How do you test the efficiency of a wobbler steam engine

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Discussion Overview

The discussion revolves around methods to test the efficiency of a wobbler steam engine, focusing on practical approaches for a design project. Participants explore various techniques, including mechanical and electrical methods, to measure the engine's performance.

Discussion Character

  • Exploratory
  • Technical explanation
  • Debate/contested
  • Homework-related

Main Points Raised

  • One participant suggests using a DC motor connected with a belt to the flywheel to measure voltage output, expressing uncertainty about the implementation.
  • Another participant proposes lifting a known mass with a rope attached to the flywheel as a straightforward method to measure work done.
  • A different participant considers the DC motor approach and discusses calculating work using the formula (current * voltage), seeking advice on its validity and efficiency testing.
  • One participant critiques the simplicity of lifting a weight, recommending the construction of a prony brake for more accurate measurements, while also mentioning alternatives like a fish scale and RPM gun for crude measurements.
  • There is mention of using strain gauges and hall effect sensors for precise measurements in the context of the prony brake.

Areas of Agreement / Disagreement

Participants present multiple competing views on the methods to test the efficiency of the wobbler steam engine, with no consensus on a single approach. Some favor mechanical methods while others suggest electrical measurements.

Contextual Notes

Participants express varying levels of familiarity with the proposed methods, and there are indications of differing opinions on the practicality and accuracy of each approach. Specific assumptions about the setup and measurement techniques remain unaddressed.

Who May Find This Useful

Students and hobbyists interested in steam engine efficiency testing, mechanical engineering projects, and experimental design in physics and engineering contexts.

ME-student
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I have a project for my sophomore design class to test the efficiency of a wobbler steam engine. I have heard people talk of using a dc motor and connecting it with a belt to the flywheel to see what voltage it produces but I don't know how to do that. In addtion, some have suggested to just hang a rope with a known mass off the flywheel. If anyone could help me think of a simple way to test the efficiency of my wobbler that would be great.
 
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You need to have it do a measured amount of work.
The suggestion of making it pull a string and lift a weight seems easiest.
The energy to lift a weight = mass * g *height
 
okay. I think that a lot of people are going to do it that way so i looked into doing it with a DC motor. So far i figured out that i have to make the motor turn with my flywheel and then multiply (current*voltge) produced which equals work. Do you have any advice on if that sounds acceptable and how would I test the efficiency of the DC motor I have included in the project?
 
mgb_phys said:
You need to have it do a measured amount of work.
The suggestion of making it pull a string and lift a weight seems easiest.
The energy to lift a weight = mass * g *height


That's a great idea in theory. That isn't how it's done in the real world though. You (ME-student) want to construct what is called a prony brake. This is what you described. I'm currently making one. They are very easy to make. If you want to be crude, a Fish scale and RPM gun will suffice. If you want real measurements, you need strain gauges and hall effect sensors.

Prony brake: Google it.
 

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