Aircra& Damping Deriva/ve Es/ma/on Using STARCCM+ Angelo Lerro, - - PowerPoint PPT Presentation

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Aircra& Damping Deriva/ve Es/ma/on Using STARCCM+ Angelo Lerro, - - PowerPoint PPT Presentation

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Aircra& Damping Deriva/ve Es/ma/on Using STARCCM+ Angelo Lerro, Ph.D. Student at Politecnico di Torino Michele Visone, CFD Manager at Blue Engineering Italy Noordwijk, 22/03/2011 Summary Introduc/on Maneuvers The Looping

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SLIDE 1

Aircra& Damping Deriva/ve Es/ma/on Using STAR‐CCM+

Noordwijk, 22/03/2011

Angelo Lerro, Ph.D. Student at Politecnico di Torino Michele Visone, CFD Manager at Blue Engineering Italy

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SLIDE 2

Summary

 Introduc/on

  • Maneuvers
  • The Looping Simula/on
  • Theory Background

 CFD Computa/on  2D Results

  • Pitching Meneuver
  • Plunging Meneuver
  • Flapping Meneuver
  • Looping Meneuver using MRF

 UAV Applica/on

  • Mesh Details and Performance
  • CFD Computa/on
  • Results

 Conclusion

1 22/03/2011 Aircra& Damping Deriva/ves Es/ma/on using STAR‐CCM+

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SLIDE 3
  • Coefficients are usually linearized and expressed as follows

Introduc.on

2 22/03/2011 Aircra& Damping Deriva/ves Es/ma/on using STAR‐CCM+

  • There are unstedy and steady terms
  • To evaluate the exact value of damping deriva/ves of Eq. 1 the following

maneuvers are usually used

  • Plunging Mo/on for deriva/ves
  • Flapping/Looping Mo/on for deriva/ves
  • Some wind tunnels are provided with special devices to perform unsteady

maneuvers.

1

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SLIDE 4

Introduc.on ‐ Maneuvers

3 22/03/2011 Aircra& Damping Deriva/ves Es/ma/on using STAR‐CCM+

  • All maneuvers performed are oscillatory mo/on, and so they depend on

frequency

  • Under the linearity hypothesis, the flapping mo/on can be obtained with

superposi/on of pitching and plunging mo/on, as follows

FLAPPING MOTION PITCHING MOTION PLUNGING MOTION

=

_

FLAPPING MOTION PITCHING MOTION PLUNGING MOTION

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SLIDE 5
  • The steady state looping maneuver can be obtained with

Introduc.on ‐ The Looping Simula.on

4 22/03/2011 Aircra& Damping Deriva/ves Es/ma/on using STAR‐CCM+

  • The looping deriva/ves are usually es/mated using the Usaf DATCOM, but it is

not very suitable for unconven/onal aircra& such modern UAVs

Whirling Arm Curling Test Section

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SLIDE 6

Introduc.on – Theory background

5 22/03/2011 Aircra& Damping Deriva/ves Es/ma/on using STAR‐CCM+

  • Under the hypothesis of poten/al flow, Theodorsen developed a compact

expression for the li& and momentum coefficients for oscilla/ng airfoils

Theodorsen

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SLIDE 7

6 22/03/2011 Aircra& Damping Deriva/ves Es/ma/on using STAR‐CCM+

CFD Computa.on (1/2)

  • We want a reliable and cost-limited method to evaluate the dynamic derivatives

using STAR-CCM+

  • Main target: No-remeshing, deformable mesh, sliding mesh, and so on…
  • Time-saving technique
  • The NACA 0012 airfoil is used to validate the new methodology
  • Second order time discretization
  • Re = 3e6
  • Spalart-Allmaras Turbulence Model
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SLIDE 8
  • The Computa/onal Domain for Oscillatory Mo/ons is the same used for

steady‐state performance: you don’t need any par/cular mesh (deforming, sliding, and so on)

  • The mo/on is imposed by Rigid Body Mo/on and Moving Reference Frame

technique applied to the whole grid.

