A gas generator for providing continuous pressure rise combustion, including: a rotatable member including a forward end, an aft end, a circumferential wall and a longitudinal centerline axis extending therethrough; an outer circumferential wall, wherein the rotatable member is positioned therein so that the circumferential wall of the rotatable member is spaced radially inwardly from the outer circumferential wall; at least one helical channel formed by a plurality of helical sidewalls extending between the circumferential wall of the rotatable member and the outer circumferential wall, each helical channel being open at the forward end and the aft end of the rotatable member so as to provide flow communication therethrough; an air supply for providing air to each helical channel; and, a fuel supply for providing fuel to each helical channel. Each helical channel includes an inlet portion having a first cross-sectional area for receiving a flow having a designated shape and orientation, a throat portion downstream of the inlet portion having a second cross-section less than the first cross-section of the inlet portion, and a diffusion portion downstream of the throat portion having a third cross-section greater than the second cross-section of the throat portion. A device is also positioned downstream from the diffusion portion of each helical channel for holding flame therein. A mixture of the fuel and air is continuously combusted downstream of the diffusion portion of each helical channel in a manner such that combustion gases exit therefrom with an increased pressure and temperature.