scholarly journals Casing wall static pressure distribution behavior in a centrifugal compressor with asymmetric inlet/outlet structures

2018 ◽  
Vol 233 (1) ◽  
pp. 37-51 ◽  
Author(s):  
Ce Yang ◽  
Hanzhi Zhang ◽  
Dengfeng Yang ◽  
Dazhong Lao ◽  
Changmao Yang
Keyword(s):  
Pressure Distribution ◽  
Flow Rate ◽  
Static Pressure ◽  
Inlet Pipe ◽  
Static Pressure Distribution ◽  
Bent Pipe ◽  
Small Flow ◽  
High Static Pressure ◽  
Casing Pressure ◽  
Distribution Behavior

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.

Investigation on the Backflow Induced Pre-Rotation of RCP

2014 ◽  
Author(s):  
Junlian Yin ◽  
Jingjing Li ◽  
Hui Chen ◽  
Yaoyu Hu ◽  
Dezhong Wang
Keyword(s):  
Pressure Distribution ◽  
Flow Rate ◽  
Cfd Simulation ◽  
Reverse Flow ◽  
Leading Edge ◽  
Inlet Pipe ◽  
Propagation Length ◽  
Stream Surface ◽  
Small Flow Rate ◽  
Small Flow

The pre-rotation phenomenon found at the inlet pipe of a pump under small flow rate was observed but the mechanism was not discovered. To do this, an unsteady CFD simulation with the flow rate decreasing from the best design point to a small flow rate was carried out. The numerical results show that a critical point when pre-rotation occurs exists. The flow pattern evolution on the S1 and S2 stream surface, as well as the pressure distribution at in the inlet, was analyzed. It is shown that it is the reverse flow appeared near the shroud at the leading edge which leads to the occurrence of pre-rotation. The pre-rotation only exist in the periphery of the inlet pipe and the propagation length is limited.

Formation mechanism of static pressure circumferential double-peak distribution in a centrifugal compressor under the action of downstream boundary

2021 ◽  
pp. 095440702098307
Author(s):  
Botai Su ◽  
Ce Yang ◽  
Hanzhi Zhang ◽  
Xin Shi ◽  
Li Fu ◽  
...  
Keyword(s):  
Flow Field ◽  
Pressure Distribution ◽  
Mass Flow Rate ◽  
Formation Mechanism ◽  
Flow Rate ◽  
Centrifugal Compressor ◽  
Static Pressure ◽  
Double Peak ◽  
Static Pressure Distribution ◽  
Impeller Outlet

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.

Ingestion Into the Upstream Wheelspace of an Axial Turbine Stage

1994 ◽  
Vol 116 (2) ◽  
pp. 327-332 ◽  
Author(s):  
T. Green ◽  
A. B. Turner
Keyword(s):  
Pressure Distribution ◽  
Static Pressure ◽  
Three Dimensional ◽  
Computer Code ◽  
Rotor Blades ◽  
Rotor Speed ◽  
Turbine Stage ◽  
Flow Rates ◽  
Static Pressure Distribution ◽  
Axial Clearance

The upstream wheelspace of an axial air turbine stage complete with nozzle guide vanes (NGVs) and rotor blades (430 mm mean diameter) has been tested with the objective of examining the combined effect of NGVs and rotor blades on the level of mainstream ingestion for different seal flow rates. A simple axial clearance seal was used with the rotor spun up to 6650 rpm by drawing air through it from atmospheric pressure with a large centrifugal compressor. The effect of rotational speed was examined for several constant mainstream flow rates by controlling the rotor speed with an air brake. The circumferential variation in hub static pressure was measured at the trailing edge of the NGVs upstream of the seal gap and was found to affect ingestion significantly. The hub static pressure distribution on the rotor blade leading edges was rotor speed dependent and could not be measured in the experiments. The Denton three-dimensional C.F.D. computer code was used to predict the smoothed time-dependent pressure field for the rotor together with the pressure distribution downstream of the NGVs. The level and distribution of mainstream ingestion, and thus the seal effectiveness, was determined from nitrous oxide gas concentration measurements and related to static pressure measurements made throughout the wheelspace. With the axial clearance rim seal close to the rotor the presence of the blades had a complex effect. Rotor blades in connection with NGVs were found to reduce mainstream ingestion seal flow rates significantly, but a small level of ingestion existed even for very high levels of seal flow rate.

