Ranked Choice Voting (RCV) & Instant Runoff Voting (IRV) are used interchangeably.
Fair Vote has some data that might be useful.
If the Fair Vote site does not have what you need, try doing a Google search restricted to government websites. Here is an example:
Site:.gov ("Ranked Choice Voting" OR "rank choice voting" OR "instant runoff")
Try doing this same search but adding AND statistics
This will help you identify which jurisdictions use RCV/IRV, then you can use the same type of Google search (using Site:.gov) to determine the name of the agency that maintains voting statistics. The name of the agency responsible for collecting election data varies from jurisdiction to jurisdiction. Here in DC, it's the Board of Elections, in many states it is the Secretary of State.
For additional sources of voter turnout data consult this FAQ:
Where can I find voter turnout statistics? The FAQ lists many places to find voter statistics. You will need to take a look at the various sources to see if IRV/RCV stats are reported.
