Research Project Information

Research Project Summary Information

Development of Pressure Actuated Leaf Seals for Improved Turbine Shaft Sealing(ST9887-1)



Seals are used in turbines between high pressure and intermediate or low pressure sections to reduce leakage, a critical component to machine efficiency. During start-up and shut-down, the transients experienced in the turbine lead to varying seal clearances, posing a challenge to seal designers. The goal is to minimize leakage and seal rubs which can be detrimental to the turbine. The proposer has developed a pressure activated seal where the seal leaves elastically deflect to reduce operating clearance according to the differential pressure they are subject to. The technology developed thus far has been protected under 2 US patents, presented at multiple respected industry conferences, and has been affirmed by leaders in the seal industry for the potential for improved shaft sealing. The work is now ready to be taken to the next level with application-specific design, manufacturing and testing.

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Project Description

The primary objective of the proposed project is demonstration of Pressure Actuated Leaf Seal (PALS) sealing function to confirm viability of the basic concept. Operability and durability issues will be evaluated in static and rotating rig air tests. Upon completion of rig tests, a seal will be installed in a steam turbine at the Dresser-Rand, Wellsville NY facility to demonstrate operation in that environment. Assessment of performance benefits from improved shaft sealing in power generation steam turbine applications, using steam turbine audit data, is also planned.


Benefits to NYS include reduced energy costs, higher operating efficiency turbines (a potential 3% increase in efficiency and 4% increase in kW output), reduced air pollution as a result of increased efficiency, and an increase in employment.

Project Results

CMG Tech, LLC developed a pressure-activated seal where seal leaves elastically deflect to reduce operating clearance according to the differential pressure to which they are subjected. Under this project, the contractor carried out development of application-relevant seal design, prototype manufacture, and rig testing and demonstrated concept feasibility. PALS seal leakage actually surpassed the project goal of 50% reduction relative to the larger conventional labyrinth seal clearance at design seal pressures, and approaches a 50% reduction relative to the 0.015 inch labyrinth seal clearance. The concept has been presented at respected industry conferences where seal industry leaders have affirmed the potential for improved shaft sealing with the technology. It is the subject of US patent 6,644,667 and continuation-in-part, US publication 2004/0150165. CMG has sold a license agreement to a major turbine OEM, Dresser-Rand (Olean, NY).


29 Stony Brook Dr
Rexford, NY 12148

Principle Investigator

Clayton Grondahl

Universities Involved


Project Type:

Product Development

Technologies Types:

Energy Power Supply
Combustion Turbine

NYSERDA Contact Information

James Foster


R&D -Transport & Power Systems

Contract Details

Start Date: 1/11/2010
Project Status: Active
Contract Number: ST9887-1

Last Updated: 5/8/2012 6