摘要: In an effort to improve thermal management of the gain medium in high-average power, high-intensity lasers, this study focuses on simulating the gas flow through multiple narrow channels. Actively cooling lasers of this class invo... 展开 In an effort to improve thermal management of the gain medium in high-average power, high-intensity lasers, this study focuses on simulating the gas flow through multiple narrow channels. Actively cooling lasers of this class involves flowing helium gas through an array of closely-spaced vanes, where each vane contains a thin slab of gain medium. Since the role of turbulence is crucial to both the thermal management of the gain material and to the optical quality of the laser, it is imperative that the state of the flow within these channels and over the gain medium is properly understood. In the absence of experimental data, the current work utilizes RANS turbulence models and the Langtry-Menter transition prediction model to obtain flow solutions within a representative helium gas-cooled laser amplifier design. The RANS results reveal three flow features within the amplifier head: separation at the inlet diffuser, potential relaminarization within the channels, and a separation region downstream due to the diverging sections of the channels. While computationally inexpensive and suited for exploring optimal aerodynamic design configurations of the amplifier head, the RANS solutions only provide averaged flow quantities. Since the fluctuating density field is necessary for future aero-optical analyses of the laser propagating through the gas flow, a preliminary LES is also introduced. In addition to aero-optics, it is expected the LES will shed light into the inherent unsteadiness of the aforementioned separation regions, which in turn may highlight any links to structural vibrations of the vanes themselves. A comparison of the mean flows of the RANS and LES solutions indicates good agreement within the channels and near the gain medium, and shows that the LES and RANS capture similar separation and recirculation features. 收起