Multi-hole injector optimization for spark-ignited direct-injection gasoline engines

Project Description

GM is moving to spark-ignited direct-injection (SIDI) to improve efficiency to meet current and future regulations, consumer expectations, and to be competitive in the era of rising gas prices. Within the SIDI engines, the trend has been to move towards multi-hole type gasoline injectors. Multi-hole sprays offer the flexibility to control the orientation of spray and pose a challenge in terms of optimization of this very high degree of freedom for design. Since it is not possible to test all the permutations and combinations in real hardware (both cost and time), we increasingly rely on computational techniques such as CFD to reduce the number of probable injector concepts for a given combustion system. The additional complication is that we cannot arbitrarily insert a fuel injector into an SIDI engine as that can lead to poor efficiency and emissions problems. So we have to have an integrated strategy to optimize the entire system (engine) and not just the spray. The goal of this research is to develop an analytical methodology to streamline the injector design process in the context of the overall performance of the engine. This methodology includes understanding internal nozzle flows and its effect on spray

development and subsequent performance of the engine. The Leadership Computing Facility (LCF) allows the opportunity to run the required mesh resolution along with several parametric studies to understand the important physics. The project is sub-divided into three phases:

• Phase 1 – Validate nozzle internal flow model with available spray vessel data

• Phase 2 – Coupling of nozzle internal flow with external engine spray

• Phase 3 – Optimization of injector hole pattern design for desired in-cylinder fuel-air mixture distributions to achieve best fuel economy and lowest engine-out emissions