Structure and method for measuring axial thrust of turbomachinery

Abstract

The invention discloses a turbomachinery axial thrust measuring structure and a measuring method, which are characterized in that a turbine rotor is sectionally designed into a turbine stage rotor and an auxiliary rotor, a three-support structure (double support bearings and a thrust bearing) is adopted, and a flange plate type thrust measuring device is arranged between the two sections of rotors, so that the rigid transmission and accurate measurement of axial thrust are realized. The thrust measuring device is divided into a moving ring and a static ring, the moving ring rotates along with a rotor to transmit thrust and is integrated with a force measuring element, the static ring statically receives signals and transmits the signals to a testing system, static and dynamic calibration technologies are combined, installation errors and environmental interference are eliminated, the measuring precision is remarkably improved, and the thrust measuring device is suitable for turbomachinery test research and engineering application.

Description

Technical Field

[0001] The present invention relates to the technical field of turbomachinery test measurement, and specifically to a high-precision measurement structure and method for the axial thrust of turbine stages such as steam turbines and compressors, which are applicable to the performance testing and optimal design of turbomachinery in fields such as energy, oil and gas chemical industry, aviation, and shipbuilding. Background Art

[0002] As a core device for energy conversion and power transmission, turbomachinery is widely used in fields such as industrial production, aerospace, and defense equipment. During the operation of turbomachinery, the axial thrust generated by the fluid pressure difference on both sides of the impeller is a key parameter affecting the stability, life, and reliability of the equipment. Accurately measuring the axial thrust can not only timely warn of abnormal conditions such as bearing wear and seal failure, but also provide key data support for the design optimization, maintenance cycle prediction, and operation cost control of turbomachinery.

[0003] Currently, the measurement methods for axial thrust mainly include numerical calculation and experimental measurement. Numerical calculation relies on fluid dynamics models and structural mechanics analysis, but the calculation results need to be verified by experiments, and the model correction highly depends on accurate experimental data. However, traditional experimental measurement methods have significant limitations:

[0004] Strain gauge direct measurement method: Strain gauges are pasted on the force-bearing surface of the thrust bearing, and the axial force is indirectly reflected through the strain signal. However, when the turbomachinery rotates at high speed, the contact between the rotor and the force-bearing surface of the thrust bearing is uneven, and there are installation deviations and inconsistent forces among multiple pads circumferentially distributed on the thrust bearing, resulting in a large dispersion of the measurement signal and an error rate as high as 15% - 20%.

[0005] Indirect measurement method: The axial thrust is calculated by measuring parameters such as bearing displacement and oil film pressure. This method is significantly affected by the bearing lubrication state, temperature change, and mechanical vibration. It is difficult to arrange the measurement points exactly opposite to the actual force-bearing points, and the uncertainty of the test results exceeds 10%, which cannot meet the requirements of high-precision measurement.

[0006] Structural design defect: Traditional turbomachinery rotors are mostly of integral design, and the axial thrust acts on the thrust bearing through a complex force transmission path. During the installation process, factors such as the misalignment error of the shafting and the bearing clearance are likely to cause force transmission distortion, further amplifying the measurement deviation.

[0007] The core problem of the existing technology is that the installation errors, uneven forces, and environmental interference in the axial thrust transmission path lead to the measurement results being unable to accurately reflect the actual working conditions, seriously restricting the design optimization and safety operation assessment of turbomachinery. Therefore, there is an urgent need for a new structure and method that can eliminate installation and environmental interference and achieve direct and accurate measurement of axial thrust. Summary of the Invention

[0008] The present invention aims to overcome the above-mentioned disadvantages of the prior art and provides a structure and a method for measuring the axial thrust of a turbomachine.

[0009] The technical solution adopted by the present invention is as follows:

[0010] A structure for measuring the axial thrust of a turbomachine, comprising:

[0011] A turbostage rotor, which is a double-supported structure and the radial load is borne by two support bearings;

[0012] An auxiliary rotor and a thrust bearing, the auxiliary rotor is a single-supported structure, and the radial load and the axial load of the turbostage rotor are borne by the thrust bearing;

[0013] A thrust measuring device, which is arranged between the turbostage rotor and the auxiliary rotor and is a flange structure with rigid connection, and is used for transmitting the axial thrust of the turbostage rotor and measuring the thrust signal.

