Search found 30 matches

by Francesco.Perrone
Thu Nov 05, 2015 5:50 am
Forum: Inflow Turbulence
Topic: Writing binary bts files
Replies: 3
Views: 10094

Re: Writing binary bts files

Hallo Bonnie, thanks a lot for your answer. In the meanwhile I've been checking what coherence function TurbSim supports, together with the possible time-series scaling. When setting TurbSim standard coherence for a Kaimal model, together with scaling factor at the hub height (so that to get the rig...
by Francesco.Perrone
Fri Oct 23, 2015 6:08 am
Forum: Inflow Turbulence
Topic: Writing binary bts files
Replies: 3
Views: 10094

Re: Writing binary bts files

Dear all, I answer myself: until yesterday I've been assuming a Davenport coherence function also for the v- and w- components of the wind field. Today I turned that off and moved to a TurbSim implementation, where v- and w- components are independent time series. Now, when running a fatigue analysi...
by Francesco.Perrone
Thu Oct 22, 2015 4:27 am
Forum: Inflow Turbulence
Topic: Writing binary bts files
Replies: 3
Views: 10094

Writing binary bts files

Dear all, in the last weeks I've been developing an alternative turbulent generator to TurbSim. For the time being, let's assume that the time series are generated correctly. The goal would now be saving the 4D velocity matrix as a FAST-compatible .bts file. Threfore, I've been writing the following...
by Francesco.Perrone
Tue Jun 18, 2013 7:11 am
Forum: Inflow Turbulence
Topic: Improved von Karman Spectrum
Replies: 0
Views: 20543

Improved von Karman Spectrum

Hi everybody, although the Improved von karman question is not directly implemented in TurbSim ( even if there is a chunk of code somewhere), I wonder if you may anyway shed a light about the following question. If I look at the ESDU "Characteristics of atmospheric turbulence near the ground Pa...
by Francesco.Perrone
Tue May 07, 2013 12:22 pm
Forum: Inflow Turbulence
Topic: Frequency vector and FFT
Replies: 3
Views: 12954

Re: Frequency vector and FFT

Dear Jason, I really thank you for the prompt reaction and response. I'm questioning not that much on the definition of the frequency array itself, but more about its relation to the FFT operation. Assuming that I define my frequency as follows (only half out of 4096 samples): f = (1:2048)*0.00167; ...
by Francesco.Perrone
Wed Apr 24, 2013 12:09 pm
Forum: Inflow Turbulence
Topic: Frequency vector and FFT
Replies: 3
Views: 12954

Frequency vector and FFT

Hi everybody, I've got a question concerning the definition of the frequency array and the FFT usage. For simplicity, let's assume that: Nx = 4096; T = 600 [s]; This means that the Nyquist frequency (or cut-off frequency) is fn = Nx/T = 4096/600 [Hz] = 6.82667 [Hz]; while the minimum frequency value...
by Francesco.Perrone
Sat Mar 09, 2013 12:52 pm
Forum: Inflow Turbulence
Topic: Rescale Turbulent Wind Series to Match Unitary std
Replies: 0
Views: 8645

Rescale Turbulent Wind Series to Match Unitary std

Hi everybody, as said in one of my previous threads, I am coding a MATLAB tool with the same capabilities of TurbSim, at least for the Kaimal turbulent model. Let's say that I generally have two main questions: 1) I'd appreciate to have a bibliographic reference discussing coherence formula for vv a...
by Francesco.Perrone
Sun Mar 03, 2013 2:06 pm
Forum: Inflow Turbulence
Topic: Coherence function
Replies: 5
Views: 11936

Re: Coherence function

Dear Bonnie, I thank you again for your reply. In the end, I have been able to implement the whole code for generating turbulent wind fields in MATLAB. As you pointed out, I am currently implementing no coherence for v- and w- components: only the Dirlik function is taken into account for those two ...
by Francesco.Perrone
Mon Feb 25, 2013 3:22 pm
Forum: Inflow Turbulence
Topic: Coherence function
Replies: 5
Views: 11936

Re: Coherence function

Dear Bonnie, first of all thanks for the quick reaction to my post. Secondly, I already had the hunch to pursue a procedure as the one you advised. I, therefore, tried to adjust my code accordingly: %% COHERENCE MATRIX % Define normalized power spectra psd = zeros(length(f),3); psd(:,1) = abs((4*(si...
by Francesco.Perrone
Mon Feb 25, 2013 5:51 am
Forum: Inflow Turbulence
Topic: Coherence function
Replies: 5
Views: 11936

Coherence function

Hi all, I have got a theoretical question concerning the coherence function as defined within the TurbSim user's manual. Preamble : by using Matlab, I am trying to code my own wind file generator, in accordance with Sandia theory and Kaimal spectrum. Now, assuming that N = Ny*Nz , I generally calcul...
by Francesco.Perrone
Mon Feb 11, 2013 4:55 am
Forum: Computer-Aided Engineering Software Tools
Topic: Rainflow Counting - Half Cycles
Replies: 5
Views: 5955

Re: Rainflow Counting - Half Cycles

Dear Marshall, sorry for the late reaction. I tried asking GH concerning this matter, but I don't expect that much from them: they make money out of their business, thus I assume they are not that willing to disclose their own tools or ideas with externals. Btw, I will not give up and hopefully I wi...
by Francesco.Perrone
Tue Jan 29, 2013 3:04 pm
Forum: Computer-Aided Engineering Software Tools
Topic: Rainflow Counting - Half Cycles
Replies: 5
Views: 5955

Re: Rainflow Counting - Half Cycles

Dear Marshall, first of all I'd like to thank you for the ready reply. At the moment, I'm comparing MATLAB results and BLADED results for only one run. Btw, I already came up with a procedure accounting for the Weibull/Rayleigh wind distribution. I stumbled on this MATLAB/BLADED issue absolutely by ...
by Francesco.Perrone
Fri Jan 25, 2013 3:20 pm
Forum: Computer-Aided Engineering Software Tools
Topic: Rainflow Counting - Half Cycles
Replies: 5
Views: 5955

Rainflow Counting - Half Cycles

Hi everybody, it's already a couple of weeks I'm facing the issue, so that I decided to open a thread here on the forum. The question is pretty easy: I'm trying to write a tool enabling the user to get fatigue post-processing out of BLADED output. To do this, I make use of MATLAB and of the rainflow...
by Francesco.Perrone
Sun Jul 15, 2012 11:15 am
Forum: Structural Analysis
Topic: Superimpose DELs weighted on different lifetime
Replies: 2
Views: 3505

Re: Superimpose DELs weighted on different lifetime

Dear Jason, your thoughts about Nref, DEL(20) and DEL(20.25) are absolutely right. Indeed, I myself came up with the same formula you wrote down 10' after posting my question. I just wanted to have my idea supported by somebody who has a more consistent knowledge than me. I really thank you in advan...
by Francesco.Perrone
Thu Jul 12, 2012 9:19 am
Forum: Structural Analysis
Topic: Superimpose DELs weighted on different lifetime
Replies: 2
Views: 3505

Superimpose DELs weighted on different lifetime

Hi everybody, I have got a likely pretty straightforward question. Let assume that I have a DEL value weighted over 20 years and a second value weighted over 0.25 years: is it possible to get a overall DEL weighted over a 20.25 years lifetime, starting from the two above? Nref = 1E+08 cycles and Woe...

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