Large-Scale Simulation of the Clocking Impact of 2D Combustor Profile on a Two Stage High Pressure Turbine

2014 ◽  
Author(s):  
Thomas E. Dyson ◽  
David B. Helmer ◽  
James A. Tallman
Keyword(s):  
High Pressure ◽  
Large Scale ◽  
High Pressure Turbine ◽  
Cfd Simulations ◽  
Two Stage ◽  
Substantial Impact ◽  
Sliding Mesh ◽  
Wall Flow ◽  
End Wall ◽  
Film Flows

This paper presents sliding-mesh unsteady CFD simulations of high-pressure turbine sections of a modern aviation engine in an extension of previously presented work [1]. The simulation included both the first and second stages of a two-stage high-pressure turbine. Half-wheel domains were used, with source terms representing purge and film flows. The end-wall flow-path cavities were incorporated in the domain to a limited extent. The passage-to-passage variation in thermal predictions was compared for a 1D and 2D turbine inlet boundary condition. Substantial impact was observed on both first and second stage vanes despite the mixing from the first stage blade. Qualitative and quantitative differences in surface temperature distributions were observed due to different ratios between airfoil counts in the two domains.

Advanced Statistical Analysis Estimating the Heat Load Issued by Hot Streaks and Turbulence on a High-Pressure Vane in the Context of Adiabatic Large Eddy Simulations

2017 ◽  
Author(s):  
Martin Thomas ◽  
Florent Duchaine ◽  
Laurent Gicquel ◽  
Charlie Koupper
Keyword(s):  
High Pressure ◽  
Large Scale ◽  
Guide Vane ◽  
Large Eddy Simulations ◽  
High Pressure Turbine ◽  
Substantial Impact ◽  
Lean Combustion ◽  
Large Eddy ◽  
Inlet Conditions ◽  
The Impact

The next generation of lean combustion engines promises to further decrease environmental impact and cost of air traffic. Compared to the currently employed Rich Quench Lean (RQL) concept, the flow field at the exit of a lean combustion chamber is characterized by stronger variations of velocity as well as temperature and higher levels of turbulence. These specific features may have a substantial impact on the aerothermal performance of the high-pressure turbine and thereby on the efficiency of the entire engine. Indeed, high levels of turbulence in the Nozzle Guide Vane (NGV) passages locally impact the heat flux and result in globally over dimensioned cooling systems of the NGV. In this study, Large Eddy Simulations (LES) are performed on an engine representative lean combustion simulator geometry to investigate the evolution of turbulence and the migration of hot streaks through the high-pressure turbine. To investigate the impact of non-uniform stator inlet conditions on the estimated thermal stress on the NGVs, adiabatic LES predictions of the lean combustor NGV FACTOR configuration are analyzed through the use of high statistical moments of temperature and two point statistics for the assessment of turbulent quantities. Relations between temperature statistical features and turbulence are evidenced on planes through the NGV passage pointing to the role of mixing and large scale features along with marked wall temperatures that locally can largely differ from obtained mean values.

Heat Transfer and Aerodynamics of Over-Shroud Leakage Flows in a High-Pressure Turbine

2009 ◽  
Author(s):  
Knut Lehmann ◽  
Richard Thomas ◽  
Howard Hodson ◽  
Vassilis Stefanis
Keyword(s):  
Heat Transfer ◽  
High Pressure ◽  
Large Scale ◽  
Suction Side ◽  
Surface Flow ◽  
Tip Clearance ◽  
Flow Visualisation ◽  
Leakage Flow ◽  
High Pressure Turbine ◽  
High Heat Transfer

An experimental study has been conducted to investigate the distribution of the convective heat transfer on the shroud of a high pressure turbine blade in a large scale rotating rig. A continuous thin heater foil technique has been adapted and implemented on the turbine shroud. Thermochromic Liquid Crystals were employed for the surface temperature measurements to derive the experimental heat transfer data. The heat transfer is presented on the shroud top surfaces and the three fins. The experiments were conducted for a variety of Reynolds numbers and flow coefficients. The effects of different inter-shroud gap sizes and reduced fin tip clearance gaps were also investigated. Details of the shroud flow field were obtained using an advanced Ammonia-Diazo surface flow visualisation technique. CFD predictions are compared with the experimental data and used to aid interpretation. Contour maps of the Nusselt number reveal that regions of highest heat transfer are mostly confined to the suction side of the shroud. Peak values exceed the average by as much as 100 percent. It has been found that the interaction between leakage flow through the inter-shroud gaps and the fin tip leakage jets are responsible for this high heat transfer. The inter-shroud gap leakage flow causes a disruption of the boundary layer on the turbine shroud. Furthermore, the development of the large recirculating shroud cavity vortices is severely altered by this leakage flow.