[0014] Further, the thrust measuring device comprises:

[0015] A moving ring, which is rigidly connected to the turbostage rotor and the auxiliary rotor, rotates synchronously with the rotor, and a force measuring element is integrated inside;

[0016] A stationary ring, which is arranged corresponding to the moving ring and remains stationary, and is used for receiving the thrust signal transmitted by the moving ring and transmitting it to the test system.

[0017] Further, the force measuring element is a strain gauge, a pressure sensor or a force sensor, and is uniformly arranged on the axial force receiving surface of the moving ring.

[0018] Further, the stationary ring and the moving ring are connected by a non-contact signal transmission component, and the non-contact signal transmission component comprises an electromagnetic induction coil or a wireless transmission module.

[0019] Further, the support bearing and the thrust bearing are rolling bearings or sliding bearings.

[0020] Further, a method for measuring the axial thrust of a turbomachine comprises the following steps:

[0021] S1: Install the turbostage rotor and the auxiliary rotor in sections, and form a three-supported shafting through rigid connection by the thrust measuring device;

[0022] S2: When the turbostage is operating, the axial thrust is transmitted from the turbostage rotor to the moving ring of the thrust measuring device;

[0023] S3: The force measuring element in the moving ring converts the axial force into an electrical signal, and transmits it to the test system through the stationary ring;

[0024] S4: Process the electrical signal collected by the test system to obtain the real-time axial thrust value.

[0025] Further, the step of segmented installation in step S1 includes:

[0026] Fix the turbine stage rotor to the bearing seat of the test cylinder through two support bearings;

[0027] Adjust the position of the thrust bearing seat to align the center of the thrust bearing with the axis of the turbine stage rotor;

[0028] Rigidly connect the moving ring of the thrust measuring device to the flange of the turbine stage rotor, and rigidly connect the auxiliary rotor to the other end of the moving ring.

[0029] Further, it also includes a calibration step:

[0030] Perform static calibration on the thrust measuring device, input a standard axial force, and establish a force - electrical signal calibration curve;

[0031] Perform dynamic calibration on the thrust measuring device, simulate the working condition of the high - speed rotation of the rotor, and correct the errors of inertial force and vibration interference.

[0032] Further, the test system amplifies, filters, and performs analog - to - digital conversion processing on the electrical signal, calculates the axial thrust in combination with the calibration parameters, and displays and stores the measurement data in real time.

[0033] In summary, due to the adoption of the above - mentioned technical solutions, the beneficial effects of the present invention are as follows:

[0034] Through structural innovation and optimization of the measurement principle, the present invention significantly improves the accuracy and reliability of axial thrust measurement of turbomachinery:

[0035] Segmented three - support shafting design: The turbine rotor is divided into a turbine stage rotor with double supports and an auxiliary rotor with single support. The thrust measuring device is connected through a rigid flange to form a three - support structure of "double support bearings + thrust bearing", completely eliminating the misalignment error of the shafting and the distortion of force transmission caused by bearing installation deviation of the traditional integral rotor, ensuring that the axial thrust is transmitted along the axis without attenuation by 100%, and eradicating the influence of installation errors on the measurement results from the mechanical structure.

[0036] Separation of moving and static rings and non - contact measurement: The thrust measuring device is divided into a moving ring (integrated with uniformly arranged force - measuring elements) that rotates with the rotor and a static ring (receiving signals in a non - contact manner), avoiding problems such as the winding of leads of traditional strain gauges, wear of slip rings, and electromagnetic interference. The signal noise is reduced by more than 70%. The signal transmission reliability is high during high - speed rotation, ensuring stable measurement under dynamic conditions.

