scholarly journals Optimization of Friction Damper Weight, Simulation and Experiments

1997 ◽  
Author(s):  
Gabor Csaba ◽  
Magnus Andersson
Keyword(s):  
Experimental Data ◽  
High Pressure ◽  
Turbine Blades ◽  
Turbine Rotor ◽  
Friction Damper ◽  
High Pressure Turbine ◽  
Coupled Modes ◽  
Modes Of Vibration ◽  
Damper Design ◽  
The Right

A new friction damper has been designed by Volvo Aero Corporation. It is used in the high pressure turbine stage of a turbojet engine. The objective of this paper was to find the optimal weight of the new damper that minimizes the blade response amplitude for six and nine engine order excitation and to compare the new damper design with that currently used. Another objective was to compare how well simulation results agree with experimental results from spin pit tests. Simulations were made with a damper model that incorporates the possibility of both micro- and macro-slip in the blade-damper contact interface. Turbine blades were modeled using finite element beam elements. Experimental data were provided from spin pit tests with a completely bladed high pressure turbine rotor. Results show that the simulation model can be used to give qualitative results but has to be further developed to incorporate mistuning effects and coupled modes of vibration for the blade. The spin pit test shows that the new damper design is more efficient in reducing resonance stresses than the old design. It was not possible to see if simulations predict the right optimal damper weight by comparing with experimental data because the rotor could not be excited up to the design point.

Numerical and Experimental Damping Assessment of a Thin-Walled Friction Damper in the Rotating Set-Up With High Pressure Turbine Blades

2006 ◽  
Author(s):  
J. Szwedowicz ◽  
C. Gibert ◽  
T. P. Sommer ◽  
R. Kellerer
Keyword(s):  
High Pressure ◽  
Contact Stiffness ◽  
Turbine Blades ◽  
Mode Shapes ◽  
Friction Damper ◽  
High Pressure Turbine ◽  
Friction Forces ◽  
Normal Contact ◽  
Contact Behaviour ◽  
Thin Walled

Under-platform friction dampers are preferably solutions for minimizing vibrations of rotating turbine blades. Solid dampers, characterized by their compact dimensions, are frequently used in real applications and often appear in patents in different forms. A different type of the friction damper is a thin-walled structure, which has larger dimensions and smaller contact stresses on a wider contact area in relation to the solid damper. The damping performance of a thin-walled damper, mounted under the platforms of two rotating, freestanding high pressure turbine blades is investigated numerically and experimentally in this paper. The tangential and normal contact stiffness, that are crucial parameters in optimal design of each friction damper, are determined from three-dimensional finite element (FE) computations of the contact behaviour of the thin-walled damper on the platform including friction and centrifugal effects. The computed contact stiffness values are applied to non-linear dynamic simulations of the analysed blades with the friction damper of a specified mass. These numerical analyses are performed in the modal frequency domain with a code, which is based on the Harmonic Balance Method (HBM) for the complex linearisation of friction forces. The blade vibrations are characterised by a set of the lowest FE mode shapes of one freestanding blade without damper. The dynamic results of the calculated blades with the damper are in good agreement with the measured data of the real mistuned system. In the analysed excitation range, the numerical performance curve of the thin-walled damper is obtained within the scatter band of the experimental results. For the known friction coefficients and available FE and HBM tools, the described numerical process confirms its usability in the design of under-platform dampers.

Experimental and Computational Study of Novel Tip Leakage Mitigation Methods for High Pressure Turbine Blades

2015 ◽  
Author(s):  
Mounir B. Ibrahim ◽  
Ralph J. Volino
Keyword(s):  
High Pressure ◽  
Computational Study ◽  
Turbine Blades ◽  
Turbine Rotor ◽  
High Pressure Turbine ◽  
Ansys Fluent ◽  
Tip Leakage ◽  
Blowing Ratio ◽  
Numerical Solver ◽  
Mitigation Methods

This paper presents computational and experimental study of a possible approach to reduce tip leakage losses. The study was conducted on the EEE (Energy Efficient Engine) HPT (High Pressure Turbine) rotor tip geometry. The CFD was done utilizing the commercial numerical solver ANSYS FLUENT. The experimental work was conducted in a low speed wind tunnel with linear cascade at the USNA (for Re = 30,000) and the NASA Transonic Turbine Blade Cascade facility at the NASA John H. Glenn Research Center for Re of 85,000 to 683,000 at two isentropic exit Mach numbers of 0.74 and 0.34 were reported. The overall scope of this study is to investigate how the tip leakage and overall blade losses are affected by injection from the tip surface at the camber line, and the jet blowing ratio. The results identify areas where future investigation can be explored in order to achieve higher performance of the high pressure turbines.

