scholarly journals Simulation Platform on Flow and Heat Transfer of Aero-engine Secondary Air System

2015 ◽  
Author(s):  
Guo-zhe Ren ◽  
Zhen-xia Liu ◽  
Peng-fei Zhu ◽  
Ya-guo Lyu
Keyword(s):  
Heat Transfer ◽  
Simulation Platform ◽  
Flow And Heat Transfer ◽  
Aero Engine ◽  
Air System ◽  
Secondary Air

An Integrated Approach to Simulate Gas Turbine Secondary Air System

2020 ◽  
Author(s):  
Ali Izadi ◽  
Seyed Hossein Madani ◽  
Seyed Vahid Hosseini ◽  
Mahmoud Chizari
Keyword(s):  
Heat Transfer ◽  
Gas Turbine ◽  
Turbine Blades ◽  
Great Influence ◽  
Integrated Approach ◽  
Cfd Modeling ◽  
Connectivity Matrix ◽  
Analysis Tool ◽  
Air System ◽  
Secondary Air

Abstract One of the most critical parts of a modern gas turbine that its reliability and performance has a great influence on cycle efficiency is the secondary air system (SAS). Modern systems functions to supply not only cooling air flow for turbine blades and vanes but sealing flow for bearing chambers and turbine segments as well as turbine disks’ purge flow in order to eliminate hot gas ingestion. Due to the various interactions between SAS and main gas, consideration of the former is substantially crucial in design and analysis of the whole engine. Geometrical complexities and centrifugal effects of rotating blades and disks, however, make the flow field and heat transfer of the problem so complicated AND too computationally costly to be simulated utilizing full 3-D CFD methods. Therefore, developing 1-D and 0-D tools applying network methods are of great interests. The present article describes a modular SAS analysis tool that is consisted of a network of elements and nodes. Each flow branch of a whole engine SAS network is substituted with an element and then, various branches (elements) intersect with each other just at their end nodes. These elements which might include some typical components such as labyrinth seals, orifices, stationary/rotating pipes, pre-swirls, and rim-seals, are generally articulated with characteristic curves that are extracted from high fidelity CFD modeling using commercial software such as Flowmaster or ANSYS-CFX. Having these curves, an algorithm is developed to calculate flow parameters at nodes with the aid of iterative methods. The procedure is based on three main innovative ideas. The first one is related to the network construction by defining a connectivity matrix which could be applied to any arbitrary network such as hydraulic or lubrication networks. In the second one, off-design SAS calculation will be proposed by introducing some SAS elements that their characteristic non-dimensional curves are influenced by their inlet total pressure. The last novelty is the integration of the blades coolant calculation process that incorporates external heat transfer calculation, structural conduction and coolant side modeling with SAS network simulation. Finally, SAS simulation of an industrial gas turbine is presented to illustrate capabilities of the presented tool in design point and off-design conditions.

Process Automation for Aero Engine Secondary Air System Seal Design

2020 ◽  
Author(s):  
Adele Nasti
Keyword(s):  
Holistic Approach ◽  
Business Case ◽  
Operating Conditions ◽  
System Level ◽  
Process Automation ◽  
Seal Design ◽  
Aero Engine ◽  
Air System ◽  
Secondary Air ◽  
The Impact

Abstract Secondary air system seals are crucial in aero engine design as they have a direct impact on specific fuel consumption. Their behavior is affected by several aspects of the physics of the system: the air system, the engine thermal physics, the effect of flight loads and several other effects. As a consequence, their design is a complex and iterative process, which is highly dependent on the location of the seal in the engine, on the system requirements and on the system behavior. This paper describes a methodology for multi-disciplinary assessment of secondary air system seals within an engine environment and supports standard seal design, trade-off studies on novel concepts and system-level optimization. Defining the seal design intent for a specific engine location in the form of objectives, it is possible to embed process automation into traditionally manual multi-disciplinary design processes. This allows transforming modelling and simulation tools, which typically provide predictions for a specific seal design over reference cycles, into design and optimization tools, which can provide the optimum seal design for a specific set of requirements. This approach provides predictive models of both seal performance and performance degradation and is capable of taking into account all sources of variation, for instance manufacturing variations or engine operating conditions, delivering a robust design, specific to the engine location. The methodology enables a holistic approach to system and sub-system design and provides a deeper understanding of the impact of the seal onto system and of the system onto the seal, allowing optimization of the overall solution and informing the business case for introduction of different sealing strategies. Examples of the application of this methodology are provided for both labyrinth seals and leaf seals.

