A kind of turbine expander rotor internal flaw detector

Abstract

The present application relates to a kind of turbine expander rotor internal flaw detection device, comprising: voltage detection unit and sequentially arranged on the base first adjusting rod support unit, first disc support unit, electrode support unit, second disc support unit, second adjusting rod support unit, the electrode support unit is used to support the main body of turbine expander rotor, while being provided with several electrode assemblies;The first adjusting rod support unit, first disc support unit, second disc support unit, second adjusting rod support unit are used to support the two shaft ends of turbine expander rotor, so that the rotor is horizontally placed state, and can rotate along the central axis of the rotor;The voltage detection unit is electrically connected with each electrode assembly, for being based on voltage detection principle to the internal flaw detection of the measured section of rotor.This application can be widely used in equipment detection field.

Description

Technical Field

[0001] This invention belongs to the field of equipment testing, specifically relating to an internal flaw detection device for a turbine expander rotor. Background Technology

[0002] As a highly efficient energy conversion device, the turboexpander has a wide range of applications, covering energy, chemical industry, environmental protection, aerospace, and many other fields. The working principle of the turboexpander is based on the thermodynamic law of adiabatic expansion. Through the flow of gas in the flow passage components (volute, nozzle, impeller, diffuser), the internal energy of the gas is converted into mechanical energy, thereby reducing the gas temperature and generating cooling. The mechanical energy manifests as high-speed rotation of the rotor system, generating shaft work.

[0003] As the core moving component of a turbine expander, the rotor system's high-speed rotational characteristics (typically tens of thousands to hundreds of thousands of revolutions per minute) directly determine the overall operational stability of the equipment. Most rotor system components are made of stainless steel and other metal materials, requiring high-precision dynamic balancing tests before assembly to eliminate initial imbalances. However, the long lifespan of a turbine expander, spanning several years or even longer, places higher demands on rotor reliability—relying solely on pre-assembly dynamic balancing calibration is insufficient to avoid failure risks caused by potential defects within the metal materials.

[0004] Existing metal internal defect detection technologies have significant limitations: X-ray inspection equipment is expensive and lacks sensitivity to crack-like defects; ultrasonic inspection is limited by surface finish requirements and requires professionals to determine the defect type through complex waveform analysis. Summary of the Invention

[0005] To address the aforementioned problems, the purpose of this invention is to provide an internal flaw detection device for turbine expander rotors. This device can accurately and conveniently detect internal defects in turbine expander rotors, achieving precise identification of internal rotor defects. It has significant engineering value for improving the long-term operational reliability of turbine expanders and reducing unplanned downtime losses.

[0006] To achieve the above objectives, the present invention adopts the following technical solution:

[0007] An internal flaw detection device for a turbine expander rotor, comprising: The system comprises a first adjusting rod support unit, a first disc support unit, an electrode support unit, a second disc support unit, a second adjusting rod support unit, a voltage detection unit, and a base. The first adjusting rod support unit, the first disc support unit, the electrode support unit, the second disc support unit, and the second adjusting rod support unit are sequentially arranged on the base; The electrode support unit is used to support the main body of the turbine expander rotor and is equipped with several electrode components. The first adjusting rod support unit, the first disc support unit, the second disc support unit, and the second adjusting rod support unit are used to support the two shaft ends of the rotor, so that the rotor is placed horizontally and can rotate along the central axis of the rotor. The voltage detection unit is electrically connected to each of the electrode assemblies and is used to perform internal flaw detection on different test sections of the rotor and different angles of the test interface based on the voltage detection principle.

[0008] Furthermore, the first disk support unit and the second disk support unit have the same structure, both including two support disks and a disk bracket; The bottom of the disc bracket is mounted on the base, and two support discs are symmetrically arranged on the upper part of the disc bracket via screws and bearings, so that the two support discs can rotate along the bearings; The rotor shaft end is clamped between the two support disks to effectively constrain the rotor's degrees of freedom in the radial plane in three directions: vertically downward, horizontally to the left, and horizontally to the right.

[0009] Furthermore, each of the support disks in the first and second disk support units is installed at the same height above the ground to ensure that the rotor is placed horizontally.

