System Status of the Water-Cooled Gas Turbine for the High Temperature Turbine Technology Program

This paper presents an update on the status of the technology of the water-cooled gas turbine developed by the General Electric Company under contracts with EPRI, ERDA, and DOE. Particular emphasis is devoted to the design and development of water-cooled composite turbine nozzles and buckets, and a sectoral combustor designed for low-Btu coal-derived gas operation. The operating characteristics of a low-temperature coal gas chemical cleanup system which is to be added to the coal gasification facility are also discussed. Status of the materials and process developments in support of the designs are also presented, as are updates to the Phase I HTTT Program combined-cycle studies, which evaluate the commercial viability of integrated coal gasification and combined-cycle operation.

Benefits of Solar/Fossil Hybrid Gas Turbine Systems

The potential benefits of solar/fossil hybrid gas turbine power systems were assessed. Both retrofit and new systems were considered from the aspects of: cost of electricity, fuel conservation, operational mode, technology requirements, and fuels flexibility. Hybrid retrofit (repowering) of existing combustion (simple Brayton cycle) turbines can provide near-term fuel savings and solar experience, while new and advanced recuperated or combined-cycle systems may be an attractive fuel saving and economically competitive vehicle to transition from today’s gas- and oil-fired powerplants to other more abundant fuels.

Measurements of Heat Transfer in Circular, Rectangular and Triangular Ducts, Representing Typical Turbine Blade Internal Cooling Passages Using Transient Techniques

Internal convection cooling of turbine blades and nozzle guide vanes in jet engines is a method used to prolong the life of those components, which are subjected to very high temperature flows from the engine’s combustion chambers. The cooling is effected by passing cold gas through the internal coolant passages situated in the core of the components, the shape of these passages in many cases being simple duct geometries. Experiments are described in which transient techniques were used in an Internal Flow Facility to measure the flow property variation and heat transfer in various geometries simulating typical internal coolant passages, at conditions representative of those found in engines. Results obtained from the three geometries studied (circular, rectangular, and triangular ducts) are compared with existing experimental data and an integral-approach theoretical prediction. In addition, flow in the circular duct with mass removal representing film cooling mass flow was also studied experimentally, and these results are compared with theoretical predictions.

Marine Operation of Gas Turbine Engines and Waterjet Pumps for Small Passenger Vessels

This paper describes the planning, developmental, equipment selection and operational problem phases of the high-speed ferry system presently being operated on San Francisco Bay by the Golden Gate Bridge, Highway and Transportation District. The reasons for the selection of the vessel propulsion package consisting of gas turbine engines and waterjet pumps are discussed in some detail. Most importantly, the paper covers the problems experienced to date with this equipment in continuous marine operation.

Water-Cooled Gas Turbine Technology Development: Fuels Flexibility

A continuing technology development program initiated by General Electric (GE) in the early 1960s and joined by the Electric Power Research Institute (EPRI) in 1974 is successfully resolving potential barrier problems in the development of water cooled turbines. Early work by GE Corporate Research and Development demonstrated the feasibility of closed circuit, pressurized water-cooling of stationary nozzles (vanes), and of open circuit, unpressurized water-cooling of rotating buckets (blades). A small-scale turbine was designed, fabricated, and operated at a gas temperature of 2850 F (1565 C) at 16 atm, with surface metal temperatures less than 1000 F (540 C). Early results from the EPRI sponsored Water-Cooled Gas Turbine Development Programs were presented at the 1978 Gas Turbine Conference (Report #ASME 78-GT-72). This paper reports more recent results, obtained between mid-1977 and mid-1978. Significant progress has been made in a number of areas: (a) water-cooled nozzle and bucket design and fabrication, (b) corrosion kinetics model verification and testing, (c) partially filled internal channel bucket heat transfer testing, and (d) stationary to rotating water transfer and collection testing. Results to date are encouraging with regard to the application of water-cooled turbine components to achieve improved reliability and fuels flexibility at increased turbine firing temperatures.

