Application of Multistage CFD Analysis to Low Pressure Compressor Design

2004 ◽  
Author(s):  
Lisa Brilliant ◽  
Stanley Balamucki ◽  
George Burger ◽  
Yuan Dong ◽  
Charlie Lejambre
Keyword(s):  
Three Dimensional ◽  
Development Program ◽  
Low Pressure ◽  
Cfd Analysis ◽  
Stall Margin ◽  
Surge Margin ◽  
Flow Features ◽  
Stage Matching ◽  
Engine Development ◽  
Pressure Compressor

A Low Pressure Compressor (LPC) is unique in its requirements for wide operating range during a flight mission. As a result, the aerodynamic design involves a trade-off between performance and stall margin. The requirement to reduce engine development cost and schedule has resulted in developing LPCs during the engine validation program. With engine validation and certification schedules being compressed continuously, getting the initial design right has become critical. Multistage CFD analysis is used in the current design process to optimize the airfoils and stage matching. Three-dimensional airfoil features, such as bow, that improve secondary flow features and can be optimized using CFD. The PW6000 LPC engine test data has validated the analytical results and demonstrated surge margin and efficiency levels above the requirements. The LPC also achieved all other design objectives in its first build, representing a significant cost saving for a new centerline engine development program.

Low-Pressure Compressor Near-Stall Predictions Using Unsteady CFD Methods

2021 ◽  
Author(s):  
David Vanpouille ◽  
Dimitrios Papadogiannis ◽  
Stéphane Hiernaux
Keyword(s):  
Low Pressure ◽  
Navier Stokes ◽  
Phase Lag ◽  
Sliding Mesh ◽  
Tip Leakage ◽  
Eddy Simulation ◽  
Surge Margin ◽  
Large Eddy ◽  
Unsteady Rans ◽  
Pressure Compressor

Abstract Surge margin is critical for the safety of aeronautical compressors, hence predicting it early in the design process using CFD is mandatory. However, close to surge, steady-state Reynolds Averaged Navier-Stokes (RANS) simulations are proven inadequate. Unsteady techniques such as Unsteady RANS (URANS) and Large Eddy Simulation (LES) can provide more reliable predictions. Nevertheless, the accuracy of such methods are dependent on the method used to handle the rotor/stator interfaces. The most precise method, the sliding mesh, requires simulating the full annulus or a periodic sector, which can be very costly. Other techniques to reduce the domain exist, such as the phase-lagged approach or geometric blade scaling, but introduce restrictive assumptions on the flow at near-stall conditions. The objective of this paper is to investigate the near-stall flow of a low-pressure compressor using unsteady methods of varying fidelity: URANS with the phase lag assumption, URANS on a periodic sector and a high-fidelity LES on a smaller periodic sector achieved using geometric blade scaling. Results are compared to experimental measurements. An overall good agreement is found. Results show that the tip leakage vortex is not the origin of the stall on the studied configuration and a hub corner separation is initiated. LES further validates the (U)RANS flow predictions and brings additional insight on unsteady flow separations.

scholarly journals A Navier-Stokes Analysis of the Effect of Tip Clearance on Compressor Stall Margin

1995 ◽  
Author(s):  
Robert P. Dring ◽  
William D. Sprout ◽  
Harris D. Weingold
Keyword(s):  
Three Dimensional ◽  
Axial Compressor ◽  
Tip Clearance ◽  
Navier Stokes ◽  
Stall Margin ◽  
Multi Stage ◽  
High Pressure Compressor ◽  
Practical Tool ◽  
The Impact ◽  
Pressure Compressor

A three-dimensional Navier-Stokes calculation was used to analyze the impact of rotor tip clearance on the stall margin of a multi-stage axial compressor. This paper presents a summary of: (1) a study of the sensitivity of the results to grid refinement, (2) an assessment of the calculation’s ability to predict stall margin when the stalling row was the first rotor in a multi-stage rig environment, (3) an analysis of the impact of including the effects of the downstream stator through body force effects on the upstream rotor, and (4) the ability of the calculation to predict the impact of tip clearance on stall margin through a calculation of the rear seven airfoil rows of an eleven stage high pressure compressor rig. The result of these studies was that a practical tool is available which can predict stall margin, and the impact of tip clearance, with reasonable accuracy.

