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.

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.

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.

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.

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.

An Examination of the Repeatability of Combustion Processes in a Homogeneous Stream of a Gaseous Fuel and Air

The present paper reviews some of the findings of an experimental investigation of flame initiation and spread characteristics in the controlled environment of a flowing homogeneous stream of fuel and air within a smooth cylindrical tubular reactor with a large length-to-diameter ratio; both steady and controlled pulsating flow conditions were considered with methane as a fuel. The role of some of the important factors influencing the combustion process, such as the flow characteristics and the imposition of pulsation of known frequency and amplitude, could be established. Particular attention was given to the extent of variations observed in these processes when tests were repeated under otherwise identical conditions.

A Non-Orthogonal Numerical Method for Solving Transonic Cascade Flows

Recently, external transonic aerodynamic methods have shifted from time-dependent methods to relaxation methods, and have been applied to cascade flows. The results were excellent for supercritical compressor cascades, but for more general transonic conditions, the methods proved inadequate. Detailed studies of a choked turbine cascade and corresponding compressor cascades led to the tentative conclusion that the difficulty was associated with a lack of correspondence between the difference star and differential equation region of influence. The analytical approach developed herein avoids this difficulty by construction of difference stars along a non-orthogonal grid system closely aligned to characteristic lines.

Design and Development of High Horsepower Marine Planetary Gears

This paper presents the rationale for the design and development of high horsepower marine planetary gears along with the results of some engineering studies and a progress report covering the development testing of full-scale 40,000- and 60,000-shp marine planetary transmission modules. Recent trends in ship construction, modularization, and introduction of new marine prime movers has given the impetus to the design and development of a family of modular form marine planetary reduction gears. Work completed to date including detail gear designs, transmission hardware trade-off studies, marine architectural installation studies, actual hardware manufacturing and testing, as well as information published in the literature on the use of and the performance of marine planetary gears, shows that the concept of high horsepower marine planetary gears is viable and that substantial benefits will accrue to the owner and the user of this type of equipment. Work described herein related to a joint Curtiss-Wright Power Subsystems/Maritime Administration project on planetary Marine Transmission System Development (Contract Nos. 1-35536 and 3-36247).