The Aerodynamic Design of the Low Pressure Air Delivery Ducts for a Cooled Cooling Air System

2017 ◽  
Author(s):  
A. Spanelis ◽  
A. D. Walker ◽  
P. A. Beecroft
Keyword(s):  
Heat Exchangers ◽  
Gas Turbines ◽  
Pressure Ratio ◽  
Design Tool ◽  
Aerodynamic Design ◽  
Ansys Fluent ◽  
Baseline Design ◽  
Numerical Predictions ◽  
Air System ◽  
Cooling Air

As aero gas turbines strive for higher efficiencies and reduced fuel burn, the trend is for engine overall pressure ratio to increase. This means that engine cycle temperatures will increase and that cooling of various engine components, for example the high pressure turbine, is becoming more difficult. One solution is to employ a cooled cooling air system where some of the compressor efflux is diverted for additional cooling in a heat exchanger fed by air sourced from the by-pass duct. Design of the ducting to feed the heat exchangers with coolant air is challenging as it must route the air through the scenery present in the existing engine architecture which leads to a convoluted and highly curved system. Numerical predictions using ANSYS Fluent demonstrated that a baseline design was unsuitable due to large amounts of flow separation in the proximity of the heat exchangers. This paper is mainly concerned with the aerodynamic design of this component of the duct. In order to produce a viable aerodynamic solution a numerical design methodology was developed which significantly enhances and accelerates the design cycle. This used a Design of Experiments approach linked to an interactive design tool which parametrically controlled the duct geometry. Following an iterative process, individually optimized 2D designs were numerically assessed using ANSYS Fluent. These designs were then fed into an interactive 3D model in order to generate a final aerodynamic definition of the ducting. Further CFD predictions were then carried out to confirm the suitability of the design. RANS CFD solutions, generated, using a Reynolds stress turbulence model, suggested that the new design presented significant improvement in terms of diffusion and flow uniformity.

scholarly journals Cooling and Sealing Air System in Industrial Gas Turbine Engines

1996 ◽  
Author(s):  
A. W. Reichert ◽  
M. Janssen
Keyword(s):  
Gas Turbine ◽  
Film Cooling ◽  
Gas Turbines ◽  
State Of The Art ◽  
Cooling System ◽  
Inlet Temperature ◽  
Turbine Inlet ◽  
Air System ◽  
Calculation System ◽  
Cooling Air

Siemens heavy duty Gas Turbines have been well known for their high power output combined with high efficiency and reliability for more than 3 decades. Offering state of the art technology at all times, the requirements concerning the cooling and sealing air system have increased with technological development over the years. In particular the increase of the turbine inlet temperature and reduced NOx requirements demand a highly efficient cooling and sealing air system. The new Vx4.3A family of Siemens gas turbines with ISO turbine inlet temperatures of 1190°C in the power range of 70 to 240 MW uses an effective film cooling technique for the turbine stages 1 and 2 to ensure the minimum cooling air requirement possible. In addition, the application of film cooling enables the cooling system to be simplified. For example, in the new gas turbine family no intercooler and no cooling air booster for the first turbine vane are needed. This paper deals with the internal air system of Siemens gas turbines which supplies cooling and sealing air. A general overview is given and some problems and their technical solutions are discussed. Furthermore a state of the art calculation system for the prediction of the thermodynamic states of the cooling and sealing air is introduced. The calculation system is based on the flow calculation package Flowmaster (Flowmaster International Ltd.), which has been modified for the requirements of the internal air system. The comparison of computational results with measurements give a good impression of the high accuracy of the calculation method used.

Managing Fuel Oil Nozzle Coking to Improve Gas Turbine Availability

2000 ◽  
Author(s):  
Leo R. Burgett ◽  
Tim Mercer
Keyword(s):  
Gas Turbine ◽  
Gas Turbines ◽  
Power Plants ◽  
Fuel Oil ◽  
Power Company ◽  
Ac Motor ◽  
Air System ◽  
Oil Residue ◽  
Cooling Air ◽  
Fuel Burner

