scholarly journals Effects of Inlet Guide Vanes on the Performance and Stability of an Aeronautical Centrifugal Compressor

2020 ◽  
Author(s):  
Nicolas Poujol ◽  
Isabelle Trébinjac ◽  
Pierre Duquesne
Keyword(s):  
Mass Flow ◽  
Flow Rate ◽  
Centrifugal Compressor ◽  
Compressor Stage ◽  
Lower Mass ◽  
Flow Angle ◽  
Guide Vanes ◽  
Inlet Guide Vanes ◽  
Surge Line ◽  
Stagger Angle

Abstract A research centrifugal compressor stage designed and built by Safran Helicopter Engines is tested at 3 IGV (Inlet Guide Vanes) stagger angles. The compressor stage includes 4 blade rows: axial inlet guide vanes, a backswept splittered impeller, a splittered vaned radial diffuser and axial outlet guide vanes. The methodology for calculating the performance is detailed, including the consideration of humidity in order to minimize errors related in particular to operating atmospheric conditions. The shift of the surge line towards lower mass flow rate as the IGV stagger angle increases highly depends on the rotation speed. The surge line shift is very small at low rotation speeds whereas it significantly increases at high rotation speeds. A firstorder stability analysis of the impeller and diffuser subcomponents shows that the diffuser (resp. impeller) is the first unstable component at low (resp. high) rotation speeds. This situation is unaltered by increasing the IGV stagger angle. At low rotation speeds below a given mass flow rate, rotating instabilities at the impeller inlet are detected at zero IGV stagger angle. Their occurrence is conditioned by the relative flow angle at the tip of the leading edge of the impeller. As the IGV stagger angle increases, the mass flow decreases to maintain a given inlet flow angle. Therefore, the onset of the rotating instabilities is delayed towards lower mass flow rates. At high rotation speeds, the absolute flow angle at the diffuser inlet near surge decreases as the IGV stagger angle increases. As a result, the flow is highly alternate over two adjacent channels of the radial diffuser beyond the surge line at IGV stagger angle of 0°.

scholarly journals EFFECTS OF INLET GUIDE VANES ON THE PERFORMANCE AND STABILITY OF AN AERONAUTICAL CENTRIFUGAL COMPRESSOR

2021 ◽  
pp. 1-12
Author(s):  
Nicolas Poujol ◽  
Isabelle Trebinjac ◽  
Pierre Duquesne
Keyword(s):  
Mass Flow Rate ◽  
Mass Flow ◽  
Flow Rate ◽  
Centrifugal Compressor ◽  
Lower Mass ◽  
Flow Angle ◽  
Guide Vanes ◽  
Inlet Guide Vanes ◽  
Surge Line ◽  
Stagger Angle

Abstract A research centrifugal compressor stage designed and built by Safran Helicopter Engines is tested at 3 IGV (Inlet Guide Vanes) stagger angles. The methodology for calculating the performance is detailed, including the consideration of humidity in order to minimize errors related in particular to operating atmospheric conditions. The shift of the surge line towards lower mass flow rate as the IGV stagger angle increases highly depends on the rotation speed. The surge line shift is very small at low rotation speeds whereas it significantly increases at high rotation speeds. A first-order stability analysis of the impeller and diffuser sub-components shows that the diffuser (resp. impeller) is the first unstable component at low (resp. high) rotation speeds. This situation is unaltered by increasing the IGV stagger angle. At low rotation speeds below a given mass flow rate, rotating instabilities at the impeller inlet are detected at zero IGV stagger angle. Their occurrence is conditioned by the relative flow angle at the tip of the leading edge of the impeller. As the IGV stagger angle increases, the mass flow decreases to maintain a given inlet flow angle. Therefore, the onset of the rotating instabilities is delayed towards lower mass flow rates. At high rotation speeds, the absolute flow angle at the diffuser inlet near surge decreases as the IGV stagger angle increases. As a result, the flow is highly alternate over two adjacent channels of the radial diffuser beyond the surge line at IGV stagger angle of 0°.

