Sensitivity Analysis and Uncertainty Quantification for a Coupled Secondary Air System Thermo-Mechanical Model of a Jet Engine Low Pressure Turbine Rotor

2014 ◽  
Author(s):  
Giulia Antinori ◽  
Fabian Duddeck ◽  
Andreas Fischersworring-Bunk
Keyword(s):  
Sensitivity Analysis ◽  
Uncertainty Quantification ◽  
Mechanical Model ◽  
Low Pressure ◽  
Turbine Rotor ◽  
Jet Engine ◽  
Low Pressure Turbine ◽  
Air System ◽  
Secondary Air

Statistical Methods for a Stochastic Analysis of the Secondary Air System of a Jet Engine Low Pressure Turbine

2013 ◽  
Author(s):  
Giulia Antinori ◽  
Yannick Muller ◽  
Fabian Duddeck ◽  
Andreas Fischersworring-Bunk
Keyword(s):  
Sensitivity Analysis ◽  
Uncertainty Analysis ◽  
Stochastic Analysis ◽  
Sampling Methods ◽  
Correlation Method ◽  
Low Pressure ◽  
Jet Engine ◽  
Low Pressure Turbine ◽  
Input Variables ◽  
Secondary Air

In this paper several stochastic methods are evaluated with respect to their applicability for the analysis of fluid networks. The methods are applied for the analysis of a 1D flow model of the Secondary Air System (SAS) of a three stages low pressure turbine (LPT) of a jet engine. The stochastic analysis is comprised of a sensitivity analysis followed by an uncertainty analysis. The sensitivity analysis is performed to gain a better understanding of the SAS physics and robustness, to identify the important variables and to reduce the number of parameters involved in the simulations for the uncertainty analysis. The uncertainty analysis, using probability distributions derived from the manufacturing process, allows to determine the effect of the input uncertainties on responses such as pressures, fluid temperatures and mass flow rates. A review of the most common and relevant sampling methods is performed. A comparison of the respective computational cost and of the sample points distribution is proposed with the aim of finding the most suited method. The study shows that some of the sampling methods can not be recommended since they produce spurious correlations between independent input variables. With regards to the sensitivity analysis, many literature sources state that the Pearson correlation method is only valid for linear models when assessing the importance of input variables. As the SAS is highly non-linear, non-parametric variance based methods are introduced here to make up for the limitations of the correlation method. Following the results of the study, it is recommended to combine the sampling method with a non-parametric variance based method. Thus, the main effects as well as all the interactions among variables are captured.

Robust Design Optimization of a Low Pressure Turbine Rotor Discs Secondary Air System

2017 ◽  
Author(s):  
Giulia Antinori ◽  
Ilya Arsenyev ◽  
Andreas Fischersworring-Bunk
Keyword(s):  
Parameter Space ◽  
Cooling System ◽  
Optimization Methods ◽  
Low Pressure ◽  
Life Cycles ◽  
Robust Design Optimization ◽  
Design Parameters ◽  
Low Pressure Turbine ◽  
Air System ◽  
Secondary Air

Low pressure turbine (LPT) rotor discs undergo high thermal and mechanical loads during normal aircraft missions. Therefore, to meet the minimum requirement for life, temperatures and stresses in the disk need to be maintained within certain limits. This is achieved by carefully designing the disk shape and the cooling system. The complexity of this multi-physics problem together with a large number of design parameters require the use of numerical optimization methods for the Secondary Air System (SAS) design. Moreover, possible variations in the boundary conditions due to ambient parameters (e.g. temperatures, pressures) and manufacturing tolerances of the SAS components should be taken into account within the system design and optimization phase. In this paper an application of robust optimization methods for the design of a LPT secondary air system is proposed. The objective is to increase the engine efficiency by minimizing the amount of cooling flow, which is needed to guarantee a minimum required number of life cycles and to keep maximal temperatures within the limits. In order to predict the disks life accurately, transient thermal-structural analysis is used, which is computationally demanding. For this reason, optimization should be performed with a very limited amount of system evaluations. The dimension of the parameter space is reduced through the application of global sensitivity analysis methods by selecting the parameters that most affect the results. Optimization methods are sped up by the use of surrogate models, created over the reduced parameter space, which approximate the objective function and the constraints.