scholarly journals Influences of the Geometry of the Scavenge Pipe on the Air–Oil Two-Phase Flow and Heat Transfer in an Aero-Engine Bearing Chamber

ACS Omega ◽  
2019 ◽  
Vol 4 (12) ◽  
pp. 15226-15233 ◽  
Author(s):  
Peng Lu ◽  
Lulu Fang ◽  
Xiangyang Wang ◽  
Qihang Ye ◽  
Jingzhou Zhang
Keyword(s):  
Heat Transfer ◽  
Two Phase Flow ◽  
Phase Flow ◽  
Two Phase ◽  
Flow And Heat Transfer ◽  
Aero Engine ◽  
Engine Bearing

Flow and Heat Transfer in an Industrial Rotor-Stator Rim Sealing Cavity

2000 ◽  
Author(s):  
Alexander V. Mirzamoghadam ◽  
Zhenhua Xiao
Keyword(s):  
Heat Transfer ◽  
Heat Flux ◽  
Reynolds Number ◽  
Steady State ◽  
Wall Temperature ◽  
Thermal Model ◽  
Labyrinth Seal ◽  
Cfd Model ◽  
Flow And Heat Transfer ◽  
Aero Engine

Flow and heat transfer in the row-1 upstream rotor-stator disc cavity of a large 3600-rpm industrial gas turbine was investigated using an integrated approach. A 2D axisymmetric transient thermal analysis using aero engine-based correlations was performed to predict the steady state metal temperatures and hot running seal clearances at ISO rated power condition. The cooling mass flow and the flow pattern assumption for the thermal model were obtained from the steady state 2D axisymmetric CFD study. The CFD model with wall heat transfer was validated using cavity steady state air temperatures and static pressures measured at inlet to the labyrinth seal and four cavity radial positions in an engine test which included the mean annulus static pressure at hub radius. The predicted wall temperature distribution from the matched thermal model was used in the CFD model by incorporating wall temperature curve-fit polynomial functions. Results indicate that although the high rim seal effectiveness prevents ingestion from entering the cavity, the disc pumping flow draws air from within the cavity to satisfy entrainment leading to an inflow along the stator. The supplied cooling flow exceeds the minimum sealing flow predicted from both the rotational Reynolds number-based correlation and the annulus Reynolds number correlation. However, the minimum disc pumping flow was found to be based on a modified entrainment expression with a turbulent flow parameter of 0.08. The predicted coefficient of discharge (Cd) of the industrial labyrinth seal from CFD was confirmed by modifying the carry-over effect of a correlation reported recently in the literature. Moreover, the relative effects of seal windage and heat transfer were obtained and it was found that contrary to what was expected, the universal windage correlation was more applicable than the aero engine-based labyrinth seal windage correlation. The CFD predicted disc heat flux profile showed reasonably good agreement with the free disc calculated heat flux. The irregular cavity shape and high rotational Reynolds number (in the order of 7×107) leads to entrance effects that produce a thicker turbulent boundary layer profile compared to that predicted by the 1/7 power velocity profile assumption.

