 0st The IGV loss is calculated, and the test calculation of IGV loss is completed.

[0015] Further, in step S1, the flow measurement device includes a nozzle, a differential pressure transmitter, a first pressure sensor, and a first temperature sensor; the high-pressure probe and low-pressure probe of the differential pressure transmitter are respectively disposed at the front and rear ends of the nozzle to acquire the nozzle differential pressure. The first pressure sensor and the first temperature sensor are both located at appropriate positions in front of the nozzle to measure relevant parameters in order to calculate the upstream density ρ of the nozzle.

[0016] The first parameter measuring device includes a second pressure sensor and a second temperature sensor;

[0017] The second parameter measuring device is a third pressure sensor, which is installed on the annular cavity wall after the centrifugal compressor IGV under test and before the impeller inlet.

[0018] Furthermore, step S2 specifically includes:

[0019] The nozzle differential pressure ∆P and related parameters are obtained using a flow measurement device, and the upstream density ρ of the nozzle is calculated. Based on the nozzle flow calculation formula, the inlet pipe flow rate Q of the centrifugal compressor under test is calculated. m ;

[0020] The inlet pipe flow rate Q m The calculation formula is:

[0021] ;

[0022] In the formula, Q m The unit is kg / s; α is the nozzle flow coefficient; ε is the nozzle expansion coefficient; d is the nozzle diameter, in meters; ρ is in kg / m³. 3 ; The unit is Pa.

[0023] Furthermore, step S3 specifically includes:

[0024] The static pressure P of the airflow before the IGCV of the centrifugal compressor under test is measured using the second pressure sensor. 3sThe airflow temperature T3 before the IGV of the centrifugal compressor under test is measured by a second temperature sensor, and the total pressure P at the IGV inlet is calculated accordingly. 1st and total temperature T 1st .

[0025] Furthermore, in step S3, the total pressure P at the IGV inlet... 1st The calculation formula is:

[0026] ;

[0027] In the formula, P 3st δP represents the total airflow pressure before the IGV of the centrifugal compressor under test, in Pa. 3-1 The unit is Pa, representing the pipe loss from the first parameter measuring device to the IGV inlet; ρ3 is the airflow density at the first parameter measuring device; v3 is the airflow velocity at the first parameter measuring device; and ξ is the pipe loss coefficient.

[0028] The formula for calculating the airflow density ρ3 at the first parameter measuring device is:

[0029] ;

[0030] In the formula, R is the airflow constant; T 3s The static airflow temperature at the second temperature sensor is expressed in Kelvin (K).

[0031] The static airflow temperature T at the second temperature sensor 3s The calculation formula is:

[0032]

[0033] Where γ is the recovery coefficient of the second temperature sensor, and c p Specific heat at constant pressure of airflow, expressed in J / (kg·K);

[0034] The formula for calculating the airflow velocity v3 at the first parameter measuring device is:

[0035] ;

[0036] In the formula, A3 is the cross-sectional area of ​​the pipe at the first parameter measuring device, in m². 2 ;

[0037] The total temperature T at the IGV inlet 1st The calculation formula is:

[0038]

[0039] In the formula, T 3stThe total airflow temperature at the second temperature sensor is in Kelvin (K); k is the airflow adiabatic index (M). a3 The machine Mach number at the second temperature sensor;

[0040] The machine Mach number M at the second temperature sensor a3 The calculation formula is:

[0041] .

[0042] Furthermore, step S4 specifically includes:

[0043] The static pressure P after the centrifugal compressor IGV and before the impeller inlet is measured using the third pressure sensor. 0s ;

[0044] In step S6, the formula for calculating the IGV loss is:

[0045] ;

[0046] In the formula, δP IGV For IGV loss.

[0047] Furthermore, step S5 specifically includes:

[0048] S5.1. Based on the principles of isentropic adiabatic flow and continuity, and the inlet pipe flow rate Q... m and the static pressure P measured by the third pressure sensor 0s Establish the static temperature T of the airflow after the IGV and before the impeller inlet of the centrifugal compressor under test. 0s With the total temperature of the airflow T 0st temperature ratio ;

[0049] S5.2, Based on the temperature ratio obtained in step S5.1 The total pressure P after the IGV of the centrifugal compressor under test and before the impeller inlet was calculated. 0st .

[0050] Furthermore, in step S5.1, the temperature after the IGV of the centrifugal compressor under test and before the impeller inlet is higher than that of the IGV. The calculation formula is:

[0051] ;

[0052] In the formula, M 2 The number of intermediate generations is defined based on flow rate and geometric parameters, and its physical meaning is related to the machine Mach number after IGV.

[0053] The number of intermediate generations M 2 The calculation formula is:

[0054] ;

[0055] In the formula, A0 is the area after the IGV of the centrifugal compressor under test and before the impeller inlet, in m². 2 R is the gas constant, with units of J / (kg·K);

[0056] T 0st The total temperature after the IGV of the centrifugal compressor under test and before the impeller inlet is calculated using the following formula:

[0057] ;

[0058] In step S5.2, the total pressure P after the IGV of the centrifugal compressor under test and before the impeller inlet is... 0st The calculation formula is:

[0059] ;

[0060] In the formula, T represents the temperature ratio between the IGV outlet and the impeller inlet of the centrifugal compressor under test. 0s The static temperature of the airflow after the IGV of the centrifugal compressor under test and before the impeller inlet.

