TY - GEN
T1 - Evaluation of free-stream turbulence intensity in the Mars Wind Tunnel under low Reynolds number conditions
AU - Numata, Daiju
AU - Tsuchiya, Takaaki
AU - Asai, Keisuke
PY - 2013/8/19
Y1 - 2013/8/19
N2 - It is known that the aerodynamic characteristics of low-Reynolds number airfoils be are susceptible to the free-stream turbulence in a wind tunnel. To control the turbulence intensity of the Mars Wind Tunnel (MWT) at Tohoku University, we built three types of turbulence grids and evaluated their effects on the flow fields at low pressure conditions. A hot-wire anemometer was used to measure velocity fluctuations in the test section for total pressures of 5, 11 and 22 kPa and the free-stream turbulence intensity was evaluated. The frequency analysis showed that the flow conditions were classified into four types depending on total pressure and flow velocity. The flow with no grid was almost laminar and the corresponding turbulence intensity was ranged from 0.5 up to 1.5 %. The effect of the turbulence grid was dependent on the grid type, particularly on a wire diameter. Using relatively thick wires, the turbulence intensity could be raised up to 3.0 %. The flow behind the grids was mostly turbulent except for some transitional conditions. These results indicated that, by using a properly-designed turbulence grid, we could produce relatively large free-stream fluctuations even at low Reynolds number condition.
AB - It is known that the aerodynamic characteristics of low-Reynolds number airfoils be are susceptible to the free-stream turbulence in a wind tunnel. To control the turbulence intensity of the Mars Wind Tunnel (MWT) at Tohoku University, we built three types of turbulence grids and evaluated their effects on the flow fields at low pressure conditions. A hot-wire anemometer was used to measure velocity fluctuations in the test section for total pressures of 5, 11 and 22 kPa and the free-stream turbulence intensity was evaluated. The frequency analysis showed that the flow conditions were classified into four types depending on total pressure and flow velocity. The flow with no grid was almost laminar and the corresponding turbulence intensity was ranged from 0.5 up to 1.5 %. The effect of the turbulence grid was dependent on the grid type, particularly on a wire diameter. Using relatively thick wires, the turbulence intensity could be raised up to 3.0 %. The flow behind the grids was mostly turbulent except for some transitional conditions. These results indicated that, by using a properly-designed turbulence grid, we could produce relatively large free-stream fluctuations even at low Reynolds number condition.
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M3 - Conference contribution
AN - SCOPUS:84881459657
SN - 9781624101816
T3 - 51st AIAA Aerospace Sciences Meeting including the New Horizons Forum and Aerospace Exposition 2013
BT - 51st AIAA Aerospace Sciences Meeting including the New Horizons Forum and Aerospace Exposition 2013
T2 - 51st AIAA Aerospace Sciences Meeting including the New Horizons Forum and Aerospace Exposition 2013
Y2 - 7 January 2013 through 10 January 2013
ER -