150 kW Class Two-Stage Radial Inflow Condensing Steam Turbine System

2011 ◽  
Author(s):  
Kazutaka Hayashi ◽  
Hiroyuki Shiraiwa ◽  
Hiroyuki Yamada ◽  
Susumu Nakano ◽  
Kuniyoshi Tsubouchi
Keyword(s):  
High Pressure ◽  
Steam Turbine ◽  
Output Power ◽  
Power Output ◽  
Thermal Efficiency ◽  
Rotational Speed ◽  
High Pressure Turbine ◽  
Two Stage ◽  
Electrical Efficiency ◽  
Design Value

A prototype machine for a 150 kW class two-stage radial inflow condensing steam turbine system has been constructed. This turbine system was proposed for use in the bottoming cycle for 2.4 MW class gas engine systems, increasing the total electrical efficiency of the system by more than 2%. The gross power output of the prototype machine on the generator end was 150kW, and the net power output on the grid end which includes electrical consumption of the auxiliaries was 135kW. Then, the total electrical efficiency of the system was increased from 41.6% to 43.9%. The two-stage inflow condensing turbine system was applied to increase output power under the supplied steam conditions from the exhaust heat of the gas engines. This is the first application of the two-stage condensing turbine system for radial inflow steam turbines. The blade profiles of both high- and low-pressure turbines were designed with the consideration that the thrust does not exceed 300 N at the rated rotational speed. Load tests were carried out to demonstrate the performance of the prototype machine and stable output of 150 kW on the generator end was obtained at the rated rotational speed of 51,000 rpm. Measurement results showed that adiabatic efficiency of the high-pressure turbine was less than the design value, and that of the low-pressure turbine was about 80% which was almost the same as the design value. Thrust acting on the generator rotor at the rated output power was lower than 300 N. Despite a lack of high-pressure turbine efficiency, total thermal efficiency was 10.5% and this value would be enough to improve the total thermal efficiency of a distributed power system combined with this turbine system.

The Tip and Hub Leakage Flow of a Repeated Two Stage Compressor

2002 ◽  
Author(s):  
Songtao Wang ◽  
Zhongqi Wang
Keyword(s):  
Tip Vortex ◽  
Leakage Flow ◽  
Streamwise Direction ◽  
Suction Surface ◽  
Two Stage ◽  
Tip Leakage Vortex ◽  
Tip Leakage ◽  
Weak Part ◽  
Wall Flow ◽  
End Wall

End wall flow of a repeated two stage compressor at design and choke condition were studied by numerical simulation. The vortex near the hub depends on the traverse pressure gradient and sheer force induced by the hub rotation. At the design and the choke condition the hub leakage vortex is the dominant secondary flow. The position and trajectory of the tip leakage vortex at design and choke condition were also studied. At the design condition the tip leakage vortex traverse the blade channel and impinge on the middle chord of the suction surface of the adjacent blade. At the near choke condition the tip leakage vortex would go downstream along the streamwise direction. The composition of the tip vortex was also studied. It is clearly to distinguish the strong and weak part of the tip leakage vortex for design condition while at the near choke condition there is no evident weak part of the tip leakage vortex.

