University of Illinois, Urbana Champaign
TAM 335
Objective The primary objectives of this experiment is to measure the resultant force applied by a curved rectangular duct to the air flowing within the duct, and to determine if a control-volume analysis based on the linear-momentum principle is valid. An additional objective is to determine whether the tangential velocity o
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Objective The primary objectives of this experiment is to measure the resultant force applied by a curved rectangular duct to the air flowing within the duct, and to determine if a control-volume analysis based on the linear-momentum principle is valid. An additional objective is to determine whether the tangential velocity of the air flow in the bend can be modeled by a simple idealization. Procedure Figure one: Schematic of 90 degree bend in the rectangular duct Figure one shows the device that we use for this experiment. We follow the procedure on the labVIEW program by first calibrating the pressure transducers and then record the pressure of inner, outer and side walls each time with different flow rate. After measuring the data, we import the data out. Theory Two models are introduced in this experiment. The Control-volume analysis can obtain both vertical and horizontal force on the walls. The flow in this case is assumed to be steady flow and two dimensional. For the free-vortex model, the wall is bended and a tangential velocity is calculated. For this experiment, free-vortex model is more useful because the data will be more accurate while the control volume analysis only measures the force in two dimensions. Sample Calculation For the first flow rate that we tested, we can calculating the Fx and Fy by using the following control volume analysis equation: Fx=2( Pbox−P0) A=2∗(8.43mb+0.85mb)∗100mm∗50 mm∗100 pa∗m 2 106mb∗mm 2 =9.28N

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