A variable-temperature fatigue test method for simulating complex temperature field of air-cooled turbine blade

Abstract

The application provides a variable-temperature fatigue test method for simulating a complex temperature field of an air-cooled turbine blade, comprising the following steps: step 1, constructing an air-cooled turbine blade simulation test piece, the test piece has an appearance meeting the appearance of a standard test bar, and has a through hole, and air film holes are arranged in the tensile area of the test piece; step 2, arranging an induction heating device around the tensile area of the test piece, applying a temperature field to the test piece through the induction heating device, and arranging distributed air-cooled nozzles according to the temperature field distribution of the real air-cooled turbine blade; step 3, arranging an airflow distribution device with a cavity blind hole structure in the test piece, the airflow distribution device is provided with a shunt nozzle and an impact airflow outlet hole, and the convection and impact cooling of the inner wall surface of the air-cooled turbine blade are simulated through the shunt nozzle and the impact airflow outlet hole of the airflow distribution device; and step 4, performing variable-temperature fatigue test measurement under the complex temperature field through an indirect measurement mode.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of aero-engine part test, and particularly relates to a variable-temperature fatigue test method for simulating a complex temperature field of an air-cooled turbine blade. BACKGROUND

[0002] The turbine blade of an aero-engine and a gas turbine works under high temperature and complex load conditions, and therefore has high requirements on its mechanical properties. Developing a simulation test of a simulation piece that can simulate the structure and use environment and working condition characteristics of the turbine blade is an important work of aero-engine part design, is a key link between material level test and real part test, is mainly used for verifying the effectiveness and reliability of a simulation model and an algorithm, and the result plays an important role in the examination and correction of the algorithm. Therefore, developing a fatigue test method that can accurately simulate the structure and use environment and working condition characteristics of the part is a decisive factor for determining the level of such a test.

[0003] The working condition environment of the turbine blade is complex and changeable, and there is a high demand for applying a complex temperature field to the simulation test piece of the blade. The working condition characteristics of the turbine blade cannot be simulated in the simulation test for a long time, and therefore the turbine blade fatigue simulation test is restricted from improving.

[0004] In the prior art, when the mechanical property test of the temperature parameter of the simulation turbine blade is carried out, the temperature field distribution simulation capability is insufficient, and generally only the constant temperature and variable temperature conditions of the uniform temperature field applied to the working position can be simulated. Since the surface of the air-cooled turbine blade has a certain temperature distribution, and there is a certain temperature gradient in the thickness direction under the air-cooled cooling condition in the inner cavity of the turbine blade, the current test method cannot simultaneously simulate the complex temperature field of the air-cooled turbine blade. SUMMARY

[0005] The application aims to provide a variable-temperature fatigue test method for simulating a complex temperature field of an air-cooled turbine blade, so as to solve or alleviate at least one problem in the background art.

[0006] The technical solution of the application is a variable-temperature fatigue test method for simulating a complex temperature field of an air-cooled turbine blade, comprising the following steps.

[0007] Step 1, constructing an air-cooled turbine blade simulation test piece, the shape of the air-cooled turbine blade simulation test piece meets the shape of a standard test bar, the air-cooled turbine blade simulation test piece has a through hole, the through hole has an internal thread, and the air-cooled turbine blade simulation test piece is provided with a film hole in the tensile area.

[0008] Step 2: Determine the surface temperature distribution simulation scheme for the air-cooled turbine blade simulation test piece. The surface temperature distribution simulation scheme is as follows: an induction heating device is arranged around the tensile area of ​​the air-cooled turbine blade simulation test piece. The induction heating device applies a temperature field to the air-cooled turbine blade simulation test piece. Distributed air-cooling nozzles are arranged according to the temperature field distribution of the real air-cooled turbine blade. The spray direction of the air-cooling nozzles is directed towards the air-cooled turbine blade simulation test piece.

[0009] Step 3: Determine the thickness direction temperature gradient simulation scheme for the air-cooled turbine blade simulation test piece. The thickness direction temperature gradient simulation scheme is as follows: A cavity blind hole structure airflow distribution device is set in the air-cooled turbine blade simulation test piece. The airflow distribution device is equipped with a flow divider and an impingement airflow outlet. The airflow entering the air-cooled turbine blade simulation test piece first enters the airflow distribution device, and the convection and impingement cooling of the inner wall surface of the air-cooled turbine blade are simulated through the flow divider and impingement airflow outlet on the airflow distribution device.