Modelling Conjugate Heat Transfer Within a Gas Turbine Secondary Air System Using Thermo-Fluid System Simulation

2020 ◽  
Author(s):  
David Hunt ◽  
Youming Yuan
Keyword(s):  
Heat Transfer ◽  
Thermal Analysis ◽  
Gas Turbine ◽  
Conjugate Heat Transfer ◽  
System Analysis ◽  
Design Stage ◽  
Fluid System ◽  
Air System ◽  
Secondary Air ◽  
Solid System

Abstract This paper presents a novel approach that couples system modelling of both the thermo-fluid system and the thermal solid system by modelling conjugate heat transfer within a single 1D system analysis solver and applies it to the Secondary Air System of a Gas Turbine. The Secondary Air System design has to balance minimizing engine bleed whilst ensuring sufficient cooling. To achieve this, designers model both the secondary air flow and the temperature distribution in solid components. System CFD tools like Simcenter Flomaster may be used to solve flow, pressure and temperature distributions and a 3D thermal solver used to perform the thermal analysis of the blade and disc solids. The thermal interaction between the secondary flow system and the solid components is a key part of the model and is known as conjugate heat transfer analysis (CHT). This approach is problematic early in the design cycle when detailed or stable geometry information may not be available for the 3D thermal tool. An approach that couples the modelling of both the thermo-fluid system and the thermal solid system within a single 1D/system analysis tool offers the advantage of faster modelling and consistent model accuracy of both fluid and solid components, especially in the early concept design stage. This 1D-CHT approach has been implemented within Simcenter Flomaster and validated using an idealized analytical solution. It is shown that the model can be applied to the analysis of gas turbine secondary air systems including cavity flows and thermal analysis of the rotor and stator discs that form the thermal boundary of these cavities using Simcenter Flomaster alone.

Investigation of Internal Cooling Air Flow of Gas Turbines With Attention to Heat Transfer

2003 ◽  
Author(s):  
D. Brillert ◽  
F.-K. Benra ◽  
H. J. Dohmen ◽  
O. Schneider
Keyword(s):  
Heat Transfer ◽  
Gas Turbines ◽  
Turbine Blades ◽  
Internal Cooling ◽  
Flow Physics ◽  
Cooling Flow ◽  
Air System ◽  
Secondary Air ◽  
Cooling Air ◽  
Material Temperature

The cooling air in the secondary air system of gas turbines is routed through the inside of the rotor shaft. The air enters the rotor through an internal extraction in the compressor section and flows through different components to the turbine blades. Constant improvements of the secondary air system is a basic element to increase efficiency and power of heavy duty gas turbines. It is becoming more and more important to have a precise calculation of the heat transfer and air temperature in the internal cooling air system. This influences the cooling behavior, the material temperature and consequently the cooling efficiency. The material temperature influences the stresses and the creep behavior which is important for the life time prediction and the reliability of the components of the engine. Furthermore, the material temperature influences the clearances and again the cooling flow, e.g. the amount of mass flow rate, hot gas ingestion etc. This paper deals with an investigation of the influence of heat transfer on the internal cooling air system and on the material temperature. It shows a comparison between numerical calculations with and without heat transfer. Firstly, the Navier-Stokes CFD calculation shows the cooling flow physics of different parts of the secondary air system passages with solid heat transfer. In the second approach, the study is expanded to consider the cooling flow physics under conditions without heat transfer. On the basis of these investigations, the paper shows a comparison between the flow with and without heat transfer. The results of the simulation with heat transfer show a negligible influence on the cooling flow temperature and a stronger influence on the material temperature. The results of the calculations are compared with measured data. The influence on the material temperature is verified with measured material temperatures from a Siemens Model V84.3A gas turbine prototype.

