scholarly journals APPLICATION OF AN EULER SOLVER TO SELECTED PROBLEMS IN FLIGHT DYNAMICS

Aviation ◽  
2007 ◽  
Vol 11 (2) ◽  
pp. 13-22
Author(s):  
Janusz Sznajder ◽  
Jerzy Zółtak
Keyword(s):  
Unsteady Flow ◽  
Steady Flow ◽  
Vortex Breakdown ◽  
Delta Wing ◽  
Flow Analysis ◽  
Vortical Flow ◽  
Flow Equations ◽  
Euler Solver ◽  
Unsteady Flow Analysis

Several applications of a Euler solver with the formulation of the flow equations in the noninertial reference system with steady and unsteady flow analysis are presented. The steady‐flow applications include determination of aerodynamic derivatives with respect to angular velocity and analysis of vortical flow over a delta wing at high angles of attack with the determination of aerodynamic coefficients and analysis of vortex breakdown. The unsteady flow analysis is applied in the simulation of a rapid manoeuvre for the determination of unsteady forces. The results of this simulation are compared with results of simulations using steady‐flow approximation in order to assess the advantages of unsteady flow analysis in the simulation of aircraft manoeuvres.

scholarly journals Computation of Time Linearized Transonic Flow in Oscillating Cascades

1993 ◽  
Author(s):  
G. Kahl ◽  
A. Klose
Keyword(s):  
Unsteady Flow ◽  
Steady Flow ◽  
Plate Theory ◽  
Design Procedure ◽  
Frequency Component ◽  
Flow Equations ◽  
Time Stepping ◽  
Standard Design ◽  
Euler Solver ◽  
Time Linear

A method for calculating the quasi-3D unsteady transonic flowfield in oscillating cascades is presented. The unsteady flow is assumed to be a small, harmonic perturbation of the non-linear steady flow, so that the steady flow problem is decoupled from the unsteady problem. As long as the vibration amplitudes remain moderate, the higher order terms in the governing equations derived under this assumption can be neglected and the describing unsteady flow equations become linear. Thus every frequency component can be calculated separately and the results be obtained by superposition. For the calculation of the steady state flow, about which the unsteady part is linearized, a finite-volume time-stepping Euler solver is used. Due to the similarity of the derived time-linear unsteady flow equations and the basic equations for the steady solver, the discretization is almost identical for both solvers. Thus it is possible to use much of the steady code with little modification for the time-linearized unsteady code. The time-linear unsteady flow equations are solved on a moving grid. This leads to a considerable simplification of the flow tangency boundary condition on the surfaces of the airfoils. Results obtained for various test cases compare favourably to flat plate theory and time-linearized potential methods as well as to experimental results from the Lausanne standard configurations. The approach presented is computationally more efficient than nonlinear unsteady Euler time-stepping methods, thus permitting application in the standard design procedure.

Unsteady Flow Analysis of Interaction Between Jet-Wake Flow and Blades of Low Solidity Cascade Diffuser in a Centrifugal Blower

2011 ◽  
Author(s):  
Daisaku Sakaguchi ◽  
Tengen Murakami ◽  
Hironobu Ueki ◽  
Masahiro Ishida ◽  
Hiroshi Hayami
Keyword(s):  
Unsteady Flow ◽  
Secondary Flow ◽  
Steady Flow ◽  
Pressure Ratio ◽  
Flow Analysis ◽  
Wake Flow ◽  
Low Flow ◽  
High Pressure Ratio ◽  
Low Solidity Cascade Diffuser ◽  
Unsteady Flow Analysis

A low solidity cascade diffuser (LSD) shows features of a wide operating range and a high pressure ratio in centrifugal compressors and blowers. According to the steady flow analysis results shown previously by the authors, the noise could be reduced effectively without deterioration of the LSD performance by means of a small blade tip-groove located at the shroud side, and a high blade loading could be achieved without stall even at the angle of attack as large as 15 deg. The high LSD performance at low flow rates was achieved by both formations of the stable and intense vortex in the shroud tip-groove and of the secondary flow moving circumferentially along the shroud wall toward the impeller exit. In the present study, the influence of the rotating jet-wake flow discharged from the impeller on the vortex in the shroud tip-groove and on the secondary flow moving circumferentially along the shroud wall were investigated by comparing the simulation results between the unsteady flow analysis and the steady flow one. It is clearly shown that the lift force of the LSD blade fluctuates periodically with the blade passing frequency, however, the flow behaviors of the vortex in the shroud tip-groove and the secondary flow on the shroud wall are little affected by the rotating jet-wake in the vaneless space.