[0010] Step 4: Variable temperature fatigue test measurement under complex temperature field, the process includes:

[0011] Arbitrarily select an air-cooled turbine blade simulation test piece as a test piece, and weld thermocouples to the working part point A and the non-working part point B on one side of the test piece to measure the temperature of the working part point A and the non-working part point B respectively;

[0012] Using point A, the working part of the test component, as the target temperature control location, a temperature spectrum is applied to the test component according to the temperature requirements of a real air-cooled turbine blade, and the temperature change curves of point B, the non-working part, are measured at different stages in one or more temperature cycles.

[0013] The formal test begins with any air-cooled turbine blade simulation test piece. A thermocouple is welded to point B, the non-working part of the air-cooled turbine blade simulation test piece, during the formal test. The temperature curves T at points A (working part) and B (non-working part) are measured based on the test piece. A and T B The relationship is determined by the temperature curve T. B As the temperature control target value for each stage of the temperature cycle of the simulated air-cooled turbine blade test piece in the formal test, the temperature spectrum of the working part point A meets the requirements at this time.

[0014] By applying the temperature spectrum and load spectrum simultaneously, the goal of variable temperature fatigue testing of air-cooled turbine blade simulation test specimens in complex temperature fields can be achieved.

[0015] In a preferred embodiment of this application, the induction heating device is made of a coil based on electromagnetic induction simulation. The coil contains ferrite, and the local electromagnetic field strength can be adjusted by adjusting the position of the ferrite on the coil, thereby adjusting the temperature field.

[0016] In a preferred embodiment of this application, the cooling rate of different parts of the air-cooled turbine blade simulation test piece is adjusted by adjusting the position and opening size of the air-cooled nozzle.

[0017] In a preferred embodiment of this application, the opening end of the airflow distribution device is provided with an external thread, which engages with the internal thread in the through hole of the air-cooled turbine blade simulation test piece to fix the relative position of the airflow distribution device and the air-cooled turbine blade simulation test piece.

[0018] In a preferred embodiment of this application, the main body of the airflow distribution device is smaller than the diameter of the through hole cavity of the air-cooled turbine blade simulation test piece, so that a gap is formed between the two.

[0019] In a preferred embodiment of this application, the flow divider is located between the film cooling hole of the air-cooled turbine blade simulation test piece and the cavity inlet on the lower side of the air-cooled turbine blade simulation test piece.

[0020] In a preferred embodiment of this application, the impinging airflow outlet on the airflow distribution device and the film cooling hole on the air-cooled turbine blade simulation test piece are not coaxially arranged, so that the impinging airflow outlet blows onto the walls on both sides of the film cooling hole to achieve cooling.

[0021] The variable temperature fatigue test method for simulating the complex temperature field of air-cooled turbine blades proposed in this application can simultaneously simulate the surface temperature distribution and the temperature gradient in the thickness direction of air-cooled turbine blades. By adopting indirect temperature measurement and control, the influence of direct temperature measurement on the test accuracy can be avoided, and the test results are good. Attached Figure Description

[0022] To more clearly illustrate the technical solutions provided in this application, the accompanying drawings will be briefly described below. Obviously, the drawings described below are merely some embodiments of this application.

[0023] Figure 1 This is a flowchart of the method for implementing variable temperature fatigue load in the complex temperature field of air-cooled turbine blades according to this application.

[0024] Figure 2 This is a schematic diagram of the airflow turbine blade simulation test piece (standard test bar) in this application.

[0025] Figure 3 This is a schematic diagram of the simulation scheme for the surface temperature distribution of the airflow turbine blade simulation test piece in this application.

[0026] Figure 4 This is a schematic diagram of the temperature gradient simulation scheme in the thickness direction of the airflow turbine blade simulation test piece in this application.

