Abstract:The non-axisymmetric geometry structure of the volute leads to the uneven circumferential distribution of the flow field inside centrifugal compressors. It is difficult to describe the whole flow field for few measuring points installed around the centrifugal compressor casing wall. In this paper, seventy-two static pressure measuring probes including the six circumferential position and the twelve meridional position were installed around the casing wall, and the circumferential distribution of the static pre… Show more
“…The straight and bent inlet pipe compressors on the experimental bench are shown in Figures 6 and 7, respectively. More detail describing the experimental method can be found in Yang et al 22 Both the performance and static pressure measuring experiments were carried out at three rotational speeds: 60 k r/min, 70 k r/min, and 80 k r/min, respectively. The schematic layout of the test rig is shown in Figure 8.…”
Section: Experimental Methods and Compressor Performancementioning
confidence: 99%
“…More detail describing the experimental method can be found in Yang et al. 22 Figure 4.Static sensor distribution around the casing wall in the experiment: (a) circumferential angle coordinate and the volute tongue location; (b) circumferential distribution of the sensor rows; (c) streamwise distribution of the static sensors.VT: volute tongue.Figure 5.Volute with measuring points.Figure 6.Straight pipe compressor on the experimental bench.Figure 7.Bent pipe compressor on the experimental bench.…”
Section: Experimental Methods and Compressor Performancementioning
Asymmetric structures of the bent inlet pipes and outlet volute are typically adopted in centrifugal compressors. By using asymmetric inlet/outlet structures, the uniformity of the compressor's internal flow field in the circumferential direction will be changed. The static pressure distribution behavior around the casing wall is significantly influenced by the coupling effect of the bent inlet pipe and outlet volute. In the present work, three compressors were numerically and experimentally investigated. One compressor had a straight inlet pipe, and the other two had bent inlet pipes. Seventy-two static pressure sensors were mounted around the casing wall to obtain the static pressure distribution at different flow rates for three rotational speeds. The results show that at high rotational speeds with large flow rate conditions, when the static pressure waves induced by the bent pipe and volute act on the same circumferential position, the casing wall static pressure will be increased at the corresponding position. Furthermore, this high static pressure will further influence the static pressure values at other circumferential positions and leads to a more nonuniform circumferential static pressure distribution. Near the design flow rate, when the high static pressure strips, which are induced by both the bent pipe and volute impact different circumferential positions, the high static pressure strip induced by the volute will be weakened. As a result, the high static pressure strip induced by the volute cannot propagate upstream into the impeller. At small flow rate under designed rotational speed, the influence of the volute tongue on the casing pressure distribution will be enhanced. At small flow rate under low rotational speed, the casing pressure distributions of the three models were almost the same because the secondary flow effect of the bent pipe diminishes as the flow rate reduces.
“…The straight and bent inlet pipe compressors on the experimental bench are shown in Figures 6 and 7, respectively. More detail describing the experimental method can be found in Yang et al 22 Both the performance and static pressure measuring experiments were carried out at three rotational speeds: 60 k r/min, 70 k r/min, and 80 k r/min, respectively. The schematic layout of the test rig is shown in Figure 8.…”
Section: Experimental Methods and Compressor Performancementioning
confidence: 99%
“…More detail describing the experimental method can be found in Yang et al. 22 Figure 4.Static sensor distribution around the casing wall in the experiment: (a) circumferential angle coordinate and the volute tongue location; (b) circumferential distribution of the sensor rows; (c) streamwise distribution of the static sensors.VT: volute tongue.Figure 5.Volute with measuring points.Figure 6.Straight pipe compressor on the experimental bench.Figure 7.Bent pipe compressor on the experimental bench.…”
Section: Experimental Methods and Compressor Performancementioning
Asymmetric structures of the bent inlet pipes and outlet volute are typically adopted in centrifugal compressors. By using asymmetric inlet/outlet structures, the uniformity of the compressor's internal flow field in the circumferential direction will be changed. The static pressure distribution behavior around the casing wall is significantly influenced by the coupling effect of the bent inlet pipe and outlet volute. In the present work, three compressors were numerically and experimentally investigated. One compressor had a straight inlet pipe, and the other two had bent inlet pipes. Seventy-two static pressure sensors were mounted around the casing wall to obtain the static pressure distribution at different flow rates for three rotational speeds. The results show that at high rotational speeds with large flow rate conditions, when the static pressure waves induced by the bent pipe and volute act on the same circumferential position, the casing wall static pressure will be increased at the corresponding position. Furthermore, this high static pressure will further influence the static pressure values at other circumferential positions and leads to a more nonuniform circumferential static pressure distribution. Near the design flow rate, when the high static pressure strips, which are induced by both the bent pipe and volute impact different circumferential positions, the high static pressure strip induced by the volute will be weakened. As a result, the high static pressure strip induced by the volute cannot propagate upstream into the impeller. At small flow rate under designed rotational speed, the influence of the volute tongue on the casing pressure distribution will be enhanced. At small flow rate under low rotational speed, the casing pressure distributions of the three models were almost the same because the secondary flow effect of the bent pipe diminishes as the flow rate reduces.
