Learning Forum

[meier2]

I am trying to create a diffuser for a radial compressor in BladeGen (stationary component downstream of impeller), but cannot create vanes without curvature. It seems like this is a relationship between beta and theta, but have not been able to configure the settings to achieve this vane shape. The goal is to create a wedge shaped vane with straight suction and pressure surfaces.n

[rfblumen]

It's possible to derive a mathematical relationship between beta and meridional length (or theta and meridional length) in order to generate straight lines in in Cartesian space (since theta and beta are related to each other, you would want to select one or the other to work with). This would need to be in conjunction with an appropriate normal thickness distribution that's a function of meridional length.nThe inputs to this calculation would be alpha angle (i.e. absolute flow angle from the impeller exit w.r.t. tangential or radial direction), desired inner and outer radii of the diffuser, and diffuser L/W1 and A2/A1 along with the diffuser width in the axial direction. Assuming a constant axial diffuser width, b3, this would give W2/W1 where W1 and W2 are the diffuser width w.r.t. the flow passage and L is the effective diffuser length in the flow passage). I would suggest creating a 2-D diffuser design for your radial flat-walled diffuser by hand, and maybe using a spreadsheet or using some way of programming thisnWork out the (x,y,z) coordinates in Cartesian space. Determine corresponding values of theta or beta vs meridional length and normal thickness vs meridional length based on the Cartesian (x,y,z) coordinates. Transfer these points to BladeGen using the point import option for the angle and thickness curves.nIf you follow the instructions above you should be able to generate something like this:nn