- The Report Must Contain All Raw Results And Calculated Results Must Be Presented As Well As Sample Calculation Ambi 1 (81.84 KiB) Viewed 50 times
The report must contain all raw results and calculated results must be presented as well as sample calculation.] °℃ Ambient Pressure (kPa) Temperature Orifice Orifice Varying Pressure difference Pressure Pitot tube height Position difference across the pitot difference (ha-ha) (Pz-P₁) static tube at various location (P3-P₁) 1 403 2 3 4 In 5 400 6 "1 7 if 11 (102 (1 IT " 403 " [₁ 8 9 10 11 12 13 14 15 16 Height difference across the pitot static tube at various location (ha-hs) 105 103 96 100 98 99 93 91 95 87 79 84 97 98 95 96 Venturi height difference (hz-h₂) 425 425 475 425 425 425 425 425 429 (1 11 477 14 " "1 Venturi Pressure difference (Pz-P1) QTh Discharge co- efficient for Venturi, Co Q Discharge co-efficient for Orifice, Co
T= 20+273=213 R=0.287 . A- A m³/s (P. 비해 Pair ET 101 01287 Some Relevant Theory Ambient air density must be calculated using Ideal Gas Law. Air density at ambient temperature is given by the equation P Pa = RT With the gas constant, R. being equal to 2874 J/kg-K for air, and the absolute temperature. T. being given in Kelvin (-temperature in "C+273), and the pressure given in Pa, the density will be in kg/m². . Bernoulli's Equation (ignoring any losses): pu 3·7·00₁-3₁₂- 2+2+₂ Air Velocity: This may be calculated for any point in the flow by appropriate use of the Bernoulli equation- this is the equation to be used when employing a Pitos-static tube to determine the flow speed. 3 2(P static m/s air • Continuity Equation: Mass flow rate across any section should be constant through the duct A-Pild Since the density is constant in this case. 4- all along the doct • Volume Flow Rate: The actual volume flow rate across a section of the duct is given by the equation where it is the average flow speed across the relevant section of the duct • Theoretical Volume Flow Rate: Any flow meter (including the venturi and the orifice plate) will indicate a "theoretical volume flow rate". Qn, based on a relevant measured pressure difference and areas. 2(R-B) Q (4) P1- In this equation subscript "1" refers to a section in the duct upstream of the flow meter. For the Venturi and orifice plate, subscript "2" refers to the "throat" section, which is flow meter has its minimum area. E62x -OX, A₁ = 4 (0.14) ² 10.108)2 (630.0) 1/2 = 2²7 12/27
The above equation is developed from the Bernoulli equation, and assumes that there is no energy loss between sections "1" and "2". However, the nature of the real flow in and around the flow meter does lead to energy loss and so on is not an accurate estimate of the actual volume flow rate. However. On calculated with the above equation can be used in practice to lead us to an estimate of the actual volume flow rate if we know the fluid discharge coefficient. Cp (defined below). • Fluid Discharge Coefficient: QALE C₂ = Pr =QM =CDQTM Data you will require for this experiment: Parameter Duct internal diameter Venturi throat internal diameter Orifice plate internal diameter Duct dimensions (perspex section) References Ravi Sridhar, personal communication, 2011. Value 440 mm) 89 man 108 115 mm (W) x 128 mm (H)