جستجوی مقالات مرتبط با کلیدواژه « پره توربین » در نشریات گروه « مکانیک »

In this paper, static strength analysis of superalloy Rene-80 is studied experimentally in both of the coated and uncoated cases. Superalloy Rene-80 is widely used in manufacturing aircraft turbine blades. The service temperature of this alloy is in the range of 760–982 °C. Although this superalloy has good mechanical properties and acceptable protection against oxidation and hot corrosion, it is coated to improve its resistance to surface degradation factors such as oxidation, hot corrosion and erosion at high temperatures. In this paper, penetrating aluminide coatings were applied to this superalloy with two separate methods of penetration-powder and penetration-slurry, respectively, under the brand names Codep-B and IP1041slurry, respectively and the effect of these coatings on the tensile properties of Rene-80 under ehe temperature range of 25-982 ° C was investigated. For this purpose, the samples according to ASTM-E8 standard are produced and after coating (the two methods mentioned above) along with uncoated samples are carried out a tensile testing in accordance with the ASTM-E21 standard. The results of the present study showed that at low operating temperatures, uncoated samples have better tensile strength than coated samples, but this behavior is reversed at high operating temperatures, which indicates the importance of using nickel-based superalloy coatings for extreme heat environments. Also, the model with IP1041slurry coating at high operating temperature has better yield and ultimate strengths than powder penetration coating.

The flow within a high-pressure turbine is strongly influenced by upstream flow distribution. Due to the high level of pressure, the probable roughnesses of the rotor blade's leading-edge (LE) can form vortices which can cause flow separation and blade stall. In the present work, the geometric changes of the rotor's leading-edge, which have occurred during the manufacturing process, and its influence on the flow field and on the turbine's performance were studied. The main aim of this work is to provide new criteria for acceptance of produced blades. To this end, a three-dimensional numerical analysis with the aim of observation of flow field was conducted and the results were validated with existing experimental results. Based on statistical results of manufactured blades, three types of geometric changes were applied to the blades leading edge and analyzed. The results show that the changes made on geometry, have reduced the ratio of lift over drag. These changes, affect the angle of attack and the out-flow angle, which also reduces the blades loading and lead the flow toward, separation. In contrast, in areas of the blade were separation does not occur, the temperature distribution is more uniform.

In this paper, the effect of the turbine blade rotation on the temperature distribution and film cooling effectiveness for a square pulsing cooling flow is numerically studied. The square pulsed cooling air flow is injected to the turbine blade at three frequencies of 2, 50, and 500 Hz. Four rotation speeds of 0, 500, 800, and 1000 rpm, clockwise and counter-clockwise, are considered. Geometry is modeled in Gambit and the numerical analysis is performed by Fluent software. SST k-ω turbulence model is used to apply the turbulence effects. The obtained results show that the rotation deviates the coolant flow from the centerline. Changing the coolant flow to square pulsating, centerline effectiveness changes with time in a cycle. The results show that in general, the effectiveness ​​at all speeds on the pressure side are greater than the suction side. Moreover, with increasing frequency, the average level of centerline effectiveness increases.

The thermography inspection is the most modern non-destructive test method that has been expanding in the industry in recent years. There are several benefits such as high-speed testing, along with high precision and the ability to inspect without conduct. The advantages of this method, which leads to lower costs and increase accuracy in testing, make us able to use this method to detect the defects in the gas turbine blade channels to increase the accuracy of the fault diagnosis and it reduces the maintenance costs. Gas turbines have many uses in the industry. The efficiency of these turbines increases with increasing combustion temperature. The goal is to achieve more efficiency, but there are limitations to this goal. When shape of cooling channels has a complex geometric shape, maybe the ceramic muscle cannot completely exit at the casting stage and it will break. Remaining these particles in the cooling channels can seriously affect the turbine performance. So it's very important to detect this defect before using a defective blade. In this paper, it was aimed to detect existed channels in the workpiece to examine the effect of injected vapor pressure into the channels as temperature stimulus and to investigate the influence of channel distance from the surface from the results obtained by thermography.

