Analysis of the Unsteady Flow in an Aspirated Counter-Rotating Compressor Using the Nonlinear Harmonic Method

2009 ◽  
Author(s):  
Emanuele Guidotti ◽  
Mark G. Turner
Keyword(s):  
Flow Field ◽  
Unsteady Flow ◽  
Frequency Domain ◽  
Navier Stokes ◽  
Test Case ◽  
Numerical Accuracy ◽  
Flow Solver ◽  
Harmonic Method ◽  
Flow Change ◽  
Inlet Boundary Condition

A multistage frequency domain (Nonlinear Harmonic) Navier-Stokes unsteady flow solver has been used to analyze the flow field in the MIT (rotor/rotor) aspirated counter-rotating compressor. The numerical accuracy and computational efficiency of the Nonlinear Harmonic method implemented in Numeca’s Fine/Turbo CFD code has been demonstrated by comparing predictions with experimental data and nonlinear time-accurate solutions for the test case. The comparison is good, especially considering the big savings in time with respect to a time accurate simulation. An imposed inlet boundary condition takes into account the flow change due to the IGV (not simulated in the computational model). Details of the flow field are presented and physical explanations are provided. Also, suggestions and recommendations on the use of the Nonlinear Harmonic method are provided. From this work it can be concluded that the development of efficient frequency domain approaches enables routine unsteady flow predictions to be used in the design of modern turbomachinery.

Predicting Bladerow Interactions Using a Multistage Time-Linearized Navier-Stokes Solver

2003 ◽  
Vol 125 (1) ◽  
pp. 25-32 ◽  
Author(s):  
W. Ning ◽  
Y. S. Li ◽  
R. G. Wells
Keyword(s):  
Unsteady Flow ◽  
Frequency Domain ◽  
Test Data ◽  
Computational Efficiency ◽  
Unsteady Flows ◽  
Navier Stokes ◽  
Test Cases ◽  
Numerical Accuracy ◽  
Flow Solver ◽  
Time Marching

A multistage frequency domain (time-linearized/nonlinear harmonic) Navier-Stokes unsteady flow solver has been developed for predicting unsteady flows induced by bladerow interactions. In this paper, the time-linearized option of the solver has been used to analyze unsteady flows in a subsonic turbine test stage and the DLR transonic counter-rotating shrouded propfan. The numerical accuracy and computational efficiency of the time-linearized viscous methods have been demonstrated by comparing predictions with test data and nonlinear time-marching solutions for these two test cases. It is concluded that the development of efficient frequency domain approaches enables unsteady flow predictions to be used in the design cycles to tackle aeromechanics problems.

Predicting Bladerow Interactions Using a Multistage Time-Linearized Navier-Stokes Solver

2002 ◽  
Author(s):  
W. Ning ◽  
Y. S. Li ◽  
R. G. Wells
Keyword(s):  
Unsteady Flow ◽  
Frequency Domain ◽  
Test Data ◽  
Computational Efficiency ◽  
Unsteady Flows ◽  
Navier Stokes ◽  
Test Cases ◽  
Numerical Accuracy ◽  
Flow Solver ◽  
Time Marching

A multistage frequency domain (time-linearized/nonlinear harmonic) Navier-Stokes unsteady flow solver has been developed for predicting unsteady flows induced by bladerow interactions. In this paper, the time-linearized option of the solver has been used to analyze unsteady flows in a subsonic turbine test stage and the DLR transonic counter-rotating shrouded propfan. The numerical accuracy and computational efficiency of the time-linearized viscous methods have been demonstrated by comparing predictions with test data and nonlinear time-marching solutions for these two test cases. It is concluded that the development of efficient frequency domain approaches enables unsteady flow predictions to be used in the design cycles to tackle aeromechanics problems.

