turbulence {bReeze}R Documentation

Calculation of turbulence intensity


Calculates turbulence intensity and mean wind speed for each given direction sector.


turbulence(mast, turb.set, dir.set, num.sectors=12, 
  bins=c(5, 10, 15, 20), subset, digits=3, print=TRUE)
turb(mast, turb.set, dir.set, num.sectors=12, 
  bins=c(5, 10, 15, 20), subset, digits=3, print=TRUE)



Met mast object created by mast.


Set used for turbulence intensity, specified as set number or set name (optional, if dir.set is given).


Set used for wind direction, specified as set number or set name (optional, if turb.set is given).


Number of wind direction sectors as integer value greater 1. Default is 12.


Wind speed bins as numeric vector or NULL if no classification is desired. Default is c(5, 10, 15, 20).


Optional start and end time stamp for a data subset, as string vector c(start, end). The time stamps format shall follow the rules of ISO 8601 international standard, e.g. "2012-08-08 22:55:00".


Number of decimal places to be used for results as numeric value. Default is 3.


If TRUE (the default), results are printed directly.


Turbulence can be perceived as wind speed fluctuations on a relatively short time scale and it strongly depends on surface roughness, terrain features, as well as thermal effects. High turbulence should be avoided, since it is a main driver of fatigue loads and might decrease energy output. A measure of the overall level of turbulence, is the turbulence intensity I, which is defined as:

I = sigma / v

where sigma is the standard deviation of wind speed – usually measured over a 10-minutes period – and v is the mean wind speed over this period.


Returns a data frame containing:


Mean wind speed for each direction sector.


Total turbulence intensity for each direction sector.


Turbulence intensities per direction sector for each given wind speed bin.

Optional graphical parameters for plotting

The following graphical parameters can optionally be added to customize the plot:


Christian Graul


Albers, A. (2010) Turbulence and Shear Normalisation of Wind Turbine Power Curve. Proceedings of the EWEC 2010, Warsaw, Poland

Burton, T., Sharpe, D., Jenkins, N., Bossanyi, E. (2001) Wind Energy Handbook. New York: Wiley

Langreder, W. (2010) Wind Resource and Site Assessment. In: Wei Tong (Ed.), Wind Power Generation and Wind Turbine Design, Chapter 2, p. 49–87, Southampton: WIT Press

See Also



## Not run: 
## load and prepare data
data("winddata", package="bReeze")
set40 <- set(height=40, v.avg=winddata[,2], v.std=winddata[,5],
set30 <- set(height=30, v.avg=winddata[,6], v.std=winddata[,9],
set20 <- set(height=20, v.avg=winddata[,10], v.std=winddata[,13])
ts <- timestamp(timestamp=winddata[,1])
neubuerg <- mast(timestamp=ts, set40, set30, set20)
neubuerg <- clean(mast=neubuerg)

## calculate turbulence intensity
turbulence(mast=neubuerg, turb.set=1)  # default
turbulence(mast=neubuerg, turb.set=1, dir.set=2)  # use different datasets
turbulence(mast=neubuerg, turb.set="set1", dir.set="set2")  # same as above
turbulence(mast=neubuerg, turb.set=1, num.sectors=4)  # change sector number

# calculate turbulence intensity for 1 m/s speed bins and without binning
turbulence(mast=neubuerg, turb.set=1, bins=1:25)
turbulence(mast=neubuerg, turb.set=1, bins=NULL)

# data subset
turbulence(mast=neubuerg, turb.set=1, 
  subset=c(NA, "2010-01-01 00:00:00"))

# change number of digits and hide results
turbulence(mast=neubuerg, turb.set=1, digits=2)
neubuerg.ti <- turbulence(mast=neubuerg, turb.set=1, print=FALSE)

## plot turbulence intensity object
plot(neubuerg.ti)  # default

# change colour, text size etc.
plot(neubuerg.ti, cex.axis=0.7, cex.lab=0.9, circles=c(0.05,0.20,0.05), 
  col="lightgray", col.axis="darkgray", col.border="gray", col.circle="darkgray", 
  col.cross="darkgray", col.lab="darkgray", fg=TRUE, lty.circle="dotdash", 
  lty.cross="longdash", lwd.border=1.2, lwd.circle=1.2, lwd.cross=1.2, 
  pos.axis=135, sec.space=0.6)

## End(Not run)

[Package bReeze version 0.4-3 Index]