On page Volute you can define some properties used for the spiral design.

 

 

General data:

 

Volute inlet:

 

For ηv and FQ, standard values of 1.0 are used. d4 and b4 are determined using the ratios d4/d2 and b4/b2, which are calculated from functions dependent on the specific speed nq (see Approximation function).

Clicking on the Calculate-button, to the top right, recalculates the standard values.

 

A short distance between the impeller and the cut-water is desirable for reasons of flow. For acoustic and vibration reasons, however, a certain minimum distance is necessary. The inlet width b4 should be chosen such that the width/height ratio at the end cross-section of the volute is close to 1. The ratio b4/b2 can be varied within a relatively wide range without significant negative effect on the efficiency. For radial impellers with open impeller sides, values up to b4/b2=2 are possible. At higher specific speeds (wider impellers), however, high width ratios have a negative effect on flow (intensive secondary flows, turbulence losses). In this case, b4/b2 should be between 1.05 and 1.2.

 

Values dIn and bIn are coupled to the corresponding interface values.

 

 

Various calculated values are shown, for information purposes, on the right side (Values):

 

 

 

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