[0061] Meanwhile, this invention also provides a method for calibrating IGV loss and inlet flow rate, which is characterized by including the following steps:

[0062] S1. Under multiple preset operating conditions of the centrifugal compressor under test, the above-mentioned IGV loss test calculation method is executed to obtain multiple sets of IGV losses and their corresponding inlet pipe flow rates Q. m Multiple preset operating conditions are operating conditions at different IGV angles or different machine Mach numbers;

[0063] S2, based on multiple sets of IGV losses and their corresponding inlet pipeline flow rates Q m The average loss coefficient A of the IGV is determined by fitting, and the relationship between IGV loss and inlet pipe flow rate Q is obtained. m The corresponding relationship was established to complete the calibration of IGV loss and inlet flow.

[0064] Furthermore, step S1 specifically includes:

[0065] S1.1 Select one operating condition from the different IGV angles or different machine Mach numbers of the centrifugal compressor under test;

[0066] S1.2 Under this operating condition, perform the above IGV loss test calculation method to obtain a set of IGV losses and their corresponding inlet pipe flow rates Q. m ;

[0067] S1.3. Select another operating condition from the different IGV angles or different machine Mach numbers of the centrifugal compressor under test, and return to step S1.2, until all operating conditions of the centrifugal compressor under test have been traversed, obtaining multiple sets of IGV losses and their corresponding inlet pipe flow rates Q. m ;

[0068] In step S2, the IGV loss is related to the inlet pipe flow rate Q. m The expression for the correspondence is:

[0069]

[0070] In the formula, δP IGV For IGV loss.

[0071] Compared with the prior art, the present invention has the following beneficial technical effects:

[0072] 1. This invention provides an IGV loss test and calculation method. By setting measurement points at the front end of the inlet pipe, before the IGV and after the flow measurement device, and after the IGV and before the impeller inlet, and establishing a complete test and calculation process, quantitative testing of IGV loss is achieved. This solves the problem of large errors caused by relying solely on empirical estimation in the prior art, and provides reliable experimental data support for the design of centrifugal compressors.

[0073] 2. This invention provides a method for calculating IGV loss testing. By employing a nozzle as the flow measurement device and a second pressure sensor and a second temperature sensor to measure static pressure and temperature respectively, the functions of each measuring device are clearly defined and their selection is mature, ensuring measurement accuracy while reducing the implementation cost of the testing system. Simultaneously, the inlet pipe flow rate Q is accurately obtained through the nozzle flow rate calculation formula. m By utilizing a standardized throttling flow measurement method, the flow data can be traced back to national standards, laying the foundation for the accuracy of subsequent IGV loss calculations.

[0074] 3. This invention provides an IGV loss test calculation method. It calculates the total pressure and total temperature by measuring static pressure with a second pressure sensor and temperature with a second temperature sensor. This fully utilizes the low velocity and stable flow characteristics of the airflow before the IGV, simplifying the total pressure acquisition method while ensuring calculation accuracy. Simultaneously, by introducing isentropic adiabatic flow and the continuity principle to complete the density and velocity calculations, a complete IGV inlet total pressure and total temperature calculation chain is constructed, realizing the calculation from the inlet pipe flow rate Q. m The complete transfer of specific flow parameters provides accurate upstream boundary conditions for IGV loss calculation. At the same time, it takes into account pipeline loss factors, making the calculation structure consistent with the actual physical process, and further improving the calculation accuracy of the total pressure at the IGV inlet.

[0075] 4. The present invention provides an IGV loss test calculation method. By setting a third pressure sensor on the annular cavity wall before the IGV impeller inlet to measure the static pressure, and combining it with the calculated IGV inlet total pressure, the IGV loss is directly calculated using the total pressure difference definition. The calculation logic is clear and the physical meaning is obvious, avoiding the introduction of complex empirical correction coefficients.

[0076] 5. This invention provides a method for calculating IGV loss by introducing a temperature ratio formula and a total pressure formula based on isentropic adiabatic flow, along with a defined intermediate generation number M. 2 This method overcomes the shortcomings of traditional Bernoulli equations in calculating high machine Mach numbers, and achieves accurate calculation of the total pressure after IGV under compressible fluid conditions, making the method applicable to a wider range of operating conditions.

[0077] 6. This invention provides a calibration method for IGV loss and inlet flow rate. By repeatedly testing the centrifugal compressor under test at multiple IGV angles or multiple machine Mach numbers and obtaining multiple sets of loss and flow rate data, a correspondence between IGV loss and flow rate is established. This method can be used to predict the loss characteristics of the same model or type of IGV under different operating conditions, avoiding repeated testing and saving testing costs. Furthermore, by quantifying the relationship between IGV loss and flow rate into a corresponding formula and using experimental data fitting to determine the average loss coefficient A, a simple and accurate IGV loss calculation model is provided for engineering designers. This model can be directly used for predicting the overall performance and optimizing the operation of centrifugal compressors, improving design efficiency and operational economy. Attached Figure Description

[0078] Figure 1 This is a flowchart illustrating an embodiment of the IGV loss test calculation method of the present invention;

[0079] Figure 2 This is a schematic diagram of the structure of the measuring device in step S1 of an embodiment of the IGV loss test calculation method of the present invention (in the figure, 0# represents the installation position of the second parameter measuring device, 1# represents the IGV flange section, 3# represents the installation position of the first parameter measuring device, and 5# represents the installation position of the flow measuring device).