Probabilistic Analysis of the Secondary Air System of a Low-Pressure Turbine

2014 ◽  
Author(s):  
Stefan Brack ◽  
Yannick Muller
Keyword(s):  
Correlation Coefficient ◽  
Probabilistic Analysis ◽  
Flow Model ◽  
Turbine Rotor ◽  
Effect Analysis ◽  
Low Pressure Turbine ◽  
Hot Gas ◽  
Air System ◽  
Secondary Air ◽  
The Impact

The present investigation aims at performing a probabilistic analysis of the secondary air system of a three-stage low-pressure turbine rotor in a jet engine. Geometrical engine to engine variations due to the tolerance of the different parts as well as the variation of engine performance parameters are taken into account to analyse the impact on the aerodynamic behaviour of the secondary air system. Three main functions of the secondary air system have been investigated at one engine condition — take-off. At first the variation of the turbine rotor cooling flow consumption was studied. Secondly the axial bearing loads were considered and finally the system was analysed with regard to its robustness towards disc space hot gas ingestion. To determine the uncertainty in the accomplishment of these tasks and to identify the major variation drivers, a Latin Hypercube sampling method coupled with the correlation coefficient analysis was applied to the 1D flow model. The incapability of the correlation coefficient analysis to deal with functional relationships of not monotonic behaviour or strong interaction effects was compensated by additionally applying in such cases an Elementary Effect analysis to determine the influential variables. As the 1D flow model cannot consider thermal and centrifugal growth effects, a simple mathematical model was deduced from the physical dependencies enhancing the 1D flow model to approximately capture the impact of these effects on the labyrinth seals. Results showed that the cooling mass flow and axial bearing load are both normally distributed while their uncertainties are mainly induced by the uncertainties of the state variable of the primary air system. The investigated chamber temperature ratio to analyse the hot gas ingestion showed a not normally distributed histogram and a strong influence of interaction terms. Therefore the results of the correlation coefficient analysis were complemented with the results of an Elementary Effect analysis.

Probabilistic Analysis of the Secondary Air System of a Low-Pressure Turbine

2014 ◽  
Vol 137 (2) ◽  
Author(s):  
Stefan Brack ◽  
Yannick Muller
Keyword(s):  
Correlation Coefficient ◽  
Probabilistic Analysis ◽  
Flow Model ◽  
Turbine Rotor ◽  
Effect Analysis ◽  
Low Pressure Turbine ◽  
Hot Gas ◽  
Air System ◽  
Secondary Air ◽  
The Impact

The present investigation aims at performing a probabilistic analysis of the secondary air system (SAS) of a three-stage low-pressure turbine rotor in a jet engine. Geometrical engine to engine variations due to the tolerance of the different parts as well as the variation of engine performance parameters are taken into account to analyze the impact on the aerodynamic behavior of the SAS. Three main functions of the SAS have been investigated at one engine condition—takeoff. At first the variation of the turbine rotor cooling flow consumption was studied. Second, the axial bearing loads were considered and finally the system was analyzed with regard to its robustness toward disk space hot gas ingestion. To determine the uncertainty in the accomplishment of these tasks and to identify the major variation drivers, a Latin hypercube sampling (LHS) method coupled with the correlation coefficient analysis was applied to the 1D flow model. The incapability of the correlation coefficient analysis to deal with functional relationships of not monotonic behavior or strong interaction effects was compensated by additionally applying in such cases an elementary effect analysis to determine the influential variables. As the 1D flow model cannot consider thermal and centrifugal growth effects, a simple mathematical model was deduced from the physical dependencies enhancing the 1D flow model to approximately capture the impact of these effects on the labyrinth seals. Results showed that the cooling mass flow and axial bearing load are both normally distributed while their uncertainties are mainly induced by the uncertainties of the state variable of the primary air system. The investigated chamber temperature ratio to analyze the hot gas ingestion showed a not normally distributed histogram and a strong influence of interaction terms. Therefore, the results of the correlation coefficient analysis were complemented with the results of an elementary effect analysis.

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.

