Advanced Control System Considerations for Small Shaft-Type Aircraft Gas Turbines

The next generation of free-turbine engines in the 2 to 5-lb/sec airflow class will undergo vast improvements in performance and efficiency. The improvements will be achieved concurrent with overall reductions in size and weight. Effort is required at optimization and miniaturization of the engine control system to keep pace with these improvements. This paper describes a conceptual design of an advanced engine control system for this class of engine. It provides gas generator and power turbine control with torque, temperature, load sharing and overspeed limiting functions. The control system was concepted to accommodate, with minimum hardware changes, such variants as regenerative cycle and/or variable power turbine geometry. In addition, considerations for closed and open loop modes of control and fluidic, electronic and hydromechanical technologies were studied to best meet a defined specification and a weighted set of evaluation criteria.

The Use of Fire Tunnel Test Techniques in the Design of Concorde Powerplant

In the very early design phases of Concorde Powerplant it was realized that the high airflows passing through the engine bay would pose significant problems in terms of the precautions necessary to withstand and extinguish fires within the powerplant. A better understanding of the conditions existing in the bay during fires would produce a rational approach to the problem for both the designer and the certifying authority. In order to obtain extensive coverage of all flight conditions it was necessary to depart from current practice and to construct a simulation of the engine and its environment thereby allowing a large number of tests to be carried out. Using this rig it has been possible, not only to prove the means of detection and extinguishing throughout the flight plan, but to obtain a considerable amount of generalized data for use in component design specifications.

Gas Turbine Applications in the U.S. Electric Utility Industry

This paper presents the general planning economics and types of applications for the gas (combustion) turbine generating plants in the U.S. electric utility industry. A typical generation planning study indicates 10 to 20 percent of new generation additions can economically be peaking type units. General observations of gas turbine operating requirements and practices are presented for existing gas turbine applications.

World’s Largest Single-Shaft Gas Turbine Installation

A unique 63,000-kw gas and steam turbine generator has been successfully integrated into a power plant to provide base load electric power and heat feedwater for existing boilers. The unit combined the world’s largest single-shaft gas turbine prototype with innovations of supercharging and a 20,000-kw steam turbine helper on the same shaft. The system, now a part of a Dow Chemical Power Plant in Freeport, Texas, had some minor problems mainly with the prototype turbine and has been in successful base load service since January, 1969.

Power Recovery From Gas Turbines: A Review of the Limitations, and an Evaluation of the Use of “Organic” Working Fluids

Gas-turbine waste heat appears to be a valuable source of energy, yet the number of installations in which this energy is utilized is minimal. The reasons for this are reviewed and a typical nonafterburning cycle is examined for both steam and an “organic” working fluid. The power level range over which each is attractive is obtained, and the costs of each are compared on a relative basis.

Fire Detection Technology for Turbine-Powered Transportation

The problems of providing a fire and overheat detection system for turbine-powered vehicles must be solved during the design phase of the vehicle. In order to accomplish this goal the vehicle design engineer must be aware of the basic constraints involved in the application of fire detection technology. This paper presents a condensed method for understanding, designing and evaluating fire and overheat detection systems. Advanced concepts and technologies such as optical redundancy and high temperature ultraviolet sensors are discussed. Performance of fire and overheat detection systems designed using this approach will provide maximum safety for those using the vehicles, as well as those in its operational envelope.

Requirements for and Operation of a Jet Engine Driven Electrical Generating Plant (70 MW) Sequenced and Controlled for System Peaking and Frequency Change in Venezuela

Arrangement and control features and operating results of a plant designed for unattended automatic operation through load and mode changes including dual frequency, dual fuel, synchronous compensation and isolated start.

Technological Trend of Aircraft Gas Turbines and its Effect on the Development for Ship Propulsion Plants

The effect of the main design parameters of the aero gas turbine engine cycle, namely combustion temperature and compression pressure ratio, on the specific performance values is discussed. The resulting development trend has been of essential influence on the technology. Relevant approaches are outlined. The efforts relating to weight and manufacturing expense are also indicated. In the design of aero gas turbine engines increasing consideration is given to the specific flight mission requirements, such as for instance by the introduction of the by-pass principle. Therefore direct application of aero gas turbine engines for ship propulsion without considerable modifications, as has been practiced in the past, is not considered very promising for the future. Nevertheless, there are possibilities to take advantage of aero gas turbine engine developments for ship propulsion systems. Appropriate approaches are discussed. With the experience obtained from aero gas turbine engines that will enter service in the early seventies it should be possible to develop marine gas turbine engines achieving consumptions and lifes that are competitive with those of advanced diesel units.

Precision Molding of Advanced Fiber Structures

New technologies are being developed to meet the special problems encountered in molding precision parts from highly anisotropic composite materials comprised of advanced fibers and resin. Design considerations require many different ply orientations to fully utilize superior fiber mechanical properties. Coincident with their directional mechanical properties, composites exhibit a similar degree of anisotropy in other physical properties. Measured thermal coefficients of expansion for graphite/epoxy laminates are of −0.5 × 10−6 in/in/F parallel to the fiber axis and 39 × 10−6 in/in/F perpendicular to the fiber axis. Since composite parts are cured at elevated temperatures, this anisotropy produces appreciable residual stress as well as stability problems in dimensions of the finished part. Examples of these problems are presented. In addition to specific problem areas, the many aspects of achieving a true precision molding are reviewed. Specifically, the fabrication variables associated with resin and fiber selection, consolidation, and cure procedures are discussed.

Turbocirculator for High Temperature Gas-Cooled Reactors

The present design study was part of a program undertaken for the purpose of determining the feasibility, establishing the development requirements, and estimating the cost of a turbocirculator to provide the pumping power for a 1000-MWe High Temperature Gas Cooled Reactor (HTGR). Methods were developed for the optimization of the thermodynamic cycle and the design point of the turbocirculator components. A comparison of a turbocirculator to other ways of pumping helium in a HTGR is also shown in this paper. A design of the machine with its associated bearing and seal system and gas conduits was carried out. An important feature of this design is incorporation with the other components of the nuclear steam supply system within the prestressed concrete reactor pressure vessel.