WATERBED PUMPEGR 365 – FLUID MECHANICSPURPOSE:THEORY:APPARATUS:ITEMPROCEDURE:RESULTS:ANALYSIS:CONCLUSION:Grand Valley State UniversityThe Padnos School of EngineeringWATERBED PUMPEGR 365 – FLUID MECHANICSBrad Vander Veen May 27, 2003Lab PartnersJulie WatjerThomas FreundlPURPOSE:The purpose of this lab is to measure the suction developed by a simple venturi pump as afunction of the flowrate through it, and to compare those measurements with the predictions from Bernoulli’s equation.THEORY:Consider the diagram of the waterbed pump below in Figure 1:Figure 1 – Diagram of Waterbed PumpWriting Bernoulli’s equation from (1) to (2) yields:222212112121gzvpgzvpww (1)-where p is the pressure, w is the density of water, v is the velocity, g is acceleration due to gravity, and z is the depth.It is also known that:AQv  (2)-where Q is the volumetric flowrate, and A is the cross-sectional area.Neglecting the effects of gravity on the system, the following equations can be derived from equations (1) and (2): 1214122212ddvppw (3) 121412222ddAQgzman (4)-where z is the height difference on the manometer.It is known that:atmp 2394.1ftslugswftd 0150.1ftd 0375.2Applying these values to Equation (3) yields suction_pressure as a function of volumetricflowrate Q:suction_pressure Q( ) 0.5 wQA22d2d1411144 (5)-where suction pressure is in psiThis theoretical function for suction pressure can be plotted as seen below in Figure 2: Suction Pressure vs. Flowrate0 0.00501020suction_pressure Q( )Qpsift3secFigure 2 – Theoretical Plot of Suction PressureAPPAR ATUS:ITEM Waterbed Pump Manometer FlowmeterGarden Hose TrapPROCEDURE:1). Assemble the experimental setup as seen in Figure 1.2). Using various flowrates, record the height difference from the manometer RESULTS:Table 3 below shows the manometer reading at different flowrates through the pump.Flowrate (cfs) Height (feet) 0.00474 2.625 0.00521 2.792 0.00568 3.625Table 3 – Manometer ReadingsUsing these manometer readings, the experimental suction pressure can be found using the formula:zgpressure  (6)In Table 4 below, the experimental suction pressure is shown.Flowrate (cfs) Height (feet) Suction Pressure (psi) 0.00474 2.625 1.139 0.00521 2.792 1.211 0.00568 3.625 1.573Table 4 – Experimental Suction PressureANALYSIS:The results from the theoretical and experimental resutls can be compared as seen below in Table 5:Flowrate (cfs) Theoretical S.P. (psi) Experimental S.P. (psi) % discrepency 0.00474 4.722 1.139 76% 0.00521 5.705 1.211 79% 0.00568 6.781 1.573 77%Table 5 – Comparison of Theoretical and Experimental ValuesThe theoretical values and experimental values can also be compared on the same plot as seen below in Figure 6: 0.004 0.0060510suction_pressure Q( )s_pQ qpsift3secFigure 6 – Plot of Theoretical and Experimental ValuesThe theoretical and experimental values follow the same trend, however, they disagree with a relatively large percent discrepancy. This discrepancy could be contributed mostlyto the fact that the pump is not perfect, and experiences significant losses during operation. Since our theoretical model does not compensate for the losses, there will be quite a large discrepancy between the two.CONCLUSION:In this lab, the operation of a small venturi pump was analyzed. A theoretical model was created using Bernoulli’s equation, and experimental data was also taken and compared to the theoretical model. The theoretical and experimental data followed the same trend, but did not agree numerically due to significant losses during pump