Study of Semi-Inverse Problem for the Design of Annular S-Shaped Compressor Transition Duct

2015 ◽  
Author(s):  
Peng Shan ◽  
Jingyuan Wang ◽  
Zhentao Lv
Keyword(s):  
Inverse Problem ◽  
Pressure Distribution ◽  
Static Pressure ◽  
Pressure Coefficient ◽  
Optimal Solution ◽  
Outer Wall ◽  
Wall Pressure ◽  
Design Parameters ◽  
Gradient Distribution ◽  
Static Pressure Distribution

A new aerodynamic design strategy of the S-shaped transition duct between two compressor components was studied. Based on the controlled wall pressure gradient distribution and the wall velocity distribution, a semi-inverse problem of the transition duct was proposed, the corresponding inverse and direct approach codes were developed. To verify the feasibility of this method, two axial-centrifugal compressor transition ducts were designed. The results show that the static pressure distribution on the inner wall and the duct geometry both can be controlled freely by adjusting the inverse design parameters. The designed inner wall pressure distribution can be realized through a numerical matching procedure of the outer wall geometry based on the direct problem. The new design method is practicable that, without searching the optimal solution of the static pressure distribution of the inner wall, the total pressure coefficient can be at least 0.92.

Plantar Static Pressure Distribution in Healthy Individuals

2014 ◽  
Vol 7 (4) ◽  
pp. 293-297 ◽  
Author(s):  
David Pomarino ◽  
Andrea Pomarino
Keyword(s):  
Pressure Distribution ◽  
Static Pressure ◽  
Age Groups ◽  
Case Series ◽  
Load Sharing ◽  
Standing Position ◽  
Healthy Individuals ◽  
Static Pressure Distribution ◽  
Standard Values ◽  
The Right

In literature, one finds little scientific statements regarding plantar static pressure distribution in healthy individuals. Miscellaneous studies, however, characterize pathologies of feet and associate those with abnormal static or dynamic plantar load sharing. Our study reveals that healthy individuals show significant age-dependent differences in forefoot and rear foot load measured in standing position. The forefoot and rear foot load of 238 female and 193 male individuals aged between 2 and 69 years were measured. Using a pressure distribution measurement platform, the measurements were taken barefooted in standing position. Those measurements are presented as percentage of the overall load. The measurements within the age groups A1 (2-6 years), A2 (7-10 years), and A3 (11-69 years) showed significantly different forefoot loading means of the left foot (A1, 19.9%; A2, 28.2%; A3, 39.7%) and the right foot (A1, 22.6%; A2, 29.7%; A3, 39.6%). The forefoot loadings are graphically displayed as a function of the percentiles 5, 10, 25, 50, 75, 90, and 95. Forefoot loadings are referred to as “prominent” if the measured values lie off the interquartile range; if either below the percentile 10 or above 90 the loadings are referred to as “very prominent.” Our study contains significant data regarding the extent of the static load sharing of the forefoot and rear foot of healthy individuals; the data are suited for being standard values to evaluate plantar load sharing. Levels of Evidence: Diagnostic Level IV: Case series

The Pressure Distribution on the Surface of an Ellipsoid in Inviscid Flow

1980 ◽  
Vol 31 (1) ◽  
pp. 70-84 ◽  
Author(s):  
Edward G.U. Band ◽  
Peter R. Payne
Keyword(s):  
Pressure Distribution ◽  
High Speed ◽  
Static Pressure ◽  
Inviscid Flow ◽  
Practical Applications ◽  
Static Pressure Distribution ◽  
Remarkable Result ◽  
Air Cushion ◽  
Air Cushion Vehicle ◽  
Aerodynamic Lift

SummaryThe classic equations for inviscid flow about an ellipsoid are employed to compute the corresponding static pressure distribution which can then be applied to a number of practical problems. The tension in the skin of a dirigible, the gross pressure distribution around a man in an open ejection seat, the aerodynamic lift on an air cushion vehicle, automobile or high speed boat, the “squatting” of a ship, are all examples of practical applications. A remarkable result from the theory is that the lowest pressure, that around the equator normal to the flow, is always constant around the equator, no matter how much disparity there is between the semi-axes b and c.

Sign in / Sign up

Export Citation Format

Share Document