June 26, 2011
June 26, 2011
June 29, 2011
22.37.1 - 22.37.12
A Dimensional Analysis Experiment for the Fluid Mechanics ClassroomDimensional analysis is a technique used in many fields of engineering to facilitate correlationand interpretation of experimental data. It provides a means of combining the many parametersof an experiment into a lesser number of dimensionless groups. This technique greatly reducesthe amount of experimental work needed to determine the effect of parameter variation on thedependent parameter of the experiment.In the mechanical engineering curriculum, dimensional analysis is typically taught in the fluidmechanics lecture course, where students apply the Buckingham-Pi theorem and determine theappropriate dimensionless groups for a given problem. The procedure used for determining thedimensionless groups is generally straight-forward but tedious. It is believed that the use oflaboratory demonstrations in the lecture class would increase the students’ interest in the subjectand would significantly enhance the students’ comprehension of the usefulness of dimensionalanalysis in the planning of experimental programs and the interpretation of experimental data.The intent is to have students actively participate in the performance of the demonstrations andthe gathering of data. They would also correlate the data during the class period using softwaresuch as Excel, Matlab or MathCad. The class session would be lively, with much increasedstudent participation and active learning.Accordingly, we have developed a fluid mechanics experiment dealing with the flow of fluidsthrough nozzles of different sizes. The pressure drop across the nozzle is measured for a varietyof flow rates and for different fluids. Using dimensional analysis, the students determine theappropriate dimensionless groups for the experiment and correlate the experimental data. Thestudents thereby observe first-hand the usefulness of dimensional analysis in the correlation andinterpretation of experimental data.The paper describes the experimental apparatus and procedures in detail. The apparatus isportable and can easily be transported to and from the classroom on a cart. The paper includes aparts list, a discussion of construction aspects, and includes actual data obtained from theexperiment.In summary, this paper describes a fluid mechanics experiment which can be used to enhancelectures on dimensional analysis. Through active student participation, the experiment shouldgreatly increase the students' interest in the subject and their comprehension of the use ofdimensional analysis in the planning of experiments and the correlation of experimental data.
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