Influence of Adjustable Inlet Guide Vanes on the Performance Characteristics of a Shrouded Centrifugal Compressor

2017 ◽  
Author(s):  
Yubao Tian ◽  
Yonghong Tang ◽  
Zhiheng Wang ◽  
Guang Xi
Keyword(s):  
Centrifugal Compressor ◽  
Pressure Ratio ◽  
Air Separation ◽  
Performance Characteristics ◽  
Flow Angle ◽  
Separation Unit ◽  
Guide Vanes ◽  
Inlet Guide Vanes ◽  
Lag Effect ◽  
Stagger Angle

A shrouded centrifugal compressor model stage used for 120,000 m3/h oxygen production air separation unit was designed and tested at several IGV stagger angles from −15° to +60° and machine Mach number from 0.97 to 0.5. Present research works aimed to assess the influence of the adjustable IGVs and the IGV modeling on the shrouded centrifugal compressor performance characteristics and inlet flow field and to explore the effect factors of the CFD prediction accuracy and compressor stability at different IGV stagger angles. The measured results show that the model stage with 0° IGV stagger angle yields almost the same stagnation pressure ratio performance as the stage-only model but at a lower peak isentropic efficiency. With an appropriate IGV stagger angle setting ranging from −15° to +30°, the compressor stability could be efficiently enhanced. Numerical studies indicate that a large IGV hub gap may lead to a significant lag effect on the flow angle generated by the inlet guide vanes when increasing the IGV stagger angle.

Centrifugal Compressor Inlet Guide Vanes for Increased Surge Margin

1991 ◽  
Vol 113 (4) ◽  
pp. 696-702 ◽  
Author(s):  
C. Rodgers
Keyword(s):  
Centrifugal Compressor ◽  
High Speed ◽  
System Stability ◽  
Negative Slope ◽  
Vaned Diffuser ◽  
Guide Vanes ◽  
Inlet Guide Vanes ◽  
Surge Margin ◽  
Compressor Inlet ◽  
Surge Line

This paper describes the results of compressor rig testing with a moderately high specific speed, high inducer Mack number, single-stage centrifugal compressor, with a vaned diffuser, and adjustable inlet guide vanes (IGVs). The results showed that the high-speed surge margin was considerably extended by the regulation of the IGVs, even though the vaned diffuser was apparently operating stalled. Simplified one-dimensional analysis of the impeller and diffuser performances indicated that at inducer tip Mach numbers approaching and exceeding unity, the high-speed surge line was triggered by inducer stall. Also, IGV regulation increased impeller stability. This permitted the diffuser to operate stalled, providing the net compression system stability remained on a negative slope.

Analysis of Flow Through a Twisted Vaned Diffuser

2014 ◽  
Author(s):  
Venkateswara Rao Pothuri ◽  
Venkata Ramana Murty Govindaraju ◽  
Venkata Rao Ganapathiraju
Keyword(s):  
Mass Flow ◽  
Centrifugal Compressor ◽  
Pressure Rise ◽  
Power Coefficient ◽  
Computational Results ◽  
Compressor Stage ◽  
Performance Parameters ◽  
Vaned Diffuser ◽  
Flow Angle ◽  
Centrifugal Compressor Stage

This paper describes the computational results on the performance of a centrifugal compressor stage with twisted vaned diffuser by varying the speed of the impeller and direction of twist for the diffuser vane. The centrifugal compressor stage configuration consists of a 2-D impeller (no twist is provided for the impeller vanes) with various configurations of diffusers. Diffuser configurations considered are Vaneless Diffuser (VLD), Low Solidity Vaned Diffuser (LSVD) and Twisted Vaned Diffuser (TVD). The analysis was carried at four different rotational speeds with corresponding mass flow rates of the impeller. 9° twist is given to the diffuser vane from hub to shroud by providing rotation at the leading edge, keeping the profile at hub as reference in the direction of rotation of the impeller and opposite to the direction of rotation of the impeller. The off-design cases considered includes operation at 80%, 90%, 110% and 120% of the design mass flow rate. CFD results are validated with experimental results for stages with VLD and LSVD for certain chosen performance parameters such as head coefficient, stage input power and exit flow angle. The computational results indicate that variations in impeller speed will cause changes in all significant performance parameters like the total pressure rise, power coefficient and efficiency of the stage and static pressure recovery coefficient of the diffuser. Contour plots were generated from CFD results and analyzed for better understanding of effect of rotational speed of the impeller on the performance of the centrifugal compressor. As a result of this study, it can be concluded that twisted vaned diffuser improves the performance in comparison to low solidity vaned diffuser for all the chosen impeller rotational speeds. The performance of the compressor stage is superior when diffuser vane twist is provided in the direction opposite to the rotation of impeller.