Hybrid RANS/LES Simulation of Combustor/Turbine Interactions

2020 ◽  
Author(s):  
Guoping Xia ◽  
Georgi Kalitzin ◽  
Jin Lee ◽  
Gorazd Medic ◽  
Om Sharma
Keyword(s):  
High Pressure ◽  
Thermal Field ◽  
Numerical Study ◽  
High Fidelity ◽  
Critical Aspect ◽  
High Pressure Turbine ◽  
Cfd Simulations ◽  
Turbine Inlet ◽  
Durability Design ◽  
Turbine Vanes

Abstract Accurate prediction of thermal field in high pressure turbines is a critical aspect of aerodynamic and durability design. This is particularly true when the flow at turbine inlet exhibits large gradients in temperature, both radially and circumferentially. In other words, in the presence of hot streaks from the combustor. In the numerical study presented in this paper, coupled high-fidelity eddy-resolving simulations of a combustor and a turbine are used to study the differences in the temperature profile at the exit of the first vane and the heat flux on the first blade, resulting from different positioning, or clocking, between the combustor fuel nozzles and turbine vanes. The resolved unsteadiness and turbulence from the combustor impacts mixing and secondary flow in the high pressure turbine. Temperature profiles from both actual combustor CFD simulations, as well as and modulated profiles with more pronounced variation, or pattern factor, are used at the turbine inlet. A threshold of the pattern factor that brings the benefit of clocking is identified. Clocking positioning between the combustor and vanes was studied for the most benefit.

Endwall Effusion Cooling System Behaviour Within a High-Pressure Turbine Cascade: Part 2—Heat Transfer and Effectiveness Measurements

2010 ◽  
Author(s):  
B. Facchini ◽  
L. Tarchi ◽  
L. Toni ◽  
S. Zecchi
Keyword(s):  
Heat Transfer ◽  
High Pressure ◽  
Large Scale ◽  
Cooling System ◽  
Main Flow ◽  
Turbine Cascade ◽  
High Pressure Turbine ◽  
Cooling Flow ◽  
Micro Holes ◽  
Element Approach

The cooling performance of a micro-holed endwall of a large-scale high pressure turbine cascade has been investigated within the European Project AITEB-2. The experimental investigation has been performed for a baseline configuration, with a smooth solid endwall and with a micro-holed endwall providing micro-jets ejection from the wall. A micro-holed endwall made of two modules was adopted in order to reduce the compound angle between the main flow and the micro jets axes. The micro-holed endwall is provided with a total amount of 3294 micro-holes with a diameter of 0.1 per cent of the blade chord. Four different cooling flow rates, from 1.2% to 2.6% of the main flow mass flow rate respectively, were investigated and the experimental results are reported in the paper. Both adiabatic effectiveness and heat transfer coefficient have been measured employing a steady state technique with Thermo-chromic Liquid Crystals (TLC). A thin stainless steel heating foil was used to generate the surface heat flux for the HTC measurements and a data reduction procedure based on a Finite Element approach has been developed to take into account the non uniform heat generation along the endwall.

Aerodynamic Optimization of High Pressure Turbine and Interstage Duct in a Two-Stage Air System for a Heavy-Duty Diesel Engine

2017 ◽  
Author(s):  
Uswah Khairuddin ◽  
Aaron W. Costall
Keyword(s):  
High Pressure ◽  
Diesel Engine ◽  
Operating Point ◽  
Heavy Duty ◽  
Aerodynamic Optimization ◽  
High Pressure Turbine ◽  
Two Stage ◽  
Turbine Wheel ◽  
Heavy Duty Diesel Engine ◽  
Heavy Duty Diesel

Turbochargers are a key technology for reducing the fuel consumption and CO2 emissions of heavy-duty internal combustion engines by enabling greater power density, which is essential for engine downsizing and downspeeding. This in turn raises turbine expansion ratio levels and drives the shift to air systems with multiple stages, which also implies the need for interconnecting ducting, all of which is subject to tight packaging constraints. This paper considers the challenges in the aerodynamic optimization of the exhaust side of a two-stage air system for a Caterpillar 4.4-litre heavy-duty diesel engine, focusing on the high pressure turbine wheel and interstage duct. Using the current production designs as a baseline, a genetic algorithm-based aerodynamic optimization process was carried out separately for the wheel and duct components in order to minimize the computational effort required to evaluate seven key operating points. While efficiency was a clear choice for the cost function for turbine wheel optimization, the most appropriate objective for interstage duct optimization was less certain, and so this paper also explores the resulting effect of optimizing the duct design for different objectives. Results of the optimization generated differing turbine wheel and interstage duct designs depending on the corresponding operating point, thus it was important to check the performance of these components at every other operating point, in order to determine the most appropriate designs to carry forward. Once the best compromise high pressure turbine wheel and interstage duct designs were chosen, prototypes of both were manufactured and then tested together against the baseline designs to validate the CFD predictions. The best performing high pressure turbine design, wheel A, was predicted to show an efficiency improvement of 2.15 percentage points, for on-design operation. Meanwhile, the optimized interstage duct contributed a 0.2 and 0.5 percentage-point efficiency increase for the high and low pressure turbines, respectively.