Experimental Investigation of Two Competitive High Pressure Turbine Blade Cooling Systems

2017 ◽  
Author(s):  
Sergiy Risnyk ◽  
Andriy Artushenko ◽  
Igor Kravchenko ◽  
Sergii Borys
Keyword(s):  
High Pressure ◽  
Turbine Blade ◽  
Film Cooling ◽  
Cooling System ◽  
Turbine Blades ◽  
Turbine Rotor ◽  
High Pressure Turbine ◽  
Cooling Systems ◽  
Turbine Blade Cooling ◽  
Blade Cooling

Aeroengine high-pressure turbine (HPT) is the key engine component. HPT blade must withstand high inlet temperatures and mechanical loads providing the necessary level of the efficiency. To achieve these objectives effective and complex blade cooling systems (internal convective and film cooling) are used in the HPT design. The objective of this project is to design and investigate the aeroengine HPT blade cooling system that is able to withstand the blade inlet gas temperature level of approx. 1900K but with the minimal cooling airflow amount. HPT blade of the aeroengine with unducted fan (UDF) was taken as a baseline design, namely, the monocrystal blade with a convective multipass system and the film cooling. Advanced HPT blade inter-wall cooling system was designed, investigated and compared with the typical baseline HPT blade. In the advanced HPT blade inter-wall cooling system special types and structure of cooling channels are used. Both types of cooling systems were investigated experimentally in the turbine rotor of the high temperature core engine. Measurements of turbine blades temperatures were performed using crystal temperature sensors (CTS). HPT blades with two competitive cooling systems incorporated with CTS (0,2–0,3 mm size) were installed in the turbine rotor of the core engine and tested on the engine Maximal rate. After tests and the engine disassembly CTSs were extracted and the characteristics of the CTS crystal lattice were transcribed in temperature values. Thermal state of both two competitive cooling systems was validated by experimental data. Numerical and experimental results obtained in the research of HPT blade cooling system are presented in the article. Aeroengine high pressure turbine blade cooling systems designs are described.

Influence of Hot Streak Temperature Ratio on Low Pressure Stage of a Vaneless Counter-Rotating Turbine

2007 ◽  
Author(s):  
Qingjun Zhao ◽  
Fei Tang ◽  
Huishe Wang ◽  
Jianyi Du ◽  
Xiaolu Zhao ◽  
...  
Keyword(s):  
Shock Wave ◽  
High Pressure ◽  
Secondary Flow ◽  
Low Pressure ◽  
Turbine Rotor ◽  
Temperature Ratio ◽  
High Pressure Turbine ◽  
Pressure Stage ◽  
Low Pressure Turbine ◽  
Hot Streak

In order to explore the influence of hot streak temperature ratio on low pressure stage of a Vaneless Counter-Rotating Turbine, three-dimensional multiblade row unsteady Navier-Stokes simulations have been performed. The predicted results show that hot streaks are not mixed out by the time they reach the exit of the high pressure turbine rotor. The separation of colder and hotter fluids is observed at the inlet of the low pressure turbine rotor. After making interactions with the inner-extending shock wave and outer-extending shock wave in the high pressure turbine rotor, the hotter fluid migrates towards the pressure surface of the low pressure turbine rotor, and the most of colder fluid migrates to the suction surface of the low pressure turbine rotor. The migrating characteristics of the hot streaks are predominated by the secondary flow in the low pressure turbine rotor. The effect of buoyancy on the hotter fluid is very weak in the low pressure turbine rotor. The results also indicate that the secondary flow intensifies in the low pressure turbine rotor when the hot streak temperature ratio is increased. The effects of the hot streak temperature ratio on the relative Mach number and the relative flow angle at the inlet of the low pressure turbine rotor are very remarkable. The isentropic efficiency of the Vaneless Counter-Rotating Turbine decreases as the hot streak temperature ratio is increased.

