Blade properties

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Blade properties

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► IMPELLER | Blade properties

Definition of blade properties is made in three steps:

(1) Cu-specification

(2) Blade profile selection

(3) Kinematics

Specification of number of blades and number of spans

Information

In the right panel some information are displayed which result from calculated or determined values:

(1) Velocity triangles

The velocity triangles of inflow and outflow are displayed.

Continuous lines represent flow velocities on hub (blue) and shroud (green).

Velocities directly before and behind blade area are displayed by dashed lines to show the influence of blockage in the flow domain.

Furthermore the blade angles are displayed by thick lines in order to see the incidence angle on the leading edge and the flow deviation caused by slip velocity on trailing edge.

(2) Values

Numerical values of velocity components and flow angles are displayed in a table. The track bar on top of table can be used to get the values at any span. A short description is at mouse cursor too:

z

Axial co-ordinate

d

Diameter

αF

Angle of absolute flow to circumferential direction

βF

Angle of relative flow to circumferential direction

u

Circumferential velocity

cm

Meridional velocity  (cm=wm)

cu

Circumferential component of absolute velocity

cr

Radial component of absolute velocity

cax

Axial component of absolute velocity

c

Absolute velocity

wu

Circumferential component of relative velocity: wu+cu=u

w

Relative velocity

τ

Obstruction by blades (see below)

i

Incidence angle: i = βB1 - β1

δ

Deviation angle: δ = βB2 - β2

w2/w1

Deceleration ratio of relative velocity

ΔαF

Absolute deflection angle

ΔβF

Relative deflection angle

ΔβB

Blade deflection angle

γ

Slip coefficient

Δ(cu·r)

Swirl difference

M

Torque

Δpt

Pressure difference (total-total)

(3) Meridian

The Meridian with locations of the spans is displayed in this diagram.

(4) Curves

Here blade angles as well as relative flow angles are displayed versus span.

Progressions of geometric parameters (angles):

β1/2

Angle of relative flow to circumferential direction

βB1/2

Blade angles at leading and trailing edge

 

(5) Criteria

Progressions of aerodynamic and airfoil parameters:

Re

Reynolds-number

l/t

solidity

DH

DeHaller critierion

ST

Strscheletzky critierion

DF01

diffusion number