[0080] Figure 3 This is a schematic flowchart illustrating an embodiment of the IGV loss and inlet flow calibration method of the present invention. Detailed Implementation

[0081] To make the objectives, advantages, and features of the present invention clearer, the following detailed description, in conjunction with the accompanying drawings and specific embodiments, provides a method for calculating IGV loss and calibrating IGV loss relative to inlet flow rate. Those skilled in the art should understand that these embodiments are merely illustrative of the technical principles of the present invention and are not intended to limit the scope of protection of the present invention.

[0082] An IGV loss test and calculation method is provided for testing and calculating the IGV loss of a centrifugal compressor, such as... Figure 1 As shown, the specific steps include the following:

[0083] S1. Setting up the measuring device

[0084] In the test system of the centrifugal compressor under test, the following are arranged sequentially along the airflow direction: Figure 2 The measurement section shown:

[0085] Section 5 (where a flow measurement device is installed): Located at the front end of the inlet pipe of the centrifugal compressor under test, the flow measurement device at this section is a nozzle in this embodiment, used to measure the inlet pipe flow rate Q. m The nozzle's structure, dimensions, and installation method all comply with relevant testing standards (such as ASME PTC-10 or GB / T 25630). Pressure taps are located before and after the nozzle, connecting to the high and low pressure sides of a differential pressure transmitter respectively, for acquiring the nozzle differential pressure. Meanwhile, a first pressure sensor and a first temperature sensor are installed at an appropriate position upstream of the nozzle to measure relevant parameters and calculate the upstream density ρ of the nozzle.

[0086] Section 3 (where the first parameter measuring device is installed): Located before the IGV of the centrifugal compressor under test and after the flow measuring device (i.e., on the inlet pipe after section 5). At this section, four static pressure measuring points are arranged at 90° intervals around the pipe circumference according to the testing standard. The results from each measuring point are collected via an equalizing ring and then connected to a second pressure sensor to obtain the average static pressure P at this section. 3s Simultaneously, a second temperature sensor (such as a platinum resistance thermometer or thermocouple) is installed at this cross-section to measure the gas flow temperature T3. It should be noted that cross-section #3 is located on a straight pipe section upstream of the IGV, where the gas flow velocity is low (machine Mach number is typically less than 0.15), and the flow is stable and uniform. Therefore, the influence of velocity on parameters such as pressure and temperature can be ignored, and the total pressure can be calculated from static pressure using Bernoulli's equation, making the calculation simple and quick. However, in this invention, considering the pipe loss between cross-section #3 and the IGV inlet, a pipe loss coefficient ξ is introduced to correct the total pressure calculation and improve the calculation accuracy.

[0087] Section 1 (IGV flange section): Located at the IGV inlet flange of the centrifugal compressor under test, representing the actual inlet position of the IGV. Since the airflow state at this section is complexly affected by the IGV guide vane adjustment, directly arranging measuring points at this section presents space constraints and measurement difficulties. Therefore, this invention does not directly measure the parameters of section 1, but instead uses the measured value of section 3, subtracting the pipe loss δP between the two.3-1 Indirectly obtain the total pressure P at the IGV inlet 1st and total temperature T 1st This indirect acquisition method ensures measurement accuracy while overcoming the engineering difficulties of directly setting up measuring points at the IGV flange.

[0088] Section 0# (where the second parameter measuring device is installed): Located on the annular cavity wall after the IGV and before the impeller inlet. This section is one of the key measuring points of this invention. Unlike the traditional measuring point arrangement of a straight pipe section with uniform cross-section, section 0# is located in the annular contraction cavity after the airflow passes through the IGV guide vanes. Due to the throttling and guiding effect of the IGV guide vanes, the airflow velocity at this section increases dramatically, the machine Mach number is much greater than 0.15, and there is swirling flow. The velocity direction has a certain angle with the measuring section and is unevenly distributed. Under these conditions of high machine Mach number, compressibility, and non-uniform flow, the traditional Bernoulli equation based on the incompressibility assumption is no longer applicable, and a total pressure calculation method based on isentropic adiabatic flow is required.

[0089] At section 0#, a static pressure measuring hole is opened only on the wall of the annular cavity, and the wall static pressure P at this section is measured by a third pressure sensor. 0s The specific location of the measuring holes should avoid the direct wake region of the IGV guide vane trailing edge and be selected in the middle section of the annular cavity to obtain representative static pressure values. This measuring point arrangement fully utilizes the response characteristics of the annular cavity wall static pressure to the total airflow pressure, avoiding the technical difficulties of directly measuring the total pressure in high-speed swirling airflow.

[0090] This invention obtains the necessary original measurement parameters by arranging the measuring points on the above three cross sections.

[0091] S2. Obtain the inlet pipe flow rate Q of the centrifugal compressor under test using a flow measurement device. m Specifically:

[0092] The nozzle differential pressure is obtained through a flow measurement device. The relevant parameters were obtained, and the upstream density ρ of the nozzle was calculated. Based on the nozzle flow rate calculation formula, the inlet pipe flow rate Q of the centrifugal compressor under test was calculated. m .

