A boundary layer turbomachine, comprising: a housing defining an interior space and having an inlet opening (112, 113, 114) and an outlet opening (112, 113, 114) to facilitate movement of a fluid through the housing; a rotor assembly (120, 420, 520) disposed in the housing and configured to rotate about an axis of rotation, the rotor assembly having a plurality of disks (121, 421, 450, 521) spaced apart along the axis of rotation and defining an interior opening configured as a void centred on the axis of rotation, wherein the fluid passes through gaps (354, 454) between the disks (121, 421, 450, 521) and the interior opening (426, 526) as the fluid moves through the housing, wherein the turbomachine is configured such that fluid moving through the housing is guided into or from the gaps at a plurality of locations around outer edges of the disks; and a partition circumferentially dividing the interior space into an outer chamber having an annular volume and a rotor chamber located radially inward of the outer chamber, wherein the rotor assembly (120, 420, 520) is disposed in the rotor chamber, the partition having partition openings spaced circumferentially around the partition such that fluid is movable through the partition between the outer chamber and the rotor chamber at the plurality of locations, characterised in that a pair of extension members couple the rotor assembly (120, 420, 520) to the housing and are configured to facilitate rotation of the rotor assembly about the axis of rotation, the pair of extension members being attached to the plurality of disks opposite one another inline with the axis of rotation, wherein the extension members each further include a fluid port in fluid communication with the interior opening (426, 526) to allow fluid to enter or exit the interior opening via the fluid ports. a housing defining an interior space and having an inlet opening (112, 113, 114) and an outlet opening (112, 113, 114) to facilitate movement of a fluid through the housing; a rotor assembly (120, 420, 520) disposed in the housing and configured to rotate about an axis of rotation, the rotor assembly having a plurality of disks (121, 421, 450, 521) spaced apart along the axis of rotation and defining an interior opening configured as a void centred on the axis of rotation, wherein the fluid passes through gaps (354, 454) between the disks (121, 421, 450, 521) and the interior opening (426, 526) as the fluid moves through the housing, wherein the turbomachine is configured such that fluid moving through the housing is guided into or from the gaps at a plurality of locations around outer edges of the disks; and a partition circumferentially dividing the interior space into an outer chamber having an annular volume and a rotor chamber located radially inward of the outer chamber, wherein the rotor assembly (120, 420, 520) is disposed in the rotor chamber, the partition having partition openings spaced circumferentially around the partition such that fluid is movable through the partition between the outer chamber and the rotor chamber at the plurality of locations, characterised in that a pair of extension members couple the rotor assembly (120, 420, 520) to the housing and are configured to facilitate rotation of the rotor assembly about the axis of rotation, the pair of extension members being attached to the plurality of disks opposite one another inline with the axis of rotation, wherein the extension members each further include a fluid port in fluid communication with the interior opening (426, 526) to allow fluid to enter or exit the interior opening via the fluid ports. a plurality of disks (121, 421, 450, 521) spaced apart along the axis of rotation and defining an interior opening configured as a void centred on the axis of rotation, wherein the fluid passes through gaps (354, 454) between the disks (121, 421, 450, 521) and the interior opening (426, 526) as the fluid moves through the housing, wherein the turbomachine is configured such that fluid moving through the housing is guided into or from the gaps at a plurality of locations around outer edges of the disks; and a partition circumferentially dividing the interior space into an outer chamber having an annular volume and a rotor chamber located radially inward of the outer chamber, wherein the rotor assembly (120, 420, 520) is disposed in the rotor chamber, the partition having partition openings spaced circumferentially around the partition such that fluid is movable through the partition between the outer chamber and the rotor chamber at the plurality of locations, characterised in that a pair of extension members couple the rotor assembly (120, 420, 520) to the housing and are configured to facilitate rotation of the rotor assembly about the axis of rotation, the pair of extension members being attached to the plurality of disks opposite one another inline with the axis of rotation, wherein the extension members each further include a fluid port in fluid communication with the interior opening (426, 526) to allow fluid to enter or exit the interior opening via the fluid ports.