The Hydrostatic Vacuum Tube: a Low-Cost Thermal Fluid Science Laboratory
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Authors
Drenth, Aaron
Cornwell, Phillip
Feier, Ioan
Sidebotham, George
Issue Date
2022-08
Type
Other
Language
en_US
Keywords
Alternative Title
Abstract
Students often comment that they benefit from exposure to both analytical and experimental results of concepts discussed in class, especially in the abstract thermal-fluid sciences emphasis area of a Mechanical Engineering curriculum. As educators, we sought to address this deficiency by developing a new test apparatus, the Hydrostatic Vacuum Tube (HVT). In short, a HVT is a vertical tube partially filled with water and a trapped air pocket at the top, initially at atmospheric pressure. One experiment involves opening a valve at the bottom to expose an exit port of sufficiently small exit diameter to prevent backflow of air. Water is collected and measured until the flow stops due to the hydrostatic vacuum created as the air pocket expands. A second experiment (the Draining Tank) can be conducted without trapping the air, by exposing/venting the liquid surface to ambient pressure. The height of the water is measured versus time as the tank drains, driven by a hydrostatic head. Predictive theory is developed and results compared with experiment, with excellent agreement. Key thermodynamics concepts involved are expansion of an ideal gas, hydrostatic pressure, and mass conservation in a control volume. The device could be used in other courses, such as Fluid Mechanics, Engineering System Dynamics, Heat Transfer and Experimental Mechanics. Using the same lab equipment in several courses iteratively will make connections between subject areas. The construction and use of the lab hardware and relevant theory is discussed in this paper. Plans are outlined for assessment of the effectiveness of the lab in improving conceptual understanding of the technical content, broadening the experimental experience, and enhancing the ability to use appropriate technical language when comparing test data and theoretical predictions.
Description
Citation
Drenth, Aaron & Sidebotham, George & Cornwell, Phillip & Feier, Ioan. (2022). The Hydrostatic Vacuum Tube: a Low-Cost Thermal Fluid Science Laboratory. 10.18260/1-2--41469.
Publisher
ASEE