scholarly journals Теоретичні та експериментальні методи визначення характеристик міцності лопаток турбін при термомеханічному навантаженні

2021 ◽  
pp. 93-101
Author(s):  
Євген Олександрович Неманежин ◽  
Валерій Миколайович Івко ◽  
Юрій Іванович Торба
Keyword(s):  
Stress State ◽  
Turbine Blades ◽  
Complex Loading ◽  
Effect Of Temperature ◽  
Internal Cooling ◽  
Centrifugal Forces ◽  
Thermomechanical Loading ◽  
Engine Operation ◽  
Thermomechanical Testing ◽  
Volumetric Stress

The subject of this article is the methods of research and evaluation of the properties of turbine blades of a cooled structure under thermomechanical loading. The purpose of the article is to review the world achievements of leading enterprises and research institutions in the issue of fatigue tests of turbine blades under complex loading (cyclic temperature exposure, dynamic and static loading), as well as an overview of the state of this topic at SE "Ivchenko-Progress" and suggestions for its further studying. As a result of the analysis of publications and scientific articles, it can be concluded that specialized research institutes and leading aircraft engine-building enterprises from the end of the twentieth century are studying the properties of turbine blades in the conditions of their operation as part of an engine. In world practice, there are calculated and experimental methods for thermomechanical testing of turbine blades. These tests are aimed at determining the most damaging loads, establishing the flight cycle modes at which these loads are recorded. As a result, it was found that the greatest threat to the strength of the turbine blades is carried by transient modes of engine operation, which are short in time (measured in seconds), but at which there is a change in the parameters of the temperature field, loads from axial and centrifugal forces. And it is the cycling of these parameters that leads to a decrease in the cyclic durability of the turbine blades, especially of the cooled structure (the presence of perforations, internal cooling channels, and other structural elements leads to a complication of the volumetric stress state of the blades). The article analyzes various crystallographic structures of blades and their relationship with the volumetric stress state; examples of studies that were carried out at SE "Ivchenko-Progress" and their results are given, which emphasize the need for further experiments in the field of assessing strength characteristics under complex cyclic loading. An example of an installation for testing blade joints and samples of gears is considered, which can be adapted for testing blades with three-component loading (temperature, dynamic loads, and imitation of the effect of centrifugal forces). It is concluded that when using exclusively computational methods, it is impossible to reliably estimate the level of stresses and their distribution since the calculations are limited by the boundary conditions, which are set according to the capabilities of a particular computational model. Summing up, it can be noted that it is advisable to start assessing the strength of blades under thermomechanical loading with several series of tests of samples of blade material to study the effect of temperature and power cycles of loads, the effect of the orientation of the load vector concerning the crystallographic orientation of the blade. It is noted that tests of full-scale blades under thermomechanical loading are also important since the features of the volumetric stress state of the material during real operation of the blades as part of an engine are not reproduced during testing of samples. The above entails the development of methods and specialized installations for thermomechanical testing.

Effect of Coriolis and Centrifugal Forces on Turbulence and Heat Transfer at High Rotation and Buoyancy Numbers in a Rib-Roughened Internal Cooling Channel

2004 ◽  
Author(s):  
A. K. Sleiti ◽  
J. S. Kapat
Keyword(s):  
Heat Transfer ◽  
Turbine Blades ◽  
Three Dimensional ◽  
Internal Cooling ◽  
Cooling Channel ◽  
Centrifugal Forces ◽  
Reynolds Stresses ◽  
Rsm Model ◽  
Density Ratios ◽  
Rib Roughened

Prediction of three-dimensional flow field and heat transfer in a two pass rib-roughened square internal cooling channel of turbine blades with rounded staggered ribs rotating at high rotation and density ratios is the main focus of this study. Rotation, buoyancy, ribs, and geometry affect the flow within these channels. The full two-pass channel with bend and with rounded staggered ribs with fillets (e/Dh = 0.1 and P/e = 10) as tested by Wagner et. al [1992] is investigated. RSM is used in this study and enhanced wall treatment approach to resolve the near wall viscosity-affected region. RSM model was validated against available experimental data (which are primarily at low rotation and buoyancy numbers). The model was then used for cases with high rotational numbers (0.24, 0.475, 0.74 and 1) and high-density ratios (0.13, 0.23, and 0.3). Particular attention is given to how secondary flow, Reynolds stresses, turbulence intensity, and heat transfer are affected by coriolis and buoyancy/centrifugal forces caused by high levels of rotation and density ratios. A linear correlation for 4-side-average Nusselt number as a function of rotation number is derived.

scholarly journals Optimization Design of Lattice Structures in Internal Cooling Channel with Variable Aspect Ratio of Gas Turbine Blade

Energies ◽  
2021 ◽  
Vol 14 (13) ◽  
pp. 3954
Author(s):  
Liang Xu ◽  
Qicheng Ruan ◽  
Qingyun Shen ◽  
Lei Xi ◽  
Jianmin Gao ◽  
...  
Keyword(s):  
Heat Transfer ◽  
Aspect Ratio ◽  
Optimization Model ◽  
Lattice Structure ◽  
Turbine Blades ◽  
Internal Cooling ◽  
Cooling Channel ◽  
Cooling Channels ◽  
Mechanical Performances ◽  
Type Lattice