Unsteady Flow Modeling Across the Rotor/Stator Interface Using the Nonlinear Harmonic Method

2006 ◽  
Author(s):  
S. Vilmin ◽  
E. Lorrain ◽  
Ch. Hirsch ◽  
M. Swoboda
Keyword(s):  
Steady State ◽  
Unsteady Flow ◽  
Frequency Domain ◽  
Flow Simulation ◽  
Navier Stokes ◽  
Nonlinear Method ◽  
State Equations ◽  
Flow Perturbation ◽  
Time Frequency ◽  
Harmonic Method

The paper presents results of the incorporation of the harmonic nonlinear method into an existing turbomachinery Navier-Stokes code. This approach, introduced by He and Ning in 1998, can be considered as a bridge between classical steady state and full unsteady calculations, providing an approximate unsteady solution at affordable calculation costs. The unsteady flow perturbation is Fourier decomposed in time, and by a casting in the frequency domain transport equations are obtained for each time frequency. The user controls the accuracy of the unsteady solution through the order of the Fourier series. Alongside the solving of the time-averaged flow steady-state equations, each frequency requires the solving of two additional sets of conservation equations (for the real and imaginary parts of each harmonic). The method is made nonlinear by the injection of the so-called deterministic stresses, resulting from all the solved frequencies, into the time-averaged flow solver. Because of the transposition to the frequency domain, only one blade channel is required like a steady flow simulation. The presented method also features a new improved treatment that enhances the flow continuity across the rotor/stator interface by a reconstruction of the harmonics and the time-averaged flow on both sides of the interface. A non-reflective treatment is applied as well at each interface. Validation for analytical and turbomachinery test cases are presented. In particular, results are compared between the harmonic method, steady-state mixing plane and full unsteady calculations. The comparison with the reference full unsteady calculation provides a quantitative indication of the accuracy of the approach, as well as the significant gain in CPU time, whereas the comparison with classical quasi-steady state solutions indicates the gain of accuracy. A multistage compressor flow is also presented to show the capabilities of the method.

Investigation of the Unsteady Rotor Flow Field in a Single HP Turbine Stage

2000 ◽  
Author(s):  
Friedrich Kost ◽  
Frank Hummel ◽  
Maik Tiedemann
Keyword(s):  
Flow Field ◽  
Unsteady Flow ◽  
Turbine Rotor ◽  
Navier Stokes ◽  
Blade Surface ◽  
Turbine Stage ◽  
Numerical Work ◽  
Pressure Transducers ◽  
Measurement Results ◽  
Flow Vectors

Within a European project a high-pressure turbine stage was investigated at DLR, Göttingen. The investigations consisted primarily of experiments carried out in the windtunnel for Rotating Cascades (RGG), but some numerical work was also performed. Detailed measurements were carried out at mid section of a turbine rotor using a Laser-2-Focus device which served as a velocimeter measuring 2D-velocity vectors and turbulence quantities and as a tool to determine the concentration of coolant ejected at the trailing edge of the stator blades. The measurement of coolant concentration downstream of the stator and inside the rotor provided a detailed picture of the stator wake development and its interaction with the moving rotor. Axial measurement locations reached from the stator exit through the rotor to a downstream measurement plane. Measurement results are presented as instantaneous flow values. Unsteady flow vectors and turbulence intensities could be related at 16 time instants representing one rotor blade passsing period to the wake development made visible by the coolant concentration. The measured unsteady flow vectors and unsteady pressures, measured with semi-conductor pressure transducers, are compared with results from a numerical calculation using the Navier-Stokes code “TRACE-U” which allows the computation of the unsteady flow field. The measured steady and unsteady flow quantities served to validate the Navier-Stokes code. A comparison of the wake entropy trajectories outside the blade boundary layers and at the wall gives an impression of the lag between the arrival time of the wake in the freestream near the blade surface and the time the boundary layer quantities at the blade surface itself are affected.

scholarly journals Simulations of Aeroelasticity in an Annular Cascade Using a Parallel 3-Dimensional Navier-Stokes Solver

