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EXPERIMENTAL & NUMERICAL INVESTIGATION OF WIND LOADS ON ROOFS FOR VARIOUS GEOMETRIES

EXPERIMENTAL & NUMERICAL INVESTIGATION OF WIND LOADS ON ROOFS FOR VARIOUS GEOMETRIES. İsmail EKMEKÇ İ , Mustafa ATMACA * and Hakan Soyhan The University of Sakarya, Engineering Faculty, Sakarya, Turkey * Marmara University,Technical Education Faculty, İstanbul,Turkey. Outline.

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EXPERIMENTAL & NUMERICAL INVESTIGATION OF WIND LOADS ON ROOFS FOR VARIOUS GEOMETRIES

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  1. EXPERIMENTAL & NUMERICAL INVESTIGATION OF WIND LOADS ON ROOFS FOR VARIOUS GEOMETRIES İsmail EKMEKÇİ , Mustafa ATMACA* and Hakan Soyhan The University of Sakarya, Engineering Faculty, Sakarya, Turkey *Marmara University,Technical Education Faculty, İstanbul,Turkey

  2. Outline • Background and Problem Statement • Goals and Requirements • Wind Tunnel and Measurements • Experimental Roof Setup and Measurements • Model and Calculation Method • Experimental wind pressure coefficients • Numerical wind pressure coefficients • Comparison of Experimental & Numerical Results • Conclusions • Future Work

  3. Wind Tunnel 1- Inlet part, 2- turbulence regulating chamber, 3- collector, 4- Section area, 5- Diffuser Adapter 6- Diffuser, 7- Outlet chamber, 8- Fan connection, 9- Fan cabin, 10- Fan, 11- Tunnel chassis, 12- Tunnel carrying wheel, 13- Velocity control unit, 14- Pitot tub, 15- Manometer, 16- Temperature probe, 17- Computer 18- Hot wire anemometer unit, 19- Oscilloscope, 20- Table, 21-Roof model, 22- Differential pressure sensor 23-Interface console 24- Wattmeter 25-Interface

  4. Experimental Roof Setup and Measurements

  5. Dimensions of the Roof Model Measurement Points

  6. Calculation Method for Measured Data • Dimensionless pressure coefficients (Cp) [3] : • Mean Wind Pressure (Pmean) and mean wind pressure coefficients ( ) :

  7. Numerical Calculations Effects of Mesh refinement in the 3-D simulations

  8. Mesh Class Maximum Number of Nods Maximum Number of Elements Mean Relative Error of the Cp Values% A 4812 23668 40,18 B 5813 29538 33,46 C 6945 35574 20,45 D 8689 45512 8,32 E 11761 63160 10,22 Effects of Mesh refinement on the Mean Error of the Cp Values

  9. Numerical Calculations Effects ofdifferentturbulence models on thePressure distribution (3-D simulations)

  10. Cross section computational domain

  11. Experimental wind pressure coefficients of α=10o roof slope for severalwind directions Φ=0o Φ=30o Φ=60o Φ=90o

  12. Experimental wind pressure coefficients of α=20o roof slope for severalwind directions Φ=0o Φ=30o Φ=60o Φ=90o

  13. Experimental wind pressure coefficients of α=30o roof slope for severalwind directions Φ=0o Φ=30o Φ=60o Φ=90o

  14. Numerical wind pressure coefficients of α=10o roof slope for severalwind directions Φ=0o Φ=30o Φ=60o Φ=90o

  15. Numericalwind pressure coefficients of α=20o roof slope for severalwind directions Φ=0o Φ=30o Φ=60o Φ=90o

  16. Numericalwind pressure coefficients of α=30o roof slope for severalwind directions Φ=0o Φ=30o Φ=60o Φ=90o

  17. Comparison of Experimental and Numerical Results for Mean Pressure Coefficients

  18. CONCLUSIONS - I • Although it is obtained convenient pressure coefficient (Cp) values between experimental measurements and numerical computations, there are some inconveniences at some points. These deviations mostly occurred at roof corner points and back surfaces. Reasons for those differences are grid structure, mesh dimension, sample space dimension, insufficiency of selected turbulence model and could not making experimentally sensitive measures at these points. • In numerical computation initially the effect of mesh structure is investigated. • In numerical computations to investigate the effect of turbulence model 6, turbulence models (k-ε, RNG, Grimaji, Zero-equation, New k-ε, Shi-Zhu-Lumley) are tested at ANSYS-Flotron. Zero-equation turbulence model gives more accurate results comparing to other turbulence models. Hence Zero-equation model is used at all numerical computations.

  19. CONCLUSIONS - II • For 100 roof slope critical suction pressure coefficients are obtained for 00 and 300 wind directions at x/s=0,1 and x/s=0,5, for 600 and 900 wind directions at x/s=0,5. For 200 and 300 roofs slope critical pressure coefficients are obtained for 00, 300, 600 and 900 wind directions at x/s=0,5. • For 100, 200 and 300 roofs slope, at 900 wind direction and at z/d=0.16, 0.33, 0.5, 0.66 suction pressure coefficients are observed smaller than other wind directions. • For 100, 200 and 300 roofs slope at 600 and 900 wind directions maximum suction pressure coefficients have been obtained at z/d=0,83. • For 300 roof slope at 00, 300 and 600 wind directions, positive pressure coefficients have been obtained between x/s=0-0,4.

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