Search found 37 matches

by Vishal.Sairam
Tue May 11, 2021 2:30 am
Forum: Computer-Aided Engineering Software Tools
Topic: Extreme events
Replies: 35
Views: 15999

Re: Extreme events

Hi Jason, I am using the controller NREL has provided. I downloaded it from the GitHub repository. Thank you for sharing your thesis with me, I believe I found the answer. I will simulate wind speeds after rated to capture the pitch fault, where 1 blade pitches to 0 and then the other 2 blades pitch...
by Vishal.Sairam
Mon May 10, 2021 1:00 am
Forum: Computer-Aided Engineering Software Tools
Topic: Extreme events
Replies: 35
Views: 15999

Re: Extreme events

Hi Jason, I did enable the pitch controller (TPCOn) at the start of the simulation at 0.0 s, but then when I overrode the pitch control for blade 1 at 100.1 s, the pitch for the other two blades started oscillating between -180 and 180 degrees, indicating an instability. But when I did not enable th...
by Vishal.Sairam
Fri May 07, 2021 1:48 am
Forum: Computer-Aided Engineering Software Tools
Topic: Extreme events
Replies: 35
Views: 15999

Re: Extreme events

Hello all, I am trying to simulate a load case with internal electrical faults according to IEC 61400-1 Ed.3 (Design Load Case 2.2). I am considering two sub cases here - first where 1 blade is stuck at minimum pitch and second where all blades pitch to go to minimum pitch rapidly. The operating con...
by Vishal.Sairam
Thu Mar 18, 2021 6:21 am
Forum: Structural Analysis
Topic: Loads extrapolation
Replies: 10
Views: 4426

Re: Loads extrapolation

Hi Jason,

Thank you for your and Pat's replies!

Best regards,
Vishal
by Vishal.Sairam
Thu Mar 11, 2021 5:22 am
Forum: Structural Analysis
Topic: Loads extrapolation
Replies: 10
Views: 4426

Re: Loads extrapolation

Hi everybody,

I was looking into load extrapolation of DLC1.1 to Vref and I found this thread. I would greatly appreciate it if someone has literature/documentation on how to proceed down this path that you can share with me.

Many thanks in advance!

Best regards,
Vishal
by Vishal.Sairam
Thu Feb 04, 2021 3:40 am
Forum: Structural Analysis
Topic: Tower top tilt moment and Tower bottom side-side moment looking strange
Replies: 18
Views: 2227

Re: Tower top tilt moment and Tower bottom side-side moment looking strange

Dear Jason,

I re-ran the steady state simulations with a power law exponent of 0.2 and plotted the mean values against the mean values for turbulent wind simulations at 0 yaw.

Steady and Turbulent Comparison.PNG
Steady and Turbulent Comparison.PNG (270.39 KiB) Viewed 749 times


It is the shear that is causing uneven loading over the rotor.

Best regards,
Vishal
by Vishal.Sairam
Thu Feb 04, 2021 2:17 am
Forum: Structural Analysis
Topic: Tower top tilt moment and Tower bottom side-side moment looking strange
Replies: 18
Views: 2227

Re: Tower top tilt moment and Tower bottom side-side moment looking strange

Dear Jason,

The power law exponent was actually 0 for the steady state simulations but the hub height was the same. I will resimulate steady state files with 0.2 power law exponent and make the same comparison again.

Best regards,
Vishal
by Vishal.Sairam
Wed Feb 03, 2021 6:45 am
Forum: Structural Analysis
Topic: Tower top tilt moment and Tower bottom side-side moment looking strange
Replies: 18
Views: 2227

Re: Tower top tilt moment and Tower bottom side-side moment looking strange

Dear Jason, I have plotted the time series of wind speed in X,Y and Z directions against azimuth for the 216 cases (4-26 m/s in steps of 2; 8,0,-8 yaw and 6 turbulence seeds needed for DLC13), but I am not able to very clearly observe the shear. What did you mean when you said "You should also ...
by Vishal.Sairam
Fri Jan 29, 2021 9:58 am
Forum: Structural Analysis
Topic: Tower top tilt moment and Tower bottom side-side moment looking strange
Replies: 18
Views: 2227

Re: Tower top tilt moment and Tower bottom side-side moment looking strange

Dear Jason, I have used the IEC recommended shear factor value for the TurbSim input when I generated .wnd files (I believe it is 0.2). I would have to look at the mean wind speed in X,Y and Z directions against azimuth to obtain a wind speed profile across the rotor disk, should I not? Best regards...
by Vishal.Sairam
Fri Jan 29, 2021 9:54 am
Forum: Rotor Aerodynamics
Topic: Simulation error while simulating extreme yaw case
Replies: 9
Views: 1219

Re: Simulation error while simulating extreme yaw case

Dear Jason, I am simulating many load cases specified by the IEC standard for onshore turbines and I am using a reduced Design Load Basis document used by DTU. One of the load cases specifies power production with failure of yaw system leading to abnormal yaw error, in the operating range of 4-26 m/...
by Vishal.Sairam
Fri Jan 29, 2021 2:15 am
Forum: Rotor Aerodynamics
Topic: Simulation error while simulating extreme yaw case
Replies: 9
Views: 1219

Re: Simulation error while simulating extreme yaw case

Dear Jason, I am attaching a pdf with the input files I have used for one of the cases which ran completely but does not have meaningful results. The case in question is for a mean wind speed of 24 m/s, Normal Turbulence Model, -165 deg nacelle yaw. I have set the initial RPM and pitch values in the...
by Vishal.Sairam
Wed Jan 20, 2021 2:07 am
Forum: Rotor Aerodynamics
Topic: Simulation error while simulating extreme yaw case
Replies: 9
Views: 1219

Re: Simulation error while simulating extreme yaw case

Dear Jason, I reset the initial conditions according to VHub*Cos(yaw), and this solved the problem for quite a few of the simulations, they ran completely fine. But there were still some that failed, and due to the same reason (grid too small in Z direction). I changed the turbulence seed for the on...
by Vishal.Sairam
Mon Jan 18, 2021 9:10 am
Forum: Structural Analysis
Topic: Tower top tilt moment and Tower bottom side-side moment looking strange
Replies: 18
Views: 2227

Re: Tower top tilt moment and Tower bottom side-side moment looking strange

Dear Jason, I have not focused much on this topic for the last few weeks, but I am trying to figure out what could be causing this abnormal load behavior. Like you suggested, I compared the mean loads for steady state condition like in the NREL 5 MW report with the mean loads for turbulent condition...
by Vishal.Sairam
Mon Jan 18, 2021 9:06 am
Forum: Rotor Aerodynamics
Topic: Simulation error while simulating extreme yaw case
Replies: 9
Views: 1219

Re: Simulation error while simulating extreme yaw case

Dear Jason, Apologies, I posted some old TurbSim parameters I was using, I got the error message in the last post when I used the following TurbSim parameters - --------Turbine/Model Specifications----------------------- 31 NumGrid_Z - Vertical grid-point matrix dimension 31 NumGrid_Y - Horizontal g...
by Vishal.Sairam
Mon Jan 18, 2021 12:50 am
Forum: Rotor Aerodynamics
Topic: Simulation error while simulating extreme yaw case
Replies: 9
Views: 1219

Simulation error while simulating extreme yaw case

Good morning all, I am trying to simulate one of the sub cases in DLC 22 for the NREL 5MW according to the DTU Design Load Cases definition, which is DLC22y - Power production with abnormal yaw error. The simulation parameters are 4-26 m/s in steps of 2 m/s, 1 turbulence seed with NTM model per wind...

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