2002 ◽  
Author(s):  
Ivan McBean ◽  
Feng Liu ◽  
Kerry Hourigan ◽  
Mark Thompson
Keyword(s):  
Unsteady Flow ◽  
Flow Model ◽  
Standard Test ◽  
Navier Stokes ◽  
Test Case ◽  
Turbine Cascade ◽  
3 Dimensional ◽  
Flow Through ◽  
The Stability ◽  
Annular Cascade

A parallel multi-block Navier-Stokes solver with the k-ω turbulence model is developed to simulate the 3-dimensional unsteady flow through an annular turbine cascade. Results at mid-span are compared with the experimental results of Standard Test Case 4. Comparisons are made between 3-dimensional and 2-dimensional, and inviscid and viscous simulations. The inclusion of a viscous flow model does not greatly affect the stability of the configuration.

scholarly journals NUMERICAL INVESTIGATION OF A TONE NOISE OF THE FAN WITH CASING TREATMENT

2021 ◽  
pp. 24-38
Author(s):  
Yaroslav Druzhinin ◽  
◽  
Viktor Mileshin ◽  
Anton Rossikhin ◽  
◽  
...  
Keyword(s):  
Flow Field ◽  
Unsteady Flow ◽  
Numerical Investigation ◽  
Significant Influence ◽  
Aerodynamic Characteristics ◽  
Operational Conditions ◽  
Casing Treatment ◽  
Harmonic Method ◽  
Surge Line ◽  
Bypass Ratio

Numerical investigation of influence of a slot-type casing treatment on acoustic and aerodynamic characteristics of the fan of ultra-high bypass ratio turbofan is presented. The investigation was performed using NUMECA FINE/Turbo solver. NLH harmonic method was used to simulate the effect of casing treatment on unsteady flow field in the turbomachine. Two operational conditions were investigated – “sideline” and “approach”. The attention for the first operational condition was paid for aerodynamic characteristics. Significant influence of casing treatment on them was found especially near the surge line. At the “approach” operational conditions the attention was paid for the proper calculation of tone noise. It was shown that the installation of casing treatment leads to decrease of power of tone noise radiated through the inlet. However the power of the tone noise, radiated through the nozzle, and also the overall power of tone noise increase.

Time-Space Spectral Method for Rotor–Rotor/Stator–Stator Interactions

2019 ◽  
Vol 141 (11) ◽  
Author(s):  
Xiuquan Huang ◽  
Ding Xi Wang
Keyword(s):  
Flow Field ◽  
Spectral Method ◽  
Harmonic Balance ◽  
Harmonic Balance Method ◽  
Frequency Domain Method ◽  
Test Case ◽  
Flow Solver ◽  
Time Space ◽  
Space Harmonics

Abstract The paper presents a time-space spectral method for an efficient analysis of rotor–rotor/stator–stator interactions in the framework of the time spectral form harmonic balance method. The method treats time and space harmonics in a coherent way and allows for easy choice of time and passage through the introduction of pseudo-shaft frequency and composite frequency. The proposed method can accommodate passage to passage variation of time-averaged flow field and amplitude of unsteady flow field of a given frequency as needed for rotor–rotor/stator–stator interactions. Minimum change is required to extend an existing harmonic balance flow solver to incorporate the proposed method. The proposed method is the most concise and the simplest one of its kind so far. The first three blade rows of a two-stage fan are used as a test case to demonstrate the validity and effectiveness of the proposed method. Numerical results demonstrate the necessity of including rotor–rotor/stator–stator interaction in an analysis using a frequency-domain method and the capability of the proposed method for such a purpose. It is also concluded from the case study that extra spatial and temporal harmonics are needed to adequately analyze a rotor–rotor/stator–stator interaction.