Film cooling is one of the most effective methods for protecting turbine blades from thermal overheating. For steady gas flow, the film cooling has been extensively investigated, but there is insufficient knowledge of how the pulsation affects the film cooling performance. In this study, the effects of air coolant injection with sinusoidal pulsations on temperature distribution and film cooling effectiveness of a turbine blade is numerically investigated. Cooling air is injected through the three plenums to leading edge, pressure and suction sides of the blade at five blowing ratios of 0.5, 0.75, 1, 1.5, 2, and 2.5 with frequency of 50Hz. Also, the effect of main flow Reynolds number on cooling performance is studied. Finite volume method was used to solve flow governing equations. Obtained results show that pulsating the blade cooling mass flow rate causes the size of counter vortex rotating pair to be varied, resulting in change of temperature distribution of the surface at each time steps. The averaged centerline pulsed film cooling effectiveness distribution is maximized on downstream of the injection hole of leading edge, pressure side and suction side at blowing ratio of 0.75, 0.5 and 1, respectively.

In this paper, the optimization of the film cooling effectiveness over a rotating blade is performed using the laterally diffused hole. The three-dimensional numerical simulation of blade cooling is performed using RNG k-ε turbulence model for three rotating speeds, i.e., 0, 300 and 500 rpm. Results show that the film trajectory always inclines due to the Coriolis force acts in the centrifugal direction. The film cooling deflection becomes greater with increasing the rotational speed. The comparisons of results show that, for the laterally diffused hole, the mixing of the hot gas flow with the injected coolant flow is less that the cylindrical hole. Applying the laterally diffused hole consequences the increase of film cooling effectiveness by the 39, 38 and 35 percent at the rotating speeds of 0,300 and 500 rpm respectively.

In recent years, optimization of Turbomachinery performance parameters is one of the most important topics for researchers and industrial scholars. The aerodynamic optimization of blades has been done by variety of algorithms and methods until now; however new tools have better suggestions in this field.
This paper reports a 3D numerical analysis and geometrical optimization of fully turbulent flow around a turbine's rotor blades. Numerical analysis is done using the AUSM scheme and SST k –ω turbulence model. An Ad-joint Algorithm gradient method is used in geometrical aerodynamic optimization of blades. This algorithm has been used previously for 2D models as build-in codes and for 3D models is done for the first time in this research.
The total to total isentropic efficiency as objective function and other performance parameters have a good agreement with the experimental measurements in validation process. Through the optimization process, the objective function is improved by 0.18, which in comparison with other's reported works is a good progress in performance improvement.

Always in the production of turbine blades tried use less of secondary operations. Such as for increasing the quality of surface finishing that reduces the level of geometric accuracy. Accordingly in this paper, improvement of roughness and surface texture turbine blade directly with the optimization of machining parameters is been studied. Variable parameters of this research include tool diameter, depth of cut and feed rate. Experimental work by using a four-axis CNC milling machine was done on turbine blade aluminum. Experimental work by using four-axis CNC milling machine and the turbine blade was aluminum. Design of experimental was full factorial and All permutations of variable parameters been implemented. The surface roughness of machined areas by using surface roughness tester and the texture was examined using a stereo microscope. By using roughness tester, surface roughness of machined areas was measured. Form of surface texture was examined by a stereo microscope. Finally, by comparing data the best mode was introduced.

During the operation, the turbine blades of hot gas path suffer service induced degradation due to ýdifferent causes such as creep, fatigue, oxidation, corrosion and etc. The present study was carried ýout the effect of long-term service at the high temperature exposure to remaining life assessment gas ýturbine blade made of Inconel 792 nickel base superalloy. That is investigated by studying on ýmicrostructure by optical and scanning electron microscopy, mechanical properties such as high ýtemperature tensile and stress-rupture test and stress analyses of turbine blade. The result has been ýshown the gamma prime rafting and TCP phase formation has occurred at the microstructure. ýBecause of long-term service at high temperature, stress- rupture properties of blade reduced and ýý20% lower than new IN 792 alloys. The stress analyses with ANSYS software and creep life ýassessment results by use Larson-miller parameter, the safety factor of blade lower than 1 and life ýtime of turbine blade is finished.ý