[0027] Figure 5 This is a schematic diagram of the working part point A and the non-working part point B of a standard test bar in one embodiment of this application, along with the corresponding temperature curve. Detailed Implementation

[0028] To make the objectives, technical solutions, and advantages of this application clearer, the technical solutions in the embodiments of this application will be described in more detail below with reference to the accompanying drawings.

[0029] To simulate the variable temperature fatigue test of air-cooled turbine blades under complex temperature fields, this application proposes a method for simulating the fatigue test of air-cooled turbine blades under complex temperature distributions. This method can greatly improve the test effect of the simulation test of air-cooled turbine blade operating conditions.

[0030] like Figure 1 As shown, the variable temperature fatigue test method for simulating the complex temperature field of air-cooled turbine blades provided in this application includes the following steps:

[0031] Step 1: Construct a simulated test specimen of an air-cooled turbine blade.

[0032] like Figure 2 The diagram shown is a schematic of the airflow turbine blade simulation test piece provided in this application. The simulation test piece includes turbine blade characteristic structures and processes—that is, it includes characteristic structures such as air holes and ribs of simulated gas turbine blades, as well as the same process features such as thin-walled precision casting and coating of turbine blades.

[0033] Figure 2 The image shows a simulated test piece for an air-cooled turbine blade, manufactured using the same precision casting process as turbine blades. This simulated test piece is also called the standard test bar 10. The standard test bar 10 is machined according to relevant standards or specifications. The standard test bar 10 has a through-hole 11, forming a cylindrical structure. One or both ends of the through-hole 11 are provided with internal threads 12. One or more turns of film cooling holes 13 are provided approximately in the middle of the standard test bar 10. These film cooling holes 13 connect to the through-hole 11 and are used to simulate the film cooling holes on a turbine blade.

[0034] Step 2: Determine the simulation scheme for the surface temperature distribution of the air-cooled turbine blade simulation test piece.

[0035] like Figure 3 As shown, the temperature control of the outer wall surface of the standard test bar 10 adopts a scheme of combined induction heating and airflow impact cooling.

[0036] The specific scheme of induction heating is as follows: an induction heating device 20 is set at the position of the air film hole 13 in the standard test bar 10. The induction heating device 20 is made of a coil based on electromagnetic induction simulation and contains ferrite 30. The local electromagnetic field intensity can be adjusted by adjusting the position of the ferrite 30 on the coil.

[0037] The specific scheme of airflow impact cooling is as follows: Distributed air-cooling nozzles 40 are set according to the temperature field distribution. The spray direction of the air-cooling nozzles 40 is roughly aligned with the air film hole 13 of the standard test bar 10. The cooling rate of different parts is adjusted by adjusting the position and opening size of the air-cooling nozzles 40.

[0038] Step 3: Determine the simulation scheme for the temperature gradient in the thickness direction of the air-cooled turbine blade simulation test piece.

[0039] Based on the convection and impingement cooling methods of air-cooled turbine blades, this application designs an airflow distribution device 50 to effectively simulate the two heat exchange and cooling methods of convection and impingement cooling on the inner wall of air-cooled turbine blades.

[0040] like Figure 4 As shown, the upper and lower ends of the standard test bar 10 are connected to the test fixture 60 to apply the load. The test fixture 60 is also a hollow structure, allowing airflow to enter the inner cavity of the standard test bar 10 from the air source through the cavity inside the test fixture 60.

[0041] An airflow distribution device 50 is disposed within the cavity of the standard test bar 10. It is a blind-hole structure with one open end and the other blind end. An external thread is provided on the open side of the airflow distribution device 50, which engages with the internal thread 12 of the standard test bar 10's cavity to secure the airflow distribution device 50. The main body of the airflow distribution device 50 is slightly smaller than the inner diameter of the standard test bar 10, with a gap between them. The airflow distribution device 50 can further guide the airflow introduced into the cavity of the standard test bar 10 by the test fixture 60 into the airflow distribution device 50, simulating the airflow process on the inner wall of an air-cooled turbine blade.

