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91 lines
2.8 KiB
91 lines
2.8 KiB
""" |
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Copyright (c) 2017, Sensirion AG |
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All rights reserved. |
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Redistribution and use in source and binary forms, with or without |
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modification, are permitted provided that the following conditions are met: |
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* Redistributions of source code must retain the above copyright notice, this |
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list of conditions and the following disclaimer. |
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* Redistributions in binary form must reproduce the above copyright notice, |
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this list of conditions and the following disclaimer in the documentation |
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and/or other materials provided with the distribution. |
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* Neither the name of Sensirion AG nor the names of its |
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contributors may be used to endorse or promote products derived from |
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this software without specific prior written permission. |
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THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" |
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AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE |
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IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE |
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DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE |
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FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL |
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DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR |
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SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER |
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CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, |
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OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE |
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OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. |
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""" |
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import numpy as np |
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import matplotlib.pyplot as plt |
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## differential pressure, sensor values in Pascal |
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dp_SDP33=np.linspace(0,800,100) |
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## total length tube in mm = length dynamic port+ length static port; compensation only valid for inner diameter of 1.5mm |
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l_tube=400 |
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## densitiy air in kg/m3 |
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rho_air=1.29 |
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## flow through sensor |
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flow_SDP33=(300.805 - 300.878/(0.00344205*dp_SDP33**0.68698 + 1))*1.29/rho_air |
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## additional dp through pitot tube |
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dp_Pitot=28557670. - 28557670./(1 + (flow_SDP33/5027611)**1.227924) |
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## pressure drop through tube |
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dp_Tube=flow_SDP33*0.000746124*l_tube*rho_air |
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## speed at pitot-tube tip due to flow through sensor |
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dv=0.0331582*flow_SDP33 |
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## sum of all pressure drops |
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dp_tot=dp_SDP33+dp_Tube+dp_Pitot |
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## computed airspeed without correction for inflow-speed at tip of pitot-tube |
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airspeed_uncorrected=np.sqrt(2*dp_tot/rho_air) |
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## corrected airspeed |
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airspeed_corrected=airspeed_uncorrected+dv |
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## just to compare to value without compensation |
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airspeed_raw=np.sqrt(2*dp_SDP33/rho_air) |
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plt.figure() |
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plt.plot(dp_SDP33,airspeed_corrected/airspeed_raw) |
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plt.xlabel('differential pressure raw value [Pa]') |
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plt.ylabel('correction factor [-]') |
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plt.show() |
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plt.figure() |
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plt.plot(airspeed_corrected,(airspeed_corrected-airspeed_raw)/airspeed_corrected) |
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plt.xlabel('airspeed [m/s]') |
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plt.ylabel('relative error [-]') |
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plt.show()
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