What is the phonetic pronunciation of Charles Ardai?

I assume you're only asking about the pronunciation of "Ardai," not of "Charles."

"Ardai" is pronounced with the emphasis on the first syllable ("AR") and with the second syllable sounding like the substance that changes the color of cloth ("dye").

So: AR-dye. Ryhmes with "HARD-eye" (or "GUARD-eye," etc.).