(a)
(b)
Fig. 8. (a) Streamlines of wind velocity from north at z=70m (b) streamlines and contours of velocity in vertical plane.
Installation of wind turbine in urban location is highly
affected by the wind resource and the flow directions.
The presence of building in the flow path affects the wind
direction, thus, creating a wake region behind the
building. This wake region behind the buildings
comprises of vertical flow field, which results in
recirculation zones.
Fig. 8(a) above shows the streamlines of wind velocity
plotted at 70m above the bottom of the computational
domain for flow direction from north. The contours of
pressure coefficient are also plotted to indicate the effect
of presence of buildings on the incoming flow. It can be
clearly seen that the direction of wind flow changes when
it comes in contact with bluff bodies, resulting in flow
channelling and venturi type effects. The drop in wind
velocity due to presence of stagnation point can also be
seen. The red colour indicates higher velocity magnitude
while blue indicates lower velocity magnitude.
Fig. 8(b) shows the streamlines of wind velocity
plotted on a vertical plane. The contours of wind velocity
for wind flow from south are evident. The key
observation from Fig. 8(b) is the wake region behind the
buildings. The streamlines plotted on the plane show the
formation of vortex core region, indicating the presence
of recirculation regions d-vue to flow separation caused
by the building edges.
The results also show that the wind velocity magnitude
at the top of buildings in the wake region is low, making
it a less promising area for any wind turbine installation.
B. Wind safety assessment
To evaluate the wind safety in an urban complex,
Figure 9 below provides the contours of local
amplification factors as defined in earlier section. The
contours of local amplification factor were plotted at 4
different heights i.e., 40m, 50m, 60m, and 70 m. The
flow direction was from south.
(a)
(b)
(c)
(d)
Fig. 9. Contours of non-dimensional velocity magnitude U/U
10
in four horizontal planes, for φ=270
0
(S) at (a) 40m; (b) 50m; (c )60m; (d)70m above
the ground.
2013 International Conference on Alternative Energy in Developing Countries and Emerging Economies
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