Jig and fixture design for workpieces with freeform geometry has more complexity in comparison with the polyhedral parts. The locating and clamping system design construct the basis of the jig and fixture design activities. In this study, a theoretical analysis is suggested for automatic design of clamping points for freeform workpieces. The clamping design is performed in three main stages which the clamping application points are determined through the first two principles and being verified through the last stage. The mentioned principles consist of: (1) the minimum quantity of clamps, (2) the maximum clamping force components on the locating directions and (3) the workpiece static stability under the external wrenches. After mathematical modeling, the suggested analysis was implemented into the already designed CAFD framework by the authors. Three machining models were chosen as case studies to evaluate the capabilities of the implemented system in robust design of clamping layout. The minimum quantity of clamps (single clamp for two case studies and double clamp for the third one) was designed by the developed method that verified the robustness and reliability of the suggested and implemented clamping system design model. The automatic design of clamping scheme for workpieces (regardless of the geometry) beside its capability in integration with the other modules of fixture design activities provides the opportunity for the system to be used in industrial applications.

Due to the importance of the role of turbines in various industries, a more precise design is needed to improve their efficiency. In this line, a more exact solution of the flow passing through turbine blades is needed. Nowadays, the advancement of numerical modeling techniques has resulted in achieving more accurate tools capable of considering the discontinuities with less oscillation and numerical errors. In this study, for modeling the flow in a supersonic 1D converging-diverging channel, the AUSM upwind method and a computational standard grid are used. The obtained results for a strong vertical shock agrees well with analytical results, and is considered as an initial verification of the method. In this research and for the first time, the AUSM numerical method has been further developed by using a simple H-grid mesh for modeling an inviscid subsonic and supersonic outlet flow in turbine stator blades. Comparing the model results with the results of Jameson’s artificial dissipation technique and experimental data showed that both numerical methods have good agreement with experimental pressure data, but the AUSM method has less numerical errors and improves the mass conservation by at least 25%. It is to be noted that the AUSM method is highly recommended for higher Mach numbers.

In this paper, the fluid-structure interaction phenomenon and the research history are described. Then due to the complex and specific working conditions of a turbine blade, we have investigated the phenomenon on this subject. The fluid-structure interaction on a turbine blade model has been simulated by using structural and fluid flow section of ANSYS software. A model of turbine blade with airfoil cross section made of aluminum has been analyzed in three different inlet speed of the fluid. For analysis results the amount of turbine blade tip deviation and its impact on the fluid flow pressure exerted on the turbine blade has been considered. The results show that by increasing the speed of inlet flow, the amount of blade tip deviation increases and also its impact increases on fluid pressure exerted on the rotor. The results also show that the transverse displacement of the blade is linear across of its axis.

One of the methods of blade production is forging. But according to the complexities of the blades، they cannot be produced in one stage and it''s necessary for them to consider preform. In this research، a basic geometry with elliptical cross section for airfoil of blade، was considered and response surface method was used to optimize this preform. Optimization purposes were considered completely die filling and reduction of flash volume، forging load and strain variance. At the end، optimized preform was compared with the model of mass distribution method. Results show response surface method give better results than mass distribution method. Also physical modeling was used for verification of simulation results. Results show simulation results have a good corresponding with experimental results.

In this study, effects of lacing rods location on natural frequencies of last stage of a Steam Turbine Blades (STBs) have been investigated. STBs are critical and important elements in a turbine as well as power plants. One of the most important parameters in turbine blades is lacing rods location. In this paper, first, a three dimensional (3D) scan was used to produce the geometrical model of the blade. Then, last stage of a low pressure turbine have been produced and simulated by assembling of the one-blade model. There are two rows of lacing rods in the last stage of turbine. In this paper, effecting the lacing rods location on natural frequencies of system has been studied. According to the Campbell diagrams, the results showed there is no resonance in the last stage blades of the steam turbine for different locations of the lacing rods.

Gas Turbines have wide applications in power plants and aerospace industries. Nowadays, based on welding of two different materials, some economic methods for repairing turbine blades have been developed. In this paper, a method, for determining creep life of a RTB (Repaired Turbine Blade) of two substances, based on transient FEM method had been developed. To find the effect of the difference between creep properties of materials of two substances RTBs, a simple 2D model under centrifugal forces was modeled. The base and filler metals were GH 4049 and Inconel 718, respectively. Creep is time dependent deformation of metals at elevated temperatures, therefore stresses are also time dependent. Hence, the life of RTB was estimated using damage fraction rule. These were performed using APDL ANSYS commercial software codes. To verification of the method, an experiment test has been established which defined the way critical elements behaved. In this experiment, pure lead was used as softer and Tin70%-lead30% was used as harder metal in creep. Experimental and numerical models were compared and good agreements between them were found. Rupture point was truly predicted and relative error was only 6% (traditional methods had 20% error). Results showed that the difference between creep properties of base and filler metals for supposed geometry and repaired location, leads to 90% decrement of designed life.

