Shroud for rotary engine

A rotor assembly comprising:

• a. a plurality of rotors comprising at least a first and a second rotor having respective center axes that are not co-linear, and each having lobes and valleys,
• b. the first and a second rotor each comprising an outer surface forming part of a spherical surface arranged such that each outer partial spherical surface shares a common center;
• c. a shroud body comprising an inner spherical surface operatively configured to completely surround the outer spherical surfaces of the lobes and valleys of both of the first and second rotors through a full rotation of the first and second rotors, and the shroud body rotates at some angular velocity in the same direction as the rotors;
• and
• d. where the shroud body comprises one or more surfaces defining radial ports.