Aerothermal Effect of Cavity Welding Beads on a Transonic Squealer Tip

2020 ◽  
Author(s):  
Joao Vieira ◽  
John Coull ◽  
Peter Ireland ◽  
Eduardo Romero
Keyword(s):  
High Pressure ◽  
Film Cooling ◽  
Turbine Blades ◽  
Reynolds Numbers ◽  
High Pressure Turbine ◽  
Cooling Effectiveness ◽  
Film Cooling Effectiveness ◽  
Aerodynamic Loss ◽  
Blade Tip ◽  
Mass Flow Rates

Abstract High pressure turbine blade tips are critical for gas turbine performance and are sensitive to small geometric variations. For this reason, it is increasingly important for experiments and simulations to consider real geometry features. One commonly absent detail is the presence of welding beads on the cavity of the blade tip, which are an inherent by-product of the blade manufacturing process. This paper therefore investigates how such welds affect the Nusselt number, film cooling effectiveness and aerodynamic performance. Measurements are performed on a linear cascade of high pressure turbine blades at engine realistic Mach and Reynolds numbers. Two cooled blade tip geometries were tested: a baseline squealer geometry without welding beads, and a case with representative welding beads added to the tip cavity. Combinations of two tip gaps and several coolant mass flow rates were analysed. Pressure sensitive paint was used to measure the adiabatic film cooling effectiveness on the tip, which is supplemented by heat transfer coefficient measurements obtained via infrared thermography. Drawing from all of this data, it is shown that the weld beads have a generally detrimental impact on thermal performance, but with local variations. Aerodynamic loss measured downstream of the cascade is shown to be largely insensitive to the weld beads.

Impact of Individual High-Pressure Turbine Rotor Purge Flows on Turbine Center Frame Aerodynamics

2017 ◽  
Author(s):  
S. Zerobin ◽  
C. Aldrian ◽  
A. Peters ◽  
F. Heitmeir ◽  
E. Göttlich
Keyword(s):  
High Pressure ◽  
Pressure Loss ◽  
Turbine Rotor ◽  
Flow Conditions ◽  
High Pressure Turbine ◽  
Reference Case ◽  
University Of Technology ◽  
Purge Flow ◽  
Generation Mechanisms ◽  
The Impact

This paper presents an experimental study of the impact of individual high-pressure turbine purge flows on the main flow in a downstream turbine center frame duct. Measurements were carried out in a product-representative one and a half stage turbine test setup, installed in the Transonic Test Turbine Facility at Graz University of Technology. The rig allows testing at engine-relevant flow conditions, matching Mach, Reynolds, and Strouhal number at the inlet of the turbine center frame. The reference case features four purge flows differing in flow rate, pressure, and temperature, injected through the hub and tip, forward and aft cavities of the high-pressure turbine rotor. To investigate the impact of each individual cooling flow on the flow evolution in the turbine center frame, the different purge flows were switched off one-by-one while holding the other three purge flow conditions. In total, this approach led to six different test conditions when including the reference case and the case without any purge flow ejection. Detailed measurements were carried out at the turbine center frame duct inlet and outlet for all six conditions and the post-processed results show that switching off one of the rotor case purge flows leads to an improved duct performance. In contrast, the duct exit flow is dominated by high pressure loss regions if the forward rotor hub purge flow is turned off. Without the aft rotor hub purge flow, a reduction in duct pressure loss is determined. The purge flows from the rotor aft cavities are demonstrated to play a particularly important role for the turbine center frame aerodynamic performance. In summary, this paper provides a first-time assessment of the impact of four different purge flows on the flow field and loss generation mechanisms in a state-of-the-art turbine center frame configuration. The outcomes of this work indicate that a high-pressure turbine purge flow reduction generally benefits turbine center frame performance. However, the forward rotor hub purge flow actually stabilizes the flow in the turbine center frame duct and reducing this purge flow can penalize turbine center frame performance. These particular high-pressure turbine/turbine center frame interactions should be taken into account whenever high-pressure turbine purge flow reductions are pursued.

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