Aerodynamic Excitation Analysis of Radial Turbine Blades due to Unsteady Flow From Vaneless Turbine Housings

2017 ◽  
Author(s):  
Stephan Netzhammer ◽  
Damian M. Vogt ◽  
Stephan Kraetschmer ◽  
Johannes Leweux ◽  
Andreas Koengeter
Keyword(s):  
Test Data ◽  
Turbine Blades ◽  
Resonant Excitation ◽  
Design Parameters ◽  
Blade Vibration ◽  
Baseline Design ◽  
Housing Design ◽  
Radial Turbine ◽  
Turbine Housing ◽  
Generalized Force

Turbocharger turbine blades are subjected to resonant excitation that can lead to High Cycle Fatigue (HCF). In vaneless turbines the excitation primarily stems from asymmetries in the turbine housing such as the volute and the tongue. Given the nature of such asymmetries, the excitation is of a Low Engine Order (LEO) type. The present study deals with the effect of radial turbine housing design on LEO resonant excitation of turbine blades. The study focuses on two geometrical key design parameters of a twin-scroll turbine housing for a radial turbine which is the rotor-tongue distance and the circumferential angle between both tongues. The generalized force approach is used to identify the critical blade surface regions in order to understand the excitation mechanism of each specific design and to assess the differences of design variants with respect to the baseline design. The presented approach is highly practicable, because it is less expensive than full FSI-simulations. This approach is validated on tip timing test data from full-scale experiments. Correlation to test data shows that the presented approach is capable of capturing the relative trends reliably and hence can efficiently be employed in an industrial design process such as to minimize blade vibration amplitudes. It is shown that a reduction of blade vibration amplitudes by a factor of 10 could be achieved.

Influence of tip clearance distribution on blade vibration of vaneless radial turbine

2021 ◽  
pp. 095440702110281
Author(s):  
Lei Pan ◽  
Mingyang Yang ◽  
Shouta Murae ◽  
Wataru Sato ◽  
Naoto Shimohara ◽  
...  
Keyword(s):  
Turbine Blades ◽  
Vibration Response ◽  
Tip Clearance ◽  
Field Analysis ◽  
Pressure Amplitude ◽  
Suction Surface ◽  
Blade Vibration ◽  
Tip Leakage Vortex ◽  
Tip Leakage ◽  
Radial Turbine

As vehicle turbochargers are developed toward higher performance and lower turbo lag, high cycle fatigue (HCF) of radial turbine blades is becoming increasingly common which greatly threatens the reliability of turbochargers. Tip leakage vortex is one of potential sources of blade excitation and it’s profoundly influenced by blade tip clearance. This paper studies the influence of tip clearance distribution on blade excitation of a vaneless radial turbine via experimentally validated one-way fluid-structure interaction (FSI) numerical method. The results suggest that blade vibration response is significantly influenced by tip clearance distribution in the meridional direction. Generalized energy method is proposed to determine the key factors for blade excitation. The results manifest that complex distributions of harmonic pressure amplitude on the blade dominate blade vibration response. Detailed flow field analysis is carried out to further investigate the mechanism of blade excitation. The results show that distributions of harmonic pressure amplitude on pressure surface (PS) and suction surface (SS) are both dominated by tip leakage vortex, whereas the roles that tip leakage vortex plays are quite different. Specifically, tip leakage vortex influences harmonic pressure amplitude on SS directly because of short distance between vortex core and SS, whereas it influences harmonic pressure amplitude on PS indirectly by interfering the evolution of passage vortex. This research can guide new designs for durable vaneless radial turbines without sacrificing aerodynamic performance.

scholarly journals Dry Friction Damping Mechanisms in Engine Blades

1982 ◽  
Author(s):  
A. V. Srinivasan ◽  
D. G. Cutts
Keyword(s):  
Laboratory Test ◽  
Test Data ◽  
Dry Friction ◽  
Turbine Blades ◽  
Experimental Studies ◽  
Vibration Damping ◽  
Analytical Models ◽  
Jet Engines ◽  
Blade Vibration ◽  
Dry Friction Damping

In the context of jet engines, significant vibration damping due to dry friction can occur at (a) shroud interfaces of fans and (b) the platform of turbine blades fitted with “platform dampers.” Analytical and experimental studies in regard to this important source of nonaerodynamic damping of blade vibration are presented in this paper. Comparisons between results from analytical models and laboratory test data are made and discussed.

