Centrifugal impeller vibration damping test system and method

[0032] The technical solutions of the present invention will be described in more detail below in conjunction with embodiments:

[0033] Such as figure 1 , 4 , 5 shows: the centrifugal impeller vibration damping test system of the present invention includes a closed loop system, a wireless receiving gateway 10 and a terminal control unit 11:

[0034] The closed loop system includes a centrifugal compressor under test 5, a cooler 7, a throttle valve 1, a temperature sensor 2, a pressure sensor 3, and a cooler 7 sequentially arranged from the outlet of the centrifugal compressor 5 to the inlet of the centrifugal compressor 5. A flow meter 4; the cold source inlet of the cooler 7 is provided with a regulating valve 9 and a second flow meter 8 arranged in sequence along the flow direction of the cold source.

[0035] The surface of the centrifugal impeller 52 of the centrifugal compressor is installed with a strain sensor 521 for measuring the amount of blade strain. The front shaft end of the centrifugal impeller 52 is connected with the strain sensor 521 through a data line 522 and is connected to the wireless The wireless transmitter 6 that receives the strain signal transmitted by the gateway 10, and the wireless transmitter 6 rotates synchronously with the centrifugal impeller 52. In the present invention, a wireless transmitter 6 is installed in front of the shaft end of the centrifugal impeller 52 to transmit the vibration response measurement signal on the surface of the centrifugal impeller 52 to the wireless receiving gateway 10. The wireless receiving gateway 10 is connected to the terminal control unit 11, and the data transmission and reception adopts wireless transmission mode. The transmitter 6 is connected to the shaft end of the centrifugal impeller 52 and rotates synchronously with the centrifugal impeller 52, avoiding the disadvantages of complicated shaft end wiring and low structural reliability of the existing wired data transmission technology. The present invention is beneficial to improve the operational reliability and structure of the test system stability.

[0036] The wireless receiving gateway 10, the temperature sensor 2, the pressure sensor 3, the first flow meter 4, and the second flow meter 8 are connected to the signal receiving end of the terminal control unit 11, and the signal output end of the terminal control unit 11 is connected to the The throttle valve 1 and the regulating valve 9 are connected to control the opening of the throttle valve 1 and the regulating valve 9 respectively.

[0037] Such as figure 2 , 3 Shown: the inlet of the centrifugal compressor 5 is equipped with a plug-in plate 51, the plug-in plate 51 is provided with a through hole 511 coaxial with the inlet of the centrifugal compressor 5, and the edge of the through hole 511 faces the middle of the through hole 511 There are flaps 512 extending, and a plurality of flaps 512 are arranged at intervals along the circumference of the through hole 511. The diameter of the through hole 511 is the same as the diameter of the inlet of the centrifugal compressor 5. The split lobes 512 on the insert plate 51 of the present invention have the effect of turbulence, and can be used with the centrifugal compressor 5 to adjust the airflow excitation frequency, thereby ensuring the normal conduct of the damping measurement test.

[0038] The number of the flaps 512 is 3-6, and the total area of ​​the flaps 512 occupies 45%-55% of the area of ​​the through hole 511. The plug-in board 51 of the present invention has a simple structure, and is convenient to manufacture and install. The number and total area of ​​the split lobes 512 should not be too large or too small, too large will easily affect the normal passage of air flow, and too small will not play the role of turbulence.

[0039] The relationship between the distance L between the insert plate 51 and the centrifugal impeller 52 and the blade height h satisfies: 5h <7h, in order to avoid the turbulence intensity being significantly attenuated due to the excessive distance or the centrifugal compressor 5 flow instability due to the short distance.

[0040] The following is a method based on the described centrifugal impeller vibration damping test system, including the following steps:

[0041] Step 1. Collect the signals of the temperature sensor 2, the pressure sensor 3, the first flow meter 4, and the second flow meter 8 through the terminal control unit 11, and output control signals through signal analysis to change the throttle valve 1 and the regulating valve 9 The degree of opening, so as to realize that the centrifugal compressor 5 operates at the set intake temperature, intake pressure and flow;

[0042] Step 2. The terminal control unit 11 adjusts the rotational speed n of the centrifugal impeller 52 to change the airflow excitation frequency f caused by the insert plate 51, so as to excite the centrifugal impeller 52 to vibrate into the resonance zone, where the rotational speed n of the centrifugal impeller 52 and the airflow excitation frequency f The relationship is satisfied: f=nm/60; when the centrifugal impeller 52 vibrates into any modal resonance zone, the terminal control unit 11 obtains the vibration response of the centrifugal impeller 52 according to the strain signal transmitted by the wireless transmitter 6 to the wireless receiving gateway 10 Domain data, and obtain the frequency domain data of the vibration response of the centrifugal impeller 52 after Fourier transform;

[0043] Step 3. Substitute the frequency domain data in step b into the structural dynamic equation of the centrifugal impeller:

[0044] -(ω 2 I+iωC+K)ξ=F

[0045] Where I is the identity matrix, K is the stiffness, C is the vibration damping, F is the excitation force, ω is the circular frequency of the excitation and ω=2πf, ξ is the vibration response, i is the imaginary number, and the structure dynamic equation Solve to obtain the vibration damping C of the centrifugal impeller 52 under the set intake pressure; I, K, F, and ω in the structural dynamic equation are all known values;

[0046] Step 4. The terminal control unit 11 outputs a control signal to change the intake pressure of the centrifugal compressor 5 during operation, and repeats steps 1, 2 and 3 to obtain vibration damping under different intake pressures. -Straight-line fitting of data points on the vibration damping diagram (e.g. Image 6 (Shown), the damping value of the fitted straight line extension at zero pressure is the material damping C1 of the centrifugal impeller, and the aerodynamic damping C2=C-C1.

[0047] According to the vibration damping data of the centrifugal impeller under different intake pressures, the present invention separates the material damping through a straight-line fitting method of measuring data points, and realizes the simultaneous measurement of aerodynamic damping and material damping without adding other test means. The method of the present invention Simple and reliable.