O‌n‌e o‌f t‌h‌e c‌h‌a‌r‌a‌c‌t‌e‌r‌i‌s‌t‌i‌c‌s o‌f s‌t‌e‌a‌m f‌l‌o‌w i‌n t‌u‌r‌b‌i‌n‌e c‌a‌s‌c‌a‌d‌e‌s i‌s i‌t‌s r‌a‌p‌i‌d e‌x‌p‌a‌n‌s‌i‌o‌n a‌n‌d d‌e‌v‌i‌a‌t‌i‌o‌n f‌r‌o‌m ‌h‌e‌r‌m‌o‌d‌y‌n‌a‌m‌i‌c e‌q‌u‌i‌l‌i‌b‌r‌i‌u‌m. I‌n t‌h‌i‌s s‌t‌a‌t‌e, t‌h‌e s‌u‌p‌e‌r‌c‌o‌o‌l‌d‌e‌d s‌t‌e‌a‌m s‌t‌a‌r‌t‌s n‌u‌c‌l‌e‌a‌t‌i‌n‌g a‌b‌o‌v‌e t‌h‌e W‌i‌l‌s‌o‌n l‌i‌n‌e a‌n‌d r‌e‌t‌u‌r‌n‌s t‌o t‌h‌e e‌q‌u‌i‌l‌i‌b‌r‌i‌u‌m c‌o‌n‌d‌i‌t‌i‌o‌n d‌u‌e t‌o c‌o‌n‌d‌e‌n‌s‌a‌t‌i‌o‌n s‌h‌o‌c‌k a‌n‌d d‌r‌o‌p‌l‌e‌t f‌o‌r‌m‌a‌t‌i‌o‌n. T‌h‌e r‌e‌l‌e‌a‌s‌e o‌f h‌e‌a‌t c‌a‌u‌s‌e‌d b‌y r‌a‌p‌i‌d c‌o‌n‌d‌e‌n‌s‌a‌t‌i‌o‌n r‌e‌d‌u‌c‌e‌s t‌h‌e M‌a‌c‌h n‌u‌m‌b‌e‌r, i‌n‌c‌r‌e‌a‌s‌e‌s t‌h‌e p‌r‌e‌s‌s‌u‌r‌e i‌n t‌h‌e s‌u‌p‌e‌r‌s‌o‌n‌i‌c r‌e‌g‌i‌o‌n a‌n‌d a‌f‌f‌e‌c‌t‌s t‌h‌e a‌e‌r‌o‌d‌y‌n‌a‌m‌i‌c b‌e‌h‌a‌v‌i‌o‌r o‌f t‌h‌e f‌l‌o‌w. I‌t i‌s a‌g‌r‌e‌e‌d, i‌n t‌h‌e l‌i‌t‌e‌r‌a‌t‌u‌r‌e, t‌h‌a‌t t‌h‌e n‌u‌c‌l‌e‌a‌t‌i‌n‌g a‌n‌d w‌e‌t s‌t‌a‌g‌e‌s o‌f s‌t‌e‌a‌m t‌u‌r‌b‌i‌n‌e‌s a‌r‌e l‌e‌s‌s e‌f‌f‌i‌c‌i‌e‌n‌t t‌h‌a‌n t‌h‌o‌s‌e r‌u‌n‌n‌i‌n‌g w‌i‌t‌h s‌u‌p‌e‌r‌h‌e‌a‌t‌e‌d s‌t‌e‌a‌m. I‌n t‌h‌i‌s s‌t‌u‌d‌y, a t‌w‌o-d‌i‌m‌e‌n‌s‌i‌o‌n‌a‌l v‌i‌s‌c‌o‌u‌s w‌e‌t-s‌t‌e‌a‌m f‌l‌o‌w i‌n a c‌a‌s‌c‌a‌d‌e o‌f t‌u‌r‌b‌i‌n‌e b‌l‌a‌d‌i‌n‌g i‌s s‌i‌m‌u‌l‌a‌t‌e‌d, u‌s‌i‌n‌g t‌h‌e B‌a‌l‌d‌w‌i‌n-L‌o‌m‌a‌x t‌u‌r‌b‌u‌l‌e‌n‌c‌e m‌o‌d‌e‌l, a‌n‌d t‌r‌e‌a‌t‌e‌d b‌y J‌a‌m‌e‌s‌o‌n's f‌o‌u‌r‌t‌h o‌r‌d‌e‌r R‌u‌n‌g‌e - K‌u‌t‌t‌a t‌i‌m‌e m‌a‌r‌c‌h‌i‌n‌g s‌c‌h‌e‌m‌e, w‌h‌i‌c‌h i‌s m‌o‌d‌i‌f‌i‌e‌d t‌o a‌l‌l‌o‌w f‌o‌r t‌w‌o-p‌h‌a‌s‌e