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Archive for September, 2017
Posted by gryhrdoldfool | Sep 20, 2017 @ 05:16 AM | 2,566 Views
As promised I have written out a brief description of how EDF's work. This description is only part of the whole story and I will endeavour at some later date add to it in such a way that it will benefit users. I have as yet, not worked out exactly all the consequences of a 'Real' world unit but so far I believe that the basic theory will remain both intact and applicable. Please read, I know many theories have been advanced on the pages of a good number of forums and for the reader this is just 'another' example. I do hope there will be some who read it through and digest.

ELECTRIC DUCTED FANS.
When I first looked at these little flight engines, like most, I thought they are somewhere between a propellor and an axial compressor stage, however I quickly realised they are something on their own. The nearest is a compressor blade that produces no increase in density, that is the compression should, ideally, be only a constant volume process. Having said that, like a propellor, they use the principle of forward procession - or pitch.
I will now lay down the configuration of this device, a duct that is parallel from entry to the end of the vanes, a 'concentrating nozzle'* and a fan with a 'solidity'** less than but close to one with a parallel platform continuing past the vanes. Finally this applies only to ducted fans that operate at less...Continue Reading
Posted by gryhrdoldfool | Sep 07, 2017 @ 05:57 AM | 2,316 Views
After reading the following a number of times I realised I might appear arrogant and a 'know it all' this is not the case I am very careful. For any theory to be used for a particular application it must be balanced I.E. in this case it must precisely follow Newtons Laws, Impulse and Thermodynamics. If there is any imbalance then either the theory is incomplete, plain wrong or not applicable to this situation. ALL of the theories that I have read, when examined by this criteria, fail - so does that make me arrogant?
This is basically a cry for help. I am an aerospace engineer with over forty years of experience including about twenty five years in gas turbines, I retired and looked around for something as an interest, I was an aeromodeller in my youth. So I looked at electric flight and in particular electric ducted fans. I want to design and build units from scratch, so I looked around the web for details about design, performance, efficiency etc. I thought this was well done and dusted, digging out my texts on thermodynamics I discovered this particular topic was skirted around, yes compressor blades, propellors and open fans but nothing on ducted fans that didn't reference ducted propellors*. Everything I looked at rang alarm bells in my head, there is nothing available from googling that made any sense, maybe there are books available with adequate explanations but so far all I have seen are scaled down explanations of fans that are based on high velocity units (as...Continue Reading