Aerodynamic Excitation Analysis for Variable Tip Gap

2016 ◽  
Author(s):  
Thomas Hauptmann ◽  
Joerg R. Seume
Keyword(s):  
Experimental Data ◽  
Turbine Blades ◽  
Fluid Structure Interaction ◽  
Spare Parts ◽  
Rotor Blades ◽  
Jet Engines ◽  
Flow Conditions ◽  
Reference Case ◽  
Structure Interaction ◽  
Blade Repair

In jet engines, blade repair is often more economical than the replacement of damaged blades with spare parts. Besides such regeneration of turbine blades, blade rubbing and erosion lead to a deviation of the geometry in the tip region of the original blade. These geometric variations can introduce non-uniform flow conditions which in turn may lead to an excitation of the blades. An analysis of the aerodynamic excitation due to typical geometric variations of the radial tip gap, introduced through substantial wear, is numerically investigated using a fluid-structure interaction (FSI) approach. The model was previously validated against experimental data. The results of the analysis show up to 1.6 times higher excitation than in the reference case, because rotor blades are excited by the wakes of the stator vanes and are amplified by a modified tip flow in the rotor passage.

scholarly journals Fluid–Structure Interaction for Biomimetic Design of an Innovative Lightweight Turboexpander

Biomimetics ◽  
2019 ◽  
Vol 4 (1) ◽  
pp. 27 ◽  
Author(s):  
Ibrahim Gad-el-Hak
Keyword(s):  
Stainless Steel ◽  
Turbine Blade ◽  
Turbine Blades ◽  
Fluid Structure Interaction ◽  
Rotor Blades ◽  
Aerodynamic Forces ◽  
Fluid Structure ◽  
Structure Interaction ◽  
Composite Blade ◽  
Lower Weight

Inspired by bird feather structures that enable the resistance of powerful aerodynamic forces in addition to their lower weight to provide stable flight, a biomimetic composite turbine blade was proposed for a low-temperature organic Rankine cycle (ORC) turboexpander that is capable of producing lower weight expanders than that of stainless steel expanders, in addition to reduce its manufacturing cost, and hence it may contribute in spreading ORC across nonconventional power systems. For that purpose, the fluid–structure interaction (FSI) was numerically investigated for a composite turbine blade with bird-inspired fiber orientations. The aerodynamic forces were evaluated by computational fluid dynamics (CFD) using the commercial package ANSYS-CFX (version 16.0) and then these aerodynamic forces were transferred to the solid model of the proposed blade. The structural integrity of the bird-mimetic composite blade was investigated by performing finite element analysis (FEA) of composite materials with different fiber orientations using ANSYS Composite PrepPost (ACP). Furthermore, the obtained mechanical performance of the composite turbine blades was compared with that of the stainless steel turbine blades. The obtained results indicated that fiber orientation has a greater effect on the deformation of the rotor blades and the minimum value can be achieved by the same barb angle inspired from the flight feather. In addition to a significant effect in the weight reduction of 80% was obtained by using composite rotor blades instead of stainless steel rotor blades.

Fluid-Structure Coupled Analyses of Composite Wind Turbine Blades

2007 ◽  
Vol 26-28 ◽  
pp. 41-44
Author(s):  
Tai Hong Cheng ◽  
Il Kwon Oh
Keyword(s):  
Wind Turbine ◽  
Aerodynamic Force ◽  
Interaction Analysis ◽  
Turbine Blades ◽  
Fluid Structure Interaction ◽  
Rotor Blades ◽  
Arbitrary Lagrangian Eulerian ◽  
Wind Turbine Blades ◽  
Fluid Structure ◽  
Structure Interaction

The composite rotor blades have been widely used as an important part of the wind power generation systems because the strength, stiffness, durability and vibration of composite materials are all excellent. In composite laminated blades, the static and dynamic aeroelasticity tailoring can be performed by controlling laminate angle or stacking sequence. In this paper, the fluid-structure coupled analyses of 10kW wind turbine blades has been performed by means of the full coupling between CFD and CSD based finite element methods. Fiber enforced composites fabricated with three types of stacking sequences were also studied. First the centrifugal force was considered for the nonlinear static analyses of the wind turbine so as to predict the deformation of tip point in the length direction and maximum stress in the root of a wind turbine. And then, the aeroelastic static deformation was taken into account with fluid-structure interaction analysis of the wind turbine. The Arbitrary Lagrangian Eulerian Coordinate was used to compute fluid structure interaction analysis of the wind turbine by using ADINA program. The displacement and stress increased apparently with the increment of aerodynamic force, but under the condition of maximum rotation speed 140RPM of the wind turbine, the displacement and stress were in the range of safety.

