Sea Salt Spray Ingestion by FFG Gas Turbines.
Abstract
At-sea measurements of salt spray in the FFG-13 main propulsion gas turbine intake found 50 times more salt than on the DD963 at similar sea state. This factor of 50 resulted from (a) ten times more salt being present upstream of the inlet filters because of the inlet placement lower and flush with the hull as compared to the DD963 inboard placement, and (b) at least five times greater percentage of salt penetration through the FFG knit mesh filter medium as compared to the DD963 'barrier' or coalescer pad type of filter. The more 'open' filter medium was needed on the FFG in order to minimize pressure drop across the filter with the smaller filter space which was available with allowance for the space required for a settling chamber or 'drop space' upstream of the filters. This salt survey also determined that the drop space, while needed for green water, does not reduce the salt loading at the filter in the small particle sizes (< 20 micrometers) which create the principal problem in salt filtration. In view of this finding, NRL recommends (for the long term) retrofitting the filter mounting to change it from athwartship to diagonally fore-to-aft with a resultant reduction in drop space, but enlargement of the filter mounting space to permit use of the tighter (higher pressure drop) 963 type coalescer pads for combined inlet and secondary cooling air filtration. For the short term it is recommended that the previous monthly engine water wash cycle be supplemented with a daily non-detergent wash of the compressor stages during at-sea missions. The water tank plumbing may need to be upgraded in order to facilitate under-way washing.
Document Details
- Document Type
- Technical Report
- Publication Date
- Jun 09, 1981
- Accession Number
- ADA100506
Entities
People
- F. K. Lepple
- R. E. Ruskin
- R. K. Jeck
Organizations
- United States Naval Research Laboratory