Reducing Blade Force Response in a Radial Turbine by Means of Jet Injection

2019 ◽  
Author(s):  
Stephan Netzhammer ◽  
Damian M. Vogt ◽  
Stephan Kraetschmer ◽  
Johannes Leweux ◽  
Jennifer Blackburne
Keyword(s):  
Vibration Amplitude ◽  
Jet Injection ◽  
Blade Vibration ◽  
Vibration Displacement ◽  
Safe Level ◽  
Air Jet ◽  
Turbine Housing ◽  
Generalized Force ◽  
Blade Failure ◽  
Positive Results

Abstract Radial turbines consisting of a spiral volute inlet casing, such as those found in turbochargers, are subject to excitations caused by the inlet flow. In the absence of inlet guide vanes, the asymmetries from the volute are accentuated and lead to Low Engine Order (LEO) excitations. These excitations can be particularly troublesome as they are likely to resonate with the first bending mode (M1) at high rotational speeds, causing large vibration displacement amplitudes which will result in High Cycle Fatigue (HCF). It is therefore imperative to ensure these vibration amplitudes are low enough to make certain blade failure will not occur. This paper deals with the possibility of actively influencing the excitation pressure pattern on the blades such that the amplitude and phase of the forcing is affected. This active influence is through the use of an air jet injection at the tip of the turbine blade and has the potential to substantially reduce the blade vibrations caused by the LEO excitations. This theory of using air jets to alter the blade vibration amplitude is investigated in this paper both experimentally, using standard turbine housing equipped with a rotatable device with a single jet nozzle, and numerically, using Computation Fluid Dynamics (CFD) software ANSYS CFX. The tests yielded positive results indicating that a single air injection was able to significantly decrease, as well as increase, the blade vibration amplitude. At certain jet injection locations, decreases in blade vibration amplitude of 70% were measured which was backed up by numerical results. To numerically calculate these differences in the vibration amplitude, the generalized force approach was used successfully. The positive results obtained from this study show real potential for this method to become a useful tool in keeping blade vibration to a safe level and avoiding failures in turbomachines.

Scaling of Composite Wind Turbine Blades for Rotors of 80 to 120 Meter Diameter

2001 ◽  
Vol 123 (4) ◽  
pp. 310-318 ◽  
Author(s):  
Dayton A. Griffin ◽  
Michael D. Zuteck
Keyword(s):  
Wind Turbine ◽  
Turbine Blades ◽  
Scaling Up ◽  
Rotor Blades ◽  
Design Parameters ◽  
Power Performance ◽  
Wind Turbine Blades ◽  
Baseline Design ◽  
Scaling Model ◽  
Wide Range

As part of the U.S. Department of Energy’s Wind Partnerships for Advanced Component Technologies (WindPACT) Program, a scaling study was performed on composite wind turbine blades. The study’s objectives were to assess the scaling of current commercial blade materials and manufacturing technologies for rotors of 80 to 120 meters in diameter, to develop scaling curves of estimated weight and cost for rotor blades in that size range, and to identify practical limitations to the scaling of current conventional blade manufacturing and materials. Aerodynamic and structural calculations were performed for a matrix of baseline blade design parameters, and the results were used as a basis for constructing a computational scaling model. The scaling model was then used to calculate structural properties for a wide range of aerodynamic designs and rotor sizes. Blade designs were evaluated on the basis of power performance, weight, static strength in flapwise bending, fatigue life in edgewise bending, and tip deflection under design loads. Calculated results were compared with weight data for current commercial blades, and limitations were identified for scaling up the baseline blade configurations. A series of parametric analyses was performed to quantify the weight reductions possible by modifying the baseline design and to identify the practical limits of those modifications. The model results provide insight into the competing design considerations involved in scaling up current commercial blade designs.

