A Free-Wake Euler and Navier-Stokes CFD Method and its Application to Helicopter Rotors Including Dynamic Stall

1993 ◽  
Author(s):  
Ganapathi R. Srinivasan
Keyword(s):  
Dynamic Stall ◽  
Navier Stokes ◽  
Helicopter Rotors ◽  
Cfd Method ◽  
Free Wake

TURNS: A Free-Wake Eule/Navier-Stokes Numerical Method for Helicopter Rotors

AIAA Journal ◽  
1993 ◽  
Vol 31 (5) ◽  
pp. 959-962 ◽  
Author(s):  
G. R. Srinivasan ◽  
J. D. Baeder
Keyword(s):  
Numerical Method ◽  
Navier Stokes ◽  
Helicopter Rotors ◽  
Free Wake

Aerodynamic Analysis of an Airfoil With Leading Edge Pitting Erosion

2017 ◽  
Vol 139 (6) ◽  
Author(s):  
Yan Wang ◽  
Ruifeng Hu ◽  
Xiaojing Zheng
Keyword(s):  
Wind Turbine ◽  
Indirect Effects ◽  
Leading Edge ◽  
Aerodynamic Performance ◽  
Navier Stokes ◽  
Distribution Area ◽  
Navier Stokes Equation ◽  
Turbine Performance ◽  
Wind Turbine Airfoil ◽  
Cfd Method

Leading edge erosion is a considerable threat to wind turbine performance and blade maintenance, and it is very imperative to accurately predict the influence of various degrees of erosion on wind turbine performance. In the present study, an attempt to investigate the effects of leading edge erosion on the aerodynamics of wind turbine airfoil is undertaken by using computational fluid dynamics (CFD) method. A new pitting erosion model is proposed and semicircle cavities were used to represent the erosion pits in the simulation. Two-dimensional incompressible Reynolds-averaged Navier–Stokes equation and shear stress transport (SST) k–ω turbulence model are adopted to compute the aerodynamics of a S809 airfoil with leading edge pitting erosions, where the influences of pits depth, densities, distribution area, and locations are considered. The results indicate that pitting erosion has remarkably undesirable influences on the aerodynamic performance of the airfoil, and the critical pits depth, density, and distribution area degrade the airfoil aerodynamic performance mostly were obtained. In addition, the dominant parameters are determined by the correlation coefficient path analysis method, results showed that all parameters have non-negligible effects on the aerodynamics of S809 airfoil, and the Reynolds number is of the most important, followed by pits density, pits depth, and pits distribution area. Meanwhile, the direct and indirect effects of these factors are analyzed, and it is found that the indirect effects are very small and the parameters can be considered to be independent with each other.

scholarly journals Airflow inside the nasal cavity: visualization using computational fluid dynamics

2010 ◽  
Vol 4 (4) ◽  
pp. 657-661 ◽  
Author(s):  
Mohammed Zubair ◽  
Vizy Nazira Riazuddin ◽  
Mohammed Zulkifly Abdullah ◽  
Rushdan Ismail ◽  
Ibrahim Lutfi Shuaib ◽  
...  
Keyword(s):  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
Nasal Cavity ◽  
Three Dimensional ◽  
Clinical Importance ◽  
Navier Stokes ◽  
Tomographic Images ◽  
Computed Tomographic ◽  
Continuity Equations ◽  
Cfd Method

Abstract Background: It is of clinical importance to examine the nasal cavity pre-operatively on surgical treatments. However, there is no simple and easy way to measure airflow in the nasal cavity. Objectives: Visualize the flow features inside the nasal cavity using computational fluid dynamics (CFD) method, and study the effect of different breathing rates on nasal function. Method: A three-dimensional nasal cavity model was reconstructed based on computed tomographic images of a healthy Malaysian adult nose. Navier-Stokes and continuity equations for steady airflow were solved numerically to examine the inspiratory nasal flow. Results: The flow resistance obtained varied from 0.026 to 0.124 Pa.s/mL at flow-rate from 7.5 L/min to 40 L/min. Flow rates by breathing had significant influence on airflow velocity and wall shear-stress in the vestibule and nasal valve region. Conclusion: Airflow simulations based on CFD is most useful for better understanding of flow phenomenon inside the nasal cavity.