Experimental Validation of Forced Response Methods in a Multi-Stage Axial Turbine

2018 ◽  
Author(s):  
Thomas Hauptmann ◽  
Christopher E. Meinzer ◽  
Joerg R. Seume
Keyword(s):  
Experimental Data ◽  
Vibration Amplitude ◽  
Turbine Blades ◽  
Service Condition ◽  
Sensitivity Study ◽  
Forced Response ◽  
Tip Clearance ◽  
Computational Time ◽  
Reference Case ◽  
Axial Turbine

Depending on the in service condition of jet engines, turbine blades may have to be replaced, refurbished, or repaired in the course of an engine overhaul. Thus, significant changes of the turbine blade geometry can be introduced due to regeneration and overhaul processes. Such geometric variances can affect the aerodynamic and aeroelastic behavior of turbine blades. One goal in the development of the regeneration process is to estimate the aerodynamic excitation of turbine blades depending on these geometric variances caused during the regeneration. Therefore, this study presents an experimentally validated comparison of two methods for the prediction of forced response in a multistage axial turbine. Two unidirectional fluid structure interaction (FSI) methods, a time-linearized and a time-accurate with a subsequent linear harmonic analysis, are employed and the results validated against experimental data. The results show that the vibration amplitude of the time-linearized method is in good agreement with the experimental data and, also requires lower computational time than the time-accurate FSI. Based on this result, the time-linearized method is used to perform a sensitivity study of the tip clearance size of the last rotor blade row of the five stage axial turbine. The results show that an increasing tip clearances size causes an up to 1.35 higher vibration amplitude compared to the reference case, due to increased forcing and decreased damping work.

scholarly journals FSI in Wind Turbines: A Review

2020 ◽  
Vol 8 (3) ◽  
pp. 37
Author(s):  
Yogesh Ramesh Patel
Keyword(s):  
Wind Turbine ◽  
Wind Turbines ◽  
Stokes Equations ◽  
Turbine Blades ◽  
Fluid Structure Interaction ◽  
Arbitrary Lagrangian Eulerian ◽  
Wind Turbine Blades ◽  
Fluid Structure ◽  
Structure Interaction ◽  
Deformable Structure

This paper provides a brief overview of the research in the field of Fluid-structure interaction in Wind Turbines. Fluid-Structure Interaction (FSI) is the interplay of some movable or deformable structure with an internal or surrounding fluid flow. Flow brought about vibrations of two airfoils used in wind turbine blades are investigated by using a strong coupled fluid shape interplay approach. The approach is based totally on a regularly occurring Computational Fluid Dynamics (CFD) code that solves the Navier-Stokes equations defined in Arbitrary Lagrangian-Eulerian (ALE) coordinates by way of a finite extent method. The need for the FSI in the wind Turbine system is studied and comprehensively presented.

Implicit Partitioned Fluid-Structure Interaction Coupling

2006 ◽  
Author(s):  
Michael Scha¨fer ◽  
Saim Yigit ◽  
Marcus Heck
Keyword(s):  
Experimental Data ◽  
Numerical Simulation ◽  
Finite Element ◽  
Fluid Structure Interaction ◽  
Solution Procedure ◽  
Volume Flow ◽  
Fluid Structure ◽  
Flow Solver ◽  
Solution Approach ◽  
Structure Interaction

The paper deals with an implicit partitioned solution approach for the numerical simulation of fluid-structure interaction problems. The solution procedure involves the finite-volume flow solver FASTEST, the finite-element structural solver FEAP, and the coupling interface MpCCI. The method is verified and validated by comparisons with benchmark results and experimental data. Investigations concerning the influence of the grid movement technique and an underrelaxation on the performance of the method are presented.

scholarly journals Fluid Structure Interaction Modelling of Tidal Turbine Performance and Structural Loads in a Velocity Shear Environment

Energies ◽  
2018 ◽  
Vol 11 (7) ◽  
pp. 1837 ◽  
Author(s):  
Mujahid Badshah ◽  
Saeed Badshah ◽  
Kushsairy Kadir
Keyword(s):  
Fluid Dynamic ◽  
Turbine Blades ◽  
Fluid Structure Interaction ◽  
Angular Position ◽  
Uniform Flow ◽  
Velocity Shear ◽  
Power Coefficient ◽  
Fluid Structure ◽  
Structure Interaction ◽  
Stress And Deformation

