Originally Posted By: Shannow
Originally Posted By: A_Harman
Originally Posted By: shanneba
One Cup engine flows approximately 70 gallons-per-minute of water at 9,000 RPM.
http://www.hendrickmotorsports.com/news/...rsports-engines
That's actually not very much water flow, considering the power they make. They have a very efficient cooling system.
surely makes use of nucleate boiling to get the job done...
http://energy.gov/sites/prod/files/2014/03/f13/vssp_14_yu.pdf
Uh-oh, the government is talking about using nucleate boiling to cool engines again. This is something that they bring up like it's a new thing about every 10 years. I ran headlong into this when I worked at John Deere Rotary Engine Division in the late 80's. Nucleate boiling cooled engines have been a pipe dream of theirs since the 1930's, when they conceived the Hyper aero engine project, which never got anything into production. Rolls-Royce dabbled in it on their Goshawk engine to great negative effect. Run for the sake of your mental health when a contracting officer asks you to design an engine cooled by nucleate boiling, or demand full payment up front and agree to no liability on the outcome.
Nucleate boiling in the design of cooling systems is similar to boundary lubrication in the design of conventional bearings: it is there as a last resort to save your machine in case the normal mode fails. In cooling systems, the normal mode is forced convection, and nucleate boiling is used as a "safety valve" to effectively transfer heat if pressurization is lost. If an engine is designed to cool with nucleate boiling as the normal operating mode, it is operating on a razor's edge between nucleate and film boiling. Once the engine goes into film boiling, heat transfer is greatly impeded, and the engine starts melting down.
