<< Click to Display Table of Contents >>

Navigation:  Impeller > Main dimensions >


Previous pageReturn to chapter overviewNext page

Dimensioning of the shaft diameter is made under application of strength requirements. It is a result of torque M=P/ω to be transmitted by the shaft and the allowable torsional stress τ of the material.

You can directly enter allowable stress or select the value from a list by pressing settings button right beside the input area.

In a small dialog window you can see some materials and its allowable stress. The basis of these values is the allowable torsional stress of the material. Due to the fact that the shaft is additionally loaded by bending in the same order of magnitude, a safety factor of 10 ... 15 is used typically, which leads to the relatively low stress values (see References: Steinhilper/ Röper).

The list can be extended or reduced by and button. You can confirm selected value by pressing the OK-button.

At File location the file containing material properties is shown. The file is originally called Stress.cftst and is located in the installation directory of CFturbo. Modifications of the list will be saved if the user is leaving the dialog window by clicking the OK-button. In case there are no write permissions the user can choose another directory to save the file. Renaming of files is possible by Save as- functionality. By clicking the Open-button a previously saved file can be opened.

To consider a higher load, e.g. due to operating conditions away from the design point, a safety factor SF may be specified leading to a modified proposed shaft diameter d.

The hub diameter dH is usually selected as small as possible and depends on the kind of connection of hub and shaft.