A Three-Dimensional Viscous Transonic Inverse Design Method

2000 ◽  
Author(s):  
W. T. Tiow ◽  
M. Zangeneh
Keyword(s):  
Design Method ◽  
Flow Analysis ◽  
Three Dimensional ◽  
Viscous Effects ◽  
Flow Equations ◽  
Flow Solution ◽  
Turbomachinery Blades ◽  
A Cell ◽  
Inverse Design Method ◽  
Euler Solver

The development and application of a three-dimensional inverse methodology is presented for the design of turbomachinery blades. The method is based on the mass-averaged swirl, rV~θ distribution and computes the necessary blade changes directly from the discrepancies between the target and initial distributions. The flow solution and blade modification converge simultaneously giving the final blade geometry and the corresponding steady state flow solution. The flow analysis is performed using a cell-vertex finite volume time-marching algorithm employing the multistage Runge-Kutta integrator in conjunction with accelerating techniques (local time stepping and grid sequencing). To account for viscous effects, dissipative forces are included in the Euler solver using the log-law and mixing length models. The design method can be used with any existing solver solving the same flow equations without any modifications to the blade surface wall boundary condition. Validation of the method has been carried out using a transonic annular turbine nozzle and NASA rotor 67. Finally, the method is demonstrated on the re-design of the blades.

scholarly journals Developing Virtual Reality Visualizations for Unsteady Flow Analysis of Dinosaur Track Formation using Scientific Sketching

2019 ◽  
Vol 25 (5) ◽  
pp. 2145-2154 ◽  
Author(s):  
Johannes Novotny ◽  
Joshua Tveite ◽  
Morgan L. Turner ◽  
Stephen Gatesy ◽  
Fritz Drury ◽  
...  
Keyword(s):  
Virtual Reality ◽  
Unsteady Flow ◽  
Flow Analysis ◽  
Track Formation ◽  
Unsteady Flow Analysis

scholarly journals A Numerical Method of Unsteady Flow Analysis in Duct with Junction

1977 ◽  
Vol 43 (366) ◽  
pp. 596-604
Author(s):  
Takeshi ADACHI ◽  
Harutaka TSUJIMURA ◽  
Masamichi IMAIZUMI
Keyword(s):  
Unsteady Flow ◽  
Numerical Method ◽  
Flow Analysis ◽  
Unsteady Flow Analysis

A New Indicator for Unsteady Flow Analysis in Pressurized Irrigation Systems

2018 ◽  
Vol 32 (9) ◽  
pp. 3219-3232 ◽  
Author(s):  
Nicola Lamaddalena ◽  
Roula Khadra ◽  
Bilal Derardja ◽  
Umberto Fratino
Keyword(s):  
Unsteady Flow ◽  
Flow Analysis ◽  
Irrigation Systems ◽  
Pressurized Irrigation ◽  
Unsteady Flow Analysis

Real Gas Effect on Unsteady Flow of Natural Gases in Shock Tubes

2011 ◽  
Vol 361-363 ◽  
pp. 603-606
Author(s):  
Yu Qiang Dai ◽  
Jiu Peng Zou ◽  
Che Zhu ◽  
Jin Tao Wu ◽  
Da Peng Hu
Keyword(s):  
Unsteady Flow ◽  
Flow Analysis ◽  
Shock Tubes ◽  
Wave Rotor ◽  
Real Gas ◽  
Natural Gases ◽  
Reflection And Refraction ◽  
Real Gas Effect ◽  
Unsteady Flow Analysis ◽  
Gas Effect

The unsteady flow behaviors in devices like gas wave machines, wave rotor refrigerators and so on are complex due to real gas effect at high operational pressure and low temperature. In this work, a detail computational model for unsteady flow analysis of real natural gases is established. The real effect on unsteady behaviors of natural gases in shock tubes have been studied extensively. Results show that the non-classical flow of the gases will not exist. The discipline of reflection and refraction of various gas waves or discontinuities remain unchanged for natural gases. Attention should be paid only to the deviations between perfect gas model and real gas model for gasdynamic waves.

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