CFD Computa.on (2/2)

22/03/2011 Aircra& Damping Deriva/ves Es/ma/on using STAR‐CCM+ 7

Pressure Outlet Velocity Inlet RBM MRF

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SLIDE 9

2D Results – Pitching Menuver (1/2)

8 22/03/2011 Aircra& Damping Deriva/ves Es/ma/on using STAR‐CCM+

  • While the airfoil is pitching an unsteady wake is generated downstream
  • The aerodynamic response is oscilla/ng itself
  • f = 10Hz; αmax = 5deg

Theodorsen STAR-CCM+

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SLIDE 10

2D Results – Pitching Menuver (2/2)

9 22/03/2011 Aircra& Damping Deriva/ves Es/ma/on using STAR‐CCM+

  • There is a very good agreement with Theodorsen theory
  • With analy/cal manipula/on it is easy to obtain the value of deriva/ves
  • STAR‐CCM+ is able to calculate with great accuracy the dynamic deriva/ves
  • ver a wide range of frequency
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SLIDE 11

2D Results – Plunging Menuver

10 22/03/2011 Aircra& Damping Deriva/ves Es/ma/on using STAR‐CCM+

  • f = 10Hz; αmax,induced = 5deg

Theodorsen STAR-CCM+

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SLIDE 12

2D Results – Flapping Menuver (1/2)

11 22/03/2011 Aircra& Damping Deriva/ves Es/ma/on using STAR‐CCM+

  • Flapping simula/ons with:
  • f = 10Hz
  • αmax = 0deg
  • qmax = 5.5rad/s

Theodorsen STAR-CCM+

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SLIDE 13

2D Results – Flapping Menuver (2/2)

12 22/03/2011 Aircra& Damping Deriva/ves Es/ma/on using STAR‐CCM+

  • There is a very good agreement with Theodorsen theory
  • STAR‐CCM+ is able to calculate with great accuracy the dynamic deriva/ves
  • ver a wide range of frequency
  • In the range of linearity the flapping mo/on can also be obtained using a

“combined mo/on” of pure pitching and plunging mo/on combined motion Theodorsen flapping motion

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SLIDE 14

2D Results – Looping Menuver using MRF

13 22/03/2011 Aircra& Damping Deriva/ves Es/ma/on using STAR‐CCM+

  • Looping maneuver with different values of

radius and q and the same velocity at the quarter of chord (V=50m/s)

  • There is a quite perfect agreement between

analy/cal data from Theodorsen theory and numerical results of STAR‐CCM+ simula/ons R = 20, q = 2.5rad/s R = 100, q = 0.5rad/s

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SLIDE 15

UAV Applica.on

Double-hull configuration*

  • Performance
  • Static Stability
  • Dynamic Stability

14 22/03/2011 Aircra& Damping Deriva/ves Es/ma/on using STAR‐CCM+

*property of Nautilus s.p.a

  • The dynamic deriva/ves are extremely important to set up aicra& models
  • In this presenta/on the looping maneuvers will be showed
  • The q‐deriva/ves evalua/on will be presented
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SLIDE 16

22/03/2011 15 Aircra& Damping Deriva/ves Es/ma/on using STAR‐CCM+

UAV Applica.on – Mesh Details and Performance

  • Sta/c performance and

sta/c stability have been evaluated

  • ~ 4E6 polyhedral cells
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SLIDE 17

Looping Maneuver Descrip/on

UAV Applica.on – CFD Computa.on

16 22/03/2011 a = 0; b = 0  Xb Yb Zb = Xw Yw Zw

TEST CASES

R

(0,0,0)

q V q Z X

Xb = Xw Zb = Zw

V V

Aircra& Damping Deriva/ves Es/ma/on using STAR‐CCM+

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SLIDE 18

UAV applica.on – Results

17 22/03/2011 Aircra& Damping Deriva/ves Es/ma/on using STAR‐CCM+

  • Steady state looping maneuver
  • The two methods are perfectly

equivalent (max devia/on less than 10%) RBM (R=60m, q=0.13rad/s) MRF (R=40m, q=0.2rad/s)

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SLIDE 19

Conclusions

18 22/03/2011 Aircra& Damping Deriva/ves Es/ma/on using STAR‐CCM+

  • STAR‐CCM+ helps us to simulate the unsteady maneuvers with an almost

perfect agreement with the analy/cal results of Theodorsen theory;

  • This allows us to validate the CFD technique used to es/mate both unsteady

dynamic deriva/ves and steady‐state dynamic deriva/ves;

  • Complete analysis of any aircra& can be carried out in order to set up a non‐

linear model

ANY QUESTIONS?