Investigation of the Unsteady Flow for the Supersonic Jet Element

2011 ◽  
Vol 201-203 ◽  
pp. 2178-2181 ◽  
Author(s):  
Yong Xu ◽  
Guo Qing Zhang ◽  
Fei Wang
Keyword(s):  
Unsteady Flow ◽  
Viscous Flow ◽  
Supersonic Jet ◽  
Unsteady Flows ◽  
Time Stepping ◽  
Dual Time Stepping ◽  
Unsteady Viscous Flow ◽  
Thrust Fluctuation

The unsteady viscous flow of the supersonic jet element (SJE) was simulated numerically based on CFD technology. A dual time-stepping scheme and AMG scheme were employed to solve the unsteady flows in SJE, and the reasons of thrust fluctuation during the wall-attachment state of SJE are found out. Based on the pressure cloud and streamlines, the vortices generated by the unsteady flow on attached wall had also been investigated and drawn some conclusions.

Improvements to a dual-time-stepping method for computating unsteady flows

AIAA Journal ◽  
1997 ◽  
Vol 35 ◽  
pp. 1548-1550 ◽  
Author(s):  
S. DeRango ◽  
D. W. Zingg
Keyword(s):  
Unsteady Flows ◽  
Time Stepping ◽  
Dual Time Stepping

Numerical Solution of Incompressible Unsteady Flows in Turbomachinery

2000 ◽  
Vol 123 (3) ◽  
pp. 680-685 ◽  
Author(s):  
L. He ◽  
K. Sato
Keyword(s):  
Stokes Equations ◽  
Three Dimensional ◽  
Unsteady Flows ◽  
Navier Stokes ◽  
Time Step ◽  
Navier Stokes Equations ◽  
Flow Solver ◽  
Time Stepping ◽  
Incompressible Viscous Flow ◽  
Dual Time Stepping

A three-dimensional incompressible viscous flow solver of the thin-layer Navier-Stokes equations was developed for the unsteady turbomachinery flow computations. The solution algorithm for the unsteady flows combines the dual time stepping technique with the artificial compressibility approach for solving the incompressible unsteady flow governing equations. For time accurate calculations, subiterations are introduced by marching the equations in the pseudo-time to fully recover the incompressible continuity equation at each real time step, accelerated with a multi-grid technique. Computations of test cases show satisfactory agreements with corresponding theoretical and experimental results, demonstrating the validity and applicability of the present method to unsteady incompressible turbomachinery flows.

Numerical Simulation of the Viscous Flow for the Supersonic Jet Element

2011 ◽  
Vol 189-193 ◽  
pp. 2362-2365
Author(s):  
Yong Yu ◽  
Guo Qing Zhang ◽  
Fei Wang
Keyword(s):  
Experimental Data ◽  
Numerical Simulation ◽  
Unsteady Flow ◽  
Viscous Flow ◽  
Steady Flow ◽  
Supersonic Jet ◽  
Calculated Data ◽  
Numerical Precision ◽  
Good Agreement

The viscous flow of the supersonic jet element was simulated numerically based on CFD technology, and many tests have been done to verify the numerical precision. The results show that the calculated data are good agreement with the experimental data. So the numerical simulation of the viscous flow for the supersonic jet element is accurate and reliable, and it can be applied to investigate the steady flow and unsteady flow in supersonic jet element.

scholarly journals Blending Dual Time Stepping and Newton-Krylov Methods for Unsteady Flows

PAMM ◽  
2009 ◽  
Vol 9 (1) ◽  
pp. 597-598
Author(s):  
Philipp Birken ◽  
Antony Jameson
Keyword(s):  
Unsteady Flows ◽  
Krylov Methods ◽  
Time Stepping ◽  
Dual Time Stepping

scholarly journals Rotor Cascade Shape Optimization with Unsteady Passing Wakes Using Implicit Dual-Time Stepping and a Genetic Algorithm