[0093] Among them, the inlet pipeline flow rate Q m The calculation formula is:

[0094] ;

[0095] In the formula, Q mThe unit is kg / s; α is the nozzle flow coefficient, determined by the nozzle geometry and Reynolds number, which can be obtained through calibration or by consulting relevant standards; ε is the nozzle expansion coefficient, used to correct for the influence of gas compressibility on flow measurement; d is the nozzle diameter, in meters; ρ is the upstream density of the nozzle, in kg / m³. 3 The value is calculated from the upstream static pressure and temperature using the ideal gas law. The nozzle differential pressure is expressed in Pa. The methods for obtaining and calculating these parameters are common knowledge in this field and will not be elaborated upon here.

[0096] S3. Measure the static pressure P of the airflow before the centrifugal compressor IGV under test using the first parameter measuring device. 3s Based on the airflow temperature T3, the total pressure P at the IGV inlet is calculated. 1st and total temperature T 1st Specifically:

[0097] First, calculate the airflow velocity v3 at section 3 (the first parameter measuring device). The calculation formula is as follows:

[0098] ;

[0099] In the formula, A3 is the cross-sectional area of ​​the pipe at the first parameter measuring device, in m². 2 ρ3 is the airflow density at the first parameter measuring device, calculated using the ideal gas law, and its calculation formula is:

[0100] ;

[0101] In the formula, R is the airflow constant; T 3s The static temperature of the airflow at the second temperature sensor is expressed in Kelvin (K).

[0102] Then, the static pressure P of the airflow before the IGV of the centrifugal compressor under test is measured using a second pressure sensor. 3s The airflow temperature T3 before the IGV of the centrifugal compressor under test is measured by a second temperature sensor, and the total pressure P at the IGV inlet is calculated accordingly. 1st and total temperature T 1st .

[0103] Among them, the total pressure P at the IGV inlet 1st The calculation formula is:

[0104] ;

[0105] In the formula, P 3st δP represents the total airflow pressure before the IGV of the centrifugal compressor under test, in Pa. 3-1The unit is Pa, representing the pipe loss from the first parameter measuring device to the IGV inlet; ρ3 is the airflow density at the first parameter measuring device; v3 is the airflow velocity at the first parameter measuring device; and ξ is the pipe loss coefficient, which can be determined by the straight pipe section loss formula or by experimental calibration. In engineering practice, if the distance between section #3 and the IGV inlet is relatively close and the inner wall of the pipe is smooth, the pipe loss is small. In some embodiments, this correction can be ignored, i.e., ξ=0.

[0106] The airflow temperature T3 and the static temperature T measured by the second temperature sensor 3s The following relationship exists between them:

[0107] ;

[0108] Wherein, γ is the recovery coefficient of the second temperature sensor, typically ranging from 0.85 to 0.95, with the specific value determined by the sensor's form and installation method; c p It is the specific heat of the gas at constant pressure, and the unit is J / (kg·K).

[0109] Since there is no external work input and no heat exchange between section 3 and the IGV inlet (section 1), and the flow is adiabatic, the total temperature is conserved, i.e., T. 1st =T 3st Therefore, the total temperature T at the IGV inlet... 1st The calculation formula is:

[0110] ;

[0111] In the formula, T 3st The total airflow temperature at the second temperature sensor is in Kelvin (K); k is the airflow adiabatic index (M). a3 This is the machine Mach number at the second temperature sensor.

[0112] The machine Mach number M at the second temperature sensor a3 The calculation formula is:

[0113] ;

[0114] The derivation of the above machine Mach number formula is based on the total static pressure relationship for isentropic flow. Those skilled in the art will understand that this formula converts the velocity head at section #3 into a machine Mach number expression, applicable to conditions where airflow velocity cannot be ignored. Because P 3st It depends on the flow rate and the machine Mach number. In actual calculations, an initial value for the machine Mach number must be assumed first, and the solution must be iterated until convergence (e.g., the deviation between two adjacent iterations is less than 1 × 10). -6 After that, the final P is obtained. 1st .

[0115] S4. Measure the static pressure P after the IGV and before the impeller inlet of the centrifugal compressor under test using the second parameter measuring device. 0s Specifically, the static pressure P after the IGV of the centrifugal compressor under test and before the impeller inlet is measured using a third pressure sensor. 0s .

[0116] S5. Based on the principles of isentropic adiabatic flow and continuity, and the inlet pipe flow rate Q... m Total temperature T at the IGV inlet 1st The static pressure P measured by the second parameter measuring device 0s Calculate the total pressure P after the IGV of the centrifugal compressor under test and before the impeller inlet. 0st Specifically:

[0117] S5.1. Based on the principles of isentropic adiabatic flow and continuity, and the inlet pipe flow rate Q... m and the static pressure P measured by the third pressure sensor 0s Establish the static temperature T of the airflow after the IGV and before the impeller inlet of the centrifugal compressor under test. 0s With the total temperature of the airflow T 0st temperature ratio .

[0118] Among them, the total temperature T after the IGV of the centrifugal compressor under test and before the impeller inlet 0st The calculation formula is:

[0119] .

