Influence of Gap Detailing on Calculated Unsteady Non-Adjacent Blade Row Aero-Forcing in a Transonic Compressor Stage

2020 ◽  
Vol 142 (11) ◽  
Author(s):  
Tobias Gezork ◽  
Paul Petrie-Repar
Keyword(s):  
Guide Vane ◽  
Computational Cost ◽  
Life Time ◽  
Forced Response ◽  
Inlet Guide Vane ◽  
Compressor Blades ◽  
Transonic Compressor ◽  
Forcing Function ◽  
Gap Flow ◽  
Blade Row

Abstract Resonant or close to resonant forced response excitation of compressor blades limits component life time and can potentially lead to high-cycle fatigue failure if the exciting forces are large and damping is insufficient. When numerically quantifying the forcing function by means of simulations, simplifications are typically made in the analysis to reduce complexity and computational cost. In this paper, we numerically investigate how the blade forcing function is influenced by the rotor tip gap flow and by flow across gaps in the upstream variable inlet guide vane row. Unsteady simulations are made using a test rig geometry where a forcing crossing with an excitation from a non-adjacent blade row had previously been measured. The effects of the gaps on the forcing function for the first torsion mode are presented for both the non-adjacent blade row excitation (changes compared with a case without gaps indicating a 20% reduction) and an adjacent excitation (changes indicating an 80% increase in terms of forcing function amplitude comparing with a case without gaps).

Time Transformation Simulation of 1.5 Stage Transonic Compressor

2015 ◽  
Author(s):  
Laith Zori ◽  
Paul Galpin ◽  
Rubens Campregher ◽  
Juan Carlos Morales
Keyword(s):  
Steady State ◽  
Transient Flow ◽  
Computational Cost ◽  
Aerodynamic Performance ◽  
Forced Response ◽  
Time Transformation ◽  
Pitch Change ◽  
Transonic Compressor ◽  
Blade Row ◽  
State Mixing

The accurate prediction of the aerodynamic and aeromechanical performance in a modern transonic compressor often exceeds the capability of traditional steady state mixing plane simulation methods. Time accurate transient blade row simulation approaches are required when there is a close coupling of the flow between the blade rows, and for fundamentally transient flow phenomena such as aeromechanical analysis including blade flutter and forced response, aerothermodynamic analysis and aero-acoustic analysis. Transient blade row simulations can be computationally impractical when all of the blade passages must be modeled to account for the unequal pitch between the blade rows. Most turbomachines consist of multiple stages, further exacerbating the computational challenge. In order to reduce the computational cost, time accurate pitch-change methods are utilized so that only a sector of the turbomachine (one or few passages per row) is modeled. The extension of the time-transformation pitch-change method to multistage machines has recently shown good promise in predicting both aerodynamic performance and resolving dominant blade passing frequencies for a subsonic compressor, while keeping the computational cost affordable. In this work, a modified one and a half stage Purdue transonic compressor (modified for unequal pitch for all three blade rows) is examined. The goal is to assess the ability of the multistage time-transformation method to accurately predict the aerodynamic performance and transient flow details in the presence of transonic blade row interactions. The results from the multistage time-transformation simulation are compared in detail with a transient full-wheel simulation, a profile transformation simulation, as well as to a steady-state mixing-plane model. Flow details are examined including an FFT analysis of select signals, and the onset of stall is compared between all methods. The relative computational effort is compared between all of the analysis methods.

Transonic Compressor Influences on Upstream Surface Pressures With Axial Spacing

1999 ◽  
Author(s):  
Peter J. Koch ◽  
Douglas P. Probasco ◽  
J. Mitch Wolff ◽  
William W. Copenhaver ◽  
Randall M. Chriss
Keyword(s):  
Surface Pressure ◽  
High Speed ◽  
Guide Vane ◽  
Navier Stokes ◽  
Inlet Guide Vane ◽  
Transonic Compressor ◽  
Unsteady Surface Pressure ◽  
Blade Row ◽  
Non Linear ◽  
Unsteady Loading

A set of inlet guide vane (IGV) unsteady surface pressure measurements is presented. The unsteady aerodynamic effects of a highly loaded, high speed downstream compression stage on the upstream inlet guide vane stator surface pressures are characterized through experimental and computational analysis. The axial spacing between the IGV and rotor was varied between 12%, 26%, and 56% of the IGV chord for a 105% speed, peak efficiency operating condition, which is transonic. Unsteady IGV surface pressures were acquired for two spanwise locations on both blade surfaces. The largest unsteady surface pressure magnitudes were obtained at the 12% axial spacing configuration and 95% chord location. In general, spanwise variations were found to be important. The upstream bow shock effect is non-linear in character. Comparisons to a two-dimensional, non-linear unsteady multi-blade row Navier-Stokes analysis at 50% span show a good agreement with the IGV unsteady surface pressure results and higher harmonic content. The results of the study indicate significant variations in the IGV unsteady loading caused by changes in axial spacing.

