Centrifugal compressor assembly and method

A method of controlling aerodynamic blockage, distribution and swirl of the refrigerant through a centrifugal compressor having a compressor housing, said compressor for compressing a refrigerant, comprising the steps of:

• a. positioning an inlet flow conditioning assembly upstream of an impeller disposed within the compressor housing said inlet flow conditioning assembly further comprising:
• i. an inlet flow conditioning housing positioned within the compressor the inlet flow conditioning housing upstream of an impeller housed in the compressor;
• said impeller having impeller blades with leading edges;
• the inlet flow conditioning housing forming a flow conditioning channel axially extending from a channel inlet to a channel outlet;
• ii. a flow conditioning body having a first body end with a first body end radius, an intermediate portion with a body radius and a second body end with a second body end radius;
• said flow conditioning body being substantially centrally positioned along a length of the flow conditioning channel;
• the flow conditioning body is arranged coincident to a flow conditioning nose at the first body end and coincident to the impeller hub of the impeller at the second body end, said flow conditioning body having a streamline curvature where the body radius relative to an axis of rotation of the impeller that exceeds a radius of the impeller hub and where the first body end radius and second body radius are less than the body radius;
• iii. a plurality of inlet guide vanes positioned between said channel inlet and channel outlet;
• said plurality of inlet guide vanes being rotatably mounted on a support shaft at a location along the flow conditioning body where the radius relative to the axis of rotation of the impeller exceeds the radius of the impeller hub;
• and
• iv. a strut including a first strut end and a second strut end, the first strut end being attached at the flow conditioning nose and the second strut end being attached to the inlet flow conditioning housing, and the strut designed to have a substantially s-shape in a plane substantially parallel to the channel inlet and
• b. drawing the refrigerant through said inlet flow conditioning assembly to the impeller during operation of the compressor,
• wherein the flow conditioning body, the flow conditioning nose and the plurality of inlet guide vanes are axially spaced along and relative to the flow conditioning channel to condition the refrigerant in the flow conditioning channel such that leading edges of the plurality of inlet guide vanes, in a fully open position, are aligned with a primarily axial flow distribution of the refrigerant in the fluid conditioning channel at and upstream of the plurality of inlet guide vanes and the plurality of inlet guide vanes, in a fully open position, impart on the primarily axial flow distribution of refrigerant, from the leading edges of the plurality of inlet guide vanes to trailing edges of the plurality of inlet guide vanes, a non-zero target swirl distribution, in a range between about 0 degrees to about 20 degrees, on the refrigerant flowing into leading edges of the impeller blades.

An inlet flow conditioning assembly for use in a variable speed compressor to control aerodynamic blockage, distribution, and swirl of a refrigerant, comprising:

• a. an inlet flow conditioning housing positioned within a compressor the inlet flow conditioning housing upstream of an impeller housed in the compressor;
• the impeller having impeller blades with a hub, mid, and shroud radii;
• the inlet flow conditioning housing forming a flow conditioning channel axially extending from a channel inlet to a channel outlet;
• b. a flow conditioning body having a first body end with a first body end radius, an intermediate portion with a body radius and a second body end with a second body end radius;
• said flow conditioning body being substantially centrally positioned along a length of the flow conditioning channel;
• the flow conditioning body is arranged coincident to a flow conditioning nose at the first body end and coincident to the impeller hub of the impeller at the second body end, said flow conditioning body having a streamline curvature where the body radius relative to an axis of rotation of the impeller that exceeds a radius of the impeller hub and where the first body end radius and second body radius are less than the body radius;
• c. a plurality of inlet guide vanes positioned between said channel inlet and channel outlet;
• said plurality of inlet guide vanes having hub, mid, and shroud radii greater than the impeller blades hub, mid, and shroud radii and said plurality of inlet guide vanes being rotatably mounted on a support shaft at a location along the flow conditioning body where the radius relative to the axis of rotation of the impeller exceeds the radius of the impeller hub;
• and
• d. a strut including a first strut end and a second strut end, the first strut end being attached at the flow conditioning nose and the second strut end attached to the inlet flow conditioning housing, the strut being configured to distribute wake across more than one row of the plurality of inlet guide vanes, and the strut having a substantially s-shape in a plane substantially parallel to said channel inlet
• wherein the flow conditioning body, the flow conditioning nose and the plurality of inlet guide vanes are axially spaced along and relative to the flow conditioning channel to condition the refrigerant in the flow conditioning channel such that leading edges of the plurality of inlet guide vanes, in a fully open position, are aligned with a primarily axial flow distribution of the refrigerant in the fluid conditioning channel at and upstream of the plurality of inlet guide vanes and the plurality of inlet guide vanes, in a fully open position, impart on the primarily axial flow distribution of refrigerant, from the leading edges of the plurality of inlet guide vanes to trailing edges of the plurality of inlet guide vanes, a non-zero target swirl distribution, in a range between about 0 degrees to about 20 degrees, on the refrigerant flowing into leading edges of the impeller blades.