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afazio
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CITAZIONE (Paul Thomassen @ 11/4/2016, 12:58) Thanks for your very interesting review of Ashes.
Thank you Paul for answers.
I want to take the answers as a starting point for a discussion with Paul, but my English is too poor to be able to argue the discussion in that language.
I expose in Italian and then I'll try to translate the essential.
I propose again the Table 2 extracted from standard IEC 61400-1 "Design load cases" that we have to consider in the design of a wind turbine on-shore.
Among the various load cases I want to dwell on the cases referred DLC1.1 and DLC1.2, the first relating to Ultimate Limit State analysis (U) and the second for fatigue analysis (F)
It has indicated that it is necessary to consider the wind speed at hub level variables between the start-up speed and shutdown speed;
Vin <vhub < Vout
with the specification:
When a wind speed range is indicated in Table 2, wind speeds leading to the most adverse condition for wind turbine design shall be considered. The range of wind speeds may be represented by a set of discrete values, in which case the resolution shall be sufficient to assure accuracy of the calculation6. In the definition of the design load cases reference is made to the wind conditions described in Clause 6.
and the note(6):
In general a resolution of 2 m/s is considered sufficient.
This means that we should create as many turbulent wind patterns NTM how many speeds considered in the discretization.
For example,
if Vin = 4.0 m / s
Vout = 24.0 m / s
and we assume a discretization of 2.0 m / s
then we should create turbulent models of the following series of speed:
VHub= 4.0; 6.0; 8.0; 10.0; 12.0; 14.0; 16.0; 18.0; 20.0; 22.0; 24.0 m / s
and for each turbulent wind model run the analysis.
In case of fatigue analysis is needed all load histories relating to speed that I have listed above
and it is here that some statistical distribution (Weibull or Rayleigh) is required: In the absence of a statistical distribution in the long term it is not possible to proceed to a check for fatigue.
In Ashes must be performed repeatedly Turbism, save the results to a file * .wnd and indicate to Ashes the files to be analyzed in the batch process?
which standards currently adopted Ashes?
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14 replies since 7/4/2016, 06:46 779 views
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