Experimental Reduction of Transonic Fan Forced Response by Inlet Guide Vane Flow Control

2009 ◽  
Vol 132 (2) ◽  
Author(s):  
S. Todd Bailie ◽  
Wing F. Ng ◽  
William W. Copenhaver
Keyword(s):  
Flow Control ◽  
Guide Vane ◽  
Leading Edge ◽  
Forced Response ◽  
Inlet Guide Vane ◽  
Resonant Response ◽  
Compressor Blades ◽  
Resonant Amplitude ◽  
Blade Vibrations ◽  
Transonic Fan

The main contributor to the high cycle fatigue of compressor blades is the response to aerodynamic forcing functions generated by an upstream row of stators or inlet guide vanes. Resonant response to engine order excitation at certain rotor speeds can be especially damaging. Studies have shown that flow control by trailing edge blowing (TEB) can reduce stator wake strength and the amplitude of the downstream rotor blade vibrations generated by the unsteady stator-rotor interaction. In the present study, the effectiveness of TEB to reduce forced fan blade vibrations was evaluated in a modern single-stage transonic fan rig. Data were collected for multiple uniform full-span TEB conditions over a range of rotor speeds including multiple modal resonance crossings. Resonant response sensitivity was generally characterized by a robust region of strong attenuation. The baseline resonant amplitude of the first torsion mode, which exceeded the endurance limit on the critical blade, was reduced by more than 80% with TEB at 1.0% of the total rig flow. The technique was also found to be modally robust; similar reductions were achieved for all tested modal crossings, including more than 90% reduction in the second leading-edge bending response using 0.7% of the rig flow.

The Influence of Wake–Wake Interactions on Loss Fluctuations of a Downstream Axial Compressor Blade Row

1998 ◽  
Vol 120 (4) ◽  
pp. 695-704 ◽  
Author(s):  
G. J. Walker ◽  
J. D. Hughes ◽  
I. Ko¨hler ◽  
W. J. Solomon
Keyword(s):  
Free Stream ◽  
Guide Vane ◽  
Axial Compressor ◽  
Inlet Guide Vane ◽  
Viscous Losses ◽  
Wake Interaction ◽  
Blade Row ◽  
Wake Interactions ◽  
Periodic Fluctuations ◽  
Disturbance Field

The interaction between wakes of an adjacent rotor–stator or stator–rotor blade row pair in an axial turbomachine is known to produce regular spatial variations in both the time-mean and unsteady flow fields in a frame relative to the upstream member of the pair. This paper examines the influence of such changes in the free-stream disturbance field on the viscous losses of a following blade row. Hot-wire measurements are carried out downstream of the outlet stator in a 1.5-stage axial compressor having equal blade numbers in the inlet guide vane (IGV) and stator rows. Clocking of the IGV row is used to vary the disturbance field experienced by the stator blades; the influence on stator wake properties is evaluated. The magnitude of periodic fluctuations in ensemble-averaged stator wake thickness is significantly influenced by IGV wake-rotor wake interaction effects. The changes in time-mean stator losses appear marginal.

Numerical and Experimental Investigation on the Influence of Blades Gap Flow on Axial Blood Pump Performance

2019 ◽  
Author(s):  
Guangmao Liu ◽  
Donghai Jin ◽  
Mengyu Wang ◽  
Xingmin Gui
Keyword(s):  
Rotor Blade ◽  
Guide Vane ◽  
Flow Characteristics ◽  
Pressure Rise ◽  
Blood Pump ◽  
Inlet Guide Vane ◽  
Pump Efficiency ◽  
Blade Root ◽  
Gap Flow ◽  
Blade Tip

Abstract The axial blood pump body primarily contains the Inlet Guide Vane (IGV), Rotor Impeller (RI), Outlet Guide Vane (OGV) and pump casing. There must be gaps between rotor blade tip and pump casing or between OGV blade root and rotor hub for the impeller rotating in the pump. The flow characteristics inside an axial blood pump with different blade gaps were numerically simulated and analyzed. Hydraulics experiments were conducted to verify the numerical results. The results show that the pump efficiency decreased slowly when the OGV blade gap increased from 0.1 mm to 0.3 mm, but quickly when the rotor blade gap increased from 0.1 mm to 0.3 mm. The hydraulics characteristic results indicate that the pressure rise and efficiency are mainly influenced by the rotor blade gap. The OGV blade root gaps have little influence on the decrease of pressure rise and efficiency. The novel configuration with uneven blade gaps inside the pump result in improved hydraulics and hemolytic performance compared with the similarly sized configuration with even blade gaps.

Towards Improved Throughflow Capability: The Use of 3D Viscous Flow Solvers in a Multistage Environment

1990 ◽  
Author(s):  
W. N. Dawes
Keyword(s):  
Experimental Evidence ◽  
Steam Turbine ◽  
Guide Vane ◽  
Navier Stokes ◽  
Flow Properties ◽  
Transonic Compressor ◽  
Compressor Rotor ◽  
Blade Row ◽  
Nozzle Guide Vane ◽  
Nozzle Guide

A methodology is presented for simulating turbomachinery blade rows in a multistage environment by deploying a standard 3D Navier-Stokes solver simultaneously on a number of blade rows. The principle assumptions are that the flow is steady relative to each blade row individually and that the rows can communicate via inter-row mixing planes. These mixing planes introduce circumferential averaging of flow properties but preserve quite general radial variations. Additionally, each blade can be simulated in 3D or axisymmetrically (in the spirit of throughflow analysis) and a series of axisymmetric rows can be considered together with one 3D row to provide, cheaply, a machine environment for that row. Two applications are presented: a transonic compressor rotor and a steam turbine nozzle guide vane simulated both isolated and as part of a stage. In both cases the behaviour of the blade considered in isolation was different to when considered as part of a stage and in both cases was in much closer agreement with the experimental evidence.