[0010] Furthermore, the first adjusting rod support unit and the second adjusting rod support unit have the same structure, both including a fixed rod, an adjusting rod, a locking device, a fixed rod bracket and a pulley; The locking device includes a fixed part and a movable part. The movable part can rotate along the fixed part and be locked in any position by the bolt. One end of the fixing rod is fixedly connected to the fixing part of the locking device, the other end of the fixing rod is fixedly connected to the upper part of the fixing rod bracket, and the bottom of the fixing rod bracket is disposed on the base; One end of the adjusting rod is fixedly connected to the movable part of the locking device, and the other end of the adjusting rod is a free end that can rotate in the vertical plane with the movable part of the locking device. The pulley is located at the free end of the adjusting rod. By adjusting the position of the adjusting rod and fixing the movable part with bolts, the outer circular surface of the pulley contacts the shaft end of the rotor, thereby effectively constraining the vertical upward degree of freedom and axial degree of freedom of the rotor in the radial plane.

[0011] Furthermore, the electrode support unit includes an electrode bracket, the lower part of which is disposed in the base, and the upper end of which adopts a disc structure; The disk structure has a first through hole in the middle for the turbine expander rotor to pass through. The disk structure has an even number of second through holes evenly distributed in an array along the circumference, and each second through hole contains an electrode assembly.

[0012] Furthermore, the voltage detection unit includes an excitation signal source, a voltage measurement module, and a visualization terminal; The positive and negative terminals of the excitation signal source module are respectively connected to electrode assemblies disposed in a pair of second through holes that run through the center of the disk structure, so as to provide an excitation signal and make the measured cross section of the rotor full of charge. The positive and negative terminals of each voltage measurement module are respectively connected to the electrode assemblies set in the other pairs of second through holes that penetrate the center of the disk structure, for measuring the voltage at their respective points and uploading it to the visualization terminal. The visualization terminal is used to display the voltage values ​​at each point so as to determine whether there is internal damage to the measured cross section of the rotor based on the voltage difference.

[0013] Furthermore, the electrode assembly includes an electrode, an electrode adjustment rod, and an electrode wire; The electrode is disposed inside the electrode adjusting rod and is in contact with the surface of the rotor; The electrode adjustment rod is disposed in the second through hole and is used to adjust the position of the electrode to adapt to the detection of internal damage of rotors with different shaft diameters; One end of the electrode wire is connected to the electrode, and the other end is connected to the excitation signal source module or voltage measurement module.

[0014] Furthermore, the electrode is made of a flexible conductive material.

[0015] Furthermore, the electrode support is manufactured using 3D printing, and the height and radius of the first through hole can be adjusted to accommodate rotors of different sizes.

[0016] Furthermore, a sliding groove is provided in the middle of the base, and the first adjusting rod support unit, the first disc support unit, the rotor support unit, the second disc support unit, and the second adjusting rod support unit are all arranged in the sliding groove, and can all move horizontally along the sliding groove to adapt to rotors of different sizes to be tested.

[0017] This invention, by adopting the above technical solutions, has the following advantages: Through the coordinated operation of its components, this invention forms a highly efficient internal flaw detection device and method for turbine expander rotors, possessing significant advantages and technical effects. Specifically, by adjusting the positions of the disc support and the fixed rod support on the base, it can accommodate rotors of different lengths; by using two sets of supporting discs to support the rotor, it can accommodate rotors of different radii, effectively constraining the rotor's degrees of freedom in the radial plane in three directions: vertically downward, horizontally to the left, and horizontally to the right; by rotating the adjusting rods at both ends in the vertical plane to adjust the positions of the two pulleys, it can effectively constrain the rotor's vertically upward and axial degrees of freedom in the radial plane; the electrode support, through 3D printing, can be quickly adjusted to accommodate rotors of different specifications, and by adjusting the position of the electrode support on the base, internal damage at different axial positions of the rotor can be detected; the electrodes are made of flexible conductive material, which does not damage the rotor surface, and the position of the electrode adjusting rod can be adjusted to accommodate changes in the rotor shaft diameter. This structure not only accurately achieves non-destructive testing of internal defects in turbine expander rotors, but also significantly reduces testing costs through technological innovation. By combining a modular design with adjustable components, the versatility of the device is greatly improved, ultimately forming a comprehensive performance advantage that combines non-destructive testing, low cost, and high versatility.

