HARPPP: Autonomous Geometric Design Optimisation of Stirred Tank Reactor Impellers and Baffles

Abstract

Designing and optimising the geometry of industrial process equipment remains slow and still largely ad hoc: engineers make small tweaks to one standard shape at a time, build prototypes, and hope for gains. We introduce HARPPP, an autonomous design loop that couples a compact, programmable geometry model to power-controlled CFD and evolutionary search. The geometry model is a single mathematical description that reproduces every standard impeller as a special case while spanning an unlimited set of manufacturable shapes. Working with Johnson Matthey on an industrial vessel, HARPPP explored a 23-parameter impeller-baffle space at constant power (3024 W), executing 3,000 simulation cycles in 15 days. The search uncovered multiple design families that outperform a Rushton/4-baffle baseline in both mixing intensity and uniformity, including twisted-plate impellers and pitched/curved baffles (intensity +18 to +78 percent; uniformity CoV -16 to -64 percent). A clear intensity-uniformity Pareto frontier emerged, enabling application-specific choices. Because HARPPP treats the simulator as the objective, it generalises to other equipment wherever credible physics models exist.