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.

Analysis of the Scatter of the Elastic Properties in Conventionally Cast Nickel Base Superalloys: Quantification, Modeling and Evaluation of the Impact on Gas Turbine Blade Design

2014 ◽  
Author(s):  
Andrea Riva ◽  
Andrea Bessone
Keyword(s):  
Gas Turbine ◽  
Young’S Modulus ◽  
Elastic Properties ◽  
Young's Modulus ◽  
Turbine Blades ◽  
Mode Shapes ◽  
Elastic Behavior ◽  
Nickel Base Superalloys ◽  
Nickel Base ◽  
The Impact

Cast nickel-base superalloys elastic properties have a very large scatter, mainly because of the coarse grain microstructure and in-grain anisotropy. This high dispersion must be taken into account in the design of gas turbine blades, in particular when evaluating phenomena directly linked to the elastic behavior, such as blades vibration. This source of elastic properties scatter becomes even more important on specimens for material characterization because of their inferior size, which entails a lesser number of grains (i.e. a larger scatter). In this paper a model aimed to quantify such scatter is proposed. The performances of the model in predicting the standard deviation of the Young’s modulus (and consequently of the eigenfrequencies) are also shown, both for tested specimens and blades excited on clamps. Finally, a sensitivity FEM modal analysis is performed in order to evaluate how the elastic property dispersion might affect the blade eigenfrequencies and the relative mode shapes, with particular emphasis on the case of a specific region of a geometrically complex component affected by an anomalous Young’s modulus. Besides, the influence of the blade mass is evaluated through both experimental clamp impact tests and FEM analyses. The effect on blades of such source of scatter is then compared to the effect of the elastic properties dispersion. ANSYS program has been used for the simulations.

Optimum NURBS Curve Fitting for Geometry Parameterization of Gas Turbine Blades’ Sections: Part I — Evolutionary Optimization Techniques

2012 ◽  
Author(s):  
A. Safari ◽  
H. G. Lemu
Keyword(s):  
Gas Turbine ◽  
Curve Fitting ◽  
Error Function ◽  
Turbine Blades ◽  
Leading Edge ◽  
Suction Side ◽  
Evolutionary Optimization ◽  
Optimization Techniques ◽  
Advantages And Disadvantages ◽  
Geometry Parameterization

This paper presents two evolutionary optimization methods: Genetic Algorithm and Differential Evolution, aimed at optimizing the location of a set of NURBS control points that are used to calculate the NURBS points for leading edge, trailing edge, suction side and pressure side of an airfoil shape. The approach is illustrated on point cloud of several 2D sections of a typical gas turbine compressor blade, so that the results can be used for both reverse engineering purposes and geometry parameterization in airfoil aerodynamic shape optimization process. The optimization algorithms in this research are based on minimization of an analytical error function related to the distance between the fitted curve and original data points. Finally, the obtained results from these two techniques are compared with each other to distinguish the advantages and disadvantages of each method for such curve fitting problems.

scholarly journals Design and Experimental Validation of a Supersonic Concentric Micro Gas Turbine

2015 ◽  
Vol 138 (2) ◽  
Author(s):  
Gabriel Vézina ◽  
Hugo Fortier-Topping ◽  
François Bolduc-Teasdale ◽  
David Rancourt ◽  
Mathieu Picard ◽  
...  
Keyword(s):  
Steady State ◽  
Combustion Chamber ◽  
Gas Turbine ◽  
Structural Model ◽  
Structural Integrity ◽  
Turbine Blades ◽  
External Diameter ◽  
Impulse Turbine ◽  
Micro Gas Turbine ◽  
Steady State Operation

This paper presents the design and experimental results of a new micro gas turbine architecture exploiting counterflow within a single supersonic rotor. This new architecture, called the supersonic rim-rotor gas turbine (SRGT), uses a single rotating assembly incorporating a central hub, a supersonic turbine rotor, a supersonic compressor rotor, and a rim-rotor. This SRGT architecture can potentially increase engine power density while significantly reducing manufacturing costs. The paper presents the preliminary design of a 5 kW SRGT prototype having an external diameter of 72.5 mm and rotational speed of 125,000 rpm. The proposed aerodynamic design comprises a single stage supersonic axial compressor, with a normal shock in the stator, and a supersonic impulse turbine. A pressure ratio of 2.75 with a mass flow rate of 130 g/s is predicted using a 1D aerodynamic model in steady state. The proposed combustion chamber uses an annular reverse-flow configuration, using hydrogen as fuel. The analytical design of the combustion chamber is based on a 0D model with three zones (primary, secondary, and dilution), and computational fluid dynamics (CFD) simulations are used to validate the analytical model. The proposed structural design incorporates a unidirectional carbon-fiber-reinforced polymer rim-rotor, and titanium alloy is used for the other rotating components. An analytical structural model and numerical validation predict structural integrity of the engine at steady-state operation up to 1000 K for the turbine blades. Experimentation has resulted in the overall engine performance evaluation. Experimentation also demonstrated a stable hydrogen flame in the combustion chamber and structural integrity of the engine for at least 30 s of steady-state operation at 1000 K.

scholarly journals Verification of Thermal Models of Internally Cooled Gas Turbine Blades

2018 ◽  
Vol 2018 ◽  
pp. 1-10 ◽  
Author(s):  
Igor Shevchenko ◽  
Nikolay Rogalev ◽  
Andrey Rogalev ◽  
Andrey Vegera ◽  
Nikolay Bychkov
Keyword(s):  
Heat Transfer ◽  
Gas Turbine ◽  
Turbine Blades ◽  
Heat Removal ◽  
Leading Edge ◽  
Jet Impingement ◽  
Local Heat Transfer ◽  
Transfer Coefficients ◽  
Single Experiment ◽  
Heat Transfer Coefficients

