Another Dam Lego Project
Individual Project Concept Study
by Todd Schmidt
for
Engineering 498A:
Multidisciplinary Engineering Design Laboratory
Introduction
This paper aims to present a project study for the development of a freshman-level laboratory project that would entail the design and construction of a dam in order to create a reservoir, which then could be further harnessed for electrical power, drinking water, and irrigation through systems designed and built by the students. Freshman engineering prospectives would thereby receive an introduction to the basics of civil, electrical and mechanical engineering as well as water resource management and the Òreal worldÓ aspects of engineering planning and decision-making.
General Project Description
The project would entail designing a dam that would create a small reservoir, and furthermore developing and building systems to make full use of such a reservoirÕs potential benefits. The distinct elements of the project I foresee as follows: structural design and construction of the dam face, development of a simple turbine and electric power generator, and the creation of a pumping station to transfer reservoir water to a position of higher elevation, simulating the use of such a reservoir as a water source for residential, commercial, and agricultural use. Each of these three elements, along with their respective technologies introduced, possibilities for competition, and additional equipment needed are described in futher detail below.
Dam Construction
Description: Students would design a dam structure which would close off the open end of an open-top, three-sided rectangular tank that would be provided for student use. The dam would be expected to sustain the hydrostatic forces incurred when the tank were filled with water. Previous to the project, the development team would have determined the strength of the Lego connections in order to give the freshmen some basis for strength design. An additional requirement would be the incorporation of a flood control mechanism into the dam which would open and release water out the bottom of the dam should the resevoir level get too high.
Technologies/Concepts: In order for the students to build a dam structure which would withstand the forc of the water without breaking or tipping over, simple concepts of hydrostatics and dam design would be introduced, with the actual calculations completed by the freshmen. This knowledge, with a basic introduction to moments and moment arms would enable the design of the flood-control mechanism.
Challenges/Additional Equipment: Depending upon the number of groups working on the project simultaneously, a small number of tanks would be needed. A design challenge for the senior development group would be to find a way to make the dams fit in and be water-tight.
Electric Power Generation:
Description: Students would be instructed to design a turbine and simple electric generator capable of converting the kinetic energy of water falling through pipes to electrical current which could conceivably be used or sold.
Technologies/Concepts: Freshman could be introduced to elementary fluid mechanics in having them decide which diameter of ÒpipeÓ provides the highest velocity and most kinetic energy to turn the turbine. In addition, some knowledge and exposure to the practical applications of the conservation of energy (however incomplete), and the nature of magnetic fields and electrical current could be gained. A comparison between the initial potential energy of the water at the top of the reservoir and the electrical power actually produced would introduce the concept of efficiency, and a score could be given each group depending on the efficiency of their generator.
Challenges/Additional Equipment: Plastic tubing would be necessary to act as piping, a small coil of wire and a magnet would be provided for a generator, and an ammeter could be used to measure electrical output.
Pumping Station
Description: This portion of the project would require incorporation of the provided motors in the design and construction of a pump that would move water from the top of the resevoir to a simulated home or farm at a higher elevation while keeping a required pressure in the ÒpipeÓ. In addition, sensors could be given to the students in order for them to design a pressure gage at the home or farm from which the operation of the pump motors could be controlled and monitored.
Technologies/Concepts: An understanding of the physical operation of a pump, as well as the concepts of energy transfer, efficiency, and pressure measurement could be introduced in this phase of the project.
Challenges/Additional Equipment: Besides tubing to be used as pipes, the provided kits would be sufficient for this portion of the assignment.
Resource Management
In order to emphasize the fact that much of engineering involves working with such groups as communty organizations, government, landowners -- a facet which commonly gets lost in the shuffle of numbers and equations -- the write-up for this project could take the form of a project feasiblility/impact report. In such a report, students could take given information, such as watershed size and precipitation values, and calculate available water resources. Second, the population patterns could be studied in order that the freshmen could estimate the needs of the population, both human and otherwise. Third, a cost/benefit analysis could be performed and the group could make and justify a recommendation on whether the project should or should not be undertaken.
Conclusion
The project outlined above ennumerates many possibilities for learning about practical applications of fundamental physical principles, in different fields of engineering -- mainly civil, mechanical, environmental and electrical, as well as the Ònon-technicalÓ aspects of the engineering professsion. Depending upon the actual development, the scope and detail of the project could be modified to a size deemed appropriate -- challenging but not overwhelming -- to a freshman engineering student.