Traditional cooling structures in gas turbines greatly improve the high temperature resistance of turbine blades; however, few cooling structures concern both heat transfer and mechanical performances. A lattice structure (LS) can solve this issue because of its advantages of being lightweight and having high porosity and strength. Although the topology of LS is complex, it can be manufactured with metal 3D printing technology in the future. In this study, an integral optimization model concerning both heat transfer and mechanical performances was presented to design the LS cooling channel with a variable aspect ratio in gas turbine blades. Firstly, some internal cooling channels with the thin walls were built up and a simple raw of five LS cores was taken as an insert or a turbulator in these cooling channels. Secondly, relations between geometric variables (height (H), diameter (D) and inclination angle(ω)) and objectives/functions of this research, including the first-order natural frequency (freq1), equivalent elastic modulus (E), relative density (ρ¯) and Nusselt number (Nu), were established for a pyramid-type lattice structure (PLS) and Kagome-type lattice structure (KLS). Finally, the ISIGHT platform was introduced to construct the frame of the integral optimization model. Two selected optimization problems (Op-I and Op-II) were solved based on the third-order response model with an accuracy of more than 0.97, and optimization results were analyzed. The results showed that the change of Nu and freq1 had the highest overall sensitivity Op-I and Op-II, respectively, and the change of D and H had the highest single sensitivity for Nu and freq1, respectively. Compared to the initial LS, the LS of Op-I increased Nu and E by 24.1% and 29.8%, respectively, and decreased ρ¯ by 71%; the LS of Op-II increased Nu and E by 30.8% and 45.2%, respectively, and slightly increased ρ¯; the LS of both Op-I and Op-II decreased freq1 by 27.9% and 19.3%, respectively. These results suggested that the heat transfer, load bearing and lightweight performances of the LS were greatly improved by the optimization model (except for the lightweight performance for the optimal LS of Op-II, which became slightly worse), while it failed to improve vibration performance of the optimal LS.

As-Built Geometry and Surface Finish Effects on Fatigue and Tensile Properties of Laser Fused Titanium 6Al-4V

2017 ◽  
Author(s):  
Onome Scott-Emuakpor ◽  
Tommy George ◽  
Emily Henry ◽  
Casey Holycross ◽  
Jeff Brown
Keyword(s):  
Tensile Properties ◽  
Surface Finish ◽  
Fatigue Behavior ◽  
Turbine Blades ◽  
Material Behavior ◽  
Small Scale ◽  
Internal Cooling ◽  
Roughness Effects ◽  
Form And Function ◽  
And Function

The as-built material behavior of additive manufactured (AM) Titanium (Ti) 6Al-4V is investigated in this study. A solution heat treated, aged, stress relieved, and hot isostatic pressed Laser Powder Bed Fusion (LPBF) AM process was used to manufacture the specimens of interest. The motivation behind this work is based on the ever-growing desire of aerospace system designers to use AM to fabricate components with novel geometries. Specifically, there is keen interest in AM components with complex internal cooling configurations such as turbine blades, nozzle vanes, and heat exchangers that can improve small scale propulsion performance. Though it is feasible to three-dimensionally print parts that meet the Fit portion of a part characteristic description and identification, the Form and Function portions have proven to be more difficult to conquer. This study addresses both the Form and Function characteristics of the LPBF AM process via the investigation of geometry variation and surface roughness effects pertaining to mechanical properties and fatigue behavior of Ti 6Al-4V. Results show that geometry variation may be the cause of increased vibration fatigue life uncertainty. Also, both fatigue and tensile properties show profound discrepancies associated with surface finish. As-built surface finish specimens have lower fatigue and ductility performance, but the results are more consistent than polished data.

scholarly journals Oscillator Fin as a Novel Heat Transfer Augmentation Device for Gas Turbine Cooling Applications

1998 ◽  
Author(s):  
Oguz Uzol ◽  
Cengiz Camci
Keyword(s):  
Heat Transfer ◽  
Kinetic Energy ◽  
Gas Turbine ◽  
Turbulent Kinetic Energy ◽  
Stokes Equations ◽  
Turbine Blades ◽  
Local Heat Transfer ◽  
Internal Cooling ◽  
Pin Fin ◽  
Heat Transfer Augmentation

A new concept for enhanced turbulent transport of heat in internal coolant passages of gas turbine blades is introduced. The new heat transfer augmentation component called “oscillator fin” is based on an unsteady flow system using the interaction of multiple unsteady jets and wakes generated downstream of a fluidic oscillator. Incompressible, unsteady and two dimensional solutions of Reynolds Averaged Navier-Stokes equations are obtained both for an oscillator fin and for an equivalent cylindrical pin fin and the results are compared. Preliminary results show that a significant increase in the turbulent kinetic energy level occur in the wake region of the oscillator fin with respect to the cylinder with similar level of aerodynamic penalty. The new concept does not require additional components or power to sustain its oscillations and its manufacturing is as easy as a conventional pin fin. The present study makes use of an unsteady numerical simulation of mass, momentum, turbulent kinetic energy and dissipation rate conservation equations for flow visualization downstream of the new oscillator fin and an equivalent cylinder. Relative enhancements of turbulent kinetic energy and comparisons of the total pressure field from transient simulations qualitatively suggest that the oscillator fin has excellent potential in enhancing local heat transfer in internal cooling passages without significant aerodynamic penalty.

