Diffuser

1. Field of the Invention

The present invention relates generally to devices for the transformation of part of the kinetic energy of a moving fluid into pressure of the fluid. More particularly the invention concerns a diffuser for use in connection with gas turbines, where an improvement of performance is obtained at the interface between the turbine and the diffuser.

2. Discussion of the Prior Art

Novel and highly successful short subsonic diffusers are described in U.S. Pat. Nos. 3,599,431, 4,029,430 and 5,603,605, all issued to the present inventor. Because of the pertinence of these three patents, and because the present invention comprises an improvement over the inventions disclosed in these patents, U.S. Pat. Nos. 3,599,431, 4,029,430, and 5,603;605 are incorporated by reference as though fully set forth herein.

The diffusers described in detail in the incorporated by reference patents recover a major fraction of the kinetic energy in the stream of gas issuing from the last stage of the turbine and efficiently transform it into an increment of static pressure and, therefore, results in an improvement of the thermodynamic efficiency of the turbine. However, a part of the kinetic energy of the gas at the inlet of the diffuser is not available for recovery because the original design of the turbine did not contemplate the possibility of the level of energy recovery enabled by the advanced diffuser of the present invention; hence, attention to the interface between the turbine and the diffuser permits an additional pressure recovery increment if the diffuser corrects the defects in the flow of the gas from the last stage of the turbine.

Accordingly, the improved diffuser of the present invention is instantiated by transferring to the structure of the diffuser certain mechanical elements that are traditionally part of the turbine structure downstream of the last stage of the turbine. The removal of these mechanical elements from the turbine improves the gas flow to the diffuser and hence improves the energy recovery by the diffuser. As will be discussed in greater detail in the paragraphs that follow, the original function of these mechanical elements can be uniquely incorporated into the structure of the diffuser in such a way as to not affect the mechanical performance of the turbine, while at the same time relying upon the diffuser itself to provide the necessary structural support.

It is an object of the present invention to provide a diffuser apparatus for use in connection with gas turbines that will markedly increase the fuel efficiency of the turbine.

More particularly it is an object of the present invention to improve the performance of the diffuser apparatus by insuring that the gas flow supplied by the turbine is free from unnecessary energy losses due to improperly located mechanical structures.

Another object of the invention is to modify the prior art turbine in a manner to incorporate into the diffuser itself certain of the mechanical structures that previously formed a part of the structure of the turbine.

Another object of the invention is to modify the prior art turbine in the manner described in the preceding of paragraph without adversely affecting the aerodynamic function of the diffuser.

Another object of the invention is to identify the stress path in the structure of the diffuser to insure adequate rigidity against deformations previously resisted by the structural elements of the turbine that were removed from the turbine and incorporated into the diffuser itself.