There is a small set of English words that have 4 consecutive vowels, such as "sequoia" and "Kauai". After trying in vain to come up with more than a few, I brute forced a solution and enjoyed reviewing the results.
I got a huge English word list from here (I used the Scowl one).
The following command line searched for all words with 4 vowels in a row and cleaned up the output:
egrep "[aeiou]{4}" * | awk -F: '{print $2}' | sort | sed -e "/'/d" | uniq
I was really surprised by how many came up (366)! Add "y" and it goes up to 694.
It's interesting to look up the definitions of the results. So far they've all been real words, albeit really obscure.
A list of the words returned is here.