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Discussion of bluff bodies - 5
Journal of Wind Engineering and IndustrialAerodynamics, 41-44 (1992) 869-870 Elsevier
869
Discussion of Bluff Bodies - 5 Session c h a i r m e n : Corporation, Japan
M. M. Zdravkovich, University of Salford, U.I~ & K. Takeda, NKK
Response of Smoc~b Body Trapezoidal Wire Overhead (Compact) Conductors to Wind Loading. S. G. Krishnasamy, M. Tababatai & J. R. Meale
Comment by G. Buresti Can you give us more details on the way drag coefficients were measured in the wind tunnel? Author's reply The aerodynamic forces on each conductor were measured by two force transducers fastened to the conductors. These transducers (which are located outside the wind tunnel) were calibrated using a pulley and weight system before each run. The drag coefficient was obtained using this force, the wind tunnel speed, air density, the exposed length of the cable and its diameter.
Field Determination of Conductor Drag Coefficients. L. Shan, L. M. Jenke & D. D. Cannon, Jr. Comment by K. R. Cooper Based on the good agreement between your first phase field measurements and wind tunnel measurements of conductor drag coefficient, would you say that the poor correlation found between test line and wind tunnel drag measurements reported previously are a result of difficulties in computing the drag coefficient in the field using the loads on a full span but wind speeds measured at one or several points not located along that span.
Author's reply Yes, we believe the differences are due to not using the correct velocity distribution over the span length and in the way the data is processed. Phase II will confirm this.
Comment by A. Laneville Were you able to compare the turbulence characteristics in the fieldto those in the wind tunnel? Author's reply W e did not have wind tunnel turbulence characteristics for the two sets of wind tunnel drag data. In general, wind tunnel turbulence characteristics should remain unchanged during the course of testing. However, the field tests on conductor drag coefficients lasted more than six months and the data was taken over a wide range of weather conditions that had various turbulence characteristics. In comparing the data, it is apparent that the difference in turbulence values did not bias the drag coefficientmeasured in the field.
Comment by M. Tabatabai The field studies you presented at the beginning of your presentation (1") were obtained from field measurements on transmission line spans of order 800 ft. Comparing the results of measurements using conductors of a few feet with those results does not address the span length effects on drag coefficients. Your second phase of study, however, the type of work that can help answer tY.isquestion, W e continue to obtain field data on wind and ice loading of conductors in the fieldfor the same purpose. "1.
Krishnasamy et al.
869
Discussion of Bluff Bodies - 5 Session c h a i r m e n : Corporation, Japan
M. M. Zdravkovich, University of Salford, U.I~ & K. Takeda, NKK
Response of Smoc~b Body Trapezoidal Wire Overhead (Compact) Conductors to Wind Loading. S. G. Krishnasamy, M. Tababatai & J. R. Meale
Comment by G. Buresti Can you give us more details on the way drag coefficients were measured in the wind tunnel? Author's reply The aerodynamic forces on each conductor were measured by two force transducers fastened to the conductors. These transducers (which are located outside the wind tunnel) were calibrated using a pulley and weight system before each run. The drag coefficient was obtained using this force, the wind tunnel speed, air density, the exposed length of the cable and its diameter.
Field Determination of Conductor Drag Coefficients. L. Shan, L. M. Jenke & D. D. Cannon, Jr. Comment by K. R. Cooper Based on the good agreement between your first phase field measurements and wind tunnel measurements of conductor drag coefficient, would you say that the poor correlation found between test line and wind tunnel drag measurements reported previously are a result of difficulties in computing the drag coefficient in the field using the loads on a full span but wind speeds measured at one or several points not located along that span.
Author's reply Yes, we believe the differences are due to not using the correct velocity distribution over the span length and in the way the data is processed. Phase II will confirm this.
Comment by A. Laneville Were you able to compare the turbulence characteristics in the fieldto those in the wind tunnel? Author's reply W e did not have wind tunnel turbulence characteristics for the two sets of wind tunnel drag data. In general, wind tunnel turbulence characteristics should remain unchanged during the course of testing. However, the field tests on conductor drag coefficients lasted more than six months and the data was taken over a wide range of weather conditions that had various turbulence characteristics. In comparing the data, it is apparent that the difference in turbulence values did not bias the drag coefficientmeasured in the field.
Comment by M. Tabatabai The field studies you presented at the beginning of your presentation (1") were obtained from field measurements on transmission line spans of order 800 ft. Comparing the results of measurements using conductors of a few feet with those results does not address the span length effects on drag coefficients. Your second phase of study, however, the type of work that can help answer tY.isquestion, W e continue to obtain field data on wind and ice loading of conductors in the fieldfor the same purpose. "1.
Krishnasamy et al.