[0120] The square of the machine Mach number after the IGV and before the impeller inlet of the centrifugal compressor under test The calculation formula is:

[0121] ;

[0122] In the formula, R is the gas constant, and the unit is J / (kg·K); The velocity squared between the IGV outlet and the impeller inlet of the centrifugal compressor under test is calculated using the following formula:

[0123] ;

[0124] In the formula, A0 is the area after the IGV of the centrifugal compressor under test and before the impeller inlet, in m². 2 ;ρ 0s The airflow density is measured after the IGV of the centrifugal compressor under test and before the impeller inlet.

[0125] The square of the Mach number after the IGV and before the impeller inlet of the centrifugal compressor under test can be obtained from the above formula. The calculation formula is:

[0126] .

[0127] Based on the isentropic adiabatic flow relationship, the static temperature T of the airflow after the centrifugal compressor IGV and before the impeller inlet is calculated. 0s With the total temperature of the airflow T 0st The following conditions must be met:

[0128] ;

[0129] It can be concluded that: ;but: ;

[0130] Let there be an intermediate generation number M. 2 M 2 The number of intermediate generations is defined based on flow rate and geometric parameters. Its physical meaning is related to the machine Mach number after IGV, and its calculation formula is as follows:

[0131] ;

[0132] The above formula can be simplified to obtain the temperature ratio between the IGV outlet and the impeller inlet of the centrifugal compressor under test. The calculation formula is:

[0133] .

[0134] The key to this formula derivation lies in utilizing the conservation properties of total temperature and total pressure in isentropic flow, as well as the relationship between mass flow rate and static parameters given by the continuity equation. Compared to traditional methods, this formula does not require iterative solutions for static temperature by introducing an intermediate iteration number M. 2 Direct analytical calculation of temperature ratio was achieved.

[0135] S5.2, Based on the temperature ratio obtained in step S5.1 The total pressure P after the IGV of the centrifugal compressor under test and before the impeller inlet was calculated. 0st .

[0136] Among them, the total pressure P after the IGV of the centrifugal compressor under test and before the impeller inlet 0st The calculation formula is:

[0137] ;

[0138] In the formula, T represents the temperature ratio between the IGV outlet and the impeller inlet of the centrifugal compressor under test. 0s The static temperature of the airflow after the IGV of the centrifugal compressor under test and before the impeller inlet.

[0139] S6. Based on the total pressure P at the IGV inlet obtained in step S3... 1stThe total pressure P obtained in step S5 after the IGV of the centrifugal compressor under test and before the impeller inlet 0st The IGV loss is calculated, and the test calculation of IGV loss is completed.

[0140] The formula for calculating IGV loss is as follows:

[0141] ;

[0142] In the formula, δP IGV This is the IGV loss, which reflects the irreversible loss caused by the throttling and turning effect of the IGV guide vanes on the airflow, and is measured in Pa.

[0143] In the design of centrifugal compressor products, it is usually necessary to know the law of IGV loss variation with flow rate, rather than the loss value at a specific operating point. Therefore, based on the aforementioned test and calculation methods, this invention further provides a calibration method for IGV loss and inlet flow rate, facilitating the application of the above-mentioned IGV loss test and calculation methods, such as... Figure 3 As shown, the specific steps include the following:

[0144] S1. Under multiple preset operating conditions of the centrifugal compressor under test, the above-mentioned IGV loss test calculation method is executed to obtain multiple sets of IGV losses and their corresponding inlet pipe flow rates Q. m Multiple preset operating conditions are for different IGV angles or different machine Mach numbers. Specifically, the preset operating conditions are: at the same IGV angle, by changing the centrifugal compressor speed or intake conditions, test data are obtained at multiple machine Mach numbers; or at the same machine Mach number, by changing the IGV angle, test data are obtained at different guide vane openings. Specifically:

[0145] S1.1 Select one operating condition from the different IGV angles or different machine Mach numbers of the centrifugal compressor under test.

[0146] S1.2 Under this operating condition, perform the above IGV loss test calculation method to obtain a set of IGV losses and their corresponding inlet pipe flow rates Q. m .

[0147] S1.3. Select another operating condition from the different IGV angles or different machine Mach numbers of the centrifugal compressor under test, and return to step S1.2, until all operating conditions of the centrifugal compressor under test have been traversed, obtaining multiple sets of IGV losses and their corresponding inlet pipe flow rates Q. m .

[0148] S2, based on multiple sets of IGV losses and their corresponding inlet pipeline flow rates Q mThe average loss coefficient A of the IGV is determined by fitting (this coefficient reflects the throttling characteristics of a specific IGV under specific guide vane angles and airflow conditions; its specific value is determined by least-squares fitting of the above-mentioned multiple sets of experimental data. The value of the average loss coefficient A varies for different IGVs or for the same IGV at different angles, and needs to be obtained through experimental measurements), thus obtaining the relationship between IGV loss and inlet pipe flow rate Q. m The corresponding relationship was established to complete the calibration of IGV loss and inlet flow.

[0149] Among them, IGV loss is related to the inlet pipeline flow rate Q. m The expression for the correspondence is:

[0150]

[0151] In the formula, δP IGV For IGV loss.

