Investigate and based on rotor momentum/ actuator disk theory, what is the theoretical velocity magnitude, w far downstream in the wake of the rotor?


In this assignment, you will perform an online search using UTSA’s library journal access portal to find a research journal article that is: (i) experimental in nature (i.e., deals with measurement and instrumentation to obtain physical data), and (ii) is of interest to you, and is related to the field of (mechanical) engineering. I would suggest that you begin with a theme/ topic you are interested in engineering, then search for journals/ articles with these keywords. You should select an article that allows you to answer the questions below.



You should preferably use UTSA’s journal access (a much larger variety of journals and articles available: presented in class to search for a journal article. Alternatively, you may use a research search engine such as Google Scholar: (



You are expected to read the article (it’s okay if you don’t understand all the terminology) and prepare an informal report that discusses the following points. Please include the name of the journal, article title, and authors somewhere on the front page of your report.


  1. In the Procedure or Methodology section, what experimental measurement techniques do they use? Include the type of sensors and data acquisition. Do they explain the issues with measurements that we have discussed in class; for example, noise and filtering/ conditioning, amplification of the signal, or other sampling concerns.


  1. Do they mention sources of errors (i.e. bias, random) in their experiment, if so how they account for errors or minimize them? Do they calculate uncertainty in the measurement; how do they present it, do they use plots with error bars or some other means?


  1. Analyze the Results/ Discussion section, do they explain to the reader the physics behind the results to understand the underlying principles, or do they essentially state measurement values or describe what can be easily seen by looking at the plots? What conclusions do they make about their work?


You may attach the journal article to your report, however it’s not required as some article can be rather long. Either way, please include publication information so that the article may be searched (journal name, volume/ year published, article title, and authors.





Problem 2 (5%)



This is an open-ended problem, as such there is no single proper way to devise a solution. The objective is to allow you to think critically and research ideas for a potential way to solve the problem. Credit will be given on your effort and reasoning behind your solution.


Problem Statement

Suppose you are asked to measure the wind velocity, w (in two components along the x and y directions; and respectively) far downstream in the wake of a hovering helicopter rotor where the wind changes minimal direction at a maximum frequency of 10 Hz. Suppose that the mean induced velocity (vi) remains nearly constant at 15 m/s at the plane of the rotor.




  1. Investigate and based on rotor momentum/ actuator disk theory, what is the theoretical velocity magnitude, w far downstream in the wake of the rotor?
  2. Suppose you are asked to measure the velocity components u and using inexpensive electronic componentsHow might you design/ build a simple wind sensor(s) that could measure the wind velocity and direction? Use sketches to present your ideas, you can assume that you can calibrate your chosen sensor/ actuator voltage output to a physical measured variable.
  3. If your wind velocity is changing direction at a maximum frequency of 10 Hz, what is the minimum frequency that you should sample your wind measurement in order to properly capture/ reproduce the wind fluctuations?

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