[0018] Therefore, this invention can be widely applied in the field of equipment testing. Attached Figure Description

[0019] Various other advantages and benefits will become apparent to those skilled in the art upon reading the following detailed description of preferred embodiments. The accompanying drawings are for illustrative purposes only and are not intended to limit the invention. Throughout the drawings, the same reference numerals denote the same parts. In the drawings: Figure 1 This is a schematic diagram of the overall structure of the internal flaw detection device for a turbine expander rotor provided in an embodiment of the present invention; Figure 2 This is a schematic diagram of the electrode support structure provided in an embodiment of the present invention; Figure 3 This is a schematic diagram of a voltage detection unit provided in an embodiment of the present invention; The labels for the attached figures are as follows: 1. Rotor; 2. Supporting disc; 3. Disc bracket; 4. Base; 5. Fixing rod; 6. Adjusting rod; 7. Locking device; 8. Fixing rod bracket; 9. Pulley; 10. Electrode; 11. Electrode adjusting rod; 12. Electrode wire; 13. Electrode bracket. Detailed Implementation

[0020] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of the present invention. All other embodiments obtained by those skilled in the art based on the described embodiments of the present invention are within the scope of protection of the present invention.

[0021] It should be noted that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the scope of exemplary embodiments according to the invention. As used herein, the singular form is intended to include the plural form as well, unless the context clearly indicates otherwise. Furthermore, it should be understood that when the terms "comprising" and / or "including" are used in this specification, they indicate the presence of features, steps, operations, devices, components, and / or combinations thereof.

[0022] In the description of this invention, it should be understood that the terms "longitudinal", "lateral", "up", "down", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, and are only for the convenience of describing this invention, and are not intended to indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of this invention.

[0023] In some embodiments of the present invention, an internal flaw detection device for a turbine expander rotor is provided, comprising: a first adjusting rod support unit, a first disc support unit, an electrode support unit, a second disc support unit, a second adjusting rod support unit, a voltage detection unit, and a base. Through the coordinated operation of these components, a highly efficient internal flaw detection device for a turbine expander rotor is formed. This invention not only enables precise non-destructive testing of internal defects in turbine expander rotors but also significantly reduces testing costs through technological innovation. Combined with a modular design with adjustable multiple components, the device's versatility is greatly improved, ultimately achieving a comprehensive performance advantage that combines non-destructive testing, low cost, and high versatility.

[0024] Example 1 like Figure 1As shown, this embodiment provides an internal flaw detection device for a turbine expander rotor, comprising: a first adjusting rod support unit, a first disc support unit, an electrode support unit, a second disc support unit, a second adjusting rod support unit, a voltage detection unit, and a base. The first adjusting rod support unit, the first disc support unit, the electrode support unit, the second disc support unit, and the second adjusting rod support unit are sequentially arranged on the base and are horizontally movable. The electrode support unit supports the rotor 1 body of the turbine expander and is equipped with an even number of electrode assemblies. The voltage detection unit is electrically connected to each electrode assembly and is used to perform internal flaw detection on the measured cross-section of the rotor 1 based on the voltage detection principle. The first adjusting rod support unit, the first disc support unit, the second disc support unit, and the second adjusting rod support unit support and fix the two shaft ends of the rotor 1, so that the rotor 1 is placed horizontally.

[0025] Furthermore, the first and second disc support units have the same structure, both including two support discs 2 and a disc bracket 3. The bottom of the disc bracket 3 is mounted on the base 4, and the upper part of the disc bracket 3 is symmetrically equipped with two support discs 2 via screws and bearings, allowing the support discs 2 to rotate along the bearings. The shaft end of the rotor 1 is clamped between the two support discs 2 to effectively constrain the rotor 1's degrees of freedom in the radial plane in three directions: vertically downward, horizontally to the left, and horizontally to the right.

[0026] Furthermore, the four support disks 2 in the first and second disk support units are installed at the same height above the ground, which can ensure that the rotor 1 is placed horizontally.

