Effect of flow in the circular 90-degree curved nozzles on ejecting oil jet behavior IntroductionNational governments are making efforts to reduce CO2 emissions and thus global warming. In particular, governments in the European Union have established regulations for the emission of CO2 from vehicles having internal combustion engines. These regulations require any new vehicle to have an average CO2 emission below 95 g/km from 2021 (Schulz M. and Kourkoulas D., 2014). The thermal efficiency of the internal combustion engine must be increased to meet these regulations. As an example, an engine is designed with a high compression ratio (Yamakawa, M. et al. 2012) and/or using a downsizing turbocharger (Petitjean, D. et al. 2004) to increase thermal efficiency. Both methods increase the heat load