The impact of tandem rotor blades on the performance of transonic axial compressors

2017 ◽  
Vol 67 ◽  
pp. 237-248 ◽  
Author(s):  
Mohamed Mohsen ◽  
Farouk M. Owis ◽  
Ali A. Hashim
Keyword(s):  
Rotor Blades ◽  
Axial Compressors ◽  
The Impact

Stator Blades Manufacturing Geometrical Variability in Axial Compressors and Impact on the Aeroelastic Excitation Forces

2021 ◽  
pp. 1-16
Author(s):  
Marco Gambitta ◽  
Arnold Kühhorn ◽  
Bernd Beirow ◽  
Sven Schrape
Keyword(s):  
Manufacturing Process ◽  
Axial Compressor ◽  
Reconstruction Algorithm ◽  
Forced Response ◽  
Rotor Blades ◽  
Compressor Blades ◽  
Input Uncertainty ◽  
Axial Compressors ◽  
Compressor Rotor ◽  
The Impact

Abstract The manufacturing geometrical variability is an unavoidable source of uncertainty in the realization of machinery components. Deviations of a part geometry from its nominal design are inevitably present due to the manufacturing process. In the aeroelastic forced response problem within axial compressors, these uncertainties may affect the vibration characteristics. Therefore, the impact of geometrical uncertainties due to the manufacturing process onto the modal forcing of axial compressor blades is investigated. The research focuses on the vibrational behavior of an axial compressor rotor blisk. In particular, the amplitude of the forces acting as source of excitation on the vibrating blades is studied. The geometrical variability of the upstream stator is investigated as input uncertainty. The variability is modeled starting from a series of optical surface scans. A stochastic model is created to represent the measured manufacturing geometrical deviations from the nominal model. A data reduction methodology is proposed to represent the uncertainty with a minimal set of variables. The manufacturing geometrical variability model allows to represent the input uncertainty and probabilistically evaluate its impact on the aeroelastic problem. An uncertainty quantification is performed in order to evaluate the resulting variability on the modal forcing acting on the vibrating rotor blades. Of particular interest is the possible rise of low engine orders due to the mistuned flow field along the annulus. A reconstruction algorithm allows the representation of the variability during one rotor revolution. The uncertainty on low harmonics of the modal rotor forcing can be therefore identified and quantified.

Stator Blades Manufacturing Geometrical Variability in Axial Compressors and Impact on the Aeroelastic Excitation Forces

2021 ◽  
Author(s):  
Marco Gambitta ◽  
Arnold Kühhorn ◽  
Bernd Beirow ◽  
Sven Schrape
Keyword(s):  
Manufacturing Process ◽  
Axial Compressor ◽  
Reconstruction Algorithm ◽  
Forced Response ◽  
Rotor Blades ◽  
Compressor Blades ◽  
Input Uncertainty ◽  
Axial Compressors ◽  
Compressor Rotor ◽  
The Impact

Abstract The manufacturing geometrical variability is a source of uncertainty, which cannot be avoided in the realization of machinery components. Deviations of a part geometry from its nominal design are inevitably present due to the manufacturing process. In the case of the aeroelastic forced response problem within axial compressors, these uncertainties may affect the vibration characteristics. For this reason, the impact of geometrical uncertainties due to the manufacturing process onto the modal forcing of axial compressor blades is investigated in this study. The research focuses on the vibrational behavior of an axial compressor rotor blisk. In particular the amplitude of the forces acting as source of excitation on the vibrating blades is studied. The geometrical variability of the upstream stator is investigated as input uncertainty. The variability is modeled starting from a series of optical surface scans. A stochastic model is created to represent the measured manufacturing geometrical deviations from the nominal model. A data reduction methodology is proposed in order to represent the uncertainty with a minimal set of variables. The manufacturing geometrical variability model allows to represent the input uncertainty and probabilistically evaluate its impact on the aeroelastic problem. An uncertainty quantification is performed in order to evaluate the resulting variability on the modal forcing acting on the vibrating rotor blades. Of particular interest is the possible rise of low engine orders due to the mistuned flow field along the annulus. A reconstruction algorithm allows the representation of the variability during one rotor revolution. The uncertainty on low harmonics of the modal rotor forcing can be therefore identified and quantified.

