Development of a Research-Oriented Cylinder Head with Modular Injector Mounting and Access for Multiple In-Cylinder Diagnostics 2017-24-0044

Alternative fuel injection systems and advanced in-cylinder diagnostics are two important tools for engine development; however, the rapid and simultaneous achievement of these goals is often limited by the space available in the cylinder head. Here, a research-oriented cylinder head is developed for use on a single cylinder 2-litre engine, and permits three simultaneous in-cylinder combustion diagnostic tools (cylinder pressure measurement, infrared absorption, and 2-color pyrometry). In addition, a modular injector mounting system enables the use of a variety of direct fuel injectors for both gaseous and liquid fuels. The purpose of this research-oriented cylinder head is to improve the connection between thermodynamic and optical engine studies for a wide variety of combustion strategies by facilitating the application of multiple in-cylinder diagnostics.

The cylinder head design was derived from the original production cylinder head used on this engine, which was sectioned and laser scanned to create a parametric model. This model was used as the basis for the design and analysis of the new cylinder head with provisions for a modular injector mounting scheme, multiple simultaneous diagnostics, and to reduce intake swirl for imaging purposes. Finite element analysis was used to evaluate the mechanical strength and computational fluid dynamics was used to optimize coolant flow, and to minimize in-cylinder charge swirl. The cylinder head was cast in nodular iron, using a 3D-printed sand mold.

The utility of the developed research engine head is demonstrated through simultaneous cylinder pressure, IR absorption, multi-color pyrometry, spatially-resolved OH*-chemiluminescence, and spatially-resolved natural luminosity measurements of pilot-ignited, non-premixed combustion of natural gas using Westport Fuel Systems’ high-pressure direct injection (HPDI) injector. Equivalent operating conditions are compared for all-metal (thermodynamic) and optical (Bowditch piston) engine configurations. This paper presents a low-investment, low-risk method for the development of research-oriented cylinder heads with multiple diagnostic accesses and flexible injector mounting.