Stall Margin Improvement in Three-Stage Low Pressure Compressor by Use of Slot Type Casing Treatments

2014 ◽  
Author(s):  
F. Sh. Gelmedov ◽  
V. I. Mileshin ◽  
P. G. Kozhemyako ◽  
I. K. Orekhov
Keyword(s):  
Pressure Ratio ◽  
Axial Compressor ◽  
Low Pressure ◽  
Design Parameters ◽  
Experimental Investigations ◽  
Stable Operation ◽  
Local Flow ◽  
Flow Passage ◽  
Stall Margin ◽  
Pressure Compressor

The Central Institute of Aviation Motors (CIAM) has been engaged in the development of methods and technologies extending the range of stable operation for GTE axial compressors on the basis of systematic experimental and theoretical investigations of processes before and after flow disturbances for many years. The general sources of experimental data were stage models of various types. They are first supersonic stages with 0.3–0.45 hub ratio and subsonic stages with 0.75 hub ratio, as well as high-loaded stages with low aspect ratio. As a result of these investigations, a structural configuration of the casing treatment (CT) was designed to prevent local flow separation on flow passage surfaces of a compressor stage. The CT structure includes the following components: - Slotted spacer installed above the inlet rotor section; - Attached ring covering the slotted spacer. An approximate procedure for selecting the optimal CT geometric parameters and their interrelations was developed for CT designing. Using this procedure, special investigations were completed and detected the CT effects on operation of the axial compressor. These effects are: - Effect of air back and forward leakage through slots between the blade tips and the inlet rotor section; - Effect of stall deceleration in the stage flow passage; - Pulsation damping at the stage tip when flowing around the CT slotted spacer. Based on this methodology, CT prototypes were developed and tested in various single-stage and multi-stage compressors. As an example of CT advantages, we can show test results for a three-stage low-pressure compressor (LPC) designed by CIAM. The LPC in take-off conditions provides the following design parameters: - Pressure ratio: 3.4; - Corrected tip speed: 418 m/s; - Stall margin: 20% … 21% within 0.5–1.0 corrected RPM. According to experimental investigations, the use of CT results in a considerable increase in LPC stall margin without losses in other design parameters. Additionally, the results of 3D viscous flow calculation are shown for compressor performance analysis.

A Three-Dimensional Diffuser Design for the Retrofit of a Low Pressure Turbine Using In-House Exhaust Design System

2011 ◽  
Author(s):  
Sungho Yoon ◽  
Felix Joe Stanislaus ◽  
Thomas Mokulys ◽  
Gurnam Singh ◽  
Martin Claridge
Keyword(s):  
Three Dimensional ◽  
Low Pressure ◽  
Geometric Constraints ◽  
Design System ◽  
Exhaust Hood ◽  
Three Dimensional Flow ◽  
Strongly Coupled ◽  
Dimensional Flow ◽  
Flow Features ◽  
Last Stage

The performance of the last stage of a Low Pressure (LP) steam turbine is strongly coupled with the downstream exhaust hood performance. In particular, the effect of the diffuser within the exhaust hood on the pressure recovery is very important in retrofitting existing machines, which dictate many geometric constraints. Alstom’s in-house Exhaust Design System (EDS) simulates the three-dimensional flow in the exhaust hood by coupling the last stage blades and the exhaust hood. This EDS system can be used to design an LP diffuser in the exhaust hood and to achieve the required performance targets. In the first part of this paper, the EDS system is validated against measurements within model turbines, which represent both a standard machine as well as a retrofit machine. In the second part of this paper, an LP diffuser was redesigned to improve the performance using the EDS method. To begin with, an axi-symmetric diffuser was designed using numerical simulations of a passage in the last stage turbine as well as a slice of the diffuser and the exhaust hood. By carefully controlling the profile of the diffuser casing, the flow separation at the original casing walls was reduced significantly and this, in turn, improved the performance of the turbine substantially. Then, the full geometry of the exhaust hood was modeled in order to investigate the effect of the three-dimensional flow features. Based on the examined flow features, an asymmetric change was introduced to the diffuser casing to improve the three-dimensional flow structure. This new asymmetric diffuser was found to maximize the exhaust performance.

