Epicyclic Gearing for Gas Turbine Main Propulsion

The success of epicyclic gears in marine main propulsion has been well established. Their small size and weight has led to their introduction in many types of vessel. Epicyclic gears were used in many of the very early naval gas turbine powered vessels and, indeed since then, nearly 250 gears have been supplied for use with a marinized version of the “Proteus” gas turbine. The construction of this and other gas turbine propulsion gears is discussed in some detail to illustrate the basic concepts and design of the gearing. Because of the difficulties in providing astern power in a gas turbine powered ship without the use of a C.P. propeller, there has been interest in the use of a high power reversing gear. Here epicyclic gearing shows a definite advantage over the equivalent alternatives and indeed was used in the naval vessels referred to earlier. Some of the parameters relating to large reversing epicyclic gears are described and the future role of reversing gears is discussed. The description of recently delivered merchant marine triple reduction epicyclic gears is given. The gears transmit 8200 kw from an industrial type of gas turbine and are each installed in a 45,000 tons bulk carrier. Epicyclic gears have played a significant role in the development of gas turbine ship’s propulsion and their future role is discussed in relation to present and projected requirements.

Program Plan for the Design and Spin Test of Ceramic Blade-Metal Disk Attachments

A current NASA-sponsored contract will develop attachment technology for hybrid turbine rotors having dovetailed ceramic ceramic blades and a wrought metal disk. The approach and sequence of activities are described in detail. The program scope includes design, fabrication, and spin testing of hot-pressed silicon nitride blades for operation at rotor inlet temperatures of 2192 F (1200 C) or greater.

Swirl-Can Combustor Performance to Near-Stoichiometric Fuel-Air Ratio

Emissions and performance characteristics were determined for two full-annulus swirl-can modular combustors operated to near-stoichiometric fuel air ratios. The purposes of the tests were to obtain stoichiometric data at inlet-air temperatures up to 894 K and to determine the effect of module number by investigating 120 and 72 module swirl-can combustors. The maximum average exit temperature obtained with the 120-module swirl-can combustor was 2465 K with a combustion efficiency of 95 percent at an inlet-air temperature of 894 K. The 72-module swirl-can combustor reached a maximum average exit temperature of 2306 K with a combustion efficiency of 92 percent at an inlet-air temperature of 894 K. At a constant inlet air temperature, maximum oxides of nitrogen emission index values occurred at a fuel-air ratio of 0.037 for the 72-module design and 0.044 for the 120-module design. The combustor average exit temperature and combustion efficiency were calculated from emissions measurements. The measured emissions included carbon monoxide, unburned hydrocarbons, oxides of nitrogen, and smoke.

A Simple Variable-Geometry Combustor for the Automotive-Turbine Engine

A combustor utilizing concepts of swirling flow and orifices in order to optimize mixing rates was developed for application in low-emissions automotive gas turbine engines. Low emissions were obtained at one operating condition with a fixed-geometry configuration. Addition of a variable opening in the dome of the combustor provided low emissions over the expected operating range for an automotive gas turbine engine. Emissions of NOx obtained on a simulated Federal driving cycle were near the Federal statutory limit, and emissions of CO and HC were considerably lower.

Packaging of Gas Turbines Type 7 and Type S 7

A few years ago, Sulzer introduced two new gas turbines to the market, namely the 9-MW single-shaft type 7 and split-shaft type S 7 machines. Twenty-six units have been delivered to date, and over 100,000 field operating hours accumulated. The positive experience with this machine has allowed an uprating to 10 MW. Changes in the structure of the market, particularly the importance of platform installations, have caused Sulzer to redesign the machine’s auxiliaries, which have been, to a great extent, integrated into the gas turbine package. Flexibility in the application of the machine, easy maintainability, and ruggedness were maintained by reducing the required space to less than half the ground area. The main purpose of this paper is to describe the improved turbine of today. The prototype is briefly described and operating experience is listed. The main part of the paper is devoted to a comprehensive description of the redesigned gas turbine package and its new auxiliary system.

Salt in Sea Atmosphere and its Removal for Gas Turbines

Concentration and size distribution of sea salt particles in air were investigated aboard four different ships (a 10,000-GT class cargo carrier, a 200,000-DWT class oil tanker, and two destroyer-escorts) under various conditions of weather and maneuvering of ships. The data for the concentration and size distribution were converted into basic design data in the light of theories of geophysics. In the meanwhile, the performance characteristics of the demister elements (the fibrous filter and the vane separator), e.g., the pressure loss and collection efficiencies for the particle size in mist, were determined by bench tests. Based on those findings, a demister system applicable to actual ships was proposed, and its performance was predicted for various weather conditions.

Transfer of Heat in Rotating Systems

A calculation procedure has been developed for predicting fluid-flow and heat-transfer phenomena in axisymmetrical, rotating, turbulent, steady flows, with special reference to those mainly confined within cavities. The procedure has been used for predicting boundary-layer flow between a rotating disk and a stationary one, and flow and heat transfer in a shrouded-disk system. Agreement with experimental measurements is satisfactory.

A Simple Method for Supersonic Compressor Cascading Performance Prediction

This investigation is an effort to break down the very complicated flow of a supersonic compressor cascade into a simple model which, in spite of the simplifications, is able to predict realistic values of overall cascade performance parameters. The investigation is limited to high reaction cascades and is focused on design conditions for Double-Circular-Arc blading. The selected flow model includes the inlet flow, which determines the incidence angle and the massflow, the λ-shaped passage shock followed by a boundary-layer separation, the formation of a jet and wake flow, the second shock, and finally the mixing process to a uniform flow downstream of the cascade. Calculated results (inlet Mach number range 1.1 to 1.5) are compared to measured data taken from the literature.

The Redundant Omega Clutch: A Marine Propulsion Clutch for Turbines

The Redundant Omega Clutch is an output shaft-driven centrifugal clutch with an inbuilt hydraulic governor. The clutch is designed with a backup engaging system that provides two separated engaging systems to assure clutch plate clamp. Centrifugal thrust in the engaging cylinders alone is sufficient to maintain clutch engagement for a period of time in the unlikely event of loss of clutch apply pressure from both systems. The clutch has capability to maintain a selected output speed independent of input speed variations and to accept continuous slip heat energy. This paper deals with the design of the clutch and its control system, the principles of operation, performance characteristics, and testing results.

The Use of Experimental Interstate Data for Matching the Performance of Axial Compressor Stages Having Variable-Setting-Angle Blade Rows

Stage performance characteristics provide a powerful analytic tool for experimentally matching the stages and blade rows of an axial-flow compressor, while the variable stage compressor component test rig provides a most powerful experimental tool for developing compressors. This paper describes: Why and how the stage characteristics “normalized” to correct them for changes of stator setting angles, how these normalized characteristics can be fully defined for every stage; and how these characteristic can point the way to a well-matched configuration of setting angles. In addition, it proposes methods for distinguishing between the stall of rotors and stators and for normalizing the characteristics of stages with variable-setting rotor blade rows.