[0027] In this embodiment, the rotor 1 is positioned between two support discs, which can accommodate rotors 1 with different shaft diameters and effectively constrain the rotor 1's degrees of freedom in the radial plane in three directions: vertically downward, horizontally to the left, and horizontally to the right. At the same time, the support discs 2 and the rotor 1 are in point contact, which can significantly reduce frictional resistance when the rotor 1 rotates.

[0028] Furthermore, the first and second adjusting rod support units have the same structure, both including a fixed rod 5, an adjusting rod 6, a locking device 7, a fixed rod bracket 8, and a pulley 9. The locking device 7 includes a fixed part and a movable part, with the movable part rotating along the fixed part and fixed in any position by bolts. One end of the fixed rod 5 is fixedly connected to the fixed part of the locking device 7, and the other end is fixedly connected to the upper part of the fixed rod bracket 8. The bottom of the fixed rod bracket 8 is mounted on the base 4. One end of the adjusting rod 6 is fixedly connected to the movable part of the locking device 7, and the other end is a free end that can rotate in the vertical plane with the movable part of the locking device 7. The pulley 9 is located at the free end of the adjusting rod 6. By adjusting the position of the adjusting rod 6 and fixing the movable part with bolts, the outer surface of the pulley 9 contacts the shaft end of the rotor 1, effectively constraining the vertical upward and axial degrees of freedom of the rotor 1 in the radial plane.

[0029] like Figure 1 As shown, the fixing rod 5 and the locking device 7 are welded together on one side, and the adjusting rod 6 and the locking device 7 are welded together on the other side. The locking device 7 is preloaded by bolts on both sides. When it is necessary to adjust the angle of the adjusting rod 6, the bolts are loosened and the adjusting rod 6 can rotate along the vertical plane. After the position is appropriate, the bolts are tightened to fix the angle of the adjusting rod 6 by friction.

[0030] By fixing the shaft end of the rotor 1 with the pulley 9 at the end of the adjusting rod 6, the vertical upward degree of freedom and axial degree of freedom of the rotor 1 in the radial plane can be effectively constrained. Combined with the fixing method of the support disk 2, the six translational degrees of freedom of the rotor 1 are completely restricted at this time. The rotor 1 can only rotate along the central axis to prevent the position of the rotor from changing during the detection process.

[0031] Furthermore, such as Figure 2 As shown, the electrode support unit includes an electrode bracket 13. The lower part of the electrode bracket 13 is set in the base 4, and the upper end adopts a disk structure. The center of the disk structure is provided with a first through hole for the rotor to be tested to pass through. The disk structure is evenly arrayed with an even number of second through holes along the circumferential direction, and each second through hole is provided with an electrode assembly.

[0032] In this embodiment, the electrode support 13 is fabricated using 3D printing. The height and radius of the center of the circular portion from the ground are adjusted to accommodate rotors 1 of different sizes. The number of through holes along the circumference is an even number of ≥4 and they are evenly distributed in an array. Figure 2 The example in the text has 8 electrodes, which are represented by A1, A2, B1, B2, C1, C2, D1, and D2 respectively. It can be understood that the more electrodes there are, the higher the accuracy of the internal damage detection.

[0033] Furthermore, the electrode assembly includes an electrode 10, an electrode adjusting rod 11, and an electrode wire 12. The electrode 10 is disposed within the electrode adjusting rod 11 and contacts the surface of the rotor 1. The electrode adjusting rod 11 is disposed within a second through hole for adjusting the position of the electrode 10 to accommodate the detection of internal damage to rotors 1 with different shaft diameters. One end of the electrode wire 12 is connected to the electrode 10, and the other end is connected to the excitation signal source module or high-precision voltage measurement module in the voltage detection unit.

[0034] Reference Figure 3 As shown in the example, when there are 8 electrode wires 12, they can be divided into 4 groups (A, B, C, D). One group can be connected to the excitation signal source module to provide a stable voltage, while the other three groups are connected to the high-precision voltage measurement module to measure the voltage value at their respective points.

[0035] Furthermore, the electrode 10 is made of a flexible conductive material, which can effectively avoid damage to the surface of the rotor 1.