[0037] Calibration correction and multi-parameter coordination: The non-linear error of the force measuring element is corrected through static calibration, and the vibration interference is compensated through dynamic calibration, with high measurement accuracy, improved compared to traditional methods; the integrated torque measuring device realizes real-time synchronous acquisition of axial thrust, rotational speed, and torque, providing a complete data set for the performance analysis of turbomachinery and improving the test efficiency.

[0038] Wide applicability: Supports flexible selection of rolling / sliding types for journal bearings and thrust bearings, adapts to different working conditions such as low-speed heavy-load of steam turbines and high-speed light-load of compressors, broadens the application scenarios in industries, aviation, etc., and provides high-precision data support for the safety operation assessment, design optimization, and maintenance cycle prediction of turbomachinery. Brief Description of the Drawings

[0039] Figure 1 is a schematic diagram of the thrust measurement test system of the present invention.

[0040] Markings in the figure:

[0041] 1 - Journal bearing; 2 - Turbine stage rotor; 3 - Auxiliary rotor; 4 - Thrust measurement device; 5 - Power source; 6 - Thrust bearing; 7 - Torque measurement device. Detailed Embodiment

[0042] The present invention will be described in detail below with reference to the accompanying drawings.

[0043] In order to make the objectives, technical solutions, and advantages of the present invention clearer, the present invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention.

[0044] In this embodiment, as Figure 1 shown, an axial thrust measurement structure for a turbomachine includes:

[0045] A turbine stage rotor, which is a double-supported structure, and the radial load is borne by two journal bearings;

[0046] An auxiliary rotor and a thrust bearing. The auxiliary rotor is a single-supported structure, and the radial load and the axial load of the turbine stage rotor are borne by the thrust bearing;

[0047] A thrust measurement device, which is arranged between the turbine stage rotor and the auxiliary rotor and is a flange structure with a rigid connection, used to transmit the axial thrust of the turbine stage rotor and measure the thrust signal.

[0048] Specifically: The turbine stage rotor is horizontally arranged in the test cylinder, and its two ends are respectively fixed on the bearing pedestals through support bearings, forming a double-support structure that only bears radial loads; one end of the auxiliary rotor is connected to the thrust measurement device, and the other end is installed in an independent bearing pedestal through a thrust bearing, forming a single-support structure that bears both the radial load of the auxiliary rotor itself and the axial load transmitted by the turbine stage rotor. The thrust measurement device is of a flange structure, and its two ends are rigidly connected to the rear flange of the turbine stage rotor and the front flange of the auxiliary rotor through high-strength bolts, forming a complete shafting system.

[0049] When the turbine stage is operating, the pressure difference on both sides of the impeller generates an axial thrust. This thrust is transmitted along the axis of the turbine stage rotor to the thrust measurement device, directly acting on the auxiliary rotor through the rigid flange, and finally borne by the thrust bearing. Since the turbine stage rotor adopts double-support independent positioning, the auxiliary rotor is singly supported by the thrust bearing, and the three are coaxially connected through a rigid flange, eliminating the shafting alignment error caused by bearing installation deviation of the traditional integral rotor, and ensuring that the axial thrust is transmitted without deviation along the axis.

[0050] The traditional integral rotor relies on the force-bearing surface of the thrust bearing to indirectly transmit the axial force, and it is easy to cause force transmission distortion due to uneven bearing installation; in this embodiment, through segmented double-support + single-support rigid connection, the axial thrust transmission path is shortened and there is no intermediate flexible link, and the force transmission efficiency reaches 100%, eradicating the influence of installation error on the measurement result from the structural design.

[0051] Further, the thrust measurement device includes a moving ring and a stationary ring:

[0052] The moving ring is connected to the turbine stage rotor and the auxiliary rotor through a rigid flange, rotates synchronously with the rotor, and integrates a commercially available force measurement element to sense the axial thrust;

[0053] The stationary ring is fixed to the test bench base, is coaxial with the moving ring and keeps a non-contact state, receives the thrust signal transmitted by the moving ring and accesses the test system.

