本文主要采用CO2气体体积分数测量法研究一种带缘板修型的静盘深腔型复合封严结构。同时选取轴向封严结构和叠覆封严结构作为比较基准,重点关注主流雷诺数(0.75×105≤Rew≤9.4×105)、封严流量(流量比FR=0.2%~2.5%)、旋转雷诺数(1.6×105≤Reφ≤8.1×105)等典型工况参数对盘腔内压力分布和封严效率的影响情况;并在此基础上开展了相应的数值研究,获得了封严腔室内详细的流场信息。结果表明:在试验设计工况范围内,主流雷诺数的改变对静叶尾缘和动叶前缘的周向压力分布影响显著。主流雷诺数增加,主流通道内压力升高,主流气体入侵加剧;增加封严流量有利于提高盘腔内压力,从而提升盘腔封严效率,但这对静叶尾缘压力影响较小;增加旋转雷诺数会增大静叶尾缘和动叶叶间通道前缘的静压,加重主流气体入侵,降低盘腔封严效率。相比轴向封严结构,叠覆封严结构由于高半径封严容腔的设置,改变了盘腔流场结构,有效地将主流气体阻隔在封严容腔内,保证了低半径盘腔的封严效率在80%以上。新型封严结构的静盘深腔和缘板造型设置,不仅保证了低半径盘腔的封严效率在85%以上,还能提高高半径处封严容腔处的封严效率,在低流量比(FR=0.2%)工况下,其封严容腔区域的封严效率提升了10%。
In this study, the composite rim seal with the deep cavity in the static disc and the modified platform(the following abbreviation “C rim seal”)was investigated by measuring the CO2 concentration. Simultaneous-ly, an axial and an overlapping rim seal has been selected as a baseline to compare and analyze the effects of the mainstream Reynolds number (0.75×105≤Rew≤9.4×105), the sealing flow rate (flow rate ratio FR= 0.2%~2.5%), and rotating Reynolds number (1.6×105≤Reφ≤8.1×105) on the distribution of pressure and the sealing efficiency in the disc cavity. Furthermore, a corresponding numerical study was carried out to ob-tain the detailed flow characteristics. The results show that the main flow Reynolds number significantly affects the circumferential pressure distribution in the main flow channel. With the main flow Reynolds number increasing,the pressure in the main flow channel also increased and the gas ingestion intensified. The higher coolant flow rate is beneficial to improve the sealing efficiency of the disc cavity by increasing the pressure in the disc cavity, but it has less effect on the pressure at the trailing edge of the vane. An im-provement in the rotating Reynolds number increases the static pressure in the main flow channel and de-creases the sealing efficiency of the disc cavity. The flow structure of the disc cavity is changed by the set-ting of the high-radius sealing cavity, which effectively blocks the mainstream gas inside the sealing cavity and ensures that the sealing efficiency of the low-radius cavity is above 80%. The C rim seal structure not only guarantees the sealing efficiency of 85% at the low-radius disc cavity, but also improves the sealing efficiency at the high-radius sealing cavity. At a low sealing flow ratio (FR=0.2%), the sealing efficiency of the C rim seal structure is 10% higher than the other two rim seal structures.
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