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为了研究非对称波瓣下外扩张角对S型喷管气动热力性能的影响规律,以含非对称波瓣的S型喷管为研究对象,保持非对称波瓣长度、内扩张角、高宽比及上外扩张角不变,取定非对称波瓣下外扩张角依次为17.75°,22.75°,27.75°,32.75°,建立了一组具有不同下外扩张角的非对称波瓣S型喷管模型。通过数值求解Reynolds-Averaged Navier-Stokes(RANS)方程,得到了S型喷管气动热力性能随非对称波瓣下外扩张角的变化规律。研究结果表明:第一个弯道上游流场中,流向涡具有较强的混合能力,其核心区无量纲涡量值随非对称波瓣下外扩张角增大而逐渐增大;然而,在第一个弯道下游流场中,所有模型对应的流向涡核心区无量纲涡量值均已非常微弱。在S型喷管弯道区域,流道流向、截面形状发生巨大改变,使得内外涵流体混合效果显著提高,但混合流体的总压恢复系数却急剧下降。混合流体热混合效率值受下外扩张角影响不明显,但S型喷管下半部分内壁面温度随下外扩张角增大而逐渐上升。在S型喷管出口,下外扩张角为17.75°模型的总压恢复系数为0.9464,高于其他3种模型,并且相对于该截面上总压恢复系数最低值增加了0.55%。
In order to study the effect of asymmetric lobe flare angle on the aerodynamic performance of S-type nozzle, the S-type nozzle with asymmetric lobe was selected as the research object, and the asymmetric lobe length, internal divergence angle and width And the upper and lower external expansion angles were the same. The external flaring angles were 17.75 °, 22.75 °, 27.75 ° and 32.75 °, respectively. A set of asymmetric lobes S-shaped Nozzle model. By numerical solution of the Reynolds-Averaged Navier-Stokes (RANS) equation, the aerodynamic performance of the S-type nozzle is obtained with the variation rule of the outward divergence angle under asymmetric lobe. The results show that the flow direction vortex has a strong mixing ability in the flow field upstream of the first bend, and the dimensionless vorticity value in the core region gradually increases with the increase of the outer flared angle under asymmetric lobe. However, In the flow field downstream of the first curve, the dimensionless vorticity values of all the models in the core region of the vortex flow are very weak. In the S-shaped nozzle bend area, the flow direction and the cross-sectional shape of the nozzle change greatly, which makes the mixing effect of the inner and outer culverts significantly increase, but the total pressure recovery coefficient of the mixed fluid drops sharply. However, the temperature of the inner wall of the lower half of the S-type nozzle gradually increases with the increase of the outside flare angle. The total pressure recovery coefficient of the model with outlet divergence angle of 17.75 ° at the exit of S-nozzle was 0.9464, which was higher than the other three models and increased 0.55% with respect to the lowest value of the total pressure recovery coefficient at this section.