scholarly journals Flutter Analysis of a Transonic Fan

2002 ◽  
Author(s):  
R. Srivastava ◽  
M. A. Bakhle ◽  
T. G. Keith ◽  
G. L. Stefko
Keyword(s):  
Energy Exchange ◽  
Stokes Equations ◽  
Navier Stokes ◽  
Exchange Method ◽  
Navier Stokes Equations ◽  
Aerodynamic Damping ◽  
Aeroelastic Analysis ◽  
Flutter Analysis ◽  
Blade Shape ◽  
Transonic Fan

This paper describes the calculation of flutter stability characteristics for a transonic forward swept fan configuration using a viscous aeroelastic analysis program. Unsteady Navier-Stokes equations are solved on a dynamically deforming, body fitted, grid to obtain the aeroelastic characteristics using the energy exchange method. The non-zero inter-blade phase angle is modeled using phase-lagged boundary conditions. Results obtained show good correlation with measurements. It is found that the location of shock and variation of shock strength strongly influenced stability. Also, outboard stations primarily contributed to stability characteristics. Results demonstrate that changes in blade shape impact the calculated aerodynamic damping, indicating importance of using accurate blade operating shape under centrifugal and steady aerodynamic loading for flutter prediction. It was found that the calculated aerodynamic damping was relatively insensitive to variation in natural frequency.

scholarly journals Computation of Aerodynamic Damping for Flutter Analysis of a Transonic Fan

2011 ◽  
Author(s):  
Parthasarathy Vasanthakumar
Keyword(s):  
Phase Angle ◽  
Stokes Equations ◽  
Mode Shapes ◽  
Navier Stokes ◽  
Aerodynamic Load ◽  
Exchange Method ◽  
Flow Solver ◽  
Aerodynamic Damping ◽  
Transonic Fan ◽  
Operating Points

This paper describes the computational analysis of aerodynamic damping for prediction of flutter characteristics of a transonic fan stage that consists of a highly loaded rotor along with a tandem stator. Three dimensional, linearized Navier-Stokes flow solver TRACE is used to numerically analyse the flutter stability of the fan. The linear flow solver enables the modeling of a single blade passage to simulate the desired inter-blade phase angle. The unsteady aerodynamic load on a vibrating blade is obtained by solving the unsteady Navier-Stokes equations on a dynamically deforming grid and the energy exchange method is used to calculate the aerodynamic damping. The calculation of aerodynamic damping for the prediction of flutter characteristics of the fan rotor is carried out with and without considering the influence of the disk. The blade mode shapes from finite element modal analysis are obtained accordingly and the flutter calculations are carried out for three blade vibration modes at the design speed and at part speeds for all possible inter-blade phase angles. Two operating points, one on the working line and the other near stall are investigated at every rotational speed. Different aspects that affect the aerodynamic damping behaviour like part speed operation, variation in unsteady blade surface pressure fluctuation between operating points on the working line and at near stall and the corresponding variation in aerodynamic work, inter-blade phase angle etc., are described. This analysis primarily focuses on the variations in aerodynamic damping of the fan with and without the influence of the disk. In addition, influence and effect of shock wave on the aerodynamic damping is also discussed.

An energy method for flutter analysis of wing using one-way fluid structure coupling

2016 ◽  
Vol 231 (14) ◽  
pp. 2560-2569
Author(s):  
Jize Zhong ◽  
Zili Xu
Keyword(s):  
Energy Method ◽  
Stokes Equations ◽  
Navier Stokes ◽  
Navier Stokes Equations ◽  
Fluid Structure ◽  
Aerodynamic Damping ◽  
Wing Vibration ◽  
Flutter Analysis ◽  
Flutter Boundary ◽  
Reynolds Averaged Navier Stokes

In this paper, an energy method for flutter analysis of wing using one-way fluid structure coupling was developed. To consider the effect of wing vibration, Reynolds-averaged Navier–Stokes equations based on the arbitrary Lagrangian Eulerian coordinates were employed to model the flow. The flow mesh was updated using a fast dynamic mesh technology proposed by our research group. The pressure was calculated by solving the Reynolds-averaged Navier–Stokes equations through the SIMPLE algorithm with the updated flow mesh. The aerodynamic force for the wing was computed using the pressure on the wing surface. Then the aerodynamic damping of the wing vibration was computed. Finally, the flutter stability for the wing was decided according to whether the aerodynamic damping was positive or not. Considering the first four modes, the aerodynamic damping for wing 445.6 was calculated using the present method. The results show that the aerodynamic damping of the first mode is lower than the aerodynamic damping of higher order modes. The aerodynamic damping increases with the increase of the mode order. The flutter boundary for wing 445.6 was computed using the aerodynamic damping of the first mode in this paper. The calculated flutter boundary is consistent well with the experimental data.

scholarly journals Design Optimization of a Transonic-Fan Rotor Using Numerical Computations of the Full Compressible Navier-Stokes Equations and Simplex Algorithm

2014 ◽  
Vol 2014 ◽  
pp. 1-16 ◽  
Author(s):  
M. A. Aziz ◽  
Farouk M. Owis ◽  
M. M. Abdelrahman
Keyword(s):  
Stokes Equations ◽  
Pressure Ratio ◽  
Three Dimensional ◽  
Simplex Algorithm ◽  
Navier Stokes ◽  
Numerical Computations ◽  
Navier Stokes Equations ◽  
Pressure Losses ◽  
Optimization Parameters ◽  
Transonic Fan