Unsteady Simulation of a Two-Stage Cooled High Pressure Turbine Using an Efficient Non-Linear Harmonic Balance Method

2013 ◽  
Author(s):  
Venkataramanan Subramanian ◽  
Chad H. Custer ◽  
Jonathan M. Weiss ◽  
Kenneth C. Hall
Keyword(s):  
High Pressure ◽  
Harmonic Balance ◽  
Nearest Neighbor ◽  
Harmonic Balance Method ◽  
Balance Method ◽  
High Pressure Turbine ◽  
Two Stage ◽  
Nearest Neighbor Algorithm ◽  
Blade Row ◽  
Unsteady Simulation

The harmonic balance method is a mixed time domain and frequency domain approach for efficiently solving periodic unsteady flows. The implementation described in this paper is designed to efficiently handle the multiple frequencies that arise within a multistage turbomachine due to differing blade counts in each blade row. We present two alternative algorithms that can be used to determine which unique set of frequencies to consider in each blade row. The first, an all blade row algorithm, retains the complete set of frequencies produced by a given blade row’s interaction with all other blade rows. The second, a nearest neighbor algorithm, retains only the dominant frequencies in a given blade row that arise from direct interaction with the adjacent rows. A comparison of results from a multiple blade row simulation based on these two approaches is presented. We will demonstrate that unsteady blade row interactions are accurately captured with the reduced frequency set of the nearest neighbor algorithm, and at a lower computational cost compared to the all blade row algorithm. An unsteady simulation of a two-stage, cooled, high pressure turbine cascade is achieved using the present harmonic balance method and the nearest neighbor algorithm. The unsteady results obtained are compared to steady simulation results to demonstrate the value of performing an unsteady analysis. Considering an unsteady flow through a single blade row turbine blade passage, it is further shown that unsteady effects are important even if the objective is to obtain accurate time-averaged integrated values, such as efficiency.

Disc Design and Air System Comparison Between a Single and a Two Stage High Pressure Turbine Aero Engine

2000 ◽  
Author(s):  
Fathi Ahmad ◽  
Alexander V. Mirzamoghadam
Keyword(s):  
High Pressure ◽  
Boundary Conditions ◽  
Cover Plate ◽  
High Pressure Turbine ◽  
Two Stage ◽  
Know How ◽  
Aero Engine ◽  
Structural Tests ◽  
Cooling Air ◽  
Effective Design

The design of the high pressure turbine (HPT) module of an aero engine and the method used to predict disc life and burst margin are different among the manufactures. In this paper, two different disc design methods are presented and compared, namely, the strain instability and the Chambers methods. The results of the disc study show that the strain instability method introduces low disc weight compared to the Chambers method. Both methods satisfy the burst speed requirement of 125% of the red line limit speed. The strain instability method was applied to design the disc of a single stage (SS) and of a two stage (TS) HPT configuration. The design philosophy of the SS is to run the HPT with a high rpm and a low SOT, whereas the TS design is based on low rpm and high SOT. The disc preliminary design considered the mechanical boundary conditions only without a temperature gradient. The total boundary conditions (thermal and mechanical) were then applied to the detailed disc design. A comparison between the two applied air systems of the SS and the TS design configuration was also performed. In comparing the two, the SS presents a design with low cooling air consumption, and it is also found that a cover plate is necessary for the front side of the SS configuration. The results of this study could be useful for the design engineer to know how and what is needed to accomplish a safe and effective design. Complementary thermal and structural tests should be performed to identify the limits and benefits of each approach.

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