THE BENEFITS TO BE REALISED BY THE DEVELOPMENT OF THE COMPUTER CODE ARE THE DESIGN OF MORE EFFICIENT COMBUSTION UNITS HENCE IMPROVED FUEL ECONOMY, REDUCED EXHAUST EMISSIONS AND INCREASED COMPETITIVENESS OF EUROPEAN MANUFACTURERS.
A computational fluid dynamics code called SPEED has been developed to simulate the 30 in cylinder flow field and turbulence in arbitrarily shaped combustion chambers. It will operate successfully with nonorthogonal, unstructured and locally refined meshes, allowing accurate definition of any chamber geometry. Its main restriction is the limited availability of automatic mesh movement routinesto aid successful manipulation of complex meshes through a full simulation cycle. A well developed preprocessing and postprocessing environment is available. The code has undergone extensive testing on a wide range of geometries during its development.
The project has now provided combustion engineers with an important design aid to increase understanding, and improve optimisation, of the flow processes in reciprocating engines. Design and development programmes will become faster and more cost effective, with the resultant combustion systems giving further improvements in fuel economy and exhaust emission reduction.

A computational fluid dynamics code called SPEED has been developed to simulate the 30 in cylinder flow field and turbulence in arbitrarily shaped combustion chambers. It will operate successfully with nonorthogonal, unstructured and locally refined meshes, allowing accurate definition of any chamber geometry. Its main restriction is the limited availability of automatic mesh movement routines to aid successful manipulation of complex meshes through a full simulation cycle. A well developed preprocessing and postprocessing environment is available. The code has undergone extensive testing on a wide range of geometries during its development.
The project has now provided combustion engineers with an important design aid to increase understanding, and improve optimisation, of the flow processes in reciprocating engines. Design and development programmes will become faster and more cost effective, with the resultant combustion systems giving further improvements in fuel economy and exhaust emission reduction.
THIS IS A PART OF A WIDER THEORETICAL STUDY OF THE BEHAVIOUR OF AIR FUEL MIXTURES IN COMBUSTION ENGINE CYLINDERS BOTH BEFORE AND DURING THE COMBUSTION PROCESS. THIS PARTICULAR PART DEALS ONLY WITH THE BEHAVIOUR OF THE GASEOUS CHARGE BEFORE FIRING (COLD FLOW) AND AIMS TO PRODUCE A THREE DIMENSIONAL COMPUTER MODEL OF FLOW AND TURBULENCE IN THE CYLINDER.

THE FIRST PHASE OF THE WORK HAS ALREADY PRODUCED SUCH A MODEL FOR A LIMITED RANGE OF COMBUSTION CHAMBER SHAPES AND PHASE 2 WILL EXTEND THIS TO SIMULATE THE FLOW INSIDE A MUCH WIDER RANGE OF CHAMBER GEOMETRIES.

COMBUSTION CHAMBER DESIGN IS CRITICALLY IMPORTANT TO FUEL ECONOMY, EXHAUST EMISSIONS AND POWER OUTPUT BUT HITHERTO DEVELOPMENT HAS BEEN ALMOST ENTIRELY EXPERIMENTAL AND THEREFORE LONG AND COSTLY. AN IMPORTANT PART OF THE PRESENT PROJECT WILL BE TO TEST AND EVALUATE THE THEORETICAL PREDICTIONS AGAINST EXPERIMENTAL DATA. THE LATTER WILL BE OBTAINED BY LASER DOPPLER ANEMOMETRY USING AN EXTERNALLY MOTORED PLEXIGLASS ENGINE TO ALLOW OPTICAL ACCESS TO THE COMBUSTION CHAMBER.

THE WORK WILL INVOLVE NOT ONLY THE DEVELOPMENT OF SUITABLE COMPUTER PROGRAMMES BUT ALSO THE PREPARATION OF APPROPRIATE INPUT, OUTPUT AND GRAPHICS MODULES. THE INTENTION IS TO PRESENT A FINAL COMPUTER PACKAGE WHICH CAN BE USED FOR COMBUSTION CHAMBER ANALYSIS AND DEVELOPMENT BY DESIGN ENGINEERS WHO ARE NOT THEMSELVES COMPUTER SPECIALISTS.