Numerical simulation of temperature field of cooled turbine blades is a required element of gas turbine engine design process. The verification is usually performed on the basis of results of test of full-size blade prototype on a gas-dynamic test bench. A method of calorimetric measurement in a molten metal thermostat for verification of a thermal model of cooled blade is proposed in this paper. The method allows obtaining local values of heat flux in each point of blade surface within a single experiment. The error of determination of local heat transfer coefficients using this method does not exceed 8% for blades with radial channels. An important feature of the method is that the heat load remains unchanged during the experiment and the blade outer surface temperature equals zinc melting point. The verification of thermal-hydraulic model of high-pressure turbine blade with cooling allowing asymmetrical heat removal from pressure and suction sides was carried out using the developed method. An analysis of heat transfer coefficients confirmed the high level of heat transfer in the leading edge, whose value is comparable with jet impingement heat transfer. The maximum of the heat transfer coefficients is shifted from the critical point of the leading edge to the pressure side.

Gas Turbine Blade Damper: A Design Optimization Study to Mitigate High Resonance Blade Vibration

2013 ◽  
Author(s):  
Dilip Kumar ◽  
Sanjay Barad ◽  
T. N. Suresh
Keyword(s):  
Design Optimization ◽  
Gas Turbine ◽  
Turbine Blade ◽  
Turbine Blades ◽  
Full Scale ◽  
Original Design ◽  
Blade Vibration ◽  
Mass System ◽  
Optimization Study ◽  
Blade Tip

This paper describes the design optimization study of an under platform damper to mitigate high vibration problem of a gas turbine rotor blade under resonance condition. An existing theoretical model explicitly, Casba friction damper model was used to evaluate the dynamic characteristics of the turbine blade with under platform damper. Turbine blade is approximated as two degrees of spring-damper-mass system, which is dynamically equivalent to real turbine blades for its first two eigen values. Blade tip response predictions were carried out for different damper mass, stiffness and coefficient of friction under simulated rotational speed of the rotor, to arrive at an optimum mass to control the blade tip response. As a practical application, along with damper mass optimization, shape and mass distribution of the damper is obtained by design trials to ensure good contact between the blade root and damper upper surface. Contact analysis was carried using the ANSYS software. The asymmetric skewed damper geometry posed complications with respect to modelling and optimisation. In realistic application, with the kind of uncertainties in contact pattern, variation in friction coefficient, geometric tolerances, validation/verification plays a major role in assessing the design. As part of verification of this damper design, a full scale gas turbine engine test program was envisaged and completed. Modified optimum damper was implanted as a design change, engine was instrumented for blade vibration measurement. Non-Intrusive Stress Measurement system was used for measuring blade tip amplitudes from all the blades in the rotor. Test blade tip vibration was analysed and compared against the predications. This optimised damper configuration has showed significant reduction in blade amplitudes during full-scale gas turbine testing, in comparison to original design proving the efficacy of new modified damper.

scholarly journals On the Effect of Functionally Graded Materials on Resonances of Rotating Beams

2012 ◽  
Vol 19 (6) ◽  
pp. 1315-1326 ◽  
Author(s):  
Arnaldo J. Mazzei Jr.
Keyword(s):  
Young’S Modulus ◽  
Functionally Graded Materials ◽  
Young's Modulus ◽  
Ritz Method ◽  
Turbine Blades ◽  
Functionally Graded ◽  
Graded Materials ◽  
Rotating Beams ◽  
Helicopter Blades ◽  
Aerospace Applications

Radially rotating beams attached to a rigid stem occur in several important engineering applications. Some examples include helicopter blades, turbine blades and certain aerospace applications. In most studies the beams have been treated as homogeneous. Here, with a goal of system improvement, non-homogeneous beams made of functionally graded materials are explored. The effects on the natural frequencies of the system are investigated. Euler-Bernoulli theory, including an axial stiffening effect and variations of both Young's modulus and density, is employed. An assumed mode approach is utilized, with the modes taken to be beam characteristic orthogonal polynomials. Results are obtained via Rayleigh-Ritz method and are compared for both the homogeneous and non-homogeneous cases. It was found, for example, that allowing Young's modulus and density to vary by approximately 2.15 and 1.15 times, respectively, leads to an increase of 23% in the lowest bending rotating natural frequency of the beam.

scholarly journals On the Effect of Functionally Graded Materials on Resonances of Rotating Beams

2012 ◽  
Vol 19 (4) ◽  
pp. 707-718 ◽  
Author(s):  
Arnaldo J. Mazzei Jr.
Keyword(s):  
Young’S Modulus ◽  
Functionally Graded Materials ◽  
Young's Modulus ◽  
Ritz Method ◽  
Turbine Blades ◽  
Functionally Graded ◽  
Graded Materials ◽  
Rotating Beams ◽  
Helicopter Blades ◽  
Aerospace Applications

Radially rotating beams attached to a rigid stem occur in several important engineering applications. Some examples include helicopter blades, turbine blades and certain aerospace applications. In most studies the beams have been treated as homogeneous. Here, with a goal of system improvement, non-homogeneous beams made of functionally graded materials are explored. The effects on the natural frequencies of the system are investigated. Euler-Bernoulli theory, including an axial stiffening effect and variations of both Young's modulus and density, is employed. An assumed mode approach is utilized, with the modes taken to be beam characteristic orthogonal polynomials. Results are obtained via Rayleigh-Ritz method and are compared for both the homogeneous and non-homogeneous cases. It was found, for example, that allowing Young's modulus and density to vary by approximately 2.15 and 1.15 times, respectively, leads to an increase of 23% in the lowest bending rotating natural frequency of the beam.

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