Database of Sail Shapes vs. Sail Performance and Validation of Numerical Calculation for Upwind Condition

2007 ◽  
Author(s):  
Yutaka Masuyama ◽  
Yusuke Tahara ◽  
Toichi Fukasawa ◽  
Naotoshi Maeda
Keyword(s):  
Numerical Method ◽  
Vortex Lattice ◽  
Three Dimensional ◽  
Turbulence Models ◽  
Numerical Calculations ◽  
Navier Stokes ◽  
Coupling Scheme ◽  
Aerodynamic Coefficients ◽  
Lattice Method ◽  
Cfd Method

Database of full-scale three-dimensional sail shapes are presented with the aerodynamic coefficients for the upwind condition of IMS type sails. Three-dimensional shape data are used for the input of numerical calculations and the results are compared with the measured sail performance. The sail shapes and performance are measured using a sail dynamometer boat Fujin. The Fujin is a 34-foot LOA boat, in which load cells and charge coupled devices (CCD) cameras are installed to measure the sail forces and shapes simultaneously. The sailing conditions of the boat, such as boat speed, heel angle, wind speed, wind angle, and so on, are also measured. The tested sail configurations are as follows: mainsail with 130% jib, mainsail with 75% jib and mainsail alone. Sail shapes are measured at several height positions. The measured shape parameters are chord length, maximum draft, maximum draft position, entry angle at the luff and exit angle at the leech. From these parameters three-dimensional coordinates of the sails are calculated by interpolation. These three-dimensional coordinates are tabulated with the aerodynamic coefficients. Numerical calculations are performed using the measured sail shapes. The calculation methods are of two types; Reynolds-averaged Navier-Stokes (RANS)-based CFD and vortex lattice methods (VLM). A multi-block RANS-based CFD method was developed by one of the authors and is capable of predicting viscous flows and aerodynamic forces for complicated sail configuration for upwind as well as downwind conditions. Important features of the numerical method are summarized as follows: a Finite- Analytic scheme to discretize transport equations, a PISO type velocity-pressure coupling scheme, multi-block domain decomposition capability, and several choices of turbulence models depending on flows of interest. An automatic grid generation scheme is also included. Another calculation method, the vortex lattice method is also adopted. In this case, step-by-step calculations are conducted to attain the steady state of the sail in steady wind. Wake vortices are generated step-by-step, which flow in the direction of the local velocity vector. These calculated sail forces are compared with the measured one, and the validity of the numerical method is studied. The sail shape database and comparison with numerical calculations will provide a good benchmark for the sail performance analysis of the upwind condition of IMS type sails.

Flowfield Analysis of Modern Helicopter Rotors in Hover by Navier‐Stokes Method

1993 ◽  
Vol 38 (3) ◽  
pp. 3-13 ◽  
Author(s):  
G. R. Srinivasan ◽  
V. Raghavan ◽  
E. P. N. Duque ◽  
W. J. McCroskey
Keyword(s):  
Navier Stokes ◽  
Helicopter Rotors

A Navier-Stokes/full potential/free wake method for rotor flows

1997 ◽  
Author(s):  
Mert Berkman ◽  
Lakshmi Sankar ◽  
Charles Berezin ◽  
Michael Torok ◽  
Mert Berkman ◽  
...  
Keyword(s):  
Navier Stokes ◽  
Full Potential ◽  
Free Wake

Navier-Stokes/Full Potential/Free-Wake Method for Rotor Flows

1997 ◽  
Vol 34 (5) ◽  
pp. 635-640 ◽  
Author(s):  
Mert E. Berkman ◽  
Lakshmi N. Sankar ◽  
Charles R. Berezin ◽  
Michael S. Torok
Keyword(s):  
Navier Stokes ◽  
Full Potential ◽  
Free Wake

Navier-Stokes Computation on a Pivoting Doors Thrust Reverser and Comparison With Tests

1992 ◽  
Author(s):  
L. Schreiber ◽  
M. Legras
Keyword(s):  
Flow Field ◽  
Complex Geometry ◽  
Numerical Data ◽  
Navier Stokes ◽  
Complex Flow ◽  
Static Test ◽  
Development Delay ◽  
Cfd Method ◽  
Thrust Reverser ◽  
Reverse Thrust