Dry Friction Damping Mechanisms in Engine Blades

1983 ◽  
Vol 105 (2) ◽  
pp. 332-341 ◽  
Author(s):  
A. V. Srinivasan ◽  
D. G. Cutts
Keyword(s):  
Laboratory Test ◽  
Test Data ◽  
Dry Friction ◽  
Turbine Blades ◽  
Experimental Studies ◽  
Vibration Damping ◽  
Analytical Models ◽  
Jet Engines ◽  
Blade Vibration ◽  
Dry Friction Damping

In the context of jet engines, significant vibration damping due to dry friction can occur at (a) shroud interfaces of fans and (b) the platform of turbine blades fitted with “platform dampers.” Analytical and experimental studies in regard to this important source of nonaerodynamic damping of blade vibration are presented in this paper. Comparisons between results from analytical models and laboratory test data are made and discussed.

scholarly journals Investigations on the Blade Vibration of a Radial Inflow Micro Gas Turbine Wheel

2007 ◽  
Vol 2007 ◽  
pp. 1-10 ◽  
Author(s):  
Shijie Guo
Keyword(s):  
Gas Turbine ◽  
Young’S Modulus ◽  
Young's Modulus ◽  
Turbine Blades ◽  
Pressure Fluctuations ◽  
Leading Edge ◽  
Coupled Modes ◽  
Blade Vibration ◽  
Turbine Wheel ◽  
Micro Gas Turbine

This paper demonstrates the investigations on the blade vibration of a radial inflow micro gas turbine wheel. Firstly, the dependence of Young's modulus on temperature was measured since it is a major concern in structure analysis. It is demonstrated that Young's modulus depends on temperature greatly and the dependence should be considered in vibration analysis, but the temperature gradient from the leading edge to the trailing edge of a blade can be ignored by applying the mean temperature. Secondly, turbine blades suffer many excitations during operation, such as pressure fluctuations (unsteady aerodynamic forces), torque fluctuations, and so forth. Meanwhile, they have many kinds of vibration modes, typical ones being blade-hub (disk) coupled modes and blade-shaft (torsional, longitudinal) coupled modes. Model experiments and FEM analysis were conducted to study the coupled vibrations and to identify the modes which are more likely to be excited. The results show that torque fluctuations and uniform pressure fluctuations are more likely to excite resonance of blade-shaft (torsional, longitudinal) coupled modes. Impact excitations and propagating pressure fluctuations are more likely to excite blade-hub (disk) coupled modes.

Optimization of Supersonic Axial Turbine Blades Based on Surrogate Models

2020 ◽  
Author(s):  
Markus Waesker ◽  
Bjoern Buelten ◽  
Norman Kienzle ◽  
Christian Doetsch
Keyword(s):  
Reynolds Number ◽  
Turbine Blade ◽  
Surrogate Model ◽  
Cfd Simulation ◽  
Turbine Blades ◽  
Energy System ◽  
Design Parameters ◽  
Blade Design ◽  
Axial Turbine ◽  
Velocity Coefficient

Abstract Due to the transition of the energy system to more decentralized sector-coupled technologies, the demand on small, highly efficient and compact turbines is steadily growing. Therefore, supersonic impulse turbines have been subject of academic research for many years because of their compact and low-cost conditions. However, specific loss models for this type of turbine are still missing. In this paper, a CFD-simulation-based surrogate model for the velocity coefficient, unique incidence as well as outflow deviation of the blade, is introduced. This surrogate model forms the basis for an exemplary efficiency optimization of the “Colclough cascade”. In a first step, an automatic and robust blade design methodology for constant-channel blades based on the supersonic turbine blade design of Stratford and Sansome is shown. The blade flow is fully described by seven geometrical and three aerodynamic design parameters. After that, an automated numerical flow simulation (CFD) workflow for supersonic turbine blades is developed. The validation of the CFD setup with a published supersonic axial turbine blade (Colclough design) shows a high consistency in the shock waves, separation zones and boundary layers as well as velocity coefficients. A design of experiments (DOE) with latin hypercube sampling and 1300 sample points is calculated. This CFD data forms the basis for a highly accurate surrogate model of supersonic turbine blade flow suitable for Mach numbers between 1.1 and 1.6. The throat-based Reynolds number is varied between 1*104 and 4*105. Additionally, an optimization is introduced, based on the surrogate model for the Reynolds number and Mach number of Colclough and no degree of reaction (equal inlet and outlet static pressure). The velocity coefficient is improved by up to 3 %.

