I meant to have the scholarship about Henry V and Fluellen posted a few days ago, but I've honestly had a bit of trouble finding anything. It appears that most scholars label the Welshman as the figure of "ethnicity and Welsh pride" represented in the play, and leave it at that. Well, that wasn't enough for me. I finally found a few different articles that seemed to perform at least SOMETHING of an analysis on Fluellen; I thought I'd post a brief annotation about each one and then provide you the links. They each differ on topic and opinion of Fluellen's worth, so it would probably be hard to pull a research paper out of these, but they are still interesting reads.
The first is actually one I found for Alicia--she noted the strangeness of Fluellen's name and suggested looking up some of its origin. Well, I didn't find anything to do with the Flu or with an Ellen (or a female character at all), but this article does have a number of great historical insights to the Welsh name. The author states that Fluellen's name is "readily comprehensible as Llywelyn", a variation that, with the double 'L', becomes difficult for the English to pronounce. He says this makes Fluellen a member of importance, because the other famous "Llywelyn" was the last Prince of Wales. Time is also spent discussing the fact that Fluellen, though Welsh, does not a patronymic name (meaning multiple names that give the lineage of his patriarchal line). This is of note because it makes him something of an illegitmate son, just as King Henry is also struggling to find his place in a role that is not 'rightly' his.
The next is actually a chapter in a book called Essays on Shakespeare's Dramatic Characters with an Illustration of Shakespeare's Representation of National Characters, in that of Fluellen. The chapter I am specifically going to be focusing on (and which you will need to select in the topic section if you wish to read it) is called--ironically--"The Character of Fluellen". To save a lot of your time, skim down to Part III; that's when his FINALLY starts talking about Fluellen. Richardson focuses on Fluellen's ethnicity and his pride as a Welshman, speaking lightly about the geographic natures of Wales that would make him so profoundly proud of his country. The author also refers often to the Welsh as a whole, giving a deeper insight into the nation that Fluellen is meant to represent.
The last is another book that I had to do a bit of digging for. I located the specific article on the Shakespeare Bibliography, but couldn't open and read it until I found the full-book preview on Google books. It's called Reading the Early Modern Passions: Essays in the Cultural History of Emotion. The section you'll be looking for is called "English Mettle". Much of the entry has to do specifically about the English's (supposed) superiority (not just by themselves, but also--as the battle goes along--by the French), but she also focuses on Fluellen for a time. Specifically, Floyd-Wilson talks about three things: Fluellen's military discipline, his knowledge of history, and his representation as the "England that was Before", the untamed one. Ironically, Fluellen's discipline also demonstrates the tempermental nature that the author believes was once shared between Wales and England.
Hopefully there is something of interest there. Although the section on Fluellen is perhaps the smallest in that selection, I would highly recommend the third. Floyd-Wilson brings up a number of valid points about the possible purpose for why Shakespeare would created such a gripping, show-stealing "fool".