Strength optimization of the enclosed wheels of centrifugal compressors with nonradial blades

Abstract

1. The material of the wheel elements must be chosen according to a combination of design, technical, and production considerations with specified efficiency, pressure and expense characteristics, outside diameter D2, number of blades, relative bore, and angle of the covering disk. It is desirable to make the supporting disk of a material with a lower strength than the covering. 2. Taking into account the wealth of service experience with the centrifugal compressors of the V. I. Lenin Neva Machinery Plant and the Turbine Motor Plant, disks with hD/D2=0.007–0.01 should be used. Higher values of hD/D2 are recommended for wheels pumping dense media. 3. The relative thickness of the blade hB/hD must be within the limits of 2–2.5. Higher values must be used for wheels with ϕ=8–12° and lower for ϕ=0–6°. The diameter of the rivets must be 4–6 mm less than the thickness of the blades. 4. The relative diameter of the rivets dr/t must be within the limits of 0.2–0.3. Higher values must be used for primarily static loading of the wheel with the use of a ductile material which has good resistance to brittle failure and lower for repeated static loading (frequent starting and stopping of the compressor) especially with below zero temperatures of the medium being pumped. The optimum radii of the location of the upper rU and lower rL rows of rivets have the following relative values: $$\bar r_U = \frac{{r_U }}{{r_2 }} = 0.9; \bar r_L = \frac{{rL}}{{r_1 }} = 1.4.$$