Simulation study on effect of late-intake-valve-closing Atkinson cycle on the performance of a direct injection engine based on fuel economy

Given the wide application of hybrid engines, how to improve hybrid engine fuel economy is being more and more studied, and using the Atkinson cycle to improve fuel economy is considered effective. In this study, the in-cylinder direct injection engine model was established with the data obtained from a benchmarking test using the GT-POWER simulation software. The working process of this engine was simulated after using Atkinson cycle. This simulation primarily focused on the research of the impact on engine fuel economy with different late intake valve closing strategies. The simulation results were calculated under the partial load conditions which are typically used in hybrid engines. The results indicated that engine fuel economy improved and fuel consumption decreased by using the Atkinson cycle. However, the Atkinson cycle would cause a decrease in power.

Overview of Current Hybrid Propulsion Research and Development

As dwindling federal funding continues to constrict the national space program, private entities have carried the torch of innovation in the aerospace industry. While the concept of hybrid rocket engines, systems where solid fuels and fluid oxidizers are used for combustion, was conceived during the mid-20th century, the aerospace industry only recently has substantially increased research and development of these engines. According to the literature, hybrids are safer and cheaper than their liquid counterparts due to the utilization of solid fuel and generally provide greater values of specific impulse, density specific impulse, and fuel energy density than traditional solid-fuel engines. This paper provides an overview of the design principles used to develop hybrid engines and discusses limitations currently faced by industry. Furthermore, development of hybrid engines to allow for both scalability and reusability are explored as private aerospace companies continue to demonstrate that reusable rockets are the future of rocket technology. With applications catering from low-payload cargo delivery to the increasing interest in space tourism and exploration, hybrid engines can provide a safer, less expensive solution than traditional and well-established engine selections. Suggestions for future design opportunities and methods are proposed and discussed to make the concept of hybrid engines a viable innovation in the future of rocketry.