Peter Hooper

Advanced modern low-emission two-stroke cycle engines

This paper reviews recent engines and associated technology offering potential low-emission two-stroke cycle operation for a range of applications. The study considers and discusses successfully applied modern production engines together with concepts exploring advanced possibilities for future application. The published results from research and development projects and the data from available technology are compared in terms of the specific performance. The paper does not compare combustion strategies or fluid dynamic aspects of two-stroke cycle engines but does consider and compare the data from engines using the crankcase, external, and stepped piston scavenging intended for automotive, marine, and defence applications.

Initial development of a multi‐fuel stepped piston engine for unmanned aircraft application

The SPV580 stepped piston engine has been designed and developed for UAV application. The gasoline engine produces a minimum of 30kW at 5000 RPM, increasing to 35.4kW if exhaust tuning can be permitted. The gasoline performance of this novel engine design is presented together with work to investigate the feasibility and performance characteristics of kerosene fuelling.

Experimental experience of cold starting a spark ignition UAV engine using low volatility fuel

Purpose The purpose of this paper is to present results of practical experience of cold starting a gasoline engine on low volatility fuel suitable for unmanned aerial vehicle (UAV) deployment. Design/methodology/approach Experimental research and development is carried out via dynamometer testing of systems capable of achieving cold start of a spark ignition UAV engine on kerosene JET A-1 fuel. Findings Repeatable cold starts have been satisfactorily achieved at ambient temperatures of 5°C. The approximate threshold for warm engine restart has also been established. Practical implications For safety and supply logistical reasons, the elimination of the use of gasoline fuel offers major advantages not only for UAVs but also for other internal combustion engine-powered equipment to be operated in military theatres of operation. For gasoline crankcase-scavenged two-stroke cycle engines, this presents development challenges in terms of modification of the lubrication strategy, achieving acceptable performance characteristics and the ability to successfully secure repeatable engine cold start. Originality/value The majority of UAVs still operate on gasoline-based fuels. Successful modification to allow low volatility fuel operation would address single fuel policy objectives.

Improved efficiency of an unmanned air vehicle IC engine using computational modelling and experimental verification

Purpose This paper aims to present experimental results of gasoline-fuelled engine operation of a crankcase-scavenged two-stroke cycle engine used for unmanned air vehicle (UAV)/unmanned air system application and to cross correlate with computational fluid dynamic modelling results. Design/methodology/approach Computational modelling of the engine system was conducted using the WAVE software supported by the experimental research and development via dynamometer testing of a spark ignition UAV engine to construct a validated computational model exploring a range of fuel delivery options. Findings Experimental test data and computational simulation have allowed an assessment of the potential advantages of applying direct in-cylinder fuel injection. Practical implications The ability to increase system efficiency offers significant advantages in terms of maximising limited resources and extending mission duration capabilities. The computational simulation and validation via experimental test experience provides a means of assessment of possibilities that are costly to explore experimentally and offers added confidence to be able to investigate possibilities for the development of similar future engine designs. Originality/value The software code used has not been applied to such crankcase-scavenged two-stroke cycle engines and provides a valuable facility for further simulation of the twin cylinder horizontally opposed design to offer further system optimisation and exploration of future possibilities.

Investigation Into a Stepped-piston Engine Solution for Automotive Range-extender Vehicles and Hybrid Electric Vehicles to Meet Future Green Transportation Objectives

Securing the objectives for future high-efficiency low-carbon-dioxide vehicles is a key target for automotive manufacturers. This paper considers a high-durability two-stroke cycle engine in terms of performance and computational modelling of the emissions characteristics for automotive range-extender or hybrid electric vehicle power plant application. The engine uses novel segregated pump charging via the application of stepped pistons, and a comparison of the engine characteristics is made with those of a comparable four-stroke cycle engine of similar expected power output (more than 60 kW/l). In the interests of cost minimisation, both engines are limited to parallel two-cylinder in-line configurations with the intention of still being able to achieve acceptably low noise, vibration and harshness characteristics. In order to achieve low engine exhaust emissions, computational modelling of direct injection is considered for the stepped-piston engine. A significant reduction in the nitrogen oxide emissions of between 31% and 55% is observed.