The design of a transonic-fan rotor is optimized using numerical computations of the full three-dimensional Navier-Stokes equations. The CFDRC-ACE multiphysics module, which is a pressure-based solver, is used for the numerical simulation. The code is coupled with simplex optimization algorithm. The optimization process is started from a suitable design point obtained using low fidelity analytical methods that is based on experimental correlations for the pressure losses and blade deviation angle. The fan blade shape is defined by its stacking line and airfoil shape which are considered the optimization parameters. The stacking line is defined by lean, sweep, and skews, while blade airfoil shape is modified considering the thickness and camber distributions. The optimization has been performed to maximize the rotor total pressure ratio while keeping the rotor efficiency and surge margin above certain required values. The results obtained are verified with the experimental data of Rotor 67. In addition, the results of the optimized fan indicate that the optimum design is found to be leaned in the direction of rotation and has a forward sweep from the hub to mean section and backward sweep to the tip. The pressure ratio increases from 1.427 to 1.627 at the design speed and mass flow rate.

Numerical Simulation of Transonic Fan Flutter With 3D N-S CFD Code

2008 ◽  
Author(s):  
Mizuho Aotsuka ◽  
Naoki Tsuchiya ◽  
Yasuo Horiguchi ◽  
Osamu Nozaki ◽  
Kazuomi Yamamoto
Keyword(s):  
Shock Wave ◽  
Stokes Equations ◽  
Navier Stokes ◽  
Suction Surface ◽  
Navier Stokes Equations ◽  
Blade Loading ◽  
Flow Solver ◽  
Flutter Boundary ◽  
Transonic Fan ◽  
Volume Method

This paper describes the calculation of transonic stall flutter of a fan. A new CFD code has been developed and validated. The code is an unsteady 3D multi-block flow solver. The Reynolds-Averaged Navier-Stokes equations are solved using a finite volume method with Spallart-Allmaras 1 equation turbulence model. A grid deforming system is applied, so the new code is capable of simulating an oscillating blade row. This grid deforming system produces less grid distortion and the code has robustness for a blade oscillating calculation. The code has validated on an IHI’s research transonic fan rig test, and the result was in good agreement with the test data in the prediction of the flutter boundary. In the rig test at part-speed condition, stall-side flutter was experienced. In that condition, the inlet relative Mach number in the tip region is about unity. The aerodynamic work by the CFD at the near flutter condition is positive, which means that the flutter characteristic is unstable, while at other conditions the aerodynamic work is negative. The aerodynamic work increases rapidly just before the zero damping point with the increase of the blade loading. From the detailed CFD result, the shock wave on the suction surface contributes to the excitement of the blade oscillation, and the aerodynamic work of the shock wave has large value at the flutter condition.

scholarly journals Advanced Transonic Fan Design Procedure Based on a Navier-Stokes Method

1993 ◽  
Author(s):  
C. M. Rhie ◽  
R. M. Zacharias ◽  
D. E. Hobbs ◽  
K. P. Sarathy ◽  
B. P. Biederman ◽  
...  
Keyword(s):  
Stokes Equations ◽  
Design Method ◽  
Design Procedure ◽  
Cost Savings ◽  
Inviscid Flow ◽  
Navier Stokes ◽  
Compressor Cascade ◽  
Validation Data ◽  
Navier Stokes Equations ◽  
Transonic Fan

A fan performance analysis method based upon 3D steady Navier-Stokes equations is presented in this paper. Its accuracy is established through extensive code validation effort. Validation data comparisons ranging from a 2D compressor cascade to 3D fans are shown in this paper to highlight the accuracy and reliability of the code. The overall fan design procedure using this code is then presented. Typical results of this design process are shown for a current engine fan design. This new design method introduces a major improvement over the conventional design methods based on inviscid flow and boundary layer concepts. Using the Navier-Stokes design method, fan designers can confidently refine their designs prior to rig testing. This results in reduced rig testing and cost savings as the bulk of the iteration between design and experimental verification is transferred to an iteration between design and computational verification.

Effects of stator splitter blades on aerodynamic performance of a single-stage transonic axial compressor

2020 ◽  
Vol 14 (4) ◽  
pp. 7369-7378
Author(s):  
Ky-Quang Pham ◽  
Xuan-Truong Le ◽  
Cong-Truong Dinh
Keyword(s):  
Stokes Equations ◽  
Three Dimensional ◽  
Axial Compressor ◽  
Aerodynamic Performance ◽  
Numerical Results ◽  
Single Stage ◽  
Navier Stokes ◽  
Navier Stokes Equations ◽  
Operating Stability ◽  
Length Coverage

Splitter blades located between stator blades in a single-stage axial compressor were proposed and investigated in this work to find their effects on aerodynamic performance and operating stability. Aerodynamic performance of the compressor was evaluated using three-dimensional Reynolds-averaged Navier-Stokes equations using the k-e turbulence model with a scalable wall function. The numerical results for the typical performance parameters without stator splitter blades were validated in comparison with experimental data. The numerical results of a parametric study using four geometric parameters (chord length, coverage angle, height and position) of the stator splitter blades showed that the operational stability of the single-stage axial compressor enhances remarkably using the stator splitter blades. The splitters were effective in suppressing flow separation in the stator domain of the compressor at near-stall condition which affects considerably the aerodynamic performance of the compressor.

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