Boundary Layer Trips for Low Reynolds Number Wind Tunnel Tests

Rona, Aldo; Soueid, Houssam

doi:10.2514/6.2010-399

Cited by 8 publications

(4 citation statements)

References 2 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…This is verified by surveying the kinetic energy spectrum downstream of the tripping devices, which displays a uniform energy cascade when this condition is met. Practical solutions for obtaining such a condition at low Reynolds numbers are presented and tested in Rona and Soueid (25) . Whereas a monotonic kinetic energy cascade in the kinetic energy spectrum is only one marker of a fully developed turbulent boundary layer, the reference velocity profiles in Table 1 have been selected based on the availability of kinetic energy spectra that document such a feature.…”

Section: Referencementioning

confidence: 99%

On the generation of the mean velocity profile for turbulent boundary layers with pressure gradient under equilibrium conditions

Rona

Monti²,

Airiau³

2012

Aeronaut. j.

View full text Add to dashboard Cite

The generation of a fully turbulent boundary layer profile is investigated using analytical and numerical methods over the Reynolds number range 300 ≤ Re θ ≤ 31000. The predictions are validated against reference wind tunnel measurements under zero streamwise pressure gradient. The analytical method is then tested for a low and moderate adverse pressure gradient. Comparison against experimental and DNS data show a good predictive ability under a zero pressure gradient and a moderate adverse pressure gardient, with the numerical method providing a complete velocity profile through the laminar sub-layer down to the wall. The application of the method is useful to computational fluid dynamic practitioners for generating an equilibrium thick turbulent boundary layer at the computational domain inflow.

show abstract

Section: Referencementioning

confidence: 99%

On the generation of the mean velocity profile for turbulent boundary layers with pressure gradient under equilibrium conditions

Rona

Monti²,

Airiau³

2012

Aeronaut. j.

View full text Add to dashboard Cite

show abstract

“…This Reynolds number mismatching leads to difficulties in guaranteeing flow similarity between the scaled tests and the full-size application. This problem is commonly overcome by the use of surface roughness element, also referred to as tripping device, or trip, placed at a strategic position on the surface of the scaled model [8][9][10].…”

Section: Introductionmentioning

confidence: 99%

Influence of Surface Roughness Geometry on Trailing Edge Wall Pressure Fluctuations and Noise

Santos,

Even,

Botero-Bolívar

et al. 2021

Preprint

View full text Add to dashboard Cite

Surface roughness elements are commonly used in wind tunnel testing to hasten the laminarturbulent transition of the boundary layer in model tests to mimic the aerodynamic effects present in the full-scale application. These devices can alter the characteristics of the turbulent boundary layer, such as the spanwise correlation length, the boundary layer thickness, the displacement thickness, etc. This not only affects the aerodynamic performance but also the aeroacoustic characteristics of the tested model. Few studies have investigated the effects of the surface roughness elements on the trailing edge near-and far-field noise. So far, the influence of roughness on the wall pressure fluctuations and spanwise coherence at the trailing edge has been left unexplored. Thus, this research addresses the effects of surface roughness geometries of different heights on the trailing edge wall pressure fluctuations, the spanwise coherence, and the far-field noise. The experiments were performed in the Aeroacoustic Wind Tunnel of the University of Twente adopting zigzag strips and novel sharkskin-like surface roughness installed in a NACA 0012 at zero angle of attack. The tested surface roughness heights ranged from 29% to 233% of the undisturbed boundary layer thickness. The wall pressure fluctuations and the far-field noise were measured for Reynolds numbers from 1.3 × 10 5 to 3.3 × 10 5 .It was observed that the surface roughness affects the low-and high-frequency range of the wall pressure spectrum, with trip heights in the range from 50% to 110% of the undisturbed boundary layer thickness having a slight level increase for low frequencies and no difference for high frequencies. The far-field noise increased for low and high frequencies as the trip height increased. The low-frequency increase is a consequence of the trip effects on the trailing edge wall pressure fluctuations, whereas for high frequencies the increase is due to the noise generated by the trip itself. Moreover, the sharkskin-like trip showed to be an effective tripping device. However, this geometry results in high levels of far-field noise in the high-frequency range.

show abstract

“…The Reynolds numbers that are obtained in the wind tunnel are too low to suitably maintain dynamic similarity. Thus, the addition of a boundary layer trip near the leading edge of the model's wing and fuselage is essential in order to overcome this obstacle; this is a widely used method in wind-tunnel tests [20,[32][33][34]. Trip strips can be any surface roughness that is added to a specific chord-wise location on the wing in order to trip the boundary layer.…”

Section: Trip Stripmentioning

confidence: 99%

A Wind-Tunnel Investigation of an Ultra-Light Wing and Ultra-Light Aircraft

Khaddage¹

View full text Add to dashboard Cite

A wind-tunnel investigation was undertaken on a scaled down rigid model of both an ultra-light wing and an ultra-light aircraft. The results of the ultra-light wing were compared to an existing computation fluid dynamics (CFD) simulation for validation purposes. The comparisons indicated that the results of the simulation did not agree with those from experimentation; it is most notably observed in the drag coefficient results as they are clearly erroneous and further work is required on developing a validated simulation. The basic performance characteristics along with a longitudinal and lateral static stability analysis were completed. It was observed that the aircraft's drag polar does not conform to a classic parabolic shape commonly used to describe conventional fixed-wing aircraft; the suspended fuselage was found to have a dominant effect on the shape of the drag polar when compared to the wing-only experiments. Furthermore, the aircraft was found to be statically stable in pitch and statically unstable in yaw. The pitch stiffness, c Mα , was determined to be -8.33 rad −1 . The weathercock stability derivative, c N β , was determined to be -0.0274 rad −1 implying directional instability.ii

show abstract

Boundary Layer Trips for Low Reynolds Number Wind Tunnel Tests

Cited by 8 publications

References 2 publications

On the generation of the mean velocity profile for turbulent boundary layers with pressure gradient under equilibrium conditions

On the generation of the mean velocity profile for turbulent boundary layers with pressure gradient under equilibrium conditions

Influence of Surface Roughness Geometry on Trailing Edge Wall Pressure Fluctuations and Noise

A Wind-Tunnel Investigation of an Ultra-Light Wing and Ultra-Light Aircraft

Contact Info

Product

Resources

About