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In the panel Shaft, the required shaft diameter is computed.

¢ Shaft/ Hub

The main dimensions of a rotor - suction diameter dS, hub diameter dH, rotor diameter d1 and inlet width b1 - can be seen on the tab sheet Dimensions. They can be recomputed by pressing the Calculate-button within the panel Main dimensions. The computation is based on "Euler's Equation of Turbomachinery", on the continuity equation and the relations for the velocity triangles as well as on the parameters and parameter ratios given in the tab sheets Setup and Parameters.

Individual main dimensions can be calculated separately using the button inside the value field.

One may accept the proposed values or can modify them slightly, e.g. to meet a certain normalized diameter.

In case the checkbox Automatic is activated a new calculation will accomplished after any change of parameter. Then the manual alteration of the main dimensions is not possible.


Neighboring components

In specific cases the dimensions of the neighboring components at inlet and/ or outlet can be used to get exactly matching geometry.

This feature is available only for explicitly uncoupled components or side-by-side impellers.


In the right panel of any tab sheet an information panel is situated, which holds the computed variables in accordance to the actual state of design, the resulting Meridional section as well as the Cordier-Diagramm with the location of the best point. These three sections can be chosen by the appropriate soft buttons in the heading.

In the information section of the tab sheet Dimensions the following variables are displayed for Information:

Work coefficient

Flow coefficient

Meridional flow coefficient

Diameter coefficient

Specific speed nq
(different unit definitions: see Preferences)

points to machine type and general shape of rotor

Inlet pressure, density and temperature

p1, T1, ρ1, pt1, Tt1, ρt1

static and total values

Inlet velocities

c1, cu1, cm1, w1


Peripheral speed at inlet


Blade width at inlet

Outlet pressure, density and temperature

p2, T2, ρ2, pt2, Tt2, ρt2

static and total values

Outlet velocities

c2, cu2, cm2, w2

Peripheral speed at outlet

Outlet Ma-Number

Mean diameter at outlet

Width at outlet

Ratio Width-diameter at inlet


guideline: 0.05..0.15

Diameter ratio

d2/d2min with:

guideline: 1.005..1.05

Ratio radius-width at outlet

guideline: 1.005..1.05

Isentropic velocity ratio

The guidelines given in the last column of the last three rows, should be matched within the design.

It might be that for the chosen configuration of global setup and main dimensions a reasonable thermodynamic state cannot be calculated. This may be the case if e.g. the mass flow is too high for the chosen cross sections. Then a warning is generated.


The Meridional preview is based on the main dimensions designed until this point.


The Cordier diagram can be used for checking the impeller diameter d2.

See Cordier.

The Velocity triangles are the result of a mid-span calculation and are based on the design point and the main dimensions.

The Velocity triangles are the result of a mid-span calculation and are based on the design point and the main dimensions.