Non-axisymmetric flow characteristics in centrifugal compressor

Abstract

The flow field distribution in centrifugal compressor is significantly affected by the non-axisymmetric geometry structure of the volute. The experimental and numerical simulation methods were adopted in this work to study the compressor flow field distribution with different flow conditions. The results show that the pressure distribution in volute is characterized by the circumferential non-uniform phenomenon and the pressure fluctuation on the high static pressure zone propagates reversely to upstream, which results in the non-axisymmetric flow inside the compressor. The non-uniform level of pressure distribution in large flow condition is higher than that in small flow condition, its effect on the upstream flow field is also stronger. Additionally, the non-uniform circumferential pressure distribution in volute brings the non-axisymmetric flow at impeller outlet. In different flow conditions, the circumferential variation of the absolute flow angle at impeller outlet is also different. Meanwhile, the non-axisymmetric flow characteristics in internal impeller can be also reflected by the distribution of the mass flow. The high static pressure region of the volute corresponds to the decrease of mass flow in upstream blade channel, while the low static pressure zone of the volute corresponds to the increase of the mass flow. In small flow condition, the mass flow difference in the blade channel is bigger than that in the large flow condition.

Study on alternative cycles for high-pressure low-temperature helium compressor performance experiments based on flow similarity

“…The experiments were conducted at the Beijing Institute of Technology. More detailed information about the test setup can be found in Yang et al 20 and Wang et al 21…”

“…The experiments were conducted at the Beijing Institute of Technology. More detailed information about the test setup can be found in Yang et al 20 and Wang et al 21 As shown in Figure 8, the compressor tested has the same working fluid and boundary conditions. In addition, the rotational speed range and pressure ratio are similar.…”

“…Its experiment is relatively easy thanks to its feature of low rotation speed. The NASA Lewis Research Center in the USA built a low-speed large-scale centrifugal compressor with a design tip speed of 153 ms 21 and an exit diameter of 1.524 m. 25,26 Xi'an Jiaotong University in China also has a large-scale low-speed centrifugal compressor facility. 27,28 The impeller has an outlet diameter of 0.796 m and a rotation speed of 3100 rpm.…”

“…Figure 2. Effect of the isentropic exponent on mass flow rate, _m He equals to 0.3, 0.4, and 0.5 kgs21 , respectively. For the helium compressor, T 0 1 equals to 100°K.…”

Influence of vaned diffuser on the potential effect of volute and stall inception of centrifugal compressor

“…Under the action of the volute, the circumferential flow nonuniformities in a centrifugal compressor existed in the entire flow range [28][29][30] and more near the choke. As the compressor was throttled from the near choke to design condition, the nonuniformity in the circumferential distribution of static pressure decreased gradually.…”