[0054] Specifically, as a rotating component, the moving ring is rigidly connected to the two sections of the rotor through bolts, forming a gapless force transmission path; the stationary ring is positioned by a bracket, and there is a small axial gap (2 - 3 mm) with the moving ring. A signal receiving module is arranged on its inner side and cooperates with the force measurement element of the moving ring. When the rotor rotates, the axial thrust drives the moving ring to generate elastic deformation. The force measurement element converts the mechanical signal into an electrical signal, and the stationary ring collects the signal through a non-contact component (such as an electromagnetic induction coil or a wireless module), avoiding the wear and interference problems of the traditional slip ring leads and ensuring stable signal transmission under high-speed rotation.

[0055] The aforementioned force-measuring elements can be commercially available, mature products (such as strain gauge and piezoresistive force sensors). Their placement on the rotating ring follows the principle of symmetry and uniformity to average out circumferential force variations. Specific installation details are unnecessary, as existing components are used. Non-contact signal transmission technology (such as electromagnetic coupling or wireless communication) between the stationary and rotating rings fundamentally eliminates physical contact losses between rotating and stationary components, significantly improving signal transmission reliability.

[0056] Furthermore, the support bearing and the thrust bearing are rolling bearings or sliding bearings.

[0057] The supporting bearings can be rolling bearings (such as cylindrical roller bearings) or sliding bearings (such as elliptical pad bearings), and the selection is based on the test speed and load: sliding bearings (high oil film stiffness) are used in low-speed and high-load scenarios, and rolling bearings (low friction loss) are used in high-speed and light-load scenarios; the thrust bearings can also be selected as thrust rolling bearings or thrust sliding bearings, which cooperate with the auxiliary rotor shaft end to withstand radial and axial combined loads.

[0058] The support bearing only bears radial loads to ensure stable rotation of the turbine stage rotor; the thrust bearing simultaneously bears the radial load of the auxiliary rotor and the axial thrust of the turbine stage rotor through a single support structure. The flexibility of the bearing type makes this structure suitable for different working conditions (such as low-speed and heavy-load turbines and high-speed and light-load compressors).

[0059] Traditional measuring devices rely on specific bearing types and have limited applicability. This embodiment uses a replaceable bearing type design to make the measuring structure compatible with rolling / sliding bearings, adapting to the testing requirements of different turbine machinery and broadening the application scenarios.

[0060] Furthermore, it also includes a torque measuring device and a power source. The torque measuring device is arranged between the auxiliary rotor and the power source and is used to measure the rotor speed and torque.

[0061] Specifically, the torque measurement device is a flange-type torque sensor installed in series between the rear end of the auxiliary rotor and the electric motor (or dynamometer). Both ends are connected to the auxiliary rotor and the power source via elastic couplings. The sensor has a built-in strain gauge torque measurement unit that simultaneously measures rotor speed (measured via a toothed disc) and output torque.

[0062] During turbine operation, the auxiliary rotor transmits the turbine rotor's torque to the torque measurement device. A sensor calculates the torque value by measuring the torsional deformation of the elastic shaft. Simultaneously, the sensor reads the speed signal. Axial thrust data is collected synchronously with torque and speed data to calculate turbine shaft power, enabling coordinated multi-parameter measurement.

[0063] Traditional axial thrust measurement does not integrate torque measurement, and additional equipment is required to calibrate power, resulting in poor data synchronization. In this embodiment, through an integrated design, the axial thrust is real-time associated with torque and rotational speed, providing a complete data set (such as thrust-power characteristic curve) for the performance analysis of turbomachinery, and improving the test efficiency.

[0064] Further, a method for measuring the axial thrust of a turbomachine includes the following steps:

[0065] S1: Install the turbomachine stage rotor and the auxiliary rotor in sections, and rigidly connect them through a thrust measurement device to form a three-bearing shafting system;

[0066] S2: When the turbomachine stage is operating, the axial thrust is transmitted through the turbomachine stage rotor to the moving ring of the thrust measurement device;

[0067] S3: The force measuring element in the moving ring converts the axial force into an electrical signal, which is transmitted to the test system through the stationary ring;

[0068] S4: Process the electrical signal collected by the test system to obtain the real-time axial thrust value.

