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polytropic analysis of discharging vessels

Class: Engineering Experimentation (ME 360)

Year: Spring 2019

Goal: Produce a submission-ready manuscript for external review (ASEE), for a hands-on educational exercise (experimental setup).


  • a set of coupled experiments for analyzing discharging vessels with polytropic exponents

  • exposure to and application of heat transfer, fluid dynamics, heat transfer, and thermodynamics concepts learned in theoretical classes

  • exposure to calibration, amplification, data collection, signal conditioning, and noise reduction in using sensors and electronics

  • exposure to programs such as MATLAB and Arduino IDE

  • testing hypothesis and model validation, and identification of physical limitations and assumptions


Technical Details

The coupled experiments were adapted from the previous year's Air Rocket team. The previous year's team had problems with measuring thrust of the air rocket using the load cell, so the test stand was modified to ensure that the thrust is accurately measured. Instead of having a horizontal setup, the rocket setup was changed to a vertical one, to prevent the added loads from gravity and other losses. The rocket was placed on a cantilever beam, and the load cell was calibrated with a spring scale for improved accuracy. The measured thrust was 4 times that of the previous years'.

Further improvements and modifications were made to the previous year's project. Workshop modules for both experiments were created with full instructions and learning objectives, and with suggested questions and activities. The electronics for both experiments were condensed, organized, and secured for easy debugging, clarity, and safety. Other parts of the experimental test stands were modified and updated to ensure efficiency and accuracy. Time constants and accuracy of different sensors were calculated and accounted for in simulations and data acquisition.

For both experiments, the data acquired from sensors were collected and analyzed using custom MATLAB and Arudino IDE programs, adapted form previous years but modified for accuracy, organization, and navigation. The data for both experiments were analyzed using polytropic models, and the experimental data was plotted with the theoretical, polytropic models. The data was then exported as graphs and as excel files. 

The two experimental modules were designed so that students can apply theoretical concepts taught in standard classes to real life, hands-on applications. The students are exposed to several electronics, data acquisition, signal processing, and other important aspects of engineering. Students are also exposed to limitations of models and validating the model and assumptions they create.

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