27. February 2018 Lukáš Mácha

Fighting the Units

First semester filled up with Chassis Engineering, Design Modelling in SolidWorks and Advanced Applied Scientific Methods finished by two examination weeks in January seems to be ages ago and I am in a 5th week of the second semester. The major topics for this one, are Powertrain Technology, Electronics including Engine Management Systems and Data Acquisition and Materials alongside Structural Analysis module.

All this includes one more challenge compared to the previously mentioned topics. When it comes to things such as Powertrain Engineering and more specifically than to forced induction in forms of Turbocharging (the big red-hot turbines spinning at speeds over 100 000 RPMs) or Supercharging (every Fast and Furious fan certainly recalls Dominic Toretto’s supercharged 1970 Dodge Charger R/T) or in some extreme cases both, majority of such devices comes from the States. This brings another challenge that is converting units to metrics so one can at least have a rough idea about the performance available. Typical example that can be found in Turbocharger specs is the compressor map where Pressure Ratio is plotted against Gas Turbine Flow. Logically, one would expect Flow to have a volumetric unit such as cubic meter per second, but not in the world of imperial units where this is measured in pounds per minute [lb/min], yes, the same pound word that is used as a unit of mass or currency in terms of British Pound.  So, if I recall troubles I had in couple of first weeks with converting meters per second to miles per hour or inches into meters in some classes, this makes me laugh.
Another example is studying engines performance using in-cylinder pressure curves where this can sometimes be using units in form of inches of vacuum (does not make sense, does it), typically vacuum for everyone who ever came across this term outside English speaking countries certainly means a space where a piece of iron and a feather fall at a same speed. Again, this is something different in UK, by vacuum is meant a space (tube, manifold) where the pressure is lower than atmospheric pressure (i.e. 1 bar), in Czech this is called ‘podtlak’. One can thing of this as a confusing terminology, but on which site?  
Just so I will not forget to mention, our University of Derby Formula Student Project is getting into the stage of manufacturing and assembly so stay tuned for another next blog where I will provide a feedback on the whole year worth of work at this extracurricular activity. 
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