A Processing Method for Combined Fatigue Accelerated Test Data

2017 ◽  
Author(s):  
Songwang Zheng ◽  
Cao Chen ◽  
Lei Han ◽  
Xiaoyong Zhang ◽  
Xiaojun Yan
Keyword(s):  
Data Processing ◽  
Test Data ◽  
Turbine Blades ◽  
Processing Method ◽  
Test Time ◽  
Accelerated Test ◽  
The Real ◽  
Data Processing Method ◽  
Stress Levels ◽  
Vibration Stress

To carry out combined low and high cycle fatigue (CCF) test on turbine blades in a bench environment, it is imperative to simulate the vibration loads of turbine blades in the field. Due to the low vibration stress of turbine blades in the working state, the test time will be very long if the test vibration stress is equal to the real vibration stress in working state. Therefore, an accelerated test will be used when the test life reach the target value (typically 107). During the accelerated test, each blade is tested at two or more times than the real vibration stress. That means some specimens are tested under two vibration stress levels. In this case, a reasonable data processing method becomes very important. For this reason, a data processing method for the CCF accelerated test is proposed in this paper. These test data are iterated on the basis of S-N curve. Finally, ten real turbine blades are tested in a bench environment, one of them is tested under two vibration stress levels. The test data is processed using the method proposed above to obtain the unaccelerated life data.

An Integrated Software Procedure to Support Teaching of Radial Inflow Turbine Design

2007 ◽  
Author(s):  
Carlo Cravero ◽  
Martino Marini
Keyword(s):  
Design Analysis ◽  
Design Parameters ◽  
Analysis Tool ◽  
Software Suite ◽  
Computational Tools ◽  
Blade Loading ◽  
Radial Turbine ◽  
Integrated Software ◽  
Turbine Design ◽  
Turbomachinery Design

The authors decided to organize their design/analysis computational tools in an integrated software suite in order to help teaching radial turbine, taking advantage of their research background and a set of codes previously developed. The software is proposed for use during class works and the student can either use a single design/analysis tool or face a complete design loop consisting of iterations between design and analysis tools. The intended users are final year students in mechanical engineering. The codes output are discussed with two practical examples in order to highlight the turbomachinery performance at design and off-design conditions. The above suite gives the student the opportunity of getting used to different concepts (choking, blade loading, performance maps, …) that are encountered in turbomachinery design and of understanding the effects of the main design parameters.

scholarly journals Probabilistic Design of Wind Turbine Blades with Treatment of Manufacturing Defects as Uncertainty Variables in a Framework

2017 ◽  
Author(s):  
Trey W. Riddle ◽  
Jared W. Nelson ◽  
Douglas S. Cairns
Keyword(s):  
Wind Turbine ◽  
Probabilistic Models ◽  
Low Cost ◽  
Turbine Blades ◽  
Design Parameters ◽  
State University ◽  
Wind Turbine Blades ◽  
Manufacturing Defects ◽  
Montana State University ◽  
Blade Failure

Abstract. Given that wind turbine blades are such large structures, the use of low-cost composite manufacturing processes and materials has been necessary for the industry to be cost competitive. Since these manufacturing methods can lead to inclusion of unwanted defects, potentially reducing blade life, the Blade Reliability Collaborative tasked the Montana State University Composites Group with assessing the effects of these defects. Utilizing the results of characterization and mechanical testing studies, probabilistic models were developed to assess the reliability of a wind blade with known defects. As such, defects were found to best be assessed as design parameters in a parametric probabilistic analysis allowing for establishment of a consistent framework to validate categorization and analysis. Monte Carlo simulations were found to adequately describe the probability of failure of composite blades with included defects. By treating defects as random variables, the approaches utilized indicate the level of conservation used in blade design may be reduced when considering fatigue. In turn, safety factors may be reduced as some of the uncertainty surrounding blade failure is reduced when analysed with application specific data. Overall, the results indicate that characterization of defects and reduction of design uncertainty is possible for wind turbine blades.

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