This invention relates generally to turbine engines, and, more particularly, to seals which are interposed between adjacent turbine blades.
Turbine engines have a variety of practical appications, the most important of which is in the field of aviation. In the propulsion of aircraft, the gas turbine power plant as a turbo prop or turbine jet engine has replaced the reciprocating engine in large, high speed aircraft. This change is due primary to its high power to weight ratio and its ability to be built in large horsepower sizes with high ratio of thrust per frontal area. In addition, turbine engines are useful in gas pipe line transmission, generating power in refineries and other industries as well as being useful in the marine transporation area and for the electric power generation.
The split pressure ratio design of certain turbine engines require that the outer panel flow of the turbine be sealed off from the inner panel flow, both from aerodynamic performance and mechanical reliability standpoints. Intolerably large amplitude vibratory stresses are induced in the stage two blades if the mid span joint is not sealed. The problem confronting the field is proper and reliable sealing of this mid span joint. Heretofore the joint was sealed by a simple, bonded plastic strip. Many bond failures, however, occurred in both factory and field testing, and in the production service. These seal strips became loose and extruded themselves through the opening between mid spans. As a consequence large blade stresses resulted.