“…[11][12][13] The distribution of non-uniform flow field in the compressor can be reflected by evenly arranging static pressure probes in the circumferential direction to measure the static pressure distribution on the casing wall of the compressor. For a centrifugal compressor with volute applied in automobile turbocharger, Yang and Zhang [14][15][16] analyzed the casing-wall static pressure distribution under different rotational speeds and different operating conditions through experiments and calculations to understand its stall mechanism. An interesting phenomenon was observed.…”
In the centrifugal compressor applied in the automobile turbochargers, the asymmetric structure of volute causes the non-uniform flow field in the impeller and compressor stall. The non-uniformity of the flow field in the compressor can be reflected by the casing-wall static pressure distribution. In this study, by removing the volute and directly imposing different simplified static pressure boundary conditions at the diffuser outlet, the formation mechanism of casing-wall static pressure circumferential double-peak distribution of the compressor is explored. It is found that the mass flow rate is redistributed at the impeller outlet due to local high static pressure induced by the volute tongue, which results in the formation of two airflow regions with high velocity in the diffuser, ultimately leading to the static pressure circumferential double-peak distribution in the diffuser and the impeller. Noted that because of the existence of the blades, the airflow regions with high and low velocity formed in the diffuser are locked within a limited range of one or more widths of the blade passage. When the number of blades in the compressor is large, the static pressure can appear as multi-peak distribution in the circumferential direction. Moreover, the result of the mass flow rate redistribution at the impeller outlet is determined by the static pressure distribution characteristics at the diffuser outlet.
“…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.…”
In the automotive turbochargers centrifugal compressor, the volute has a strong potential effect, leading to circumferential nonuniformity of the impeller flow field and compressor stall. In this study, full-annulus unsteady simulations for centrifugal compressors with vaned/vaneless diffusers are carried out. The influence of the diffuser vane on the potential effect of the volute and stall behavior of a centrifugal compressor is studied in detail. Based on the distribution of the casing static pressure, the formation mechanism of the circumferential distribution of static pressure and the reverse propagation process of pressure waves caused by pressure distortion are revealed. The results of this study show that the diffuser vanes can weaken the potential effect of the volute on the impeller flow field by reducing the degree of static pressure distortion. The number of static pressure peaks in the circumferential direction is related to the number of vanes/blades. The diffuser vanes can change the circumferential position of the stall inception, but cannot eliminate the “locking effect” of the volute tongue on the circumferential position of the stall. In other words, the circumferential position of the stall inception is still determined by the volute tongue for a centrifugal compressor with a vaned diffuser. Although the degree of circumferential static pressure distortion inside the impeller is reduced, the stable operating range of the compressor cannot be significantly widened by adjusting the stagger angle of the diffuser vane when the stall first occurs at the impeller inlet.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
