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.

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.

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.

Impacts of Engine Secondary Air System Uncertainties on Gas Turbine Compressor Heat Transfer

2010 ◽  
Author(s):  
Sohail Alizadeh ◽  
Naveen Gopinathrao
Keyword(s):  
Heat Transfer ◽  
Uncertainty Quantification ◽  
Gas Turbine ◽  
Operating Conditions ◽  
Design Parameters ◽  
Influence Coefficient ◽  
Resource Requirement ◽  
Uncertainty Sources ◽  
Air System ◽  
Secondary Air

The compressor is a particularly sensitive component in a gas turbine engine. Variations from design geometry or operating conditions can have detrimental effects on performance, efficiency and compressor life. In this work the propagation of secondary air system operational uncertainty sources on a rotor-stator cavity at the front of a large turbofan IPC are assessed. The calculations are carried through from appropriate Computational Fluid Dynamics (CFD) analyses, characterising the flow and heat transfer in the cavity adjacent to an IP1 disc, to the FE Thermo-mechanical calculations. The application provides an example demonstration how uncertainty quantification may be undertaken for compressor analysis involving intensive CFD computations. The non-deterministic solution provides probabilistic definitions for disc temperatures and blade tip clearances, as key parameters in the design of the component. Whilst CFD has found increasing use in gas turbine air system R&D and design applications, resource requirement has almost always limited its use to deterministic single-input single-output cases. Here, by employing efficient uncertainty quantification based on Polynomial Chaos Methodologies to CFD, the air mass flow and temperature feed to the cavity are treated as operational uncertainty sources. Both single variable and multi-variable sources are considered. The CFD-FE link is established through a Temperature Influence Coefficient methodology and in propagating and managing the uncertainties through both analyses, means and standard deviations in the key design parameters are derived. The value of such a methodology in contrast to deterministic calculations is discussed from the view point of the designer with reference to component temperatures and thermal growths.

An Approximate Method for Intact Stability of Fishing Vessels

1999 ◽  
Vol 36 (03) ◽  
pp. 171-174
Author(s):  
Hüseyin Yilmaz ◽  
Abdi Kükner
Keyword(s):  
Design Stage ◽  
Design Parameters ◽  
Preliminary Design ◽  
Ship Stability ◽  
Fishing Vessels ◽  
Initial Stability ◽  
Intact Stability ◽  
Preliminary Design Stage ◽  
Reduce Risk ◽  
Vessel Stability

It is well known that stability is the most important safety requirement for ships. One should have some information on ship stability at the preliminary design stage in order to reduce risk. Initial stability of ships is an important criterion and can be closely evaluated in terms of form parameters and vertical center of gravity. In this study, using some sample ship data, approximate formulations are derived by means of regression analysis for the calculations expressed in terms of ship preliminary design parameters that can easily provide approximate GM calculations. Thus designers can be provided with ship stability at the preliminary design stage, and also a set of appropriate design parameters for improving vessel stability can easily be determined.

Virtual Gas Turbines Part II: an Automated Whole-Engine Secondary Air System Model Generation

2021 ◽  
Author(s):  
Davendu Y. Kulkarni ◽  
Luca di Mare
Keyword(s):  
Gas Turbine ◽  
Network Model ◽  
Design Analysis ◽  
Model Generation ◽  
Time Cost ◽  
Flow Network ◽  
Turbine Engine ◽  
Geometry Model ◽  
Air System ◽  
Secondary Air

Abstract The design and analysis of the secondary air system (SAS) of gas turbine engine is a complex and time-consuming process because of its complicated geometry topology. The conventional SAS design-analysis model generation process is quite tedious, time consuming. It is still heavily dependent on human expertise and thus incurs high time-cost. This paper presents an automated, whole-engine SAS flow network model generation methodology. During the SAS preprocessing step, the method accesses a pre-built whole-engine geometry model created using a novel, in-house, feature-based geometry modelling environment. It then transforms the engine geometry features into the features suitable for SAS flow network analysis. The proposed method not only extracts the geometric information from the computational geometry but also retrieves additional non-geometric attributes such as, rotational frames, boundary types, materials and boundary conditions etc. Apart from ensuring geometric consistency, this methodology also establishes a bi-directional information exchange protocol between engine geometry model and SAS flow network model, which enables making engine geometry modifications based on SAS analysis results. The application of this feature mapping methodology is demonstrated by generating the secondary air system (SAS) flow network model of a modern three-shaft gas turbine engine. This capability is particularly useful for the integration of geometry modeler with the simulation framework. The present SAS model is generated within a few minutes, without any human intervention, which significantly reduces the SAS design-analysis time-cost. The proposed method allows performing a large number of whole-engine SAS simulations, design optimisations and fast re-design activities.

