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Friction, Lubrication, and Wear Technology (1997) Part 9

Tham khảo tài liệu 'friction, lubrication, and wear technology (1997) part 9', kỹ thuật - công nghệ, cơ khí - chế tạo máy phục vụ nhu cầu học tập, nghiên cứu và làm việc hiệu quả | Radius of hemispherical end - 1 in. CD - 0-005 in. Pin diameter 0.375 In. Fig. 22 Bushing insert for pivoted-pad hydrostatic journal bearing. Source Ref 21 Three-Sector Journal Bearing This journal bearing with three equally spaced axial grooves has shown some degree of stability against self-excited whirl. Castelli and Pirvics Ref 26 have presented comprehensive numerically computed performance characteristics for three- and four-axial grooved gas-lubricated journal bearings. Angular extent of each groove is considered to be 5 . Thus for a three-sector bearing the arc length of a sector would be 120 - 5 115 . Figure 23 lists results in terms of the dimensionless load capacity parameter W W pa rl plotted against the bearing compressibility number X . Note that the value of X used here is actually the same as in Eq 1. The applied load is directed toward the center of one sector. Evaluating W and Xwill determine the eccentricity ratio and thus the minimum film thickness. AÈA-R4NG NUMẸĨR. A Fig. 23 Load function W versus Xfor three-groove journal bearing. Source Ref 26 Information on many other sizes load directions and attitude angles can be found in Ref 26 and 27. Helical-Grooved Journal Bearings The helical grooving in this type of journal bearing enhances stability by reducing the attitude angle below that obtained from a plain cylindrical journal bearing. These bearings are known for their stability and are often used as a possible substitute for tilting-pad journal bearings. Castelli and Vohr Ref 28 solved the appropriate equations numerically for load capacity and attitude angle for the case of l d 1.0 with various values of X. Figure 24 lists the geometric parameters for the spiral-grooved bearing as used in Ref 28. Figure 25 lists the results showing the load parameter W Wpa as a function of .with the eccentricity ratio as the third variable. Malanoski Ref 29 shows good comparison between the theoretical predictions of Castelli and Vohr and his own measured .