[0152] To verify the effectiveness of the method of the present invention and reveal the variation law of IGV loss, the above method was applied for the first time in the thermodynamic performance test of a basic stage (such as the 01# basic stage) in the laboratory. During the test, each measuring device was installed according to the aforementioned measuring point arrangement, and tests were conducted at various IGV angles and multiple machine Mach numbers. The IGV loss was measured and the average loss coefficient A under different conditions was determined. The test results are summarized in Table 1.

[0153] Table 1. Average loss coefficients determined under different IGV states during the 01# basic level test.

[0154]

[0155] The following patterns can be observed from the data in Table 1:

[0156] (1) When the IGV angle is constant, the average loss coefficient A changes with the machine Mach number:

[0157] When the IGV angle remains constant (taking 90° as an example), the average loss coefficient A shows a trend of first decreasing and then increasing as the machine Mach number increases. Specifically, within a smaller range of machine Mach numbers, as the machine Mach number increases, the gas velocity increases, the flow tends to stabilize, and the separation zone relatively decreases, leading to a slight decrease in the average loss coefficient A. However, when the machine Mach number increases to a certain extent, compressibility effects such as shock waves begin to appear, and the average loss coefficient A increases rapidly with the increase of the machine Mach number. This phenomenon indicates that during the operation of a centrifugal compressor, there exists an optimal machine Mach number range that minimizes the average loss coefficient A, and the design should aim to place the most efficient operating point within this range.

[0158] However, when the IGV angle deviates from the design angle by a certain range (e.g., less than 45°), the average loss coefficient A increases monotonically with the increase of the machine Mach number. This is because at a small opening, the IGV guide vanes are in a state of large angle of attack, resulting in severe flow separation. The increase in the machine Mach number further exacerbates the expansion of the separation zone and the increase in losses.

[0159] (2) When the machine Mach number is constant, the average loss coefficient A varies with the IGV angle:

[0160] When the machine Mach number remains constant (taking 0.7 as an example), the average loss coefficient A increases as the IGV angle decreases (i.e., the guide vanes close less). The average loss coefficient A is minimum when the IGV is fully open (90°), as the airflow passes through the IGV with almost no pre-swirl, resulting in the lowest flow loss. As the IGV angle gradually decreases from 90°, the throttling and steering effects of the guide vanes on the airflow intensify, leading to increased flow separation and a gradual increase in the average loss coefficient A. Particularly when the angle is less than 45°, the increase in the average loss coefficient A accelerates significantly, indicating a sharp increase in losses under small IGV opening conditions. In engineering applications, prolonged operation at excessively small IGV openings should be avoided as much as possible.

[0161] The above-mentioned variation patterns were derived through statistical analysis of experimental data, which can guide the formulation of centrifugal compressor operation control strategies. That is, under the premise of meeting the user's process flow requirements, the operating combination (machine Mach number and IGV angle) that minimizes the average loss coefficient A should be selected first to achieve efficient operation of the whole machine.

[0162] To further verify the accuracy of the method and the portability of the average loss coefficient A, a verification experiment was conducted on another basic level (such as the 02# basic level). In the 02# basic level test, the average loss coefficient A measured in the 01# basic level was directly used to calculate the IGV loss of the 02# basic level under various operating conditions using the formula. At the same time, the IGV loss was actually measured at the actual measuring points arranged on the 02# basic level according to the method of the present invention. The two were compared, and the comparison results are summarized in Tables 2 and 3.

[0163] Table 2 shows the losses at different machine Mach numbers under a certain IGV angle during the basic level test (02#).

[0164]

[0165] Table 3 shows the losses at different IGV angles when the machine Mach number is constant during the basic level test (02#).

[0166]

[0167] The verification data in Table 2 shows that, for the vast majority of operating points, the deviation between the calculated loss and the measured loss is within ±5%, indicating good agreement and demonstrating that the average loss coefficient A determined by the method of this invention has good portability and prediction accuracy. For individual measuring points with larger deviations (such as the 9th point with a machine Mach number of 0.7 and a deviation of 62.73% in Table 2, and the 9th point with a machine Mach number of 1.11 and a deviation of -35.37%), analysis confirmed that these deviations were not caused by the calculation method itself, but rather by the fact that the operating condition corresponding to that measuring point was close to or had entered the surge region, resulting in distortion of the centrifugal compressor inlet pressure test value. When surge occurs, the internal flow of the centrifugal compressor experiences violent periodic oscillations, and aerodynamic parameters such as pressure and flow rate fluctuate significantly. The measured wall static pressure cannot accurately reflect the time-averaged flow state; therefore, the measured loss data for that operating point is unreliable.

[0168] The verification data in Table 3 further demonstrates the universality of the method of the present invention under different IGV angles. At all test angles, such as 105°, 90° (as shown in Table 2), 75°, 60° and 45°, the deviation between the calculated loss and the measured loss is controlled within ±8.5%, and the deviation at most operating points is within ±5%, verifying the accuracy and engineering applicability of the method of the present invention.

