wdryd1.hlp

MATLAB在飞行动力学和控制中应用的工具

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WDRYD1 = Vertical Dryden filter #1. This masked subsystem block
which is contained in the library WINDLIB from the subdirectory
WIND, implements a vertical Dryden filter with constant coeffi-
cients. The user must specify the scale lenght Lwg, the standard
deviation sigma_wg and the airspeed V. In reality, V will not be
constant, but often, the resulting changes in the filter coeffi-
cients may be neglected, without affecting the resulting gust
velocities very much. Use the block WDRYD2 if the airspeed varies
so much that the filter coefficients cannot be held constant any-
more (see WDRYD2.HLP for more info).

The vertical gust velocity wg is obtained by passing white noise
through a Dryden filter, which is defined by the following trans-
fer function:

            b0 + b1*s        a0 = (V/Lwg)^2
  Hwg = -----------------    a1 = 2*(V/Lwg)
         s^2 + a1*s + a0     b0 = sigma_wg*sqrt(Lwg/V)*(V/Lwg)^2
                             b1 = sigma_wg*sqrt(3*Lwg/V)*(V/Lwg)
where:

  V       : true airspeed [m/s]
  sigma_wg: standard deviation of vertical gust velocity [m/s]
  Lwg     : scale length for vertical gust [m]

Here, V is pre-specified by the user in one of the dialog-boxes
from the block WDRYD1.

Outputs from the block WDRYD1:
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  wg      : vertical gust velocity [m/s]
  d(wg)/dt: time derivative of wg [m/s^2]

The block WDRYD1 has no inputs.

The gust velocity and its time derivative have to be added to the
total wind velocity component ww and its time derivative wwdot in
the vector uwind.

More info.
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See UDRYD1.HLP, VDRYD1.HLP, and TURB1.HLP for more info about
other Dryden filters with constant coefficients. See UDRYD2.HLP,
VDRYD2.HLP, WDRYD2.HLP, and TURB2.HLP for more info about Dryden
filters with coefficients that vary with the airspeed V.

See CWIND.HLP and BLWIND.HLP for more information about blocks
to compute the components of wind along the aircraft's body-axes
(constant wind and a wind profile in the Earth's boundary layer,
respectively). The use of the vector uwind within the aircraft
model is outlined in the helpfiles LEVEL1.HLP, FWIND.HLP, and
XYHDOT.HLP, which refer to blocks within the system BEAVER.

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The FDC toolbox, Copyright Marc Rauw 1994-1998.