Numerical study on the performance of nozzle flow for supersonic chemical oxygen–iodine lasers

Abstract

Laser performance is greatly dependent on its operating conditions due to the strong coupling among multiphysics such as gas-dynamics, chemical reaction kinetics and optics in the mixing nozzle of COIL. In this paper, 3D CFD technology is used to simulate the mixing and reactive flow of subsonic cross jet scheme at different conditions. Results obtained show that the jet penetration depth plays a dominant role in the spatial distribution of small signal gains. In the case of over-penetration, unsteady flow structures are induced by impinging between the opposing jets. The optimum spatial distribution of the chemical performance cannot be obtained even if the full penetration condition is achieved through the subsonic transverse jet mixing scheme in the COIL nozzle flow.

On the numerical technique for the simulation of hypervelocity test flows

“…For this case, the velocity of the test flow is around 8.8 km/s which exceeds the orbital speed. Why does the scheme work well in previous simulations [21][22][23][24][25] of chemically reactive flow but lead to spurious oscillation in the present simulation?…”

“…1 (right). The DCD scheme has been applied to simulate shock wave problems in inert or reacting flows [21][22][23][24][25][26][27]. However, serious spurious oscillation occurs when the original DCD scheme is used for the simulation of hypervelocity test flow in the detonation-driven expansion tube, JF-16 [13,14].…”

“…The DCD scheme, without any tunable parameters, avoids encountering the 'carbuncle' phenomena altogether even for the case of very strong shock wave. It has also been successfully applied to chemically reacting flows for compressible multi-component mixtures [21][22][23][24][25] and flows in the presence of strong shock wave interaction [26,27]. The mentioned applications have attested to the DCD scheme as fairly robust, computationally efficient, and capable of resolving strong discontinuities.…”

“…(11). The original DCD scheme is easy for programming and computationally cheap due to the aforementioned simplicity which has been used successfully in a series of applications [21][22][23][24][25][26][27] except the simulation of shockexpansion tube running at high enthalpy. For the updated DCD scheme, however, the flow variables used for calculating the eigenvectors and eigenvalues are different from those used for the unknown vector as can be seen from Eq.…”

Numerical investigation on the flowfield of “swallowtail” cavity for supersonic mixing enhancement

“…Numerical investigation was carried out by solving the Reynolds-averaged Navier-Stokes equations and the k-ε two-equation turbulence model based on the accepted governing equations to simulate turbulent mixing. Doing so is because that numerical simulations are now more and more important in studying supersonic mixing [12,13], as well as that the numerical work can give details which are difficult to be measured in experiments and moreover very helpful for the previous design of experiments. Physical models and numerical algorithms were validated first.…”