Impact of Inlet Swirl on High-Speed High-Flow Centrifugal Stage Performance

2007 ◽  
Author(s):  
Angelo Grimaldi ◽  
Libero Tapinassi ◽  
Andrea Bernocchi ◽  
Fernando Roberto Biagi ◽  
Denis Guenard ◽  
...  
Keyword(s):  
Mach Number ◽  
High Speed ◽  
Guide Vane ◽  
Three Dimensional ◽  
Flow Coefficient ◽  
Inlet Guide Vane ◽  
Design Activity ◽  
Operating Range ◽  
Centrifugal Stage ◽  
Inlet Conditions

Cooling cycle in applications such as Liquefied Natural Gas makes use of centrifugal impellers associated with heavy gas. Increasing projects handled flow leads compressor manufacturers to try to increase flow coefficient and peripheral Mach Number of those stages to limit compressor size. As a consequence, severe aerodynamic problems linked to the blade aspect ratio, meridional channel curvature and inlet tip relative Mach number arise. Of the three, the onset of transonic or supersonic inlet conditions at tip is a matter of concern since it can significantly reduce stage range and performance. Very aggressive blade redesign is often not possible due to mechanical limitations. An accurate coupling of the impeller with the upstream stator parts may partly overcome the problem. The paper summarizes the design activity of a centrifugal stage designed for inlet pre-rotation, covering the most significant considerations made during its design, starting from 1D preliminary design until three dimensional CFD verifications. Finally, the paper draws conclusions on comparison with the results of an experimental campaign the purpose of which was to evaluate the benefits brought about by the new impeller design and different inlet configurations. The new impeller design allowed to reach still acceptable operating range even with relative Mach Number of 1.05 but with a noticeable efficiency decay. Use of Inlet Guide Vane with prewhirl, to bring Mach down to lower value, allowed to recover efficiency values without any further gain of operating range.

Study of a Surge-Free Centrifugal Compressor With Automatically Variable Inlet and Diffuser Vanes

1996 ◽  
Author(s):  
Hideomi Harada
Keyword(s):  
Centrifugal Compressor ◽  
Guide Vane ◽  
Pressure Ratio ◽  
Three Dimensional ◽  
Low Flow ◽  
Inlet Guide Vane ◽  
Analysis Method ◽  
Unstable Flow ◽  
Flow Angle ◽  
Operating Range

In order to improve the operating range of a centrifugal compressor, computer-controlled variable inlet and diffuser vanes were attached to a compressor with a pressure ratio of 2.5. Low-solidity cascade vanes capable of controlling the vane angle up to 0 degrees from the tangential direction were used for the vaned diffuser. The compressor’s overall performance was then tested using a closed-loop test stand. By automatically adjusting the diffuser vanes to the most suitable flow angle, pressure fluctuations caused by the unstable flow in the diffuser during low-flow operation of the centrifugal compressor could be suppressed, and the compressor could be operated nearly up to the shut-off flow rate without any surge. The author experimentally confirmed the critical operating range of both the impeller and diffuser at two different tip speeds and five inlet guide vane angles. Furthermore, a three-dimensional viscous flow-analysis method was applied to the impeller, and a three-dimensional momentum integral analysis method was applied to the diffuser. Then the critical operating ranges obtained in the experiments were qualitatively validated. The operating range of a centrifugal compressor under low-flow conditions, which has until now been limited because of surge, dramatically improved in this study, thereby demonstrating that it may be possible to develop a surge-free centrifugal compressor.

scholarly journals Effect of the Reynolds Number and Clearance Flow on the Aerodynamic Characteristics of a New Variable Inlet Guide Vane

Aerospace ◽  
2021 ◽  
Vol 8 (7) ◽  
pp. 172
Author(s):  
Hengtao Shi
Keyword(s):  
Reynolds Number ◽  
Guide Vane ◽  
Three Dimensional ◽  
High Growth ◽  
Aerodynamic Characteristics ◽  
Inlet Guide Vane ◽  
Separation Region ◽  
Clearance Flow ◽  
New Type ◽  
Variable Inlet Guide Vane