Fuel oil nozzle coking has been a continuing problem for operators of gas turbine power plants. Over the years, several “solutions” to eliminate the coking of the fuel oil have been implemented to improve plant reliability and availability. When the fuel oil nozzle is “coked”, the startup and operation of the gas turbine are impaired and an unscheduled outage is needed to clean the fuel oil nozzle. In 1997, a project was initiated to investigate the coking problem as it affects the operation of the dual fuel burner of the ABB ALSTOM POWER Inc. GT11N1 single burner (SBK) gas turbine. The GT11N1 SBK fuel oil nozzle (see FIGURE 1) was failing to operate properly because of “coked” fuel oil residue on its internal components (stationary and moveable). ABB ALSTOM POWER Inc. teamed with Savannah Electric & Power Company and collected data that indicated adequate nozzle cooling air could reduce the rate of fuel oil coking. A nozzle cooling air system modification was installed on one of the ABB ALSTOM POWER Inc. 11N1 gas turbines at the Savannah Electric & Power Company McIntosh Power Plant. The modification included an AC motor driven air blower to provide cooling air to the fuel oil nozzle after shutdown of the gas turbine. Inspection of the components inside the fuel oil nozzle showed that very little fuel oil oxidation had occurred inside the nozzle during the three-month test period. By improving the fuel oil nozzle cooling air system, the coking problem can be better managed.

scholarly journals Impact of a Cooled Cooling Air System on the External Aerodynamics of a Gas Turbine Combustion System

2017 ◽  
Vol 139 (5) ◽  
Author(s):  
A. Duncan Walker ◽  
Bharat Koli ◽  
Liang Guo ◽  
Peter Beecroft ◽  
Marco Zedda
Keyword(s):  
Gas Turbines ◽  
Pressure Loss ◽  
Total Pressure ◽  
Outer Wall ◽  
Total Pressure Loss ◽  
Test Facility ◽  
Combustion System ◽  
Air System ◽  
External Aerodynamics ◽  
Cooling Air

To manage the increasing turbine temperatures of future gas turbines a cooled cooling air system has been proposed. In such a system some of the compressor efflux is diverted for additional cooling in a heat exchanger (HX) located in the bypass duct. The cooled air must then be returned, across the main gas path, to the engine core for use in component cooling. One option is do this within the combustor module and two methods are examined in the current paper; via simple transfer pipes within the dump region or via radial struts in the prediffuser. This paper presents an experimental investigation to examine the aerodynamic impact these have on the combustion system external aerodynamics. This included the use of a fully annular, isothermal test facility incorporating a bespoke 1.5 stage axial compressor, engine representative outlet guide vanes (OGVs), prediffuser, and combustor geometry. Area traverses of a miniature five-hole probe were conducted at various locations within the combustion system providing information on both flow uniformity and total pressure loss. The results show that, compared to a datum configuration, the addition of transfer pipes had minimal aerodynamic impact in terms of flow structure, distribution, and total pressure loss. However, the inclusion of prediffuser struts had a notable impact increasing the prediffuser loss by a third and consequently the overall system loss by an unacceptable 40%. Inclusion of a hybrid prediffuser with the cooled cooling air (CCA) bleed located on the prediffuser outer wall enabled an increase of the prediffuser area ratio with the result that the system loss could be returned to that of the datum level.

Analysis of Gas Turbine Rotating Cavities by an One-Dimensional Model

2009 ◽  
Author(s):  
Riccardo Da Soghe ◽  
Bruno Facchini ◽  
Luca Innocenti ◽  
Mirko Micio
Keyword(s):  
Gas Turbine ◽  
Gas Turbines ◽  
Design Tool ◽  
Operating Conditions ◽  
Outer Flow ◽  
One Dimensional ◽  
Wide Range ◽  
Air System ◽  
Secondary Air ◽  
Radial Outflow

Reliable design of secondary air system is one of the main tasks for the safety, unfailing and performance of gas turbine engines. To meet the increasing demands of gas turbines design, improved tools in prediction of the secondary air system behavior over a wide range of operating conditions are needed. A real gas turbine secondary air system includes several components, therefore its analysis is not carried out through a complete CFD approach. Usually, that predictions are performed using codes, based on simplified approach which allows to evaluate the flow characteristics in each branch of the air system requiring very poor computational resources and few calculation time. Generally the available simplified commercial packages allow to correctly solve only some of the components of a real air system and often the elements with a more complex flow structure cannot be studied; among such elements, the analysis of rotating cavities is very hard. This paper deals with a design-tool developed at the University of Florence for the simulation of rotating cavities. This simplified in-house code solves the governing equations for steady one-dimensional axysimmetric flow using experimental correlations both to incorporate flow phenomena caused by multidimensional effects, like heat transfer and flow field losses, and to evaluate the circumferential component of velocity. Although this calculation approach does not enable a correct modeling of the turbulent flow within a wheel space cavity, the authors tried to create an accurate model taking into account the effects of inner and outer flow extraction, rotor and stator drag, leakages, injection momentum and, finally, the shroud/rim seal effects on cavity ingestion. The simplified calculation tool was designed to simulate the flow in a rotating cavity with radial outflow both with a Batchelor and/or Stewartson flow structures. A primary 1D-code testing campaign is available in the literature [1]. In the present paper the authors develop, using CFD tools, reliable correlations for both stator and rotor friction coefficients and provide a full 1D-code validation comparing, due to lack of experimental data, the in house design-code predictions with those evaluated by CFD.

