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为了得到非设计攻角下涡轮叶片的叶型损失规律,采用数值模拟的方法对某高负荷低压涡轮前加载叶型在5种不同攻角下的流动进行了详细的分析,得到了5种攻角下叶片表面的各种流动参数。结果表明:在设计攻角下,叶片的性能表现最佳,此时叶栅中的气流流动均匀,速度梯度、压力梯度分布符合一定规律,并未发生明显的附面层分离现象;在负攻角下,吸力面的流动情况保持良好而压力面的损失较为明显,且随着负攻角的增大损失系数也逐渐增大,但负攻角下损失系数的增幅整体上并不大,当负攻角增加到-20°时其损失系数只有0.048;在正攻角下,压力面的流动情况保持良好而吸力面的损失较为明显,且这种损失比负攻角下压力面的损失要大得多;当正攻角为10°时其损失系数已达到0.141,远远超过-20°攻角下的损失系数。因此,在进行叶型设计的时候一定要留有合适的正攻角裕度。
In order to get the non-design angle of attack turbine blade leaf loss rules, the numerical simulation method for a high load low pressure turbine pre-loaded leaflet flow at five different angles of attack were analyzed in detail, got five kinds of attack Various flow parameters of the blade surface under the angle. The results show that under the design attack angle, the performance of the blade is the best. At this time, the airflow in the cascade flows evenly, the distribution of velocity gradient and pressure gradient accords with a certain rule, and no obvious detachment occurs. In the negative attack The flow of suction surface is well maintained and the loss of pressure surface is more obvious, and the loss coefficient increases with the increase of negative angle of attack, but the increase of loss coefficient at negative angle of attack is not large in general When the negative angle of attack increases to -20 °, the loss coefficient is only 0.048. At the positive angle of attack, the flow of the pressure surface is well maintained and the loss of the suction surface is more obvious, and the loss is greater than the loss of the pressure surface under the negative angle of attack Is much larger; when the angle of attack is 10 °, the loss coefficient has reached 0.141, which far exceeds the loss coefficient at -20 ° angle of attack. Therefore, in the leaf design must leave a proper margin of attack angle.