Numerical Investigation of a Cantilevered Compressor Stator at Varying Clearance Sizes

2015 ◽  
Author(s):  
Chengwu Yang ◽  
Xingen Lu ◽  
Yanfeng Zhang ◽  
Shengfeng Zhao ◽  
Junqiang Zhu
Keyword(s):  
Flow Field ◽  
Axial Compressor ◽  
High Flow ◽  
Leakage Flow ◽  
Streamwise Direction ◽  
Stall Margin ◽  
Axial Compressors ◽  
Pressure Surface ◽  
The Impact ◽  
Highly Loaded

The clearance size of cantilevered stators affects the performance and stability of axial compressors significantly. Numerical calculations were carried out using the commercial software FINE/Turbo for a 2.5-stage highly loaded transonic axial compressor, which is of cantilevered stator for the first stage, at varying hub clearance sizes. The aim of this work is to improve understanding of the impact mechanism of hub clearance on the performance and the flow field in high flow turning conditions. The performance of the front stage and the compressor with different hub clearance sizes of the first stator has been analyzed firstly. Results show that the efficiency decreases as clearance size varies from 0 to 3% of hub chordlength, but the operating range has been extended. For the first stage, the efficiency decreases about 0.5% and the stall margin is extended. The following analysis of detailed flow field in the first stator shows that the clearance leakage flow and elimination of hub corner separation is responsible for the increasing loss and stall margin extending respectively. The effects of hub clearance on the downstream rotor have been discussed lastly. It indicates that the loss of the rotor increases and the flow deteriorates due to increasing of clearance size and hence the leakage mass flow rate, which mainly results from the interaction of upstream leakage flow with the passage flow near pressure surface. The affected region of rotor passage flow field expands in spanwise and streamwise direction as clearance size grows. The hub clearance leakage flow moves upward in span as it flows toward downstream.

The Impact of Inlet Distortion and Reduced Frequency on the Performance of Centrifugal Compressors

2018 ◽  
Vol 141 (2) ◽  
Author(s):  
A. Grimaldi ◽  
V. Michelassi
Keyword(s):  
Experimental Data ◽  
Liquefied Natural Gas ◽  
Design Phase ◽  
Centrifugal Compressors ◽  
Axial Compressors ◽  
Inlet Distortion ◽  
Side Stream ◽  
Reduced Frequency ◽  
The Impact

This paper discusses the impact of inlet flow distortions on centrifugal compressors based upon a large experimental data base in which the performance of several impellers in a range of corrected flows and corrected speeds have been measured after been coupled with different inlet plenums technologies. The analysis extends to centrifugal compressor inlets including a side stream, typical of liquefied natural gas applications. The detailed measurements allow a thorough characterization of the flow field and associated performance. The results suggest that distortions can alter the head by as much as 3% and efficiency of around 1%. A theoretical analysis allowed to identify the design features that are responsible for this deviation. In particular, an extension of the so-called “reduced-frequency,” a coefficient routinely used in axial compressors and turbine aerodynamics to weigh the unsteadiness generated by upstream to downstream blade rows, allowed to determine a plenum-to-impeller reduced frequency that correlates very well with the measured performance. The theory behind the new coefficient is discussed together with the measurement details and validates the correlation that can be used in the design phase to determine the best compromise between the inlet plenum complexity and impact on the first stage.

scholarly journals Experimental evaluation of a vibro-impact model for two adjacent shear-building structures

2018 ◽  
Vol 211 ◽  
pp. 03004
Author(s):  
Marcus Varanis ◽  
Arthur Mereles ◽  
Anderson Silva ◽  
José Balthazar ◽  
Ângelo Tusset ◽  
...  
Keyword(s):  
Beam Theory ◽  
Rotor Blades ◽  
Contact Theory ◽  
Building Structures ◽  
Impact Model ◽  
Nonlinear Characteristics ◽  
Strongly Nonlinear ◽  
Shear Building ◽  
The Impact ◽  
Euler Bernoulli Beam

The vibro-impact phenomenon is found in many engineering applications, from impact of floating ice with ships to rubbing between the stator structure and rotor blades in turbomachinery, and in most cases it is important to know the implication of this phenomenon in the mechanical system. This is often done by proposing vibro-impact models for describing the behavior of the system when subjected to periodically impacts. However, this modelling may be challenging due to the strongly nonlinear characteristics of the impact phenomenon. Therefore, this paper presents a vibro-impact model of two shearbuilding structures positioned side by side, where one of them is driven by an unbalanced DC motor. The structures were modeled using the Euler-Bernoulli beam theory and the contact was modeled based on the Hertz contact theory. In order to validate the model their responses were compared with experimental signals.

