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Kategorie: Diplomové, bakalářské práce |
Tento dokument chci!
Práce popisuje principy a problémy při realizaci ultrazvukového anemometru. Je popsán princip výpočtu rychlosti větru a následné korekce výpočtu. Pro realizaci jsou využity ultrazvukové sensory a microcontrolér ARM Cortex-M3. Práce se zabývá generováním PWM signálu, jeho analogovou filtrací, zesílením a odvysíláním. Na přijímací straně jeto nízkonapěťový zesilovač a komparátor. Vyvíjený kód je popsán pomocí vývojového diagramu.
1) have add variable which represent speed wind v[m/s]. [1]
1. can expect time delay non windy conditions based this
equation:
(2.2)
There another weak dependence air humidity. can adjust this equation just calculate
2
.3)
where a[g/m3
] amount water the air.1 Correction speed
Airspeed dependent mainly temperature.4) negative. equation
(2.
1. Then have correct our measured temperature
and use the corrected temperature calculation above (2.THEORETICAL BACKGROUND
How was said, the calculation wind speed proceed knowledge time delay
between sensors. [1]
(2.2 Time delay windy conditions and wind speed
A sound wave affected the movement the transmission medium, air the
wind. With air temperature 20°C the
measured temperature with 100% relative dampness about higher.1)
where d[m] distance and c[m/s] airspeed. The increase water molecule in
the air cause increase airspeed. The correction based on
knowledge amount H2O grams per cubic meter. know the air temperature T[°C]
between sensors, can correct airspeed according following equation [1]:
(2. When vector wind
speed same oriented like direction sound propagation, obtain the equation [1]:
(2. Distance between sensors a
constant, but airspeed should corrected concrete atmospheric conditions [1].2). this case can suppose that the wind
speed the equation (2. case less time
delay obvious that airspeed increased speed wind. The wind affects the sound wave making going slower faster.4)
When the vector wind speed has opposite direction than propagation the
sound, there will increase time delay