Impact of the Secondary Air System Design Parameters on the Calculation of Turbine Discs Windage

2014 ◽  
Author(s):  
Jose Maria Rey Villazón ◽  
Toni Wildow ◽  
Robert Benton ◽  
Moritz Göhler ◽  
Arnold Kühhorn
Keyword(s):  
Flow Field ◽  
Network Model ◽  
Gas Turbines ◽  
Integral Model ◽  
Design Parameters ◽  
Flow Network ◽  
Aero Engine ◽  
Air System ◽  
Secondary Air ◽  
The Impact

The rotating components in gas turbines are very highly stressed as a result of the centrifugal and thermal loads. One of the main functions of the secondary air system (SAS) is to ensure that the rotating components are surrounded by air that optimizes disc lifing and integrity. The SAS is also responsible for the blade cooling flow supply, preventing hot gas ingestion from the main annulus into the rotor-stator cavities, and for balancing the net axial load in the thrust bearings. Thus, the SAS design requires a multidisciplinary compromise to provide the above functions, while minimizing the penalty of the secondary flows on engine performance. The phenomenon known as rotor-stator drag or windage is defined as the power of the rotor moment acting on its environment. The power loss due to windage has a direct impact on the performance of the turbine and the overall efficiency of the engine. This paper describes a novel preliminary design approach to calculate the windage of the rotor-stator cavities in the front of a typical aero engine HP turbine. The new method is applied to investigate the impact of the SAS design parameters on the windage losses and on the properties of the cooling flows leading to the main annulus. Initially, a theoretical approach is followed to calculate the power losses of each part of the HPT front air feed system. Then, a 1D-network integral model of the cavities and flow passages of the HPT front is built and enhanced with detailed flow field correlations. The new 1D-flow network model offers higher fidelity regarding local effects. A result comparison between the theoretical calculation and the prediction of the enhanced flow network model puts forward the relevance of the local flow field effects in the design concept of the SAS. Using the enhanced 1D-flow network models, the SAS design parameters are varied to assess their influence on the windage and pumping power calculation. As a conclusion, the paper shows how the SAS design can have a significant influence on the HPT overall power and the air that is fed back into the turbine blade rows. Controlling these features is essential to bid a competitive technology in the aero engine industry.

Adaptive Preliminary-Design Workflow for Aero Engine Secondary Air System Cavities With an Application Case of Windage and Heat Transfer in a Rotor-Stator Cavity With Axial Through Flow

2018 ◽  
Author(s):  
Toni Wildow ◽  
Hubert Dengg ◽  
Klaus Höschler ◽  
Jonathan Sommerfeld
Keyword(s):  
Heat Transfer ◽  
Flow Field ◽  
Design Stage ◽  
Design Parameters ◽  
Preliminary Design ◽  
Geometry Model ◽  
Through Flow ◽  
Air System ◽  
Secondary Air ◽  
The Impact

At the preliminary design stage of the engine design process, the behaviour and efficiency of different engine designs are investigated and evaluated in order to find a best matching design for a set of engine objectives and requirements. The prediction of critical part temperatures as well as the reduction of the uncertainty of these predictions is decisive to bid a competitive technology in aerospace technology. Automated workflows and Design of Experiments (DOE) are widely used to investigate large number of designs and to find an optimized solution. Nowadays, technological progress in computational power as well as new strategies for data handling and management enables the implementation of large DOEs and multi-objective optimizations in less time, which also allows the consideration of more detailed investigations in early design stages. This paper describes an approach for a preliminary-design workflow that implements adaptive modelling and evaluation methods for cavities in the secondary air system (SAS). The starting point for the workflow is a parametric geometry model defining the rotating and static components. The flow network within the SAS is automatically recognized and CFD and Thermal-FE models are automatically generated using a library of generic models. Adaptive evaluation algorithms are developed and used to predict values for structural, air system and thermal behaviour. Furthermore, these models and evaluation techniques can be implemented in a DOE to investigate the impact of design parameters on the predicted values. The findings from the automated studies can be used to enhance the boundary conditions of actual design models in later design stages. A design investigation on a rotor-stator cavity with axial through flow has been undertaken using the proposed workflow to extract windage, flow field and heat transfer information from adiabatic CFD calculations for use in thermal modelling. A DOE has been set up to conduct a sensitivity analysis of the flow field properties and to identify the impact of the design parameters. Additionally, impacts on the distribution of the flow field parameters along the rotating surface are recognized, which offers a better prediction for local effects in the thermal FE model.

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