Numerical investigation of separation for airfoils

A. Gross, Hermann F Fasel

Research output: Chapter in Book/Report/Conference proceedingConference contribution

5 Citations (Scopus)

Abstract

Separation deteriorates airfoil performance and is generally undesirable. In this paper turbulent separation from two different airfoils is investigated. The first airfoil is a modified NACA 643-618 airfoil. At a chord based Reynolds number of Re=322,000 and for an angle of attack of α = 13.2deg a laminar separation bubble forms near the leading edge and the flow separates turbulent at about mid-chord. For these conditions "coarse" grid direct numerical simulations and unsteady hybrid simulations based on a one-equation renormalization group turbulence model and the filter-based Reynolds-averaged Navier- Stokes model were carried out. The direct simulation was found to suffer from insufficient grid resolution. Results obtained from the hybrid simulations provide an adequate match with the experimental reference data at much reduced computational cost. A procedure for "seeding" turbulence velocity fluctuations in areas where the grid resolution increases in the streamwise direction was found to have no effect on the mean flow data. The second airfoil is a generic laminar airfoil. For Re=2,630,000 and α = 23deg the flow separates near quarterchord. Unsteady Reynolds-averaged Navier-Stokes simulations show a curved separation line which is indicative of stall cells. Attempts to explain the spanwise wavelength of the unsteady and steady spanwise flow structures remained unsuccessful.

Original languageEnglish (US)
Title of host publication41st AIAA Fluid Dynamics Conference and Exhibit
StatePublished - 2011
Event41st AIAA Fluid Dynamics Conference and Exhibit 2011 - Honolulu, HI, United States
Duration: Jun 27 2011Jun 30 2011

Other

Other41st AIAA Fluid Dynamics Conference and Exhibit 2011
CountryUnited States
CityHonolulu, HI
Period6/27/116/30/11

Fingerprint

Airfoils
Direct numerical simulation
Steady flow
Flow structure
Angle of attack
Turbulence models
Turbulent flow
Reynolds number
Turbulence
Wavelength
Costs

ASJC Scopus subject areas

  • Fluid Flow and Transfer Processes
  • Energy Engineering and Power Technology
  • Aerospace Engineering
  • Mechanical Engineering

Cite this

Gross, A., & Fasel, H. F. (2011). Numerical investigation of separation for airfoils. In 41st AIAA Fluid Dynamics Conference and Exhibit

Numerical investigation of separation for airfoils. / Gross, A.; Fasel, Hermann F.

41st AIAA Fluid Dynamics Conference and Exhibit. 2011.

Research output: Chapter in Book/Report/Conference proceedingConference contribution

Gross, A & Fasel, HF 2011, Numerical investigation of separation for airfoils. in 41st AIAA Fluid Dynamics Conference and Exhibit. 41st AIAA Fluid Dynamics Conference and Exhibit 2011, Honolulu, HI, United States, 6/27/11.
Gross A, Fasel HF. Numerical investigation of separation for airfoils. In 41st AIAA Fluid Dynamics Conference and Exhibit. 2011
Gross, A. ; Fasel, Hermann F. / Numerical investigation of separation for airfoils. 41st AIAA Fluid Dynamics Conference and Exhibit. 2011.
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