<div class="section abstract"><div class="htmlview paragraph">Manufacturers of internal combustion engines are changing their focus to non-conventional fuels like hydrogen in response to the worrying global warming situation. When compared to conventional fuels like gasoline or diesel, the use of gaseous hydrogen fuel in an internal combustion engine powered by hydrogen can lessen the engine's negative environmental effects. But occasionally, hydrogen can leak from the high-pressure fuel injection system to the engine top cover and as blowby within the crankcase. Static zones may emerge because of these H<sub>2</sub> leaks. Potential explosion or fire can result when the H<sub>2</sub> concentration in these stagnation zones is more than 4% and triggers a minimum ignition energy of 0.02 mJ.</div><div class="htmlview paragraph">A CFD simulation methodology incorporating multi-species model, piston, and crank motion to estimate the H<sub>2</sub> concentration within crankcase is developed. The simulation development phases has been presented in the paper. The blowby values are determined from the experimental measurement and used as the inputs. The dilution strategy by varying the number of vent ports, location, size for crankcase is examined using this simulation. The flow requirements at various speed also deduced. Further, for under hood and engine top cover, underhood analysis is carried out to ascertain the accumulation within the engine and its compartment. Fan ON and OFF scenario is studied, and results are discussed.</div><div class="htmlview paragraph">H<sub>2</sub>ICE blowby and H<sub>2</sub> % concentration at breather tube out is correlated with test for a baseline case. A good correlation matching the experimental trend is observed in the simulation.</div><div class="htmlview paragraph">The study helped engine program to complete the optimization and design verification through simulation and get the best concept implemented.</div></div>