Simulation of the Interaction of Labyrinth Seal Leakage Flow and Main Flow in an Axial Turbine

2002 ◽  
Author(s):  
Jan E. Anker ◽  
Ju¨rgen F. Mayer
Keyword(s):  
Experimental Data ◽  
Labyrinth Seal ◽  
Main Flow ◽  
Rotor Blades ◽  
Navier Stokes ◽  
Test Case ◽  
Leakage Flow ◽  
Computational Results ◽  
Axial Turbine ◽  
The Impact

This paper presents the simulation of the flow in a 1.5 stage low-speed axial turbine with shrouded rotor blades and focuses on the interaction of the labyrinth seal leakage flow with the main flow. The presented results were obtained using the Navier-Stokes code ITSM3D developed at University of Stuttgart. A comparison of the computational results with experimental data of this test case gained at Ruhr-Universita¨t Bochum verifies that the flow solver is capable of reproducing the leakage flow effects to a sufficient extent. The computational results are used to examine the influence of the leakage flow on the flow field of the turbine. By varying the clearance height of the labyrinth in the simulations, the impact of the re-entering leakage flow on the main flow is studied. As demonstrated in this paper, leakage flow not only introduces mixing losses but can also dominate the secondary flow and induce severe losses. In agreement with the experimental data the computational results show that at realistic clearance heights the leakage flow gives rise to negative incidence over a considerable part of the downstream stator which causes the flow to separate.

Tailored Structural Design and Aeromechanical Control of Axial Compressor Stall: Part II — Evaluation of Approaches

2003 ◽  
Author(s):  
L. G. Fre´chette ◽  
O. G. McGee ◽  
M. B. Graf
Keyword(s):  
Structural Parameters ◽  
Axial Compressor ◽  
Coupled System ◽  
Rotating Stall ◽  
Rotor Blades ◽  
Tip Clearance ◽  
Theoretical Evaluation ◽  
Axial Compressors ◽  
Spatial Modes ◽  
Control Authority

A theoretical evaluation was conducted delineating how aeromechanical feedback control can be utilized to stabilize the inception of rotating stall in axial compressors. Ten aeromechanical control methodologies were quantitatively examined based on the analytical formulations presented in the first part of this paper (McGee et al, 2003a). The maximum operating range for each scheme is determined for optimized structural parameters, and the various schemes are compared. The present study shows that the most promising aeromechanical designs and controls for a class of low-speed axial compressors were the use of dynamic fluid injection. Aeromechanically incorporating variable duct geometries and dynamically re-staggered IGV and rotor blades were predicted to yield less controllability. The aeromechanical interaction of a flexible casing wall was predicted to be destabilizing, and thus should be avoided by designing sufficiently rigid structures to prevent casing ovalization or other structurally-induced variations in tip clearance. Control authority, a metric developed in the first part of this paper, provided a useful interpretation of the aeromechanical damping of the coupled system. The model predictions also show that higher spatial modes can become limiting with aeromechanical feedback, both in control of rotating stall as well as in considering the effects of lighter, less rigid structural aeroengine designs on compressor stability.

scholarly journals Darmstadt Rotor No. 2, II: Design of Leaning Rotor Blades

2003 ◽  
Vol 9 (6) ◽  
pp. 385-391
Author(s):  
Jörg Bergner ◽  
Dietmar K. Hennecke ◽  
Martin Hoeger ◽  
Karl Engel
Keyword(s):  
Mechanical Stability ◽  
Three Dimensional ◽  
Stability Limit ◽  
Operating Conditions ◽  
Rotor Blades ◽  
Navier Stokes ◽  
Structural Constraints ◽  
Transonic Compressor ◽  
Aero Engines ◽  
The Impact

For Darmstadt University of Technology's axial singlestage transonic compressor rig, a new three-dimensional aft-swept rotor was designed and manufactured at MTU Aero Engines in Munich, Germany. The application of carbon fiber–reinforced plastic made it possible to overcome structural constraints and therefore to further increase the amount of lean and sweep of the blade. The aim of the design was to improve the mechanical stability at operation that is close to stall.To avoid the hazard of rubbing at the blade tip, which is found especially at off-design operating conditions close to the stability limit of the compression system, aft-sweep was introduced together with excessive backward lean.This article reports an investigation of the impact of various amounts of lean on the aerodynamic behavior of the compressor stage on the basis of steady-state Navier-Stokes simulations. The results indicate that high backward lean promotes an undesirable redistribution of mass flow and gives rise to a basic change in the shock pattern, whereas a forward-leaning geometry results in the development of a highly back-swept shock front. However, the disadvantage is a decrease in shock strength and efficiency.

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