scholarly journals An Approximate Method for Calculation of Mean Statistical Value of Ship Service Speed on a Given Shipping Line , Useful in Preliminary Design Stage

2015 ◽  
Vol 22 (1) ◽  
pp. 28-35
Author(s):  
Katarzyna Żelazny
Keyword(s):  
Wind Waves ◽  
Parametric Method ◽  
Weather Conditions ◽  
Economic Effects ◽  
Design Stage ◽  
Design Parameters ◽  
Preliminary Design ◽  
Screw Propeller ◽  
Calm Water ◽  
Preliminary Design Stage

Abstract During ship design, its service speed is one of the crucial parameters which decide on future economic effects. As sufficiently exact calculation methods applicable to preliminary design stage are lacking the so called contract speed which a ship reaches in calm water is usually applied. In the paper [11] a parametric method for calculation of total ship resistance in actual weather conditions (wind, waves, sea current), was presented. This paper presents a parametric model of ship propulsion system (screw propeller - propulsion engine) as well as a calculation method, based on both models, of mean statistical value of ship service speed in seasonal weather conditions occurring on shipping lines. The method makes use of only basic design parameters and may be applied in preliminary design stage.

Flow Structure and Heat Transfer in Stagnation Flow CVD Reactor

2010 ◽  
Author(s):  
Nasir Memon ◽  
Yogesh Jaluria
Keyword(s):  
Heat Transfer ◽  
Flow Structure ◽  
Atmospheric Pressure ◽  
Gas Flow ◽  
Flow Reactor ◽  
Chemical Vapor ◽  
Design Parameters ◽  
Stagnation Flow ◽  
Inlet Length ◽  
The Impact

An experimental study is undertaken to investigate the flow structure and heat transfer in a stagnation flow Chemical Vapor Deposition (CVD) reactor at atmospheric pressure. It is critical to develop models that predict flow patterns in such a reactor to achieve uniform deposition across the substrate. Free convection can negatively affect the gas flow as cold inlet gas impinges on the heated substrate, leading to vortices and disturbances in the normal flow path. This experimental research will be used to understand the buoyancy-induced and momentum-driven flow structure encountered in an impinging jet CVD reactor. Investigations are conducted for various operating and design parameters. A modified stagnation flow reactor is built where the height between the inlet and substrate is reduced when compared to a prototypical stagnation flow reactor. By operating such a reactor at certain Reynolds and Grashof numbers it is feasible to sustain smooth and vortex free flow at atmospheric pressure. The modified stagnation flow reactor is compared to other stagnation flow geometries with either a varied inlet length or varied heights between the inlet and substrate. Comparisons are made to understand the impact of such geometric changes on the flow structure and the thermal boundary layer. In addition, heat transfer correlations are obtained for the substrate temperature. Overall, the results obtained provide guidelines for curbing the effects of buoyancy and for improving the flow field to obtain greater film uniformity when operating a stagnation flow CVD reactor at atmospheric pressure.

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.

An Approximate Method for Cross Curves of Cargo Vessels

2001 ◽  
Vol 38 (02) ◽  
pp. 92-94
Author(s):  
Huseyin Yilmaz ◽  
Mesut Giiner
Keyword(s):  
Prediction Method ◽  
Design Stage ◽  
Series Data ◽  
Design Parameters ◽  
Preliminary Design ◽  
Hull Form ◽  
Beam Depth ◽  
Preliminary Design Stage ◽  
The Mathematical Model ◽  
Load Conditions

In this study, a formula is presented to estimate cross curves of cargo vessels and to predict statical stability at the preliminary design stage of the vessel. The predictive technique is obtained by regression analysis of systematically varied cargo vessel series data. In order to achieve this procedure, some cargo vessel forms are generated using Series-60. The mathematical model in this predictive technique is constructed as a function of design parameters such as length, beam, depth, draft, and block coefficient. The prediction method developed in this work can also be used to determine the effect of specific hull form parameters and the load conditions on stability of cargo vessels. The present method is applied to a cargo vessel and then the results of the actual ship are compared with those of regression values.

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.

Sign in / Sign up

Export Citation Format

Share Document