[0036] Furthermore, the voltage detection unit includes an excitation signal source, a high-precision voltage measurement module, and a visualization terminal. The positive and negative terminals of the excitation signal source module are connected to electrode assemblies located within a pair of second through-holes penetrating the center of the disk structure, respectively, to provide an excitation signal that charges the measured section of rotor 1. The positive and negative terminals of each high-precision voltage measurement module are connected to electrode assemblies located within other pairs of second through-holes penetrating the center of the disk structure, respectively, to measure the voltage at their respective points and upload the data to the visualization terminal. The visualization terminal displays the voltage values ​​at each point, allowing the determination of whether there is internal damage to the measured section of rotor 1 based on the voltage difference.

[0037] Furthermore, a sliding groove is provided in the middle of the base, and the first adjusting rod support unit, the first disc support unit, the rotor support unit, the second disc support unit, and the second adjusting rod support unit are all set in the sliding groove, and can all move horizontally along the sliding groove to adapt to rotors of different sizes to be tested.

[0038] In this embodiment, the positions of the disc support 3 and the fixed rod support 8 can be adjusted to accommodate rotors 1 of different sizes; the position of the electrode support 13 on the base 4 can be adjusted to change the contact position between the electrode 10 and the rotor 1, and the internal damage at different cross sections of the rotor 1 can be detected; by rotating the rotor 1, the impedance change of the rotor 1 at the same cross section position can be detected at multiple angles to ensure the reliability of the results.

[0039] The working process of this invention is as follows: like Figure 1As shown, adjust the positions of the disc bracket 3 and the fixed rod bracket 8 according to the size of the rotor 1. The rotor 1 passes through the electrode bracket 13 and is placed horizontally on the support disc 2. Adjust the angle of the adjusting rod 6 so that the pulley 9 contacts the shaft end of the rotor 1 and tighten the locking device 7. At this time, the rotor 1 can only rotate around the central axis. like Figure 2 and Figure 3 As shown, the A1 end of the electrode wire 12 is connected to the positive terminal of the excitation signal source module (S1), and the A2 end is connected to the negative terminal of the excitation signal source module (S1), so that the measured cross section of the rotor 1 is filled with charge. B1, B2, C1, C2, D1, and D2 are respectively connected to the high-precision voltage measurement module (S2) to measure the voltage at their respective points. The voltage value calculated in real time is uploaded to the visualization terminal (S3). If the material at the measured cross-section of rotor 1 is completely uniform, according to the rules of charge distribution, the voltage values ​​measured by B1 and D2, C1 and C2, and D1 and B2 should be close (since measurement errors cannot be completely equal). When internal defects such as holes or cracks appear at the measured cross-section, they will affect the charge distribution, causing significant deviations in the voltage values ​​measured by B1 and D2, C1 and C2, and D1 and B2. The larger the proportion of defects, the more obvious the voltage difference between each group. Based on the voltage difference, it can be determined whether rotor 1 has internal damage at the current cross-section; for example... Figure 1 As shown, the same cross-section can also be detected at different angles by rotating rotor 1, which improves the accuracy and efficiency of detection.

[0040] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and not to limit it. Although the present invention has been described in detail with reference to the above embodiments, those skilled in the art should understand that modifications or equivalent substitutions can still be made to the specific implementation of the present invention. Any modifications or equivalent substitutions that do not depart from the spirit and scope of the present invention should be covered within the scope of protection of the claims of the present invention.

Claims

1. A flaw detection device for the internal structure of a turbine expander rotor, characterized in that, include: The system comprises a first adjusting rod support unit, a first disc support unit, an electrode support unit, a second disc support unit, a second adjusting rod support unit, a voltage detection unit, and a base. The first adjusting rod support unit, the first disc support unit, the electrode support unit, the second disc support unit, and the second adjusting rod support unit are sequentially arranged on the base; The electrode support unit is used to support the main body of the turbine expander rotor and is equipped with several electrode components. The first adjusting rod support unit, the first disc support unit, the second disc support unit, and the second adjusting rod support unit are used to support the two shaft ends of the rotor, so that the rotor is placed horizontally and can rotate along the central axis of the rotor. The voltage detection unit is electrically connected to each of the electrode assemblies and is used to perform internal flaw detection on different test sections of the rotor and different angles of the test interface based on the voltage detection principle.