Wind Flow Simulation Around NASA KSC Vehicle Assembly Building

2004 ◽  
Author(s):  
B. T. Vu ◽  
M. J. Verdier
Keyword(s):  
Flow Field ◽  
Flow Simulation ◽  
Navier Stokes ◽  
Wind Flow ◽  
Flow Solver ◽  
Wind Speeds ◽  
Velocity Magnitude ◽  
Operations And Maintenance ◽  
Kennedy Space ◽  
Detailed Mathematical Analysis

A model of the wind flow conditions around Kennedy Space Center (KSC) Vehicle Assembly Building (VAB) is presented. An incompressible Navier-Stokes flow solver was used to compute the flow field around fixed Launch Complex 39 (LC-39) buildings and structures. The 3-D flow field, including velocity magnitude and velocity vectors, was established to simulate the localized wind speeds and directions at specified locations in and around LC-39 buildings and structures. The results of this study not only help explain the physical phenomena of the flow patterns around LC-39 buildings but also are useful to the Shuttle personnel. Current Operations and Maintenance Requirements and Specifications (OMRS) for vehicle transfer operations are based on empirically derived historical data, and no detailed mathematical analysis of wind conditions around LC-39 structures has ever been accomplished.

A Comparison Between Full RANSE and Coupled RANSE-BEM Approaches in Ship Propulsion Performance Prediction

2013 ◽  
Author(s):  
Patrick Queutey ◽  
Gan Bo Deng ◽  
Emmanuel Guilmineau ◽  
Francesco Salvatore
Keyword(s):  
Essential Feature ◽  
Boundary Integral ◽  
Navier Stokes ◽  
Test Case ◽  
Flow Solver ◽  
Marine Propellers ◽  
Propulsion Performance ◽  
Grid Technique ◽  
Design Speed ◽  
Thrust And Torque

The paper compares the development of the coupling between a viscous Reynolds-averaged Navier-Stokes (RANSE) method and an inviscid Boundary Element method (BEM) with application to the prediction of the propulsive performance of a propelled ship. The BEM computational model is implemented into the PRO-INS code developed by CNR-INSEAN. It is based on a boundary integral formulation for marine propellers in arbitrary onset non-cavitating and cavitating flow conditions. The RANSE approach is based on the unstructured finite-volume flow solver ISIS-CFD. An essential feature for full RANSE simulations with the ISIS-CFD code developed by ECN-CNRS is in the use of a sliding grid technique to simulate the real propeller rotating behind a ship hull. The STREAMLINE tanker and propeller are proposed as validation test case. Full RANSE simulations are performed for design speed only, while hybrid RANSE/BEM self-propulsion computations are performed for a speed range. Both computations are compared with experimental data and show good agreement for ship resistance and for propeller thrust and torque.

scholarly journals Assessment of Three Turbulence Models in a Compressor Rotor

1996 ◽  
Author(s):  
A. Shabbir ◽  
J. Zhu ◽  
M. Celestina
Keyword(s):  
Turbulence Models ◽  
Model Complexity ◽  
Test Case ◽  
Numerical Accuracy ◽  
Blind Test ◽  
Compressor Rotor ◽  
Wall Boundary Conditions ◽  
Sensitivity Studies ◽  
Wide Scatter ◽  
Inlet Boundary Condition

A blind test case for a compressor rotor (ROTOR 37) was organized by the ASME/IGTI at its 1994 meeting in order to assess the predictive capabilities of the turbomachinery CFD tools. The results from the different CFD codes showed a wide scatter which in part is due to the differences in the turbulence models that were used. In order to systematically isolate the capabilities and limitations of the turbulence models, ROTOR 37 flow is computed from the same numerical platform with three different turbulence models. These include: the Baldwin-Lomax model, the standard k-ϵ model, and an improved version of this k-ϵ model. The results from the three models are compared with the experiment. We find that with increasing model complexity the results move closer to the experiment. Several sensitivity studies are carried out to bracket the uncertainty in the computations. These include the effect of: wall boundary conditions for the turbulence models; numerical accuracy of the turbulence solver; and the effect of the inlet boundary condition for turbulence.

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