Drag Force Measurement

Extract

[...] For each angle, record the water columns Ho, ho and hA When the measurements are complete, turn off the fan and record the ambient temperature Ta and the absolute atmospheric pressure Pa. Analysis and lab report Complete calculations of all variables mentioned in the results table (Appendix). Experiment Plot values of the drag force versus the dynamic pressure (1/2.ρ.U2 Comment the obtained results. Experiment II: Plot in separate graphs the pressure coefficient cp and cpcosθ versus the angle θ. Determine the drag coefficient CD by performing a numerical integration. Comment the obtained results. [...]

[...] Drag Force Measurement Lab Report 06 Drag Force Measurement Done by: E.E.J. Supervised by: Pr. A.O Purpose In this lab work, drag force measurements on a circular cylinder will be performed by using two experimental methods. One is based on the balance system and the other one, on the determination of the pressure distribution on the outer surface of the cylinder. The objective is to determine the variation law of the drag force with the airspeed, to perform drag force calculation from pressure plotting, and finally to compare results obtained by both methods. [...]

[...] 2a Adjust the multimanometer vertically and check the water level to be approximately in the middle Connect the pressure taps of airbox and convergent exit to the multimanometer Adjust the weight to achieve equilibrium, record the value of the weight wo for zero airspeed (fan turned off). Note that every 1 mm on the front scale (100 g weight) represents 1 g and every 1 mm on the back scale (10 g weight) represents 0.1 g (use for fine adjustment). This zero airspeed weight should be subtracted from all the next weight readings to give an actual value of equilibrium at each wind speed Switch on the fan. Adjust the air-box pressure Ho around 200 mm WC. Wait for flow stabilization. [...]

[...] Compare results for the drag coefficient from both experiments. Comment the obtained results Compare the obtained drag coefficients values with those from literature in the case of a cylinder of diameter d. Compare the obtained drag coefficients values with those from literature in the case of a cylinder of diameter d. Experiment II: Measurement θ H0 h0 Ha P0-p0 U pA-p0 Cp Cpcosθ -78.48 - -166.77 - -333.54 -0.6296296 - -451.26 -0.8518519 - -588.6 -1.1111111 - -667.08 - -745.56 - -774.99 -1.462963 - -774.99 -1.462963 - -755.37 - -706.32 - -696.51 - -696.51 -1.3148148 - -696.51 - -696.51 -1.3148148 - -706.32 - -706.32 - -725.94 -1.3703704 - -735.75 - -774.99 -1.462963 - -784.8 - Measurement II: θ H0 h0 HA P0-p0 U pA-p0 Cp Cpcosθ -0.8111025 - -0.6837191 -0.1807384 - -19.62 -156.96 -0.2666667 -0.1400859 - -323.73 -0.55 -0.5307313 - -451.26 -0.7666667 -0.0169638 - -568.98 -667.08 -706.32 -1.2 -0.759983 - -735.75 -1.25 -1.1521891 - -725.94 -696.51 -657.27 -637.65 -1.0833333 -0.9341788 - -637.65 -637.65 -1.0833333 -0.8820294 - -637.65 -647.46 -657.27 -1.1166667 -0.7808301 - -686.7 -735.75 -1.25 -1.1724934 - -784.8 - Experiment (Balance measurements): Measurement Table Results Table H0 (mm WC) h0 (mmWC) W Po-po U q D Cd Ambient temperature Ta: 23° Atmospheric pressure Pa: 1,015 bar Air density: 1,2 Kg/m3 Zero air speed weight w0: 17 g Cylinder diameter 12.5 mm Cylinder length 48 mm Question From the chart above, we can conclude that as the velocity U increases, the dynamic pressure q increases, thus, the drag force increases. [...]

[...] Each time readjust the weights to achieve equilibrium and record the water columns Ho and ho and the value of the weights w When the measurements are complete, turn off the fan. Experiment II: The Pressure Distribution Measurements 1. Fit the circular cylinder and protractor model as depicted in Fig. 2b Connect the pressure taps from airbox convergent and cylinder to the multimanometer Set the wind speed to the maximum and the protractor to zero angle. Record the water columns Ho, ho and hA, respectively, for Po, po and pA pressures measurements. [...]