An engine thrust reverser must meet different aerodynamic requirements to take into account the engine and airplane integration. These requirements are: - Control of the exit area in order to assess a convenient engine compatibility during the reverser operation. - Generation of reverse thrust meeting the level specified by the airframe in order to slowdown the airplane. - Mimization of the reversed flow field interaction with the airplane structure such as wing and shutters. - Avoid the flow reingestion by the engine fan. In order to reduce the tests number, to decrease the development delay and to improve aerodynamic performance, SNECMA group (SNECMA and HISPANO-SUIZA) has decided to develop a CFD method adapted to pivoting doors thrust reverser aerodynamic calculation. This method uses a Navier-Stokes 3D solver (PHOENICS code) well adapted to complex geometry and complex flow field. The mesh is generated with an analytical method and only one domain is used. The computation has been completed assuming laminar viscosity. The numerical data got with this method have been compared to static test realized on a model similar to actual CFM56-5C four doors reverser. The comparison parameters are the static pressure on the doors, the flow rate and the axial reverse thrust.

A Transonic Compressor Stage: Part 2 — CFD Simulation

2004 ◽  
Author(s):  
G. V. Hobson ◽  
A. J. Gannon ◽  
R. P. Shreeve
Keyword(s):  
Cfd Simulation ◽  
Pressure Ratio ◽  
Internal Flow ◽  
Design Tool ◽  
Experimental Results ◽  
Navier Stokes ◽  
Experimental Program ◽  
Compressor Stage ◽  
Transonic Compressor ◽  
Cfd Method

The simulation of a transonic compressor stage is presented. This stage was designed using an Euler CFD code with the intent of minimizing the use of empirical design techniques. The stage has subsequently been built and tested. More recently an existing multi-block Navier-Stokes code with a steady averaging-plane to pass information between the blade rows was used to simulate the flow through the machine. Performance maps of stage pressure ratio and efficiency at 70, 80, 90 and 100% speeds from both the Euler and Navier-Stokes CFD codes are compared with the experimental results. Details of the internal flow from the Navier-Stokes code are presented. Comparison of the design Euler CFD and experimental results showed reasonable agreement and validated its use as a design tool. Agreement between experimental and the current Navier-Stokes CFD results was good, allowing the code to be used in the viewing of the internal flow field. Improvements to the initial design CFD method are discussed in light of the experimental program and more recent simulations.

scholarly journals Feasible Concept of an Air-Driven Fan with a Tip Turbine for a High-Bypass Propulsion System

Energies ◽  
2018 ◽  
Vol 11 (12) ◽  
pp. 3350 ◽  
Author(s):  
Guoping Huang ◽  
Xin Xiang ◽  
Chen Xia ◽  
Weiyu Lu ◽  
Lei Li
Keyword(s):  
Fluid Dynamics ◽  
Carbon Dioxide Emissions ◽  
Three Dimensional ◽  
Propulsion System ◽  
Navier Stokes ◽  
Three Dimensional Flow ◽  
Low Pressure Turbine ◽  
Computational Fluid Dynamics Cfd ◽  
Cfd Method ◽  
Bypass Ratio

The reduction in specific fuel consumption (SFC) is crucial for small/mid-size cost-controllable aircraft, which is very conducive to reducing cost and carbon dioxide emissions. To decrease the SFC, increasing the bypass ratio (BPR) is an important way. Conventional high-BPR engines have several limitations, especially the conflicting spool-speed requirements of a fan and a low-pressure turbine. This research proposes an air-driven fan with a tip turbine (ADFTT) as a potential device for a high-bypass propulsion system. Moreover, a possible application of this ADFTT is introduced. Thermodynamic analysis results show that an ADFTT can improve thrust from a prototype turbofan. As a demonstration, we selected a typical small-thrust turbofan as the prototype and applied the ADFTT concept to improve this model. Three-dimensional flow fields were numerically simulated through a Reynolds averaged Navier-Stokes (RANS)-based computational fluid dynamics (CFD) method. The performance of this ADFTT has the possibility of amplifying the BPR more than four times and increasing the thrust by approximately 84% in comparison with the prototype turbofan.

Sign in / Sign up

Export Citation Format

Share Document