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Mean line |
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Mean line |
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Ü Impeller | Blade mean line 
The blade mean lines are designed on the number of meridional flow surfaces which were determined in Blade properties.
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The spatially curved meridional flow surfaces are mapped to a plane by coordinate transformation. This coordinate system has the angle in circumferential direction t as abscissa and the dimensionless meridional extension m as the ordinate.
Both quantities are created by the reference of absolute distances in meridional (M) and tangential direction (T) to the local radius r:
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This conformal mapping allows the uniform handling of various impeller types (radial, mixed-flow, axial).
It should be noted that for each meridional flow surface a separate m-coordinate is existing.
The mean lines can be designed on 2 alternative methods. On panel Design mode you can select:
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m,t-geometry
The blade is designed in the conformal m,t-mapping by Bezier splines. Beta distribution is calculated and displayed for checking in the diagram right top. |
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βB progression
The blade is designed via its Beta distribution by Bezier splines. m,t-curves are calculated and displayed for information.
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Depending on the selected blade shape (see Blade properties) the design of the mean lines is more or less restricted.
¢ Freeform blades, 2D blades, Radial element blades
¢ Circular blades, Straight blades
The blades of an impeller representing a deceleration cascade for the relative velocity. Therefore the risk of flow separation exists. The user should try to obtain a continuous, smooth change of flow direction, as well as the cross section graduation of the flow channel should be as steady as possible.
If the impeller has Unlinked splitter blades (see Blade properties), then you can specify the behavior of the splitter in case the main blade is changing:
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The Frontal view (switch above the diagram) represents the designed mean lines in a frontal view, including diameters dN and d2.
Blade properties are displayed in tables and diagrams in order to check the design and for informational purposes.
The blade lean angle can be manipulated only indirectly:
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