1995 ASME Gas Turbine Award Paper: Development and Application of a Multistage Navier–Stokes Flow Solver: Part II—Application to a High-Pressure Compressor Design

1998 ◽  
Vol 120 (2) ◽  
pp. 215-223 ◽  
Author(s):  
C. R. LeJambre ◽  
R. M. Zacharias ◽  
B. P. Biederman ◽  
A. J. Gleixner ◽  
C. J. Yetka
Keyword(s):  
High Pressure ◽  
Three Dimensional ◽  
Tip Clearance ◽  
Navier Stokes ◽  
Flow Solver ◽  
Stall Margin ◽  
High Pressure Compressor ◽  
Compressor Design ◽  
Flow Through ◽  
Pressure Compressor

Two versions of a three-dimensional multistage Navier–Stokes code were used to optimize the design of an eleven-stage high-pressure compressor. The first version of the code utilized a “mixing plane” approach to compute the flow through multistage machines. The effects due to tip clearances and flowpath cavities were not modeled. This code was used to minimize the regions of separation on airfoil and endwall surfaces for the compressor. The resulting compressor contained bowed stators and rotor airfoils with contoured endwalls. Experimental data acquired for the HPC showed that it achieved 2 percent higher efficiency than a baseline machine, but it had 14 percent lower stall margin. Increased stall margin of the HPC was achieved by modifying the stator airfoils without compromising the gain in efficiency as demonstrated in subsequent rig and engine tests. The modifications to the stators were defined by using the second version of the multistage Navier–Stokes code, which models the effects of tip clearance and endwall flowpath cavities, as well as the effects of adjacent airfoil rows through the use of “bodyforces” and “deterministic stresses.” The application of the Navier–Stokes code was assessed to yield up to 50 percent reduction in the compressor development time and cost.

scholarly journals Development and Application of a Multistage Navier-Stokes Flow Solver: Part II — Application to a High Pressure Compressor Design

1995 ◽  
Author(s):  
C. R. LeJambre ◽  
R. M. Zacharias ◽  
B. P. Biederman ◽  
A. J. Gleixner ◽  
C. J. Yetka
Keyword(s):  
High Pressure ◽  
Three Dimensional ◽  
Tip Clearance ◽  
Navier Stokes ◽  
Flow Solver ◽  
Stall Margin ◽  
High Pressure Compressor ◽  
Compressor Design ◽  
Flow Through ◽  
Pressure Compressor

Two versions of a three dimensional multistage Navier-Stokes code were used to optimize the design of an eleven stage high pressure compressor. The first version of the code utilized a “mixing plane” approach to compute the flow through multistage machines. The effects due to tip clearances and flowpath cavities were not modeled. This code was used to minimize the regions of separation on airfoil and endwall surfaces for the compressor. The resulting compressor contained bowed stators and rotor airfoils with contoured endwalls. Experimental data acquired for the HPC showed that it achieved 2% higher efficiency than a baseline machine, but it had 14% lower stall margin. Increased stall margin of the HPC was achieved by modifying the stator airfoils without compromising the gain in efficiency as demonstrated in subsequent rig and engine tests. The modifications to the stators were defined by using the second version of the multistage Navier-Stokes code, which models the effects of tip clearance and endwall flowpath cavities, as well as the effects of adjacent airfoil rows through the use of “bodyforces” and “deterministic stresses”. The application of the Navier-Stokes code was assessed to yield up to 50% reduction in the compressor development time and cost.

scholarly journals Application of Composite Materials in an Upgraded Engine Low-Pressure Compressor for a Regional Passenger Aircraft

Inventions ◽  
2021 ◽  
Vol 6 (3) ◽  
pp. 54
Author(s):  
Yury Ravikovich ◽  
Alexander Arkhipov ◽  
Alexander Shakhov ◽  
Timur Erofeev
Keyword(s):  
Composite Materials ◽  
Experimental Studies ◽  
Three Dimensional ◽  
Dynamic Strength ◽  
Low Pressure ◽  
Final Decision ◽  
Structural Elements ◽  
Safety Margins ◽  
Three Dimensional Finite Element ◽  
Pressure Compressor