2. The internal flaw detection device for a turbine expander rotor as described in claim 1, characterized in that, The first disk support unit and the second disk support unit have the same structure, both including two support disks and a disk bracket; The bottom of the disc bracket is mounted on the base, and two support discs are symmetrically arranged on the upper part of the disc bracket via screws and bearings, so that the two support discs can rotate along the bearings; The rotor shaft end is clamped between the two support disks to effectively constrain the rotor's degrees of freedom in the radial plane in three directions: vertically downward, horizontally to the left, and horizontally to the right.

3. The internal flaw detection device for a turbine expander rotor as described in claim 2, characterized in that, Each of the support disks in the first and second disk support units is installed at the same height above the ground to ensure that the rotor is placed horizontally.

4. The internal flaw detection device for a turbine expander rotor as described in claim 1, characterized in that, The first adjusting rod support unit and the second adjusting rod support unit have the same structure, both including a fixed rod, an adjusting rod, a locking device, a fixed rod bracket and a pulley; The locking device includes a fixed part and a movable part. The movable part can rotate along the fixed part and be locked in any position by the bolt. One end of the fixing rod is fixedly connected to the fixing part of the locking device, the other end of the fixing rod is fixedly connected to the upper part of the fixing rod bracket, and the bottom of the fixing rod bracket is disposed on the base; One end of the adjusting rod is fixedly connected to the movable part of the locking device, and the other end of the adjusting rod is a free end that can rotate in the vertical plane with the movable part of the locking device. The pulley is located at the free end of the adjusting rod. By adjusting the position of the adjusting rod and fixing the movable part with bolts, the outer circular surface of the pulley contacts the shaft end of the rotor, thereby effectively constraining the vertical upward degree of freedom and axial degree of freedom of the rotor in the radial plane.

5. The internal flaw detection device for a turbine expander rotor as described in claim 1, characterized in that, The electrode support unit includes an electrode bracket, the lower part of which is disposed in the base, and the upper end of which adopts a disc structure. The disk structure has a first through hole in the middle for the turbine expander rotor to pass through. The disk structure has an even number of second through holes evenly distributed in an array along the circumference, and each second through hole contains an electrode assembly.

6. The internal flaw detection device for a turbine expander rotor as described in claim 5, characterized in that, The voltage detection unit includes an excitation signal source, a voltage measurement module, and a visualization terminal; The positive and negative terminals of the excitation signal source module are respectively connected to electrode assemblies disposed in a pair of second through holes that run through the center of the disk structure, so as to provide an excitation signal and make the measured cross section of the rotor full of charge. The positive and negative terminals of each voltage measurement module are respectively connected to the electrode assemblies set in the other pairs of second through holes that penetrate the center of the disk structure, for measuring the voltage at their respective points and uploading it to the visualization terminal. The visualization terminal is used to display the voltage values ​​at each point so as to determine whether there is internal damage to the measured cross section of the rotor based on the voltage difference.

7. The internal flaw detection device for a turbine expander rotor as described in claim 6, characterized in that: The electrode assembly includes electrodes, an electrode adjusting rod, and electrode wires; The electrode is disposed inside the electrode adjusting rod and is in contact with the surface of the rotor; The electrode adjustment rod is disposed in the second through hole and is used to adjust the position of the electrode to adapt to the detection of internal damage of rotors with different shaft diameters; One end of the electrode wire is connected to the electrode, and the other end is connected to the excitation signal source module or voltage measurement module.

8. The internal flaw detection device for a turbine expander rotor as described in claim 7, characterized in that, The electrodes are made of flexible conductive material.

9. The internal flaw detection device for a turbine expander rotor as described in claim 5, characterized in that, The electrode support is manufactured using 3D printing, and the height and radius of the first through hole can be adjusted to accommodate rotors of different sizes.

10. The internal flaw detection device for a turbine expander rotor as described in claim 1, characterized in that, The base has a sliding groove in the middle. The first adjusting rod support unit, the first disc support unit, the rotor support unit, the second disc support unit, and the second adjusting rod support unit are all set in the sliding groove and can all move horizontally along the sliding groove to adapt to rotors of different sizes to be tested.

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