2003 ◽  
Vol 9 (5) ◽  
pp. 353-361 ◽  
Author(s):  
Eun Seok Lee ◽  
George S. Dulikravich ◽  
Brian H. Dennis
Keyword(s):  
Genetic Algorithm ◽  
Unsteady Flow ◽  
Shape Optimization ◽  
Objective Function ◽  
Stokes Equations ◽  
Leading Edge ◽  
Geometric Parameters ◽  
Time Stepping ◽  
Acceleration Techniques ◽  
Dual Time Stepping

An axial turbine rotor cascade-shape optimization with unsteady passing wakes was performed to obtain an improved aerodynamic performance using an unsteady flow, Reynolds-averaged Navier-Stokes equations solver that was based on explicit, finite difference; Runge-Kutta multistage time marching; and the diagonalized alternating direction implicit scheme. The code utilized Baldwin-Lomax algebraic andk-εturbulence modeling. The full approximation storage multigrid method and preconditioning were implemented as iterative convergence-acceleration techniques. An implicit dual-time stepping method was incorporated in order to simulate the unsteady flow fields. The objective function was defined as minimization of total pressure loss and maximization of lift, while the mass flow rate was fixed during the optimization. The design variables were several geometric parameters characterizing airfoil leading edge, camber, stagger angle, and inter-row spacing. The genetic algorithm was used as an optimizer, and the penalty method was introduced for combining the constraints with the objective function. Each individual's objective function was computed simultaneously by using a 32-processor distributedmemory computer. The optimization results indicated that only minor improvements are possible in unsteady rotor/stator aerodynamics by varying these geometric parameters.

Application of Harmonic Balance Method to Numerical Model Unsteady Viscous Flow around Oscillating Cascade

2011 ◽  
Vol 50-51 ◽  
pp. 583-588
Author(s):  
Yong Qiang Shi ◽  
Qing Zhen Yang ◽  
Xin Hai Zhou
Keyword(s):  
Unsteady Flow ◽  
Harmonic Balance ◽  
Present Method ◽  
Oscillation Amplitude ◽  
Harmonic Balance Method ◽  
Hysteresis Effect ◽  
Balance Method ◽  
Time Stepping ◽  
Reduced Frequency ◽  
Dual Time Stepping

A harmonic balance approach has been developed to compute nonlinear viscous unsteady flows around oscillating blades. The computed results using two orders harmonic balance method are compared with those by conventional dual-time stepping method. Results obtained with the present method agree well with those from dual-time stepping method, which demonstrate the ability of the present analysis method to model accurately the unsteady flow. Furthermore，the present method is highly efficient. It is about 36 times fast than conventional dual-time stepping method in the present computation. Then the effects of oscillation amplitude and reduced frequency on unsteadiness of flows are studied. The analysis exploits the fact that, (1) the hysteresis effect of unsteady flow is hardly affected by oscillation amplitude, but the first harmonic unsteady pressure across the blade is proportional to oscillation amplitude; (2) the higher the reduced frequency, the wider the range of unsteady aerodynamic forces, the more intense the hysteresis effect.

scholarly journals Wake-Induced Unsteady Flows: Their Impact on Rotor Performance and Wake Rectification

1994 ◽  
Author(s):  
J. J. Adamczyk ◽  
M. L. Celestina ◽  
Jen Ping Chen
Keyword(s):  
Viscous Flow ◽  
Three Dimensional ◽  
Unsteady Flows ◽  
Flow Simulation ◽  
Blade Row ◽  
Unsteady Simulation ◽  
Unsteady Viscous Flow ◽  
Inlet Conditions ◽  
The Impact ◽  
Rectification Process

The impact of wake-induced unsteady flows on blade row performance and the wake rectification process is examined by means of numerical simulation. The passage of a stator wake through a downstream rotor is first simulated using a three dimensional unsteady viscous flow code. The results from this simulation are used to define two steady state inlet conditions for a three dimensional viscous flow simulation of a rotor operating in isolation. The results obtained from these numerical simulations are then compared to those obtained from the unsteady simulation both to quantify the impact of the wake-induced unsteady flow field on rotor performance and to identify the flow processes which impact wake rectification. Finally, the results from this comparison study are related to an existing model which attempts to account for the impact of wake-induced unsteady flows on the performance of multistage turbomachinery.

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