[0069] Shafting construction: Install the turbomachine stage rotor, the auxiliary rotor and the thrust measurement device to form a three-bearing shafting system of "double support bearings + thrust bearing", ensuring that the coaxiality error of each bearing housing is small;

[0070] Force transmission path: The axial thrust of the turbomachine stage impeller passes through the turbomachine stage rotor - the moving ring of the thrust measurement device - the auxiliary rotor - the thrust bearing, and the rigid connection ensures the non-decaying transmission of the force;

[0071] Signal conversion: The force measuring element in the moving ring converts the mechanical force into an electrical signal (such as the voltage change of a strain gauge), and is transmitted to the test system through non-contact transmission by the stationary ring;

[0072] Data processing: After filtering and amplifying the signal by the test system, it is converted into the axial thrust value through the calibration coefficient and displayed and stored in real time.

[0073] The design of the three-bearing shafting system ensures the "distortion-free transmission" of the axial thrust from the mechanical structure, and the signal transmission between the moving and stationary rings avoids interference from the measurement principle. The combination of the two improves the measurement accuracy compared with the traditional method.

[0074] Further, the step of installing in sections in step S1 includes:

[0075] Fix the turbomachine stage rotor to the bearing housing of the test cylinder through two support bearings;

[0076] Adjust the position of the thrust bearing housing to align the center of the thrust bearing with the axis of the turbomachine stage rotor;

[0077] Rigidly connect the moving ring of the thrust measurement device to the flange of the turbomachine stage rotor, and rigidly connect the auxiliary rotor to the other end of the moving ring.

[0078] Turbine stage rotor positioning: Lift the turbine stage rotor and hoist it into the test cylinder. Fine-tune the height of the support bearing by adjusting the bolts of the bearing housing to ensure that the level of the rotor axis is within the error range.

[0079] Thrust bearing alignment: Move the thrust bearing housing and use a laser alignment instrument to detect and ensure that the coaxiality between the center of the thrust bearing and the axis of the turbine stage rotor is within the error range.

[0080] Rigid connection: Use a torque wrench to tighten the bolts of the thrust measurement device and the rotor flange according to the design torque (such as 80 N·m) to ensure that there is no relative displacement between the moving ring and the rotor.

[0081] Traditional installation depends on manual experience and the installation accuracy of the thrust bearing surface. During operation, due to factors such as rotor floating, the forces on each thrust bearing surface are uneven, resulting in a large measurement error of axial force offset. In this embodiment, through precise alignment and rigid connection, the influence of offset is eliminated, ensuring that the axial force is transmitted purely axially along the axis.

[0082] Furthermore, it also includes a calibration step:

[0083] Conduct static calibration on the thrust measurement device, input a standard axial force, and establish a force-electric signal calibration curve.

[0084] Conduct dynamic calibration on the thrust measurement device, simulate the working condition of the rotor rotating at high speed, and correct the errors caused by inertial force and vibration interference.

[0085] Static calibration: Fix the turbine stage rotor on the test bench, apply a 0 - 10 kN standard axial force (divided into 5 gradients) to the thrust measurement device through a hydraulic loading device, record the output value of the electric signal under each load, and fit the "force-voltage" calibration curve (such as y = kx + b).

[0086] Dynamic calibration: Drive the rotor to rotate idly at different speeds (such as 1000 rpm, 3000 rpm, 5000 rpm), apply a constant axial force, measure the signal fluctuations caused by rotor vibration and inertial force, and generate a dynamic correction coefficient (such as a frequency response compensation function).

[0087] The uncalibrated measurement system has a total error due to the nonlinearity of the force measuring element and vibration interference. By static calibration, the nonlinear error is corrected, and by dynamic calibration, the vibration interference is compensated. Finally, the measurement error can be controlled within ±1%, meeting the requirements of high-precision tests.

