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Xu R.,Shenyang Aerospace University | Zhang N.,Shenyang Aerospace University | Lin X.,State Key Laboratory of Laser Interaction with Matter China | Zhao C.,Shenyang Aerospace University | Li G.,Shenyang Aerospace University
Proceedings of SPIE - The International Society for Optical Engineering | Year: 2013

In order to predict wall shear, heat flux and heat transfer coefficient on target surface and temperature field in the target under laser irradiation, fluid-solid thermal coupled computational models have been set up to simulate the subsonic near-wall airflow traversing a crater in target and heat transfer in target solid. Phase transition was not integrated in the model. The prototype of the models is the experiment section of a flow simulation experiment facility, and the model was verified by the measured flow field data in it. The results of numerical calculation show that depth of the crater, air density and velocity produce effects on flow field in a varying degree. For targets with flat surface or with shallow crater, the near-wall flow and wall shear are similar to those of plane boundary layer, while high vorticity inverse flow exists in deep crater. While wall shear increases with air density and velocity, it diminishes with increasing depth of the crater, especially for high Mach number flow. The convective heat transfer as a result of the traversing airflow influence the thermal effects of laser irradiation in several ways. For the given intensity of laser, the convective heat loss is less than 7% after the surface temperature reaches melting point in all cases, and surface heat transfer coefficient undergoes a sharp decrease from the initial high level in 1s because of the temperature difference increases. The average net heat flux at surface of crater increases slightly with depth when the crater is shallow, but the trend reverses for deeper crater. The target surface temperature rises rapidly in the initial stage, with a maximum rate of temperature up to 5000K/s, and decline gradually in the later period. In case of Mach number from 0.3 to 0.8, the maximum excess temperature at 0.5s after the irradiation is applied decreases 35∼45K, the time-lag to reach melting point prolongs slightly, and the occurrence of back surface temperature of the target defers also. © 2013 SPIE.

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