Application of Aircraft Derivative and Heavy Duty Gas Turbines in the Process Industries

Typical applications of aircraft derivative and heavy duty gas turbines in petroleum production and refining, natural gas processing, ethylene, ammonia, LNG processing plants and offshore platforms are reviewed. Guidelines are included to illustrate how gas turbines can be applied to minimize fuel consumption and cooling water requirements and optimize space utilization.

Laser Balancing Demonstration on a High-Speed Flexible Rotor

This paper describes a flexible rotor system used for two-plane laser balancing and an experimental demonstration of the laser material removal method for balancing. A laboratory test rotor was modified to accept balancing corrections using a laser metal removal method while the rotor is at operating speed. The laser setup hardware required to balance the rotor using two correction planes is described. The test rig optical configuration and a neodymium glass laser were assembled and calibrated for material removal rates. Rotor amplitudes before and after balancing, trial and correction weights, rotor speed during operation of laser, and balancing time were documented. The rotor was balanced through the first bending critical speed using the laser material removal procedure to apply trial weights and correction weights without stopping the rotor.

Feasibility of an Isolated Reverse Turbine Concept for Marine Propulsion

The feasibility of an isolated reverse turbine concept for marine propulsion was examined with emphasis on (1) the reverse turbine size needed to meet the stopping distance requirement of a particular ship during a crashback maneuver, and (2) the ahead turbine performance penalty due to reverse turbine windage losses. This particular reverse turbine system was made adaptable to the exhaust elbow and output shaft of an existing free-power-turbine gas turbine. The analysis was based on the application of this reverse turbine concept to a notational single-shaft frigate. The study-ship’s propulsion system includes two General Electric LM2500 gas turbines with reversing capability, a reduction gear, and a fixed-pitch propeller. A ship propulsion simulation was developed for the purpose of calculating steady-state ahead and backing performance data, as well as transient behavior of the ship during crashback maneuvers. The reverse turbine’s speed and torque required to stop the ship in five ship-lengths and 3.5 ship-lengths were determined from these calculations. Four reverse turbine designs were generated using a computer program for preliminary design of axial-flow turbines. The designs included a single-stage and a two-stage impulse turbine for both stopping distances. The penalty on ahead performance due to reverse turbine windage was estimated for each design, using existing experimental data found in the literature. The results obtained thus far tend to support the feasibility of this reverse turbine concept.

Distinctions Between Two Types of Self Excited Gas Oscillations in Vaneless Radial Diffusers

Experiments were conducted to determine the characteristics of oscillating flows in a centrifugal compression system with vaneless diffusers. The system was operated without a diffuser and with eight different diffuser configurations to determine the effects of diffuser diameter and width ratios on the unsteady behavior of the system. Mean and fluctuating velocity and static pressure measurements were carried out in the time and frequency domains. The system without a diffuser was found to be stable at all operating conditions. The installation of any of the eight diffusers resulted in the generation of self-excited oscillations at some operating conditions. It was found that the critical flow coefficient at which onset of oscillations was observed increased as the diffuser width ratio was decreased and as the diameter ratio was increased. Comparison between the characteristics of the oscillations observed in the present study and those observed by other investigators indicate that rotating stall in two geometrically similar diffusers can be an order of magnitude different in the non-dimensional rotational speed and level of unsteady pressure fluctuations. These differences point towards the possibility of existence of more than one set of flow conditions which could lead to the occurrence of the unsteady phenomena.

Ceramics in Rolling Element Bearings

The feasibility of using hot-pressed silicon nitride (HPSN) for rolling elements and for races in ball bearings and roller bearings has been explored. HPSN offers opportunities to alleviate many current bearing problems including DN and fatigue life limitations, lubricant and cooling system deficiencies, and extreme environment demands. The history of ceramic bearings and the results of various element tests, bearing tests in rigs, and bearing tests in a turbine engine will be reviewed. The advantages and problems associated with the use of HPSN in rolling element bearings will be discussed.