Abstract: A material collider apparatus includes at least one rotor disposed for rotational movement having a plurality of circumferentially disposed pockets, each of the pockets retaining a portion of a flow velocity regulator and an adjustable retention mechanism. The adjustable retention mechanism includes a first wedge portion and a second wedge portion, the wedge portion each having inclined surfaces that are engaged with one another. An actuating member is disposed through the first and second wedge portions, in which the second wedge portion includes a mounting surface in contact with an edge of the velocity regulator and the first wedge portion includes a mounting surface in contact with an edge surface of the pocket. The second wedge portion is movable relative to said first wedge portion when the actuating member is engaged, thereby permitting tightening and release of the velocity regulator in a defined rotor pocket.