scholarly journals Performance and operability of an electrically driven propulsor

2021 ◽  
pp. 146808742110663
Author(s):  
Ibrahim Eryilmaz ◽  
Huayang Li ◽  
Vassilios Pachidis ◽  
Panagiotis Laskaridis ◽  
Zi-Qiang Zhu ◽  
...  
Keyword(s):  
Electric Motor ◽  
Electric Propulsion ◽  
Design Space ◽  
Pressure Ratio ◽  
Design Tool ◽  
Aerodynamic Design ◽  
Direct Drive ◽  
Operational Flexibility ◽  
Ducted Fan ◽  
Motor Design

This manuscript discusses the operation of an electrically driven fan for a hybrid-electric propulsion system for BAe-146 aircraft. The thrust requirement is fed into an integrated cycle and aerodynamic design tool for the sizing of a ducted fan as one of the main propulsors, podded under the wing as a replacement for a turbofan engine. The electric motor design is initiated with the torque and speed requirements and with the dimensional constraints arising from the driven fan geometry. The fan operation and aerodynamic design are derived by changing the fan pressure ratio and hub-to-tip ratio to obtain a 2-D design space. Surface-mounted permanent magnet electric motor designs are mapped on the 2-D fan design space. The design and operational flexibility of the system is investigated through three scenarios. In the first scenario, the aircraft rate of climb is changed to downsize the electric motor. In the second scenario, the electric motor rated frequency is changed to increase the power density and in the third scenario the electric motor current density is changed for the same purpose. The investigated three scenarios provide design and operational guidelines for reducing the weight of the electric motor for a direct drive application.

Full Coverage Film-Cooled Blading in High Temperature Gas Turbines: Cooling Effectiveness, Profile Loss and Thermal Efficiency

1980 ◽  
Vol 102 (4) ◽  
pp. 957-963 ◽  
Author(s):  
H. Hempel ◽  
R. Friedrich ◽  
S. Wittig
Keyword(s):  
Thermal Efficiency ◽  
Gas Turbines ◽  
Pressure Ratio ◽  
Specific Work ◽  
Cooling Effectiveness ◽  
Common Component ◽  
Full Coverage ◽  
Cooling Air Flow ◽  
Cooling Air ◽  
Profile Loss

Extending data obtained from hot gas cascade measurements on the cooling effectiveness and profile loss coefficients of full coverage film-cooled blading, use is made of similarity considerations to determine the heat transfer characteristics under actual engine conditions. Of primary interest are stationary gas turbines. Calculations are made for a four-stage single shaft gas turbine with air preheat and common component efficiencies. As a representative result it is found that for a pressure ratio of π = 10 a relative cooling air flow of approximately 8 percent will be required in rising the temperature from 1173 to 1573 K. The resulting relative improvement of the thermal efficiency is 24 percent and that of the specific work about 70 percent.

scholarly journals Development of a Flexible Turbine Cooling Prediction Tool for Preliminary Design of Gas Turbines

2018 ◽  
Vol 140 (9) ◽  
Author(s):  
Feijia Yin ◽  
Floris S. Tiemstra ◽  
Arvind G. Rao
Keyword(s):  
Gas Turbines ◽  
Pressure Ratio ◽  
Engine Performance ◽  
Thermodynamic Cycle ◽  
Specific Power ◽  
Inlet Temperature ◽  
Turbine Cooling ◽  
Engine Efficiency ◽  
Semi Empirical ◽  
Cooling Air

As the overall pressure ratio (OPR) and turbine inlet temperature (TIT) of modern gas turbines are constantly being increased in the pursuit of increasing efficiency and specific power, the effect of bleed cooling air on the engine performance is increasingly becoming important. During the thermodynamic cycle analysis and optimization phase, the cooling bleed air requirement is either neglected or is modeled by simplified correlations, which can lead to erroneous results. In this current research, a physics-based turbine cooling prediction model, based on semi-empirical correlations for heat transfer and pressure drop, is developed and verified with turbine cooling data available in the open literature. Based on the validated model, a parametric analysis is performed to understand the variation of turbine cooling requirement with variation in TIT and OPR of future advanced engine cycles. It is found that the existing method of calculating turbine cooling air mass flow with simplified correlation underpredicts the amount of turbine cooling air for higher OPR and TIT, thus overpredicting the estimated engine efficiency.