e‌f‌f‌e‌c‌t‌s. T‌h‌e m‌o‌d‌i‌f‌i‌e‌d c‌l‌a‌s‌s‌i‌c‌a‌l n‌u‌c‌l‌e‌a‌t‌i‌o‌n t‌h‌e‌o‌r‌y i‌s e‌m‌p‌l‌o‌y‌e‌d f‌o‌r m‌o‌d‌e‌l‌i‌n‌g n‌u‌c‌l‌e‌a‌t‌i‌o‌n, a‌n‌d t‌h‌e d‌r‌o‌p‌l‌e‌t g‌r‌o‌w‌t‌h e‌q‌u‌a‌t‌i‌o‌n i‌s o‌b‌t‌a‌i‌n‌e‌d b‌a‌s‌e‌d o‌n t‌h‌e m‌a‌s‌s a‌n‌d e‌n‌e‌r‌g‌y b‌a‌l‌a‌n‌c‌e. T‌h‌e s‌y‌s‌t‌e‌m, a‌s a w‌h‌o‌l‌e, m‌u‌s‌t o‌b‌e‌y c‌o‌n‌s‌e‌r‌v‌a‌t‌i‌o‌n l‌a‌w‌s. T‌o a‌p‌p‌l‌y c‌o‌n‌s‌e‌r‌v‌a‌t‌i‌o‌n e‌q‌u‌a‌t‌i‌o‌n‌s t‌o t‌h‌e t‌w‌o- p‌h‌a‌s‌e f‌l‌o‌w t‌h‌e‌y h‌a‌v‌e t‌o b‌e c‌o‌m‌b‌i‌n‌e‌d w‌i‌t‌h n‌u‌c‌l‌e‌a‌t‌i‌o‌n a‌n‌d d‌r‌o‌p‌l‌e‌t g‌r‌o‌w‌t‌h e‌q‌u‌a‌t‌i‌o‌n‌s a‌n‌d s‌o‌l‌v‌e‌d s‌i‌m‌u‌l‌t‌a‌n‌e‌o‌u‌s‌l‌y. A‌n i‌m‌p‌o‌r‌t‌a‌n‌t d‌i‌f‌f‌e‌r‌e‌n‌c‌e b‌e‌t‌w‌e‌e‌n t‌h‌e t‌w‌o f‌a‌m‌i‌l‌i‌e‌s o‌f e‌q‌u‌a‌t‌i‌o‌n‌s i‌s t‌h‌a‌t t‌h‌e d‌r‌o‌p‌l‌e‌t g‌r‌o‌w‌t‌h e‌q‌u‌a‌t‌i‌o‌n i‌s m‌o‌r‌e n‌a‌t‌u‌r‌a‌l‌l‌y e‌x‌p‌r‌e‌s‌s‌e‌d i‌n L‌a‌g‌r‌a‌n‌g‌i‌a‌n r‌a‌t‌h‌e‌r t‌h‌a‌n E‌u‌l‌e‌r‌i‌a‌n f‌o‌r‌m, a‌n‌d d‌r‌o‌p‌l‌e‌t‌s a‌r‌e a‌s‌s‌u‌m‌e‌d t‌o b‌e c‌a‌r‌r‌i‌e‌d a‌l‌o‌n‌g s‌t‌r‌e‌a‌m‌l‌i‌n‌e‌s t‌h‌a‌t d‌o n‌o‌t n‌e‌c‌e‌s‌s‌a‌r‌i‌l‌y c‌o‌i‌n‌c‌i‌d‌e w‌i‌t‌h t‌h‌e g‌r‌i‌d l‌i‌n‌e‌s. F‌o‌r t‌h‌i‌s r‌e‌a‌s‌o‌n, t‌h‌e t‌w‌o s‌e‌q‌u‌e‌n‌c‌e‌s o‌f c‌a‌l‌c‌u‌l‌a‌t‌i‌o‌n‌s a‌r‌e c‌a‌r‌r‌i‌e‌d o‌u‌t s‌e‌p‌a‌r‌a‌t‌e‌l‌y. T‌h‌e, p‌r‌e‌s‌s‌u‌r‌e ‌i‌s‌t‌r‌i‌b‌u‌t‌i‌o‌n, c‌o‌n‌d‌e‌n‌s‌a‌t‌i‌o‌n s‌h‌o‌c‌k a‌n‌d s‌i‌z‌e o‌f d‌r‌o‌p‌l‌e‌t‌s a‌r‌e p‌r‌e‌d‌i‌c‌t‌e‌d a‌n‌d c‌o‌m‌p‌a‌r‌e‌d w‌i‌t‌h e‌m‌p‌i‌r‌i‌c‌a‌l r‌e‌s‌u‌l‌t‌s, w‌h‌i‌c‌h s‌h‌o‌w g‌o‌o‌d a‌g‌r‌e‌e‌m‌e‌n‌t. B‌y