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.

Application of Model Order Reduction to Compressor Aeroelastic Models

2000 ◽  
Author(s):  
Karen Willcox ◽  
Jaime Peraire ◽  
James D. Paduano
Keyword(s):  
Model Order Reduction ◽  
Order Reduction ◽  
Forced Response ◽  
Single Frequency ◽  
Model Order ◽  
Transonic Compressor ◽  
Influence Coefficients ◽  
Aeroelastic Analysis ◽  
Blade Row ◽  
Low Order

A model order reduction technique that yields low-order models of blade row unsteady aerodyamics is introduced. The technique is applied to linearized unsteady Euler CFD solutions in such a way that the resulting blade row models can be linked to their surroundings through their boundary conditions. The technique is applied to a transonic compressor aeroelastic analysis, in which the high-fidelity CFD forced-response results are better captured than with models that use single-frequency influence coefficients. A low-speed compressor stage is also modeled to demonstrate the multistage capability of the method. These examples demonstrate how model order reduction can be used to systematically improve the versatility, fidelity, and range of applicability of the low-order aerodynamic models typically used for incorporation of CFD results into aeroelastic analyses.

Toward Improved Throughflow Capability: The Use of Three-Dimensional Viscous Flow Solvers in a Multistage Environment

1992 ◽  
Vol 114 (1) ◽  
pp. 8-17 ◽  
Author(s):  
W. N. Dawes
Keyword(s):  
Experimental Evidence ◽  
Guide Vane ◽  
Three Dimensional ◽  
Navier Stokes ◽  
Flow Properties ◽  
Transonic Compressor ◽  
Compressor Rotor ◽  
Blade Row ◽  
Nozzle Guide Vane ◽  
Nozzle Guide

A methodology is presented for simulating turbomachinery blade rows in a multistage environment by deploying a standard three-dimensional Navier–Stokes solver simultaneously on a number of blade rows. The principal assumptions are that the flow is steady relative to each blade row individually and that the rows can communicate via inter-row mixing planes. These mixing planes introduce circumferential averaging of flow properties but preserve quite general radial variations. Additionally, each blade can be simulated in three-dimensional or axisymmetrically (in the spirit of throughflow analysis) and a series of axisymmetric rows can be considered together with one three-dimensional row to provide, cheaply, a machine environment for that row. Two applications are presented: a transonic compressor rotor and a steam turbine nozzle guide vane simulated both isolated and as part of a stage. In both cases the behavior of the blade considered in isolation was different to when considered as part of a stage and in both cases was in much closer agreement with the experimental evidence.

Influence of Disc Modes and Sideband Excitations on the Mistuned Forced Response Behaviour of an Embedded Compressor Rotor

2021 ◽  
Author(s):  
Shreyas Hegde ◽  
Andrew Madden ◽  
Robert Kielb
Keyword(s):  
Computational Cost ◽  
Axial Compressor ◽  
Travelling Wave ◽  
Forced Response ◽  
Operating Conditions ◽  
Operating Condition ◽  
Compressor Rotor ◽  
Forcing Function ◽  
Highly Sensitive ◽  
The Individual

Abstract This paper focusses on predicting the mistuned forced response behavior of an embedded compressor rotor blade row in a 3.5 stage axial compressor. The authors in previous papers studied the multi-row influence on the forcing function for multiple operating conditions. For these investigations CFX was utilized to predict the forcing However, in the mistuned predictions a consistent underprediction of the amplification factor was noted A previous investigation by the authors [32] considered an isolated mode family. The current work considers the same configuration but looks at a non-isolated mode family which is in a frequency “veering” region. Also, since the mistuning code was formulated on the lines of the fundamental mistuning model (FMM) the model only included a single DOF per ND and hence modes in the veering region were not modeled. The current paper addresses both these shortcomings and talks about the influence of sideband travelling wave excitations at the HL operating condition (the details of the mistuned predictions at the PE operating condition can be found in [32]). The paper also talks in detail about the effect of modelling the disc modes individually using the FMM model as well as together using the component mistuning model (CMM) as present in ANSYS Mechanical. Key conclusions are: 1) The mistuned response tends to be amplified by all cases including the sideband excitations, 2) The coupled influence of including a disc mode in the FMM model and sideband excitations is dependent on the proximity of the mode to the blade alone frequency, 3) Although the CMM model predicts the peak of the response accurately, it does not offer any substantial advantage over the FMM model given the computational cost required for the CMM prediction. Also, the prediction is highly sensitive to the frequency of the individual modes that can differ between codes.

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