Computational and experimental studies have been carried out to evaluate the robustness and durability of components produced of polymer composite materials (PCM), as a part of the modernization of the low-pressure compressor (LPC) of the engine for the regional aircraft. For a preliminary assessment of the static and dynamic strength of the parts, a series of three-dimensional finite element calculations and tests of laboratory specimens, structural elements cut from finished parts, have been performed. Testing the laboratory samples made it possible to compare the obtained mechanical properties with the properties declared by PCM suppliers and to conduct a mor e correct assessment of the safety margins of the parts. To decide whether to install parts on the engine, fatigue and erosion tests of the structural elements cut from the finished parts were carried out. The final decision on the performance of the PCM parts was made after testing them as part of the upgraded LPC on the engine. The criterion for evaluating the erosion resistance of PCM parts has been introduced, which makes it possible to assess their performance during operation.

Performance Analysis of a Low-Pressure Three-Stage Axial Compressor

2004 ◽  
Author(s):  
Sivakumar Subramanian ◽  
B. V. S. S. S. Prasad ◽  
S. Krishnan ◽  
C. Janakamma
Keyword(s):  
Three Dimensional ◽  
Axial Compressor ◽  
Low Pressure ◽  
Detailed Knowledge ◽  
Rotating Blade ◽  
Multi Stage ◽  
Challenging Tasks ◽  
Flow Features ◽  
Flow Through ◽  
Compressor Performance

Prediction of three-dimensional flow through a multi-stage axial compressor involving multiple frames of reference is one of the challenging tasks in CFD. When the axial gap between the stationary and rotating blade rows is reduced, the blade row interactions become important. Therefore, a detailed knowledge of flow features is essential for the optimum design of multi stage compressor. As the design and conduct of experiments and evaluation of compressor performance is expensive and time consuming, many aerospace industries prefer to obtain the same information by the computational efforts. In this context, a number of CFD codes for modelling and analysis of turbomachinery flows are used. The most exigent aspect of simulating multi-stage compressor is representing the interactions between the rotor and stator. The present work is to find out the best-suited method for the analysis of a low-pressure three-stage compressor that gives reliable results. The motivation for this effort is derived from the inability to consistently compare predicted performance parameters obtained from using the interface models with the experimental results, which is especially true for off-design operation.

CFD-Based Throughflow Analysis of Transonic Flows in Steam Turbines

2019 ◽  
Author(s):  
Martina Ricci ◽  
Roberto Pacciani ◽  
Michele Marconcini ◽  
Paolo Macelloni ◽  
Stefano Cecchi ◽  
...  
Keyword(s):  
Body Force ◽  
Force Fields ◽  
Three Dimensional ◽  
Low Pressure ◽  
Computational Time ◽  
Steam Turbines ◽  
Real Gas ◽  
Flow Features ◽  
Cfd Analyses ◽  
The Impact

Abstract A CFD-based throughflow solver is applied to the meridional analysis of low-pressure steam turbine modules. The throughflow code inherits its numerical scheme from a state-of-the-art CFD solver (TRAF code) and incorporates real gas capabilities, three-dimensional flow features and spanwise mixing models. Secondary flow effects are introduced via a concentrated vortex model. Tip gap and shroud leakage effects are modelled in terms of source vectors in the system of governing equations. The impact of part-span shrouds and snubbers are accounted for, on a local basis, through suitable body force fields. The AUSM+-up upwind strategy has been adopted as a basis to construct a numerical flux scheme explicitly suited for throughflow applications. The original formulation has been adapted to handle real gas flows and to embed the treatment of body force fields in a fully consistent framework. The capability of the procedure is assessed by analysing the low-pressure modules of two large steam turbines designed and manufactured by Ansaldo Energia. These 3-stage modules include rotor tip shrouds and part-span snubbers, and feature supersonic flow and large blade twist. Throughflow predictions in terms of main performance figures and radial distributions of flow quantities are compared to experimental data and 3D steady viscous analyses. It will be shown how the proposed CFD-based throughflow model can be fruitfully used in the early stages of the design as it delivers predictions of comparable accuracy with 3D CFD analyses at a fraction of the computational time.

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