[0042] The airflow distribution device 50 is equipped with a flow divider nozzle 51, which is located between the film gas hole 13 of the standard test bar 10 and the cavity air inlet on the lower side of the standard test bar 10. Preferably, the flow divider nozzle 51 is close to the cavity air inlet on the lower side of the standard test bar 10. Along the axial direction of the standard test bar 10, a plurality of impinging airflow outlet holes 52 are provided on the side of the airflow distribution device 50 facing the film gas hole 13 of the standard test bar 10. Preferably, the impinging airflow outlet holes 52 are not coaxially arranged with the film gas hole 13, so that the impinging airflow outlet holes 52 blow onto the walls on both sides of the film gas hole 13 to achieve cooling.

[0043] The airflow first enters the clamping end of the standard test bar 10 through the test fixture 60, and then enters the airflow distribution device 50. Part of the airflow entering the distribution device 50 flows along the inner wall of the standard test bar 10 through the splitter nozzle 51 to simulate the convection cooling flow path Q2 of the air-cooled turbine blade cavity. The other part of the airflow passes through the impingement airflow outlet hole 52 to impinge-cool the inner wall of the standard test bar 10, simulating the impingement cooling flow path Q1 of the air-cooled turbine blade cavity. After both parts of the airflow enter the inner cavity of the standard test bar 10, a portion of the gas finally flows out from the film gas hole 13 of the standard test bar 10, and the other portion is discharged from the test fixture on the opposite side (upper side).

[0044] Step 4: Variable temperature fatigue test measurement under complex temperature field.

[0045] To avoid the impact of welding thermocouples to the working surface of the standard test bar 10 on the temperature field distribution, or the potential damage to the material caused by the thermal effects of the welding process, this application employs indirect temperature control to measure and control the temperature. The temperature spectrum of the working area is converted into the temperature spectrum of a predetermined monitoring point, thereby enabling variable-temperature fatigue testing in complex temperature fields. The specific process includes:

[0046] 1) Select any standard test bar as the test piece, and construct a complex temperature field measurement scheme for surface temperature distribution and thickness direction temperature gradient according to the steps or content described above.

[0047] 2) Weld thermocouples to the working point A in the middle of the test piece and the non-working point B on one side to measure the temperature at the working point A and the non-working point B. The real-time measured temperature at the working point A is T. A The real-time measured temperature at point B, which is not the working part, is T. B .

[0048] Using point A, the working part of the test component, as the target temperature control location, a temperature spectrum is applied to the test component according to the temperature requirements of a real air-cooled turbine blade. The temperature change curves of point B, a non-working part, are measured at different stages during one or more temperature cycles. This yields the temperature curve of point B, a non-working part, under the corresponding temperature spectrum of point A. Figure 5 As shown;

[0049] 3) Begin the formal test. During the formal test, only weld the thermocouple to point B, the non-working part of the standard test bar, and calculate the temperature curve T based on the test piece. A and T B The relationship is determined using the temperature curve T. B This serves as the target temperature control value for each stage of the standard test bar temperature cycle. At this point, the working point A can obtain a temperature spectrum that meets the requirements.

[0050] 4) Finally, by applying the temperature spectrum (applied through the induction heating device) and the load spectrum (applied through the tester) simultaneously, the goal of complex temperature field variable temperature fatigue test of the air-cooled turbine blade simulation test piece can be achieved.

[0051] The variable temperature fatigue test method for simulating the complex temperature field of air-cooled turbine blades proposed in this application can simultaneously simulate the surface temperature distribution and the temperature gradient in the thickness direction of air-cooled turbine blades. By adopting indirect temperature measurement and control, the influence of direct temperature measurement on the test accuracy can be avoided, and the test results are good.

[0052] The above description is merely a specific embodiment of this application, but the scope of protection of this application is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in this application should be included within the scope of protection of this application. Therefore, the scope of protection of this application should be determined by the scope of the claims.

