 |
|
|||||||||||
|
| ||||||||||||
|
|
A commercial client contracted with Southwest Research Institute (SwRI) to design a complete new cylinder head for an existing engine. The project was prompted by problems with the durability of the current cylinder head; it was determined by the client and SwRI that complete redesign was necessary to implement the changes needed to meet the durability targets. The engine is a large, stationary natural gas-fired engine for power generation. ApproachThe preliminary design was conducted using Pro/ENGINEER™. Constraints included compatibility with the existing engine cylinder block, camshaft, and manifold locations. New valve orientations were specified to achieve a target level of swirl, and the intake and exhaust ports were designed consistent with the new orientations. New valve sizes were specified. The cylinder head design was completed by creating solid models of all the sand cores used in casting the head. All of the valve gear were also completely redesigned consistent with the reoriented valves and the objectives of reduced wear.
CNC tools were used to create flow boxes of the intake and exhaust ports, which were subsequently tested on the large engine flowbench. Swirl and flow characteristics were among the best ever measured for engines of this size.
Flow characteristics of the water jacket, critical for maintaining uniform firedeck cooling, were analyzed using CFD and bench tests of a clear plastic model of the water jacket. A brick-element mesh was constructed for the CFD work using PATRAN™ and analyzed using CFD-ACE™. The water flowbench model was used with particle imaging to determine flow velocities. The model and test matched very well, and both led to several critical changes to the water jacket to obtain the desired result.
Finite element analysis was conducted on the complete cylinder head assembly. Three-dimensional mesh models were prepared using Pro/ENGINEER™ and analyzed using ANSYS™. Loading conditions were obtained from the dynamics and cycle simulation analyses and from experience with thermal loading conditions, coupled with measured temperature data. The results indicated that installation loads were the predominant factor in creating head stresses, and several design changes were implemented to obtain acceptable stress levels.
ConclusionPrototype testing of the cylinder head was successful, meeting all objectives, and the cylinder head and associated components are now in production.
For more information about this engine design project, or how you can contract with SwRI, please contact Mark Tussing at mtussing@swri.org or (210) 522-2628.
|
|
||||||||||
|
| Design and Development | Engine, Emissions & Vehicle Research Division | SwRI Home | |
||||||||||||
|
Southwest Research Institute® (SwRI®), headquartered in San Antonio, Texas, is a multidisciplinary, independent, nonprofit, applied engineering and physical sciences research and development organization with 11 technical divisions. |
||||||||||||
|
December 28, 2012 |
||||||||||||