Numerical and Experimental Investigation for Internal Cooling of Two Pass Gas Turbine Blades Channels Using Broken V Ribs

2014 ◽  
Author(s):  
Sourabh Kumar ◽  
R. S. Amano
Keyword(s):  
Gas Turbine ◽  
Thermal Stresses ◽  
Turbine Blades ◽  
Research Work ◽  
Local Heat Transfer ◽  
Local Heat ◽  
Inlet Temperature ◽  
Internal Cooling ◽  
Cooling Channel ◽  
Square Duct

Improvements in the thermal efficiency of a gas turbine can be obtained by operating it at high inlet temperatures. This high inlet temperature develops high thermal stresses on the turbine blades in addition to improving the performance. Cooling methodologies are implemented inside the blades to withstand those high temperatures. Four different combinations of broken 60° V ribs in cooling channel are considered. The research work investigates and compares numerically and experimentally, internal cooling of channels with broken V ribs. Local heat transfer in a square duct roughened with 60° V broken ribs is investigated for three different Reynolds numbers. Aspect ratio of the channel is taken to be 1:1. The pitch of the rib is considered to be 10 times the width of the rib, which is 0.0635 m. The square cross section of the channel is 0.508 × 0.508 m2 with 0.6096 m length. This study provides information about the best configuration of a broken V rib in a cooling channel.

Study on Performance Optimization of Car Diesel Engine with VNT Based on One-Dimensional Simulation and Experimental Verification

2012 ◽  
Vol 155-156 ◽  
pp. 12-17 ◽  
Author(s):  
Lian Xu Wang ◽  
Da Wei Qu ◽  
Chang Qing Song ◽  
Ye Tian
Keyword(s):  
Experimental Data ◽  
Diesel Engine ◽  
Performance Optimization ◽  
High Speed ◽  
Turbine Blades ◽  
Simulation Software ◽  
Engine Operation ◽  
One Dimensional ◽  
Distribution Phase ◽  
Dimensional Simulation

To research the performance optimization of high speed car diesel engine，firstly according to the characteristic of car diesel engine with Variable Nozzle Turbocharger (VNT)， one-dimensional cycle model of the engine was established by using simulation software BOOST and validated by experimental data in this paper. The turbine blades’ opening corresponding to different speed was determined. Therefore the problem that the VNT surges at low engine speed and the inlet air flow is insufficient at high speed was solved. Based on the above model, this paper improved the efficiency of the engine by optimizing the compression ratio and the distribution phase of camshaft and then used the experimental data to check the simulation results. Meanwhile the fuel consumption and the possibility of the engine operation roughness decreased.

scholarly journals Force parameters of metal deformation during sheet drawing

2020 ◽  
Vol 16 (6) ◽  
pp. 493-503
Author(s):  
Yury A. Morozov
Keyword(s):  
Stress State ◽  
Strain State ◽  
Sheet Material ◽  
Forming Force ◽  
High Quality ◽  
State Process ◽  
The Matrix ◽  
Metal Deformation ◽  
Volumetric Stress ◽  
Steady State Process

The aim of the work. The effect of the curvature of the rounding of torus surfaces during the formation of a cylindrical product (glass) is investigated, taking into account the plastic thinning of the deformable material at the end edges of the matrix and pressing punch. Methods. The existing scheme for determining the power parameters of sheet drawing is analyzed, based on the assumption of the implementation of some abstract stress state in the material; mainly conditional tensile strength. At the same time, the possibility of forming the product without destruction determines the obvious overestimation of the stress level. A mathematical model of the volumetric stress state of the metal is being developed, which makes it possible to assess the deformation and stress state during the formation of a cold-drawn product, i. e. the folding of the sheet blank along the end radius of the rounding of the pressing punch and the steady-state process of drawing the blank into the deformation zone with successive bending/straightening of the material along the edge of the matrix are considered. The level of radial stresses during folding and stretching of sheet material is estimated, taking into account its strain hardening and thinning, which determine the forming force. The obtained results will make it possible to simulate the stress-strain state of the metal during the development of sheet drawing technology: to establish the amount of thinning, to estimate the level of radial stresses in the formation of rounding of torus surfaces along the end edges of the matrix and the pressing punch, as well as to determine the power parameters of the formation, which will prevent the destruction of the pulled part, guaranteeing obtaining high-quality products and more accurately choosing the deforming equipment.

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