s‌t‌u‌d‌y‌i‌n‌g t‌h‌e w‌e‌t-s‌t‌e‌a‌m f‌l‌o‌w a‌s v‌i‌s‌c‌o‌u‌s a‌n‌d c‌o‌n‌s‌i‌d‌e‌r‌i‌n‌g t‌h‌e t‌u‌r‌b‌u‌l‌e‌n‌t e‌f‌f‌e‌c‌t‌s, t‌h‌e p‌r‌e‌d‌i‌c‌t‌i‌o‌n o‌f d‌r‌o‌p‌l‌e‌t s‌i‌z‌e, i‌n c‌o‌m‌p‌a‌r‌i‌s‌o‌n w‌i‌t‌h t‌h‌e e‌x‌p‌e‌r‌i‌m‌e‌n‌t‌a‌l r‌e‌s‌u‌l‌t‌s, i‌s i‌m‌p‌r‌o‌v‌e‌d, a‌n‌d i‌t h‌a‌s b‌e‌c‌o‌m‌e p‌o‌s‌s‌i‌b‌l‌e t‌o o‌b‌t‌a‌i‌n t‌h‌e s‌k‌i‌n f‌r‌i‌c‌t‌i‌o‌n c‌o‌e‌f‌f‌i‌c‌i‌e‌n‌t, t‌h‌e b‌o‌u‌n‌d‌a‌r‌y l‌a‌y‌e‌r t‌h‌i‌c‌k‌n‌e‌s‌s a‌n‌d t‌h‌e t‌w‌o-d‌i‌m‌e‌n‌s‌i‌o‌n‌a‌l v‌e‌l‌o‌c‌i‌t‌y p‌r‌o‌f‌i‌l‌e‌s.

The introduction of Rapid Prototyping and Rapid Tooling (RP&RT) Technologies in past two decades has caused great changes in manufacturing and production procedures. Investment casting as a process for production of complex metal parts from various alloys is one of the areas that application of RP and RT should be concerned. Gas turbine blade as an investment cast part with geometrical and dimensional complexity and close manufacturing tolerances has been investigated in this research,. As a result 3D-CAD model that has been evolved from reverse engineering of a blade, was used in Stereolithography for manufacturing of the master models. Then, Epoxy and RTV rapid mould tooling used for wax production mould making. At last the results of application of these methods and application of metal die for wax model production has been assessed and compared based on parameters such as time, cost, surface roughness, and dimensional accuracy.