[0169] Comparative analysis of the method of this invention with existing methods:

[0170] Compared to the traditional Bernoulli equation method, this invention calculates the total pressure in the low-speed section before the IGV (section 3#) using a total static pressure relationship equivalent to the Bernoulli equation, consistent with existing methods. However, in the high-speed section after the IGV (section 0#), this invention abandons the traditional incompressibility assumption and uses a temperature ratio method based on isentropic adiabatic flow and continuity principles to calculate the total pressure, thus solving the problem of Bernoulli equation failure at high machine Mach numbers. Simultaneously, this invention introduces an intermediate algebra quantity M. 2 By analytically solving the temperature ratio equation, the complexity and convergence problems of iterative calculations are avoided, thus improving computational efficiency and reliability.

[0171] Compared with existing methods for estimating field operation data, this invention is based on a standardized testing environment using basic laboratory-level experiments, ensuring controllable measurement conditions and high data accuracy. Through multi-condition testing and calibration of the average loss coefficient A, a quantitative relationship model between loss and flow rate is established, avoiding the subjectivity and arbitrariness of field estimation. Experimental data shows that the calculation deviation of this invention is typically better than ±5%, far exceeding the accuracy of existing estimation methods.

[0172] The method of this invention can be directly applied to the product design and performance verification stages of centrifugal compressors:

[0173] (1) In the product design stage: When the basic level test includes IGV but the product structure does not include IGV, the method of the present invention can be used to measure the loss of IGV and determine its relationship with the flow rate, thereby accurately calculating the performance of the basic level without IGV and providing reliable input data for product design; conversely, when the basic level test does not include IGV but the product structure includes IGV, if the average loss coefficient A of the same type of IGV has been obtained through previous tests, the average loss coefficient A can be used directly to predict the performance with IGV without repeating the basic level test with IGV, thereby greatly reducing the number of tests and saving test costs.

[0174] (2) In the optimization of centrifugal compressor operation: The average loss coefficient A determined by this invention can accurately calculate the IGV loss of the centrifugal compressor under different operating conditions (different flow rates, different guide vane angles), providing a data basis for the overall efficiency analysis of the centrifugal compressor. Based on the variation law of the average loss coefficient A with the machine Mach number and IGV angle, the optimal operation control strategy can be formulated to make the centrifugal compressor operate in the operating condition range with the least loss as much as possible, thereby achieving the purpose of high efficiency and energy saving.

[0175] (3) In the development of similar products: IGV of the same model has the same average loss coefficient A characteristics on different basic levels. Once the average loss coefficient A of IGV on a certain basic level is calibrated by the method of the present invention, the average loss coefficient A can be applied to other basic levels matched with the same model of IGV without repeated calibration, which significantly improves the product development efficiency.

[0176] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and are not intended to limit them. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features therein. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the present invention.

Claims

1. A method for calculating IGV loss, used to test the IGV loss of a centrifugal compressor, characterized in that, Includes the following steps: S1. A flow measurement device is installed at the front end of the inlet pipe of the centrifugal compressor under test. A first parameter measurement device is installed before the IGV of the centrifugal compressor under test and after the flow measurement device. A second parameter measurement device is installed after the IGV of the centrifugal compressor under test and before the impeller inlet. S2. Obtain the inlet pipe flow rate Q of the centrifugal compressor under test through the flow measurement device. m ; S3. Measure the static pressure P of the airflow before the centrifugal compressor IGV under test using the first parameter measuring device. 3s Based on the airflow temperature T3, the total pressure P at the IGV inlet is calculated. 1st and total temperature T 1st ; S4. Measure the static pressure P after the IGV and before the impeller inlet of the centrifugal compressor under test using the second parameter measuring device. 0s ; S5. Based on the principles of isentropic adiabatic flow and continuity, and the inlet pipe flow rate Q... m Total temperature T at the IGV inlet 1st The static pressure P measured by the second parameter measuring device 0s Calculate the total pressure P after the IGV of the centrifugal compressor under test and before the impeller inlet. 0st ; S6. Based on the total pressure P at the IGV inlet obtained in step S3... 1st The total pressure P obtained in step S5 after the centrifugal compressor IGV and before the impeller inlet 0st The IGV loss is calculated, and the test calculation of the IGV loss is completed.

2. The IGV loss test calculation method according to claim 1, characterized in that: In step S1, the flow measurement device includes a nozzle, a differential pressure transmitter, a first pressure sensor, and a first temperature sensor; the high-pressure probe and low-pressure probe of the differential pressure transmitter are respectively disposed at the front and rear ends of the nozzle to acquire the nozzle differential pressure. The first pressure sensor and the first temperature sensor are both positioned at appropriate locations in front of the nozzle to measure relevant parameters in order to calculate the upstream density ρ of the nozzle. The first parameter measuring device includes a second pressure sensor and a second temperature sensor; The second parameter measuring device is a third pressure sensor, which is installed on the annular cavity wall after the centrifugal compressor IGV under test and before the impeller inlet.

3. The IGV loss test calculation method according to claim 2, characterized in that, Step S2 is as follows: The nozzle differential pressure is obtained through a flow measurement device. Based on the relevant parameters, the upstream density ρ of the nozzle is calculated, and the inlet pipe flow rate Q of the centrifugal compressor under test is calculated according to the nozzle flow rate calculation formula. m ; The inlet pipe flow rate Q m The calculation formula is: ； In the formula, Q m The unit is kg / s; α is the nozzle flow coefficient; ε is the nozzle expansion coefficient; d is the nozzle diameter, in meters. The unit of ρ is kg / m³ 3 ; The unit is Pa.

