Preliminary evaluation of high modulus graphite fiber-resin composites in gas turbine engine hardware has revealed a high degree of residual stresses in such materials. These residual stresses are caused by the mismatch in thermal expansion of the reinforcement and the resin. An analysis indicates that the amount of residual stress can be closely related to the design of the composite construction as well as materials selection and processing. A model was designed for qualitatively evaluating the variables affecting the residual stresses. Several epoxy resin systems were evaluated and characterized for their ability to produce defect-free composites. It was found that resin shrinkage and resin-fiber bonding (transverse tensile strength) are contributors. Recognizing composite residual stresses, an intelligent approach can be taken to composite hardware design.

This paper presents a preliminary design of a water-cooled gas turbine capable of operating on coal derived fuels and producing 73 MW when burning low Btu coal gas. Particular emphasis is placed on the critical technology issues of combustion and heat transfer at 2600 deg firing temperature. The recent technology developments; i.e., materials developments, composite construction, water cooling, fuels cleanup, etc., which now make this advanced concept possible are discussed. Detailed descriptions of the hot gas path components, the staged sectoral combustor, the water cooled nozzles and buckets, are described showing the implementation of these recent developments. The component development test program which is underway, is described and where testing results are available, design confirmation is demonstrated. Future plans for the construction of a full scale prototype machine and for design verification testing are presented. An analytical evaluation is included which demonstrates the advantages of the water-cooled gas turbine in an integrated gasification combined cycle.

During Phase II of the Department of Energy (DOE) funded High Temperature Turbine Technology (HTTT) Program, critical technology development and component verification testing related to the design of an advanced water-cooled gas turbine, firing at 2600°F (1427°C) on low-Btu gas, are being performed by General Electric. A composite construction first stage nozzle was chosen so that low surface temperature [1000°F (538°C)], necessary to control corrosion and high heat flux induced strain, would result. This paper discusses the prototype testing of a three throat segment of this design. The segment consists of two test vanes and a pressure and suction side slave. Hot gas conditions exceeded the design point conditions of 2600°F (1427°C) firing temperature, 166 psia (1.14 MPa) and 6.37 lbm/s (2.89 kg/s) per throat. Nozzle temperatures are presented as a function of firing temperature. Discussion of boiling phenomena which occurred during coolant flow reduction is included. Results are discussed as they relate to verification of the design method and to establishing the “technology readiness” of this design.

This work offers the first known three-dimensional (3-D) continuum vibration analysis for rotating, laminated composite blades. A cornerstone of this work is that the dynamical energies of the rotating blade are derived from a 3-D elasticity-based, truncated quadrangular pyramid model incorporating laminated orthotropicity, full geometric nonlinearity using an updated Lagrangian formulation and Coriolis acceleration terms. These analysis sophistications are included to accommodate the nonclassical directions of modern blade designs comprising thin, wide chord lifting surfaces of laminated composite construction. The Ritz method is used to minimize the dynamical energies with displacements approximated by mathematically complete polynomials satisfying the vanishing displacement conditions at the blade root section exactly. Several tables and graphs are presented which describe numerical convergence studies showing the validity of the assumed displacement polynomials used herein. Nondimensional frequency data is presented for various rotating, truncated quadrangular pyramids, serving as first approximations of practical blades employed in aircraft engines and fans. A wide scope of results explain the influence of a number of parameters coined to rotating, laminated composite blade dynamics, namely aspect ratio (a/b), chord ratio (c/b), thickness ratio (b/h), variable thickness distribution (h l /h t ), blade pretwist angle ( ϕ o ), composite fiber orientation angle (θ), and angular velocity (Ω). Additional examples are given which elucidate the significance of the linear and nonlinear kinematics used in the present 3-D formulation along with the importance of the Coriolis acceleration terms included in the analysis.