Claims

1. A variable-temperature fatigue test method for simulating the complex temperature field of an air-cooled turbine blade, characterized in that, include: Step 1: Construct a simulated test specimen of an air-cooled turbine blade. The shape of the simulated test specimen of the air-cooled turbine blade meets the shape of a standard test bar. The simulated test specimen of the air-cooled turbine blade has a through hole with an internal thread inside the through hole. A film pore is provided in the tensile region of the simulated test specimen of the air-cooled turbine blade. Step 2: Determine the surface temperature distribution simulation scheme for the air-cooled turbine blade simulation test piece. The surface temperature distribution simulation scheme is as follows: an induction heating device is arranged around the tensile area of ​​the air-cooled turbine blade simulation test piece. The induction heating device applies a temperature field to the air-cooled turbine blade simulation test piece. Distributed air-cooling nozzles are arranged according to the temperature field distribution of the real air-cooled turbine blade. The spray direction of the air-cooling nozzles is directed towards the air-cooled turbine blade simulation test piece. Step 3: Determine the thickness direction temperature gradient simulation scheme for the air-cooled turbine blade simulation test piece. The thickness direction temperature gradient simulation scheme is as follows: A cavity blind hole structure airflow distribution device is set in the air-cooled turbine blade simulation test piece. The airflow distribution device is equipped with a flow divider and an impingement airflow outlet. The airflow entering the air-cooled turbine blade simulation test piece first enters the airflow distribution device, and the convection and impingement cooling of the inner wall surface of the air-cooled turbine blade are simulated through the flow divider and impingement airflow outlet on the airflow distribution device. Step 4: Variable temperature fatigue test measurement under complex temperature field, the process includes: Arbitrarily select an air-cooled turbine blade simulation test piece as a test piece, and weld thermocouples to the working part point A and the non-working part point B on one side of the test piece to measure the temperature of the working part point A and the non-working part point B respectively; Using point A, the working part of the test component, as the target temperature control location, a temperature spectrum is applied to the test component according to the temperature requirements of a real air-cooled turbine blade, and the temperature change curves of point B, the non-working part, are measured at different stages in one or more temperature cycles. The formal test begins with any air-cooled turbine blade simulation test piece. A thermocouple is welded to point B, the non-working part of the air-cooled turbine blade simulation test piece, during the formal test. The temperature curves T at points A (working part) and B (non-working part) are measured based on the test piece. A and T B The relationship is determined by the temperature curve T. B As the temperature control target value for each stage of the temperature cycle of the simulated air-cooled turbine blade test piece in the formal test, the temperature spectrum of the working part point A meets the requirements at this time. By applying the temperature spectrum and load spectrum simultaneously, the goal of variable temperature fatigue testing of air-cooled turbine blade simulation test specimens in complex temperature fields can be achieved.

2. The variable-temperature fatigue test method for simulating the complex temperature field of an air-cooled turbine blade as described in claim 1, characterized in that, The induction heating device is made of a coil based on electromagnetic induction simulation. The coil contains ferrite, and the local electromagnetic field strength can be adjusted by adjusting the position of the ferrite on the coil, thereby adjusting the temperature field.

3. The variable-temperature fatigue test method for simulating the complex temperature field of an air-cooled turbine blade as described in claim 1 or 2, characterized in that, The cooling rate of different parts of the air-cooled turbine blade simulation test piece can be adjusted by adjusting the position and opening size of the air-cooled nozzle.

4. The variable-temperature fatigue test method for simulating the complex temperature field of an air-cooled turbine blade as described in claim 1, characterized in that, The airflow distribution device has an external thread at its open end, which engages with the internal thread in the through hole of the air-cooled turbine blade simulation test piece to fix the relative position of the airflow distribution device and the air-cooled turbine blade simulation test piece.

5. The variable-temperature fatigue test method for simulating the complex temperature field of an air-cooled turbine blade as described in claim 4, characterized in that, The main body of the airflow distribution device is smaller than the diameter of the through hole cavity of the air-cooled turbine blade simulation test piece, so that a gap is formed between the two.

6. The variable-temperature fatigue test method for simulating the complex temperature field of an air-cooled turbine blade as described in claim 5, characterized in that, The flow divider is located between the film cooling hole of the air-cooled turbine blade simulation test piece and the cavity inlet on the lower side of the air-cooled turbine blade simulation test piece.

7. The variable-temperature fatigue test method for simulating the complex temperature field of an air-cooled turbine blade as described in claim 6, characterized in that, The impingement airflow outlet on the airflow distribution device is not coaxial with the film cooling hole on the air-cooled turbine blade simulation test piece, so that the impingement airflow outlet blows onto the walls on both sides of the film cooling hole to achieve cooling.

Images