Experimental and Numerical Analysis of the Flow Structure and Dust Separation Inside a Pre-Swirl Cooling Air System

2003 ◽  
Author(s):  
O. Schneider ◽  
H. J. Dohmen ◽  
F.-K. Benra ◽  
D. Brillert
Keyword(s):  
Numerical Analysis ◽  
Gas Turbine ◽  
Gas Turbines ◽  
Turbine Blades ◽  
Internal Cooling ◽  
Flow Conditions ◽  
Test Rig ◽  
Complex Flow ◽  
Air System ◽  
Cooling Air

Improvements in efficiency and performance of gas turbines require a better understanding of the internal cooling air system which provides the turbine blades with cooling air. With the increase of cooling air passing through the internal air system, a greater amount of air borne particles is transported to the film cooling holes at the turbine blade surface. In spite of their small size, these holes are critical for blockage. Blockage of only a few holes could have harmful effects on the cooling film surrounding the blade. As a result, a reduced mean time between maintenance or even unexpected operation faults of the gas turbine during operation could occur. Experience showed a complex interaction of cooling air under different flow conditions and its particle load. To get more familiar with all these influences and the system itself, a test rig has been built. With this test rig, the behavior of particles in the internal cooling air system can be studied at realistic flow conditions compared to a modern, heavy duty gas turbine. It is possible to simulate different particle sizes and dust concentrations in the coolant air. The test rig has been designed to give information about the quantity of separated particles at various critical areas of the internal air system [1]. The operation of the test rig as well as analysis of particles in such a complex flow system bear many problems, addressed in previous papers [1,2,3]. New theoretical studies give new and more accurate results, compared to the measurements. Furthermore the inspection of the test rig showed dust deposits at unexpected positions of the flow path, which will be discussed by numerical analysis.

A Contribution to the Abrasive Effect of Particles in a Gas Turbine Pre-Swirl Cooling Air System

2005 ◽  
Author(s):  
O. Schneider ◽  
F.-K. Benra ◽  
H. J. Dohmen ◽  
K. Jarzombek
Keyword(s):  
Gas Turbine ◽  
Flow Structure ◽  
Film Cooling ◽  
Gas Turbines ◽  
Test Rig ◽  
Critical Areas ◽  
Air System ◽  
Quantitative Results ◽  
Film Cooling Holes ◽  
Cooling Air

With the increase of cooling air passing through the internal air system of modern gas turbines, a greater number of airborne particles is transported to the film cooling holes in the turbine blade surface. In spite of their small size, these holes are critical for airflow and must be free of blockage. A test rig has been designed to study the quantity of separated particles at various critical areas of the internal air system. Former publications for this conference gave detailed insight into the test rig, the flow structure and the particle motion during separation. The process of separation generates abrasion on the rotating and stationary parts of the system. When considering service and maintenance or even unexpected operation faults of the gas turbine, it is important to know the location and abrasion rate of these critical areas. The flow structure within the pre-swirl cooling air system results in locally focused abrasion regions, which are investigated in this paper. New simulations, taking additional physical effects into account, are discussed in the paper. The simulation results are compared to results obtained by measurements and observations within the test rig. Qualitative and quantitative results show the ability to predict the quantity of abrasion during operation on various critical areas of the system.

Investigations of Dust Separation in a Gasturbine Pre-Swirl Cooling Air System Using New, Enhanced Simulation Methods

2005 ◽  
Author(s):  
O. Schneider ◽  
H. J. Dohmen ◽  
F. K. Benra ◽  
K. Jarzombek
Keyword(s):  
Film Cooling ◽  
Gas Turbines ◽  
Navier Stokes ◽  
Flow Conditions ◽  
System A ◽  
Air System ◽  
Physical Effects ◽  
Film Cooling Holes ◽  
Cooling Air ◽  
First Time

In the last years the leading manufacturers enhanced the performance of heavy-duty gas turbines rapidly. With the increasing amount of cooling air passing the internal air system, a rising amount of air borne particles are transported to the film cooling holes at the turbine blade surface. Due to the size, these holes are critical for blockage. Experience with gas turbines during operation showed a complex interaction of cooling air under different flow conditions and its particle load. In this paper the results of a new Lagrange-Tracking simulation algorithm based on 3D-Navier-Stokes flow solution are shown for the first time. Compared to previously shown simulations the algorithm is enhanced by models, taking additional, relevant physical effects into account. The new simulation results are compared to experimental results and former simulations.

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