Secondary Air Systems in Aeroengines Employing Vortex Reducers

2001 ◽  
Author(s):  
Dimitrie Negulescu ◽  
Michael Pfitzner
Keyword(s):  
Flow Path ◽  
Supporting Evidence ◽  
Excessive Pressure ◽  
Pressure Losses ◽  
Low Pressure Turbine ◽  
Hot Gas ◽  
Air System ◽  
High Integrity ◽  
Secondary Air ◽  
Aero Engines

A secondary air system in modern aero engines is required to cool the compressor and turbine discs and make sure that no hot gas ingestion occurs into the cavities between the turbine discs, which could cause an inadvertent reduction of disc life. A high integrity solution for guiding the air from the compressor to the turbine is through an inner bleed from the compressor platform and through the space between the disc bores and the shaft connecting the fan with the low pressure turbine. Since strongly swirling air is taken from the compressor platforms to a much lower radius, a means of deswirling the air has to be used to avoid excessive pressure losses along the flow path. The paper describes a system utilizing tubeless vortex reducers to accomplish this deswirl, which are compared to a more conventional air system utilizing tubes. The working principles of both types of vortex reducer and guidelines for the design of a secondary air system using vortex reducers are explained with supporting evidence from rig tests and CFD calculations. Opportunities for the aerodynamic optimisation of the tubeless vortex reducer are elaborated and the experience gained using the system during the development of the BR700 engine is described.

Premature Fatigue Failures in the Hot Zone of Low Pressure Turbine Rotor (LPTR) Blades of Aero-Engine

2017 ◽  
pp. 65-76
Author(s):  
M. Madan ◽  
R. Bharathanatha Reddy ◽  
K. Raghavendra ◽  
M. Sujata ◽  
S. K. Bhaumik
Keyword(s):  
Low Pressure ◽  
Turbine Rotor ◽  
Low Pressure Turbine ◽  
Aero Engine ◽  
Fatigue Failures ◽  
Hot Zone

Investigation of the Impact of Unsteady Turbulence Effects on the Aeroelastic Analysis of a Low-Pressure Turbine Rotor Blade

2019 ◽  
Vol 141 (10) ◽  
Author(s):  
Jan Philipp Heners ◽  
Damian M. Vogt ◽  
Christian Frey ◽  
Graham Ashcroft
Keyword(s):  
Rotor Blade ◽  
Numerical Study ◽  
Turbulence Models ◽  
Gibbs Phenomenon ◽  
Low Pressure ◽  
Turbine Rotor ◽  
Filter Method ◽  
Turbine Rotor Blade ◽  
Low Pressure Turbine ◽  
The Impact

Abstract The impact of the unsteadiness in the considered turbulence quantities on the numerical prediction of the aeroelastic behavior of a low-pressure turbine (LPT) rotor blade is evaluated by means of a numerical study. In this context, one of the main objectives of this work is to compare different nonlinear harmonic balance (HB) approaches—one neglecting and one considering the unsteadiness in the employed turbulence models—with a conventional nonlinear solver of the unsteady Reynolds-averaged Navier–Stokes (URANS) equations in the time domain. In order to avoid unphysical oscillations in the turbulence quantities caused by the Gibbs phenomenon in the chosen HB approach, a filter method based on the Lanczos filter is developed. The developed filter method is applied in the course of the HB simulations considering the unsteadiness in the underlying turbulence model. Furthermore, the impact of its application on the solution of the flow field and on the unsteady surface pressure of the rotor blade, in particular, is discussed in the context of this work.

scholarly journals Investigation of parts assembly error, taking into account the deviation of the shape of their surfaces

2018 ◽  
Vol 224 ◽  
pp. 01098 ◽  
Author(s):  
Mikhail Bolotov ◽  
Iliya Grachev ◽  
Evgeny Kudashov
Keyword(s):  
Computer Model ◽  
Low Pressure ◽  
Turbine Rotor ◽  
Low Pressure Turbine ◽  
Geometrical Errors ◽  
Study Results ◽  
Assembly Unit ◽  
Assembly Error

In this article, we study the errors in the assembly of parts, taking into account the deviation of the shape of their surfaces. The developed computer model of the assembly of the engine low-pressure turbine rotor is designed to predict the values of the assembly parameters, such as radial and face run-out. The forecasting of the above assembly parameters is carried out based on the data of actual dimensions and shape of the surfaces of parts assembled as an assembly unit. The analysis of study results made it possible to obtain a conclusion about the qualitative influence of geometrical errors of the assembled parts on the error of the assembly parameters.

Ceramic shell moulds for investment casting of low-pressure turbine rotor blisk

2020 ◽  
Author(s):  
Y. Venkat ◽  
K.R. Choudary ◽  
D.K. Das ◽  
A.K. Pandey ◽  
Sarabjit Singh
Keyword(s):  
Investment Casting ◽  
Low Pressure ◽  
Turbine Rotor ◽  
Ceramic Shell ◽  
Low Pressure Turbine
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