4. The IGV loss test calculation method according to claim 2 or 3, characterized in that, Step S3 is as follows: The static pressure P of the airflow before the IGCV of the centrifugal compressor under test is measured using the second pressure sensor. 3s The airflow temperature T3 before the IGV of the centrifugal compressor under test is measured by a second temperature sensor, and the total pressure P at the IGV inlet is calculated accordingly. 1st and total temperature T 1st .

5. The IGV loss test calculation method according to claim 4, characterized in that, In step S3, the total pressure P at the IGV inlet 1st The calculation formula is: ； In the formula, P 3st δP represents the total airflow pressure before the IGV of the centrifugal compressor under test, in Pa. 3-1 The unit is Pa, representing the pipe loss from the first parameter measuring device to the IGV inlet; ρ3 is the airflow density at the first parameter measuring device; v3 is the airflow velocity at the first parameter measuring device; and ξ is the pipe loss coefficient. The formula for calculating the airflow density ρ3 at the first parameter measuring device is: ； In the formula, R is the airflow constant; T 3s The static airflow temperature at the second temperature sensor is expressed in Kelvin (K). The static airflow temperature T at the second temperature sensor 3s The calculation formula is: ； Where γ is the recovery coefficient of the second temperature sensor, and c p Specific heat at constant pressure of airflow, expressed in J / (kg·K); The formula for calculating the airflow velocity v3 at the first parameter measuring device is: ； In the formula, A3 is the cross-sectional area of ​​the pipe at the first parameter measuring device, in m². 2 ; The total temperature T at the IGV inlet 1st The calculation formula is: ； In the formula, T 3st The total airflow temperature at the second temperature sensor is in Kelvin (K); k is the airflow adiabatic index (M). a3 The machine Mach number at the second temperature sensor; The machine Mach number M at the second temperature sensor a3 The calculation formula is: 。 6. The IGV loss test calculation method according to claim 5, characterized in that, Step S4 is as follows: The static pressure P after the centrifugal compressor IGV and before the impeller inlet is measured using the third pressure sensor. 0s ; In step S6, the formula for calculating the IGV loss is: ； In the formula, δP IGV This is due to IGV loss.

7. The IGV loss test calculation method according to claim 6, characterized in that, Step S5 is as follows: S5.

1. Based on the principles of isentropic adiabatic flow and continuity, and the inlet pipe flow rate Q... m and the static pressure P measured by the third pressure sensor 0s Establish the static temperature T of the airflow after the IGV and before the impeller inlet of the centrifugal compressor under test. 0s With the total temperature of the airflow T 0st temperature ratio ; S5.2, Based on the temperature ratio obtained in step S5.1 The total pressure P after the IGV of the centrifugal compressor under test and before the impeller inlet was calculated. 0st .

8. The IGV loss test calculation method according to claim 7, characterized in that, In step S5.1, the temperature ratio between the IGV outlet and the impeller inlet of the centrifugal compressor under test is... The calculation formula is: ； In the formula, M 2 The number of intermediate generations is defined based on flow rate and geometric parameters, and its physical meaning is related to the machine Mach number after IGV. The number of intermediate generations M 2 The calculation formula is: ； In the formula, A0 is the area after the IGV of the centrifugal compressor under test and before the impeller inlet, in m². 2 R is the gas constant, with units of J / (kg·K); T 0st The total temperature after the IGV of the centrifugal compressor under test and before the impeller inlet is calculated using the following formula: ； In step S5.2, the total pressure P after the IGV of the centrifugal compressor under test and before the impeller inlet is... 0st The calculation formula is: ； In the formula, T represents the temperature ratio between the IGV outlet and the impeller inlet of the centrifugal compressor under test. 0s The static temperature of the airflow after the IGV of the centrifugal compressor under test and before the impeller inlet.

9. A method for calibrating IGV loss and inlet flow rate, characterized in that, Includes the following steps: S1. Under multiple preset operating conditions of the centrifugal compressor under test, the IGV loss test calculation method described in any one of claims 1-8 is executed respectively to obtain multiple sets of IGV losses and their corresponding inlet pipe flow rates Q. m ; S2, based on multiple sets of IGV losses and their corresponding inlet pipeline flow rates Q m The average loss coefficient A of the IGV is determined by fitting, and the relationship between IGV loss and inlet pipe flow rate Q is obtained. m The corresponding relationship was established to complete the calibration of IGV loss and inlet flow.

10. The method for calibrating IGV loss and inlet flow rate according to claim 9, characterized in that: Step S1 is as follows: S1.1 Select one operating condition from the different IGV angles or different machine Mach numbers of the centrifugal compressor under test; S1.2 Under this operating condition, perform the IGV loss test calculation method according to any one of claims 1-8 to obtain a set of IGV losses and their corresponding inlet pipe flow rates Q. m ; S1.

3. Select another operating condition from the different IGV angles or different machine Mach numbers of the centrifugal compressor under test, and return to step S1.2, until all operating conditions of the centrifugal compressor under test have been traversed, obtaining multiple sets of IGV losses and their corresponding inlet pipe flow rates Q. m ; In step S2, the IGV loss is related to the inlet pipe flow rate Q. m The expression for the correspondence is: ； In the formula, δP IGV This is due to IGV loss.

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