[0088] Furthermore, the test system amplifies, filters, and performs analog-to-digital conversion processing on the electric signal, calculates the axial thrust in combination with the calibration parameters, and displays and stores the measurement data in real time.

[0089] Traditional testing systems have large signal noise and low resolution, resulting in large fluctuations in measurement results. In this embodiment, through multi-stage signal processing and high-resolution acquisition, the signal-to-noise ratio is improved and the data refresh rate is increased, enabling the capture of transient changes in axial thrust (such as thrust fluctuations during start-up and shutdown processes), providing key data for the dynamic characteristic analysis of turbomachinery.

[0090] The above are only the preferred embodiments of the invention and are not intended to limit the invention. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principle of the invention shall be included within the protection scope of the invention.

Claims

1. An axial thrust measurement structure for a turbomachine, characterized in that, Comprising: A turbine stage rotor, the turbine stage rotor being of a double-supported structure, with two support bearings bearing radial loads; An auxiliary rotor and a thrust bearing, the auxiliary rotor being of a single-supported structure, bearing radial loads and the axial load of the turbine stage rotor through the thrust bearing; A thrust measurement device, arranged between the turbine stage rotor and the auxiliary rotor, being a rigidly connected flange structure for transmitting the axial thrust of the turbine stage rotor and measuring the thrust signal.

2. The axial thrust measurement structure of a turbomachine according to claim 1, characterized in that, The thrust measurement device includes: A moving ring, rigidly connected to the turbine stage rotor and the auxiliary rotor, rotating synchronously with the rotor, and integrating a force measuring element inside; A stationary ring, arranged corresponding to the moving ring and remaining stationary, for receiving the thrust signal transmitted by the moving ring and transmitting it to the test system.

3. A turbine machinery axial thrust measurement structure according to claim 2, characterized in that, The force measuring element is a strain gauge, a pressure sensor or a force sensor, and is uniformly arranged on the axial force-receiving surface of the moving ring.

4. The axial thrust measurement structure of a turbomachine according to claim 2, characterized in that, The stationary ring and the moving ring are connected by a non-contact signal transmission component, and the non-contact signal transmission component includes an electromagnetic induction coil or a wireless transmission module.

5. A turbine machinery axial thrust measurement structure according to claim 1, characterized in that, The support bearings and the thrust bearing are rolling bearings or sliding bearings.

6. A method for measuring the axial thrust of a turbomachine, which is applied to the axial thrust measurement structure of a turbomachine according to any one of claims 1-5, characterized in that, Including the following steps: S1: Install the turbine stage rotor and the auxiliary rotor in sections, and form a three-supported shafting through rigid connection by the thrust measurement device; S2: When the turbine stage is operating, the axial thrust is transmitted from the turbine stage rotor to the moving ring of the thrust measurement device; S3: The force measuring element in the moving ring converts the axial force into an electrical signal, and transmits it to the test system through the stationary ring; S4: Process the electrical signal collected by the test system to obtain the real-time axial thrust value.

7. A method for measuring the axial thrust of a turbomachine according to claim 6, characterized in that, The step of installing in sections in step S1 includes: Fix the turbine stage rotor to the bearing seat of the test cylinder through two support bearings; Adjust the position of the thrust bearing seat to align the center of the thrust bearing with the axis of the turbine stage rotor; Rigidly connect the moving ring of the thrust measurement device to the flange of the turbine stage rotor, and rigidly connect the auxiliary rotor to the other end of the moving ring.

8. A method for measuring the axial thrust of a turbomachine according to claim 6, characterized in that, It also includes a calibration step: Conduct static calibration on the thrust measurement device, input a standard axial force, and establish a force-electric signal calibration curve; Conduct dynamic calibration on the thrust measurement device, simulate the high-speed rotation condition of the rotor, and correct the inertial force and vibration interference errors.

9. A method for measuring the axial thrust of a turbomachine according to claim 6, characterized in that, The test system amplifies, filters and performs analog-to-digital conversion processing on the electrical signal, calculates the axial thrust in combination with the calibration parameters, and displays and stores the measurement data in real time.

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