Recently, a new type of low-loss variable inlet guide vane (VIGV) was proposed for improving a compressor’s performance under off-design conditions. To provide more information for applications, this work investigated the effect of the Reynolds number and clearance flow on the aerodynamic characteristics of this new type of VIGV. The performance and flow field of two representative airfoils with different chord Reynolds numbers were studied with the widely used commercial software ANSYS CFX after validation was completed. Calculations indicate that, with the decrease in the Reynolds number Rec, the airfoil loss coefficient ω and deviation δ first increase slightly and then entered a high growth rate in a low range of Rec. Afterwards, a detailed boundary-layer analysis was conducted to reveal the flow mechanism for the airfoil performance degradation with a low Reynolds number. For the design point, it is the appearance and extension of the separation region on the rear portion; for the maximum incidence point, it is the increase in the length and height of the separation region on the former portion. The three-dimensional VIGV research confirms the Reynolds number effect on airfoils. Furthermore, the clearance leakage flow forms a strong stream-wise vortex by injection into the mainflow, resulting in a high total-pressure loss and under-turning in the endwall region, which shows the potential benefits of seal treatment.

Mechanical Design and Testing of a 2.5 MW sCO2 Compressor Loop

2021 ◽  
Author(s):  
Stefan D. Cich ◽  
J. Jeffrey Moore ◽  
Chris Kulhanek ◽  
Meera Day Towler ◽  
Jason Mortzheim
Keyword(s):  
High Efficiency ◽  
Mechanical Design ◽  
Guide Vane ◽  
Operating Conditions ◽  
Inlet Guide Vane ◽  
Inlet Temperature ◽  
Design Changes ◽  
Wide Range ◽  
Inlet Conditions ◽  
Design And Testing

Abstract An enabling technology for a successful deployment of the sCO2 close-loop recompression Brayton cycle is the development of a compressor that can maintain high efficiency for a wide range of inlet conditions due to large variation in properties of CO2 operating near its dome. One solution is to develop an internal actuated variable Inlet Guide Vane (IGV) system that can maintain high efficiency in the main and re-compressor with varying inlet temperature. A compressor for this system has recently been manufactured and tested at various operating conditions to determine its compression efficiency. This compressor was developed with funding from the US DOE Apollo program and industry partners. This paper will focus on the design and testing of the main compressor operating near the CO2 dome. It will look at design challenges that went into some of the decisions for rotor and case construction and how that can affect the mechanical and aerodynamic performance of the compressor. This paper will also go into results from testing at the various operating conditions and how the change in density of CO2 affected rotordynamics and overall performance of the machine. Results will be compared to expected performance and how design changes were implanted to properly counter challenges during testing.

Aerodynamic Investigations of a Variable Inlet Guide Vane With Symmetric Profile

2014 ◽  
Author(s):  
David Händel ◽  
Reinhard Niehuis ◽  
Uwe Rockstroh
Keyword(s):  
Boundary Layer ◽  
High Speed ◽  
Guide Vane ◽  
Reynolds Numbers ◽  
Boundary Layer Transition ◽  
Inlet Guide Vane ◽  
Experimental Investigations ◽  
Wide Range ◽  
Variable Inlet Guide Vane ◽  
Symmetric Profile

In order to determine the aerodynamic behavior of a Variable Inlet Guide Vane as used in multishaft compressors, extensive experimental investigations with a 2D linear cascade have been conducted. All the experiments were performed at the High-Speed Cascade Wind Tunnel at the Institute of Jet Propulsion. They covered a wide range of Reynolds numbers and stagger angles as they occur in realistic turbomachines. Within this work at first the observed basic flow phenomena (loss development, overturning) will be explained. For the present special case of a symmetric profile and a constant decreasing chord length along the vane height, statements about different spanwise position can be made by investigating different Reynolds numbers. The focus of this paper is on the outflow of the VIGV along the vane height. Results for an open flow separation on the suction side are presented, too. Stall condition can be delayed by boundary layer control. This is done using a wire to trigger an early boundary layer transition. The outcomes of the trip wire measurement are finally discussed. The objective of this work is to evaluate the influence of the stagger angle and Reynolds number on the total pressure losses and the deviation angle. The results of the work presented here, gives a better insight of the efficient use of a VIGV.

