"Grants and contracts revenue represents the largest component of University revenue ($1.5 billion and 38%)."[0]
Indeed. Many large US universities are more accurately labeled as research centers with schools attached.
Because those grants are extremely restricted in what they can pay for, it's not quite accurate to include them in anything like an "available operating revenue" number.
[0]https://resources.finance.duke.edu/resources/docs/Financial_...
Yes, grant money must be spent according to the approved budget plan for the grant. But Duke is also one of the "elite" schools that charge over 60% "overhead" on federal research grants.