Shin, YH Kim, KH Son, BJ 2024-01-21T16:45:13Z 2024-01-21T16:45:13Z 2021-09-03 1998-08 1340-8054 https://pubs.kist.re.kr/handle/201004/142948 This study presents the measured rotating stall signal patterns in a vaneless diffuser in a centrifugal compressor with a radial bladed impeller. Unsteady flow and rotating stall in the vaneless diffuser were investigated by measuring unsteady velocity fluctuations at several different diffuser radius ratios and axial distances using a hot wire anemometer. The flow characteristics in terms of the radial and tangential velocity components and the flow angle distribution in the vaneless diffuser during rotating stall were investigated using phase-locked averaging techniques. The results clearly identified abrupt rotating stall at several different impeller rotational speeds. According to the experimental results, two different mechanisms exist for the development of the reverse flow zone in a vaneless diffuser. One is dominated by the extension of the reentering flow from the diffuser exit, and the ether is dominated by the growth of the local flow separation zone on the hub and shroud side. The fluctuation in the flow direction increases as the diffuser radius ratio increases and is dominated by the strength of the reverse flow. At the onset of rotating stall, the radial velocity for one period of the rotating stall slowly increased to a maximum value and then decreased quickly to a minimum value with an intermediate peak, However, at lower flow rates, this intermediate peak did not occur. English JAPAN SOC MECHANICAL ENGINEERS ROTATING STALL CENTRIFUGAL An experimental study on the development of a reverse flow zone in a vaneless diffuser Article 10.1299/jsmeb.41.546 1 JSME INTERNATIONAL JOURNAL SERIES B-FLUIDS AND THERMAL ENGINEERING, v.41, no.3, pp.546 - 555 JSME INTERNATIONAL JOURNAL SERIES B-FLUIDS AND THERMAL ENGINEERING 41 3 546 555 scie scopus 000075988800004 2-s2.0-0032147553 Thermodynamics Engineering, Mechanical Thermodynamics Engineering Article ROTATING STALL CENTRIFUGAL centrifugal compressor vaneless diffuser rotating stall local reverse flow reentering flow relative amplitude