The Effects of Radial Inlet on the Performance of Variable Inlet Guide Vanes in a Centrifugal Compressor Stage

2010 ◽  
Author(s):  
Jiajian Tan ◽  
Datong Qi ◽  
Rui Wang
Keyword(s):  
Centrifugal Compressor ◽  
Pressure Ratio ◽  
Flow Simulation ◽  
Stage Model ◽  
Compressor Stage ◽  
Centrifugal Compressors ◽  
Guide Vanes ◽  
Centrifugal Compressor Stage ◽  
Inlet Guide Vanes ◽  
Stage Performance

Variable inlet guide vanes (VIGVs) can regulate pressure ratio and mass flow at constant rotational speed in centrifugal compressors as a result of inducing a controlled prewhirl in front of impellers. Radial inlets and VIGVs are typical upstream components in front of the first-stage impellers in many pipeline and multistage centrifugal compressors. However, previous investigations on VIGVs in centrifugal compressors were mostly conducted under the condition of axial inlets, and present work aims to focus on the effects of radial inlet on the VIGVs performance of a centrifugal compressor stage. The axial inlet stage model was compared with the radial inlet stage model using numerical flow simulation. The flow from the radial inlet was nonuniform in both circumferential and radial direction, thus the VIGVs, the impeller, the vaneless diffuser, and the return vane channel were modeled with fully 360-deg passages. The three-dimensional flow field was numerically simulated with FINE™/Turbo at VIGVs setting angles range from −20° to +60°. The overall stage performance parameters were obtained by integrating the field quantities. The simulation results show that the performance of VIGVs was significantly degraded by its inlet flow distortions resulting from a radial inlet. The stage performance map indicates that the overall stage polytropic efficiency decreased by an average of 2.5% and total pressure ratio decreased by an average of 1% because of the flow distortions at different VIGVs setting angles, in comparison with the axial stage model.

Experimental and Numerical Investigation of Low-Pressure Preswirl Stator-Rotor Cooling System

2016 ◽  
Author(s):  
B. F. Kutlu ◽  
B. T. Ealy ◽  
J. Hossain ◽  
W. Wang ◽  
Jay Kapat ◽  
...  
Keyword(s):  
Mass Flow Rate ◽  
Mass Flow ◽  
Flow Rate ◽  
Turbulence Models ◽  
Rotor System ◽  
Rotating Frame ◽  
Local Flow ◽  
Flow Angle ◽  
Guide Vanes ◽  
Endwall Contouring

Stator-rotor systems are commonly used in many different types of turbomachinery applications to supply an air for secondary air flows. Commercial CFD codes with variety of turbulence models are widely used in order to estimate the amount of flow supplied by the preswirl stator-rotor system. CFD investigations can provide detailed information about the local flow field which is extremely difficult to obtain from rotating rig due to the measurement limitations in rotating frame, however the accuracy of CFD needs to be investigated by conducting experiments. In this study the purpose is to evaluate how accurate CFD simulations with different turbulence models can predict the flow rate supplied by the system. An experimental rig composed of a stationary preswirler, a rotating disk with an internal flow path and a stator-rotor cavity with a rim seal was used in this study. Air is supplied to the stator from the ambient due to the suction provided by the rotor which can rotate at up to 3100 rpm. Incoming air first flows through annular preswirl guide vanes located inside the stator then discharges into the stator-rotor cavity located downstream of the preswirl guide vanes. Some fraction of the flow induced into the rotor by the help of inlet guides which are attached to the rotor face and angled to match the flow angle in rotating frame. Remaining part of the flow passes through rim seal and discharges out to the ambient. Two experimental cases, one with preswirl guide vanes without endwall contouring and the other with endwall contouring were been investigated at 3100 rpm. Mass flow rate at the inlet was 14.6% higher for the case with endwall contoured configuration compared to the case without endwall contouring. For both of the cases approximately 90% of the inlet flow was purged through rim seal while remaining 10% flows through the radial rotor disk passages. CFD analysis of the rotating rig were conducted using commercial code STAR CCM+. Turbulence models of k-ε, k-ω, Reynolds stress (RST) and Spalart-Allmaras were used and the mass flow rate drawn into the system was compared with experiments. The mass flow rate into the rig from experimental measurements was 7.4% higher compared to the best CFD prediction given by RST Linear. Among all turbulence models k-w was the worst performer by predicting mass flow 13% lower compared to the experimental value. Different sub-options of these turbulence models were also investigated. This study provided significant information for preswirl stator-rotor system designers in terms of the amount of flow rate that can be obtained and how well can it be predicted by CFD.

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