Effects of Upstream Bend on Aerodynamic Performance of a Transonic Centrifugal Compressor
Effects of Upstream Bend on Aerodynamic Performance of a Transonic Centrifugal Compressor
复制标题
上游弯道对跨音速离心压气机气动性能的影响
DOI：
10.1115/gt2019-90794
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发表时间：
2019
期刊：
影响因子：
--
通讯作者：
Sasuga Ito
中科院分区：
文献类型：
--
作者：
Kazutoyo Yamada;M. Furukawa;H. Arai;Sasuga Ito
本文研究了跨声速离心式压气机正上游安装的弯曲进气管对压气机气动性能和稳定性的影响。为了明确进气管弯曲对压气机内部流场的影响，采用分离涡模拟（DES）对压气机进气管、叶轮和扩压器内部流场进行了数值模拟。为了比较，还对直管内均匀轴向流入的情况进行了模拟。为了尽可能明确弯管对非均匀流动的影响，在压缩机的正上游安装了90度弯管，即进口内径的0.86倍。
This paper describes the influence of a bent inlet pipe installed immediately upstream of a transonic centrifugal compressor on the aerodynamic performance and the stability. In order to clarify the influence of the bent inlet pipe, the internal flow fields in the inlet pipe, the impeller, and the diffuser of the compressor have been numerically investigated by a DES (Detached Eddy Simulation). For the purpose of comparison, the simulation was also conducted for the case of uniform axial inflow using a straight pipe. In order to make clear the influence of non-uniform flow with a bent pipe as far as possible, a 90-degree bent pipe was installed immediately upstream of the compressor, that is 0.86 times the inlet inner diameter.
In the case of installing the bent pipe on the upstream of the compressor, the pressure ratio decreased on the high flow rate side in the compressor performance characteristic, whereas it increased at the low flow rate side. At the low flow rate operating point, there is a reversed flow occurring in the compressor impeller on the shroud side near the blade leading-edge. Installation of the bent pipe promotes mixing between the reversed flow and the main flow at the inlet of the compressor thanks to occurrence of a secondary flow. Since the reversed flow comes out from inside of the impeller, it has a high circumferential velocity. Therefore, the mixing of the reversed flow makes the compressor inlet flow a pre-swirl flow, and thereby the incidence decreases. As a result, leading-edge separation on the blade tip side of the impeller is suppressed, and the flow field inside the impeller is improved. In the diffuser section, when the bent pipe is installed, the circumferential velocity of the impeller exit flow increases on the hub side, whereas the radial velocity decreases. As a result, the diffuser performance is deteriorated and the diffuser stall tends to occur.