Tidal Current Turbine (TCT) blades are highly flexible and undergo considerable deflection due to fluid interactions. Unlike Computational Fluid Dynamic (CFD) models Fluid Structure Interaction (FSI) models are able to model this hydroelastic behavior. In this work a coupled modular FSI approach was adopted to develop an FSI model for the performance evaluation and structural load characterization of a TCT under uniform and profiled flow. Results indicate that for a uniform flow case the FSI model predicted the turbine power coefficient CP with an error of 4.8% when compared with experimental data. For the rigid blade Reynolds Averaged Navier Stokes (RANS) CFD model this error was 9.8%. The turbine blades were subjected to uniform stress and deformation during the rotation of the turbine in a uniform flow. However, for a profiled flow the stress and deformation at the turbine blades varied with the angular position of turbine blade, resulting in a 22.1% variation in stress during a rotation cycle. This variation in stress is quite significant and can have serious implications for the fatigue life of turbine blades.

Experimentally Verified Study of Regeneration-Induced Forced Response in Axial Turbines

2014 ◽  
Vol 137 (3) ◽  
Author(s):  
Jens Aschenbruck ◽  
Joerg R. Seume
Keyword(s):  
Vibration Amplitude ◽  
Turbine Blades ◽  
Forced Response ◽  
Rotor Blades ◽  
Response Analysis ◽  
Reference Case ◽  
Angle Variation ◽  
Air Turbine ◽  
Axial Turbines ◽  
Stagger Angle

Geometrical variations occur in highly loaded turbine blades due to operation and regeneration. To determine the influence of such regeneration-induced variances of turbine blades on the aerodynamic excitation, a typical stagger angle variation of overhauled turbine blades is applied to stator vanes of an air turbine. This varied turbine stage is numerically and experimentally investigated. For the aerodynamic investigation of the vane wake, computational fluid dynamics (CFD) simulations are conducted. It is shown that the wake is changed due to the stagger angle variation. These results are confirmed by aerodynamic probe measurements in the air turbine. The vibration amplitude of the downstream rotor blades has been determined by a computational forced response analysis using a unidirectional fluid–structure interaction (FSI) approach and is experimentally verified here by tip-timing measurements. The results of the simulations and the measurements both show significantly higher amplitudes at certain operating points (OPs) due to the additional wake excitation. For typical regeneration-induced variations in stagger angle, the vibration amplitude is up to five times higher than in the reference case of uniform upstream stators. Based upon the present results, the influence of these variations and of the vane patterns on the vibration amplitude of the downstream rotor blade can and should be estimated in the regeneration process to minimize the dynamic stresses of the blades.

Verification of Low-Flow Conditions in a Multistage Turbine

2007 ◽  
Author(s):  
N. Herzog ◽  
M. Binner ◽  
J. R. Seume ◽  
K. Rothe
Keyword(s):  
Experimental Data ◽  
Electricity Market ◽  
Power Plants ◽  
Turbine Blades ◽  
Low Flow ◽  
Relative Mass ◽  
Computational Domain ◽  
Flow Conditions ◽  
Part Load ◽  
Mass Flows

Modern power plants face increasing problems with windage effects in high pressure steam turbines, due to the bigger size of the rotor blades and a more flexible demand of the electricity market, which may lead to more frequent operation at low-flow conditions. So far, no theoretical model exists to fully describe these flow phenomena which would help to prevent an overheating of the turbine blades and minimize the risk of damage. The main goal of this research project therefore is to predict the part-load behavior. Measurements of the flow field of a four-stage research air turbine were carried out at low Mach numbers to better understand the aerodynamic characteristics and the flow mechanisms at part-load. The experimental data such as temperature, pressure, velocity, and flow angles, measured in 6 different planes along the turbine annulus for different rotational speeds and different relative mass flows, have been compared with the numerical results of the CFDsolver TRACE. To obtain more realistic results than in computations published earlier, a newly generated finer grid and an extension of the computational domain at the outlet were used. It is shown that with the right initialization, the CFD-Solver is capable of providing converged calculation results even for low mass flows and high rotational speeds. The results are verified with experimental data e.g. by the temperature distribution within the four-stage turbine and the pressure and temperature profiles in the measurement planes. As a general result, the highest temperatures in the turbine do not occur behind the last stage, but in the downstream third of the machine, which agrees with experiences of damage observed in real turbines.

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