Study of High Speed Turbulent Flow Over Rotating Two Stage Three Dimensional Double Wedge

2006 ◽  
Author(s):  
Khaled Alhussan
Keyword(s):  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
Mach Number ◽  
Shock Waves ◽  
High Speed ◽  
Three Dimensional ◽  
Oblique Shock ◽  
Wave Interactions ◽  
Double Wedge ◽  
Slip Surfaces

In this paper some characteristics of non-steady, compressible, flow are explored, including compression and expansion wave interactions and creation. The work to be presented herein is a Computational Fluid Dynamics investigation of the complex fluid phenomena that occur inside three-dimensional region, specifically with regard to the structure of the oblique shock waves, the reflected shock waves and the interactions of the shock waves. The flow is so complex that there exist oblique shock waves, expansion fans, slip surfaces, and shock wave interactions and reflections. The flow is non-steady, turbulent, viscous, compressible, and high-speed supersonic. The work to be presented herein is a Computational Fluid Dynamics analysis of flow over a 15-degree angle double wedge for a compressible air, with spin angle of 10-degree and Mach number of 2.5. The problem to be solved involves formation of shock waves, expansion fans and slip surfaces, so that the general characteristics of supersonic flow are explored through this problem. Shock waves and slip surfaces are discontinuities in fluid mechanics problems. It is essential to evaluate the ability of numerical technique that can solve problems in which shocks and contact surfaces occur. In particular it is necessary to understand the details of developing a mesh that will allow resolution of these discontinuities. Results including contour plots of pressure, temperature, and Mach number will show that CFD is capable of predicting accurate results and is also able to capture the discontinuities in the flow, e.g., the oblique shock waves and the slip surfaces. Through this computational analysis, a better interpretation of the physical phenomenon of the three-dimensional shock waves interaction and reflection can be achieved.

scholarly journals Investigation on the Flow Field Entropy Structure of Non-Synchronous Blade Vibration in an Axial Turbocompressor

Entropy ◽  
2020 ◽  
Vol 22 (12) ◽  
pp. 1372
Author(s):  
Mingming Zhang ◽  
Anping Hou
Keyword(s):  
Flow Field ◽  
High Speed ◽  
Guide Vane ◽  
Leading Edge ◽  
Inlet Guide Vane ◽  
Tip Leakage Flow ◽  
Good Correspondence ◽  
Blade Vibration ◽  
Tip Leakage ◽  
Spiral Vortex

In order to explore the inducing factors and mechanism of the non-synchronous vibration, the flow field structure and its formation mechanism in the non-synchronous vibration state of a high speed turbocompressor are discussed in this paper, based on the fluid–structure interaction method. The predicted frequencies fBV (4.4EO), fAR (9.6EO) in the field have a good correspondence with the experimental data, which verify the reliability and accuracy of the numerical method. The results indicate that, under a deviation in the adjustment of inlet guide vane (IGV), the disturbances of pressure in the tip diffuse upstream and downstream, and maintain the corresponding relationship with the non-synchronous vibration frequency of the blade. An instability flow that developed at the tip region of 90% span emerged due to interactions among the incoming main flow, the axial separation backflow, and the tip leakage vortices. The separation vortices in the blade passage mixed up with the tip leakage flow reverse at the trailing edge of blade tip, presenting a spiral vortex structure which flows upstream to the leading edge of the adjacent blade. The disturbances of the spiral vortexes emerge to rotate at 54.5% of the rotor speed in the same rotating direction as a modal oscillation. The blade vibration in the turbocompressor is found to be related to the unsteadiness of the tip flow. The large pressure oscillation caused by the movement of the spiral vortex is regarded as the one of the main drivers for the non-synchronous vibration for the present turbocompressor, besides the deviation in the adjustment of IGV.

