Modeling & Simulation, Testing & Validation (MSTV)

How to Deal with Fuel Found in Theater: CYPRESS-Cylinder Pressure Based Combustion Control for Consistent Performance with Varying Fuel Properties and Types

by Geoff Jeal; Gary L. Hunter; Stephan L. Kruit


Cylinder Pressure Monitoring (CYPRESS™). This technology provides closed-loop feedback to enable a real-time calculation of the apparent heat release rate (AHRR). This makes it possible to adapt to the fuel ignition quality (cetane number) by adjusting the pilot injection quantity and the placement of the pilot and main injection events. This enables the engine control system to detect fuel quality and adapt the ignition sequence accordingly. This technology is also used to infer the total fuel energy injected by analyzing the AHRR, making it possible to vary the injected fuel volume quantity to achieve consistent (+/- 2%) full load power as the fuel energy density varies. Analysis of the position of AHRR with respect to the crank angle (CA) is dependent on the start of injection and subsequent fuel shots. The ability to control the position of the AHRR maintains thermal efficiency as fuel properties vary which are implemented by controlling the fuel injection pulse widths and common rail injection pressure levels. Key to the development of the control system and subsequent adaptation to a corresponding engine is the AVL analysis and simulation tool suite as follows: • BOOST—One-dimensional thermodynamic modeling of the engine system • FIRE—Detailed fluid mechanics of compressible and incompressible fluid flows in the engine • Engine Simulation Environment (ESE) Diesel— Simulation of the fluid mechanics and chemistry of the diesel combustion process. Through the use of a cylinder pressure sensor, the engine controller will be able to map the development of the AHRR and the mass fuel burn point (MFB50%), which provides good thermal efficiency correlation. The cylinder pressure map detects the start of combustion (SOC) and the feedback controller adjusts the start of injection (SOI) to maintain the SOC in the ideal crank position. The cylinder pressure sensor allows for accurate measurement of the power produced. By varying the volume of fuel in each injection shot the controller actively manages the engine power and noise signature with different fuels (e.g. DF-2, JP-8, JP-5, etc). The initial concept for this approach was derived from AVL’s suite of hardware and software tools developed for base engine combustion research and development. This technology is now licensed to major OEMs and is in production vehicles in Europe.