Fig. 1. Layer model of particle system
Fig. 2. The average particles number in monodisperse particle system different concentrations
Fig. 3. Lube oil absorption spectrum
Fig. 4. Lube oil infrared absorption spectroscopy
Fig. 5. Lube oil three-dimensional excitation emission matrix
Fig. 6. Spectral scanning results of lubricating oil droplets under different concentration gradients
Fig. 7. Absorption spectroscopy scan data fitting results
Fig. 8. Analyze the results of PCA
Fig. 9. Transmitted light intensity signal under stable experimental conditions
Fig. 10. Transmitted light intensity signals at different flicker frequencies
Fig. 11. Transmitted light intensity signals at different flicker frequencies
Fig. 12. Experimental instrument
Fig. 13. Oil mist droplet size frequency distribution in experiment
Fig. 14. Variance fitting results of light scintillation method
Fig. 15. Concentration test results of light scintillation and light transmission methods
| Parameter | Value | Method |
|---|
| ISO viscosity classification | 460 | ISO 3448 | | Kinematic viscosity（40℃）/cSt | 460 | ASTM D445 | | Kinematic viscosity（100℃）/cSt | 31 | ASTM D445 | | Density（40℃）/（kg·m-3） | 896 | | | Viscosity index | 95 | ISO 2909 | | Refractive index | 1.47 | Abbe refractometer | | Flash point/℃ | 260 | ISO 2592 |
|
Table 1. Physical parameters of lubricating oil
| Component | Characteristic root | Variance contribution rate/% | Accumulated variance contribution rate/% |
|---|
| 1 | 5.26 | 87.59 | 87.59 | | 2 | 0.35 | 5.83 | 93.42 | | 3 | 0.25 | 4.11 | 97.53 | | 4 | 0.11 | 1.84 | 99.36 | | 5 | 0.038 | 0.66 | 100 |
|
Table 2. Total variance explanation
| Light scintillation causes | Frequency influence |
|---|
| Media level | Temperature and pressure lead to fluctuations in the density of the medium，causing optical inhomogeneity of the medium | The whole frequency，and influence of media density fluctuation frequency is drastic | | Medium velocity | The high-frequency influence，gas velocity is positive correlated with the frequency | | Particles level | Random enter of particles in light | The low-frequency，it is related to the beam diameter and gas velocity | | Discontinuities of particle concentration | The low-frequency，and it is lower than the frequency of the random enter of particles in light | | The interaction between particles and media | Turbulence effect，the dual effect of gas velocity and particles due to turbulent movement of the medium | The whole frequency，it is related to the turbulence intensity of the medium |
|
Table 3. The causes of light scintillation and the influencing factors of scintillation frequency
| Particle | D32=1 μm |
|---|
| /（mg·m-3）（=900 kg/m3） | 20 | | v/（m·s-1） | 2 | | D/mm | 2 | | L/mm | 400 |
|
Table 4. Operating conditions of light scintillation frequency experiment
| Calibration concentration/（mg·m-3） | Intensity /V* | Intensity/V | Variance
| Scintillation concentration/（mg·m-3） | Scintillation error/% | / % | Transmission concentration/（mg·m-3） | Transmission error/% |
|---|
| 4.8 | 1.5 156 | 1.5 148 | 0.000 322 | 4.5 | 6.3 | 0.05 | 0.6 | 88.4 | | 5.2 | 1.5 132 | 0.000 334 | 5.4 | 3.8 | 0.16 | 1.7 | 67.9 | | 6.7 | 1.5 008 | 0.000 387 | 7.1 | 6.0 | 0.99 | 10.3 | 54.1 | | 8.9 | 1.5 148 | 0.000 425 | 8.2 | 7.9 | 0.05 | 0.6 | 93.8 | | 9.4 | 1.4 999 | 0.000 498 | 9.3 | 1.1 | 1.05 | 11.0 | 16.5 | | 10.5 | 1.5 025 | 0.000 708 | 9.6 | 8.6 | 0.87 | 9.1 | 13.0 | | 12.9 | 1.5 102 | 0.001 101 | 12.7 | 1.6 | 0.36 | 3.8 | 70.9 | | 13.7 | 1.4 854 | 0.000 921 | 13.0 | 5.1 | 2.03 | 21.2 | 54.6 | | 15.8 | 1.4 985 | 0.001 006 | 14.5 | 8.2 | 1.14 | 11.9 | 24.4 | | 17.9 | 1.4 895 | 0.001 253 | 18.9 | 5.6 | 1.75 | 18.3 | 2.1 | | 19.6 | 1.4 802 | 0.001 472 | 20.6 | 5.4 | 2.39 | 24.9 | 26.9 | | 20.8 | 1.4 785 | 0.001 456 | 20.5 | 1.4 | 2.51 | 26.1 | 25.4 | | 22.9 | 1.4 799 | 0.001 603 | 24.8 | 8.3 | 2.41 | 25.1 | 9.5 | | 23.6 | 1.4 811 | 0.001 700 | 21.5 | 8.9 | 2.33 | 24.2 | 2.6 | | 24.8 | 1.4 811 | 0.001 536 | 25.9 | 4.4 | 2.33 | 24.2 | 2.3 | | 26.8 | 1.4 785 | 0.001 876 | 27.6 | 3.0 | 2.51 | 26.1 | 2.7 | | 28.4 | 1.4 765 | 0.001 988 | 25.7 | 9.5 | 2.65 | 27.5 | 3.2 | | 29.3 | 1.4 705 | 0.002 242 | 31.2 | 3.4 | 3.07 | 31.8 | 8.5 | | 31.1 | 1.4 698 | 0.002 211 | 32.2 | 3.5 | 3.12 | 32.3 | 3.8 | | 33.5 | 1.4 685 | 0.002 245 | 31.2 | 6.9 | 3.21 | 33.2 | 0.9 | | 35.6 | 1.4 625 | 0.002 592 | 39.1 | 9.8 | 3.63 | 37.5 | 5.4 | | 37.9 | 1.4 601 | 0.002 653 | 37.1 | 2.1 | 3.80 | 39.2 | 3.6 | | 39.6 | 1.4 585 | 0.002 787 | 42.5 | 7.3 | 3.91 | 40.4 | 2.0 | | 40.5 | 1.4 545 | 0.003 035 | 39.5 | 2.5 | 4.20 | 43.3 | 6.9 | | 41.8 | 1.4 501 | 0.003 211 | 39.5 | 5.5 | 4.52 | 46.5 | 11.2 | | 42.9 | 1.4 526 | 0.003 003 | 45.6 | 6.3 | 4.34 | 44.7 | 4.1 | | 43.6 | 1.4 511 | 0.003 313 | 46.5 | 6.7 | 4.44 | 45.8 | 4.9 | | 45.9 | 1.4 498 | 0.002 952 | 43.5 | 5.2 | 4.54 | 46.7 | 1.7 | | 47.2 | 1.4 485 | 0.003 304 | 45.1 | 4.4 | 4.63 | 47.6 | 0.9 | | 49.5 | 1.4 398 | 0.003 465 | 52.3 | 5.7 | 5.26 | 54.0 | 9.0 | | 50.2 | 1.4 385 | 0.003 411 | 54.1 | 7.8 | 5.36 | 54.9 | 9.4 |
|
Table 5. Experimental results of concentration calibration using scintillation and transmission methods