Wall Boundary Layer Development Near the Tip Region of an IGV of an Axial Flow Compressor

1984 ◽  
Vol 106 (2) ◽  
pp. 337-345
Author(s):  
B. Lakshminarayana ◽  
N. Sitaram
Keyword(s):  
Boundary Layer ◽  
Guide Vane ◽  
Three Dimensional ◽  
Axial Compressor ◽  
Axial Flow ◽  
Inlet Guide Vane ◽  
Wall Boundary Layer ◽  
Wall Boundary ◽  
Boundary Layer Development ◽  
Flow Compressor

The annulus wall boundary layer inside the blade passage of the inlet guide vane (IGV) passage of a low-speed axial compressor stage was measured with a miniature five-hole probe. The three-dimensional velocity and pressure fields were measured at various axial and tangential locations. Limiting streamline angles and static pressures were also measured on the casing of the IGV passage. Strong secondary vorticity was developed. The data were analyzed and correlated with the existing velocity profile correlations. The end wall losses were also derived from these data.

IGV-Rotor Interaction Analysis in a Transonic Compressor Using the Navier-Stokes Equations

1996 ◽  
Author(s):  
Andrea Arnone ◽  
Roberto Pacciani
Keyword(s):  
Stokes Equations ◽  
Interaction Analysis ◽  
Guide Vane ◽  
Three Dimensional ◽  
Navier Stokes ◽  
Inlet Guide Vane ◽  
Operating Characteristics ◽  
Navier Stokes Equations ◽  
Transonic Compressor ◽  
Mass Flow Rates

A recently developed, time-accurate multigrid viscous solver has been extended to handle quasi-three-dimensional effects and applied to the first stage of a modern transonic compressor. Interest is focused on the inlet guide vane (IGV):rotor interaction where strong sources of unsteadiness are to be expected. Several calculations have been performed to predict the stage operating characteristics. Flow structures at various mass flow rates, from choke to near stall, are presented and discussed. Comparisons between unsteady and steady pitch-averaged results are also included in order to obtain indications about the capabilities of steady, multi-row analyses.

scholarly journals Wake Region Measurements of a Highly Three-Dimensional Nozzle Guide Vane Tested at DRA Pyestock Using Particle Image Velocimetry

1994 ◽  
Author(s):  
M. Funes-Gallanzi ◽  
P. J. Bryanston-Cross ◽  
K. S. Chana
Keyword(s):  
Flow Field ◽  
High Speed ◽  
Guide Vane ◽  
Three Dimensional ◽  
Light Sheet ◽  
Test Facility ◽  
Velocity Mapping ◽  
Nozzle Guide Vane ◽  
Nozzle Guide ◽  
Annular Cascade

The quantitative whole field flow visualization technique of PIV has over the last few years been successfully demonstrated for transonic flow applications. A series of such measurements has been made at DRA Pyestock. Several of the development stages critical to a full engine application of the work have now been achieved using the Isentropic Light Piston Cascade (ILPC) test facility operating with high inlet turbulence levels: • A method of seeding the flow with 0.5μm diameter styrene particles has provided an even coverage of the flow field. • A method of projecting a 1 mm thick high power Nd/YAG laser light sheet within the turbine stator cascade. This has enabled a complete instantaneous intra-blade velocity mapping of the flow field to be visualized, by a specially developed diffraction-limited optics arrangement. • Software has been developed to automatically analyze the data. Due to the sparse nature of the data obtained, a spatial approach to the extraction of the velocity vector data was employed. • Finally, a comparison of the experimental results with those obtained from a three-dimensional viscous flow program of Dawes; using the Baldwin-Lomax model for eddy viscosity and assuming fully turbulent flow. The measurements provide an instantaneous quantitative whole field visualization of a high-speed unsteady region of flow in a highly three-dimensional nozzle guide vane; which has been successfully compared with a full viscous calculation. This work represents the first such measurements to be made in a full-size transonic annular cascade at engine representative conditions.

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