Abstract: The annular Hypersonic Low Temperature (HYLTE) nozzle arrayis a gain generator of cylindrical high power chemical lasers. In thispaper, a novel design of HYLTE nozzle without base purging is presented.Based on 3D Navier-Stokes equations and the realizable k-\varepsilon model, the multi-species reacting flow field of the annular HYLTE nozzle iscalculated. The numerical simulation results show that eddies along the flowdirection and highly twisted contact surfaces between fuel and oxidizer aremajor factors for rapid mixing and reacting rate of HYLTE. Multi spectralaser outputs are compared between the old HYLTE nozzle design and the newone, which shows that with the new HYLTE design, a total of 3kW output power can beextracted from 1g F atom reacting gas by BCAR resonator, howerver, only1.6kW can be extracted with the old design. In addition, the new design notonly simplifies the fabrication of the complex HYLTE nozzle, but alsoreduces theconsumption of He used in the high-energy chemical DF laser.