Low-flow stator and method

A low-flow stator for use upstream of a rotor of a tank cleaning machine comprising:

• a body having a front surface, a rear surface and a circumferential sidewall coupling the front and rear surfaces, said body defining an axis passing through the front and rear surfaces;
• said front surface having a periphery, at least a portion of said front surface extending from said periphery axially away from the sidewall and radially inwardly;
• said body comprising a plurality of passageways fluidly coupling the front and rear surfaces, each said passageway extending from an entrance to an exit;
• each said passageway defining a generally helical flow path from said entrance to said exit so that a fluid passing along said flow path leaves said exit of said passageway at an exit angle relative to a line passing through said exit and oriented parallel to said axis;
• each said exit being completely circumferentially offset from its corresponding entrance;
• and
• wherein said passageways have an inner diameter and an outer diameter, said inner and outer diameters defining an annular surface area, said entrances of said passageways having cross-sectional areas, the sum of the cross-sectional areas of said entrances of said passageways is no more than about 30.degree. of said annular surface area.

A low-flow stator for use upstream of a rotor of a tank cleaning machine comprising:

• a body having a front surface, a rear surface and a circumferential sidewall coupling the front and rear surfaces, said body defining an axis passing through the front and rear surfaces;
• said front surface having a periphery, at least a portion of said front surface extending from said periphery axially away from the sidewall and radially inwardly;
• said body comprising a plurality of passageways fluidly coupling the front and rear surfaces, each said passageway extending from an entrance to an exit;
• each said passageway defining a generally helical flow path from said entrance to said exit so that a fluid passing along said flow path leaves said exit of said passageway at an exit angle relative to a line passing through said exit and oriented parallel to said axis;
• each said exit being completely circumferentially offset from its corresponding entrance;
• and
• wherein cross-sectional areas of said entrances and exits of said passageways are different.

A low-flow stator for use upstream of a rotor of a tank cleaning machine comprising:

• a body having a front surface, a rear surface and a circumferential sidewall coupling the front and rear surfaces, said body defining an axis passing through the front and rear surfaces;
• said front surface having a periphery, at least a portion of said front surface extending from said periphery axially away from the sidewall and radially inwardly;
• said body comprising a plurality of passageways fluidly coupling the front and rear surfaces, each said passageway extending from an entrance to an exit;
• each said passageway defining a generally helical flow path from said entrance to said exit so that a fluid passing along said flow path leaves said exit of said passageway at an exit angle relative to a line passing through said exit and oriented parallel to said axis;
• each said exit being completely circumferentially offset from its corresponding entrance;
• and
• wherein cross-sectional areas of passageways are larger at said entrances than at said exits.

An improved tank cleaning machine of the type having a stator upstream of a rotor, the improvement comprising:

• a stator body having a front surface, a rear surface and a circumferential sidewall coupling the front and rear surfaces, said body defining an axis passing through the front and rear surfaces;
• said front surface having a periphery, said front surface extending from said periphery axially away from the sidewall and radially inwardly;
• said body comprising a plurality of passageways, each said passageway extending from an entrance adjacent the front surface to an exit adjacent the rear surface;
• each said passageway defining a generally helical flow path from said entrance to said exit so that a fluid passing along said flow path leaves said exit of said passageway at an exit angle of about 5.degree. to 85.degree. relative to a line passing through said exit and oriented parallel to said axis;
• each said exit being completely circumferentially offset from its corresponding entrance by an offset angle of about 5.degree. to 170.degree.;
• and
• said passageways having an inner diameter and an outer diameter, said inner and outer diameters defining an annular surface area, said entrances of said passageways having cross-sectional areas, the sum of the cross-sectional areas of said entrances of said passageways is no more than about 30% of said annular surface area.

A method for directing a liquid to a rotor of a tank cleaning machine, the liquid passing along a flow direction, comprising the following steps:

• deflecting said liquid radially outwardly at an entrance angle to the flow direction;
• flowing said liquid into a plurality of generally helical passageways, each said passageway having an entrance and an exit;
• and
• directing said liquid from each of said exits towards the rotor at an exit angle with each said completely circumferentially offset from its corresponding entrance.