A Low NOx Combustion System and a Ceramic Cross Flow Heat Exchanger for Small Gas Turbines

A new low NOx oil-combustion system with superheated steam fuel evaporation prior to combustion has been found especially feasible for open cycle gas turbines with high turbine inlet temperatures and ceramic cross flow heat exchanger. The actual state of development of both the low NOx light fuel-oil combustion system and ceramic heat exchanger elements, especially the cross flow type, is outlined in this paper. The use of this combustion system results in considerably lower combustion temperatures in the primary combustion zone, reducing the NOx-production even at high air temperatures when the air is preheated in the heat exchanger. The water vapour used for the evaporation of the fuel oil before combustion has an improving effect on the cycle efficiency comparable to the Cheng-dual-fluid-cycle. Illustrative evaluations for a gas turbine cycle for a shaft power of 70 kW are given.

Analytical and Experimental Investigation of the Stability of the Rotor-Bearing System of a New Small Turbocharger

This paper presents an overview of the development of a reliable bearing system for a new line of small turbochargers where the bearing system has to be compatible with a new compressor and turbine design. The first part demonstrates how the increased weight of the turbine, due to a 40 % increase in flow capacity, influences the dynamic stability of the rotor-bearing system. The second part shows how stability can be improved by optimizing important floating ring parameters and by applying different bearing designs, such as profiled bore bearings supported on squeeze film dampers. Test results and stability analyses are included as well as the criteria which led to the decision to choose a squeeze film backed symmetrical 3-lobe bearing for this new turbocharger design.

Thermodynamics and Performance Projections for Intercooled/Reheat/Recuperated Gas Turbine Systems

Intercooled/Recuperated gas turbine systems provide high-efficiency and power density for naval propulsion. Current aero-derivative systems are capable of about 43% thermal efficiency in this configuration. With continued progress in gas-turbine materials and cooling technology, the possibility of further improving system performance by incorporation of gas-turbine reheat arises. A preliminary scan of this class of cycles is presented and compared with non-reheat intercooled/recuperated cycles at two levels of component technology. For conservative component technology, the reheat is found to provide very modest performance advantages. With advanced components and ceramic thermal barrier coatings, the reheat is found to offer potential for specific power improvements of up to 33% and for modest efficiency gains, on the order of one percentage point, while enabling turbine inlet temperatures well below those for the most efficient non-reheat cycles. The high-performance reheat systems, however, require reheat-combustor inlet temperatures beyond current practice. The use of water-injection in the intercooler, together with an aftercooler and a water-injected evaporative-recuperator is found to produce very large gains in efficiency as well as specific power. This modification may be feasible for land-based systems, where it can compete favourably with combined cycles. Despite the difficulty of obtaining pure water for a shipboard propulsion system, those large gains may justify further studies of this system and of means to provide its water supply in marine applications.

Altitude Tests of the XF3-30 Turbofan

The XF3-30 turbofan has been successfully developed as the propulsion system for the Japan Air Self Defence Force’s XT-4 military intermediate trainer. Altitude tests were conducted four times in ATF (AEDC and GE) and four times on FTB in the engine development program. Utilizing the results of each test, the engine has been improved in sufficient time to meet the aircraft development program schedule, and successful flight tests of XT-4 powered by XF3-30 have been made.

LM500 CODAG Propulsion for the Danish Navy Stanflex 300

A description of the Royal Danish Navy’s answer to fleet modernization — a standard hull platform with multi-mission interchangeable modules designed to replace obsolescent classes of minelayer, mine sweeper, surveillance and missile attack craft. Propulsion for this ship will be provided by a triple screw combined diesel and gas turbine (CODAG) plant comprised of a General Electric Co. (USA) type LM500 marinized aeroderivative gas turbine and two (2) Motoren und Turbinen Union (MTU) 16V396 TB84 diesels. This is the first naval application of the General Electric Co. (USA) LM500 gas turbine.

Development of the AGT101 Regenerator Seals

The design and development of the regenerator seals used in the AGT101 gas turbine engine are described in this paper. The all ceramic AGT101 gas turbine engine was designed for 100 hp at 5:1 pressure ratio with 2500F (1371C) turbine inlet temperature. Six distinct phases of seal design were investigated experimentally and analytically to develop the final design. Static and dynamic test rig results obtained during the seal development program are presented. In addition, analytical techniques are described. The program objectives of reduced seal leakage, without additional diaphragm cooling, to 3.6% of total engine airflow and higher seal operating temperature resulting from the 2000F (1093C) inlet exhaust gas temperature were met.

Forecasting “Wooden Round” Reliability During Preliminary Design

The USAF’s R&M 2000 policy emphasizes the integration of reliability and maintainability considerations into a system’s preliminary design phase. This emphasis leads to unique requirements for turbine engines, including those of “wooden rounds” such as a HARPOON type missiles. In particular, it requires the development of tools for assessing the impact of design iterations on the reliability of “wooden round” weapon systems. Such tools must account for design iterations impact on storage, captive carry and launch reliability. A Markov approach is described in this paper, which provides an ability to track the reliability of a fleet of missiles/engines on a period by period basis, allowing one to assess when scheduled maintenance is appropriate and what components require such maintenance. Thus, inputs for Life Cycle Costing are generated, as well as the ability to determine tradeoffs between R&M and performance.

High Performance Gearing for Modern Naval Gas Turbine Propulsion Systems

This paper reviews present day technology in the field of gearing for modern naval propulsion systems. It gives the Royal Schelde views on some aspects of gearing concept design and discusses gearing noise, being a most important aspect of the naval ship noise signature. The paper describes design features of a number of naval gear transmissions for gasturbine and diesel engine driven surface vessels, such as the Canadian Patrol Frigate Gear Transmission System and the Royal Netherlands Navy M-class frigate gearing. Some future trends and the probability of more stringent requirements concerning underwater noise are discussed.

Water Wash System for Marine Gas Turbine Inlet Filters

A water wash system has been developed to allow greater operating flexibility of marine gas turbine intake filters in dust/sand conditions. The water wash system provides protection against sand and dust ingestion previously obtainable only with heavy, expensive inertial separators. Routine filter maintenance is greatly simplified with the use of this system and leads to an average pressure drop reduction through the intake system. This reduction results in significant fuel savings. Furthermore, the introduction of a Propylene Glycol/sea water mixture through the water wash system has shown to be an effective alternative to conventional bleed air de-icing under ice/snow conditions.

FT8: A High Performance Industrial and Marine Gas Turbine Derived From the JT8D Aircraft Engine

This paper describes the FT8 gas turbine, which has been introduced by Turbo Power and Marine Systems (TPM). The FT8 is derived from the Pratt & Whitney JT8D aircraft engine and the TPM FT4 industrial gas turbine. The FT8 has been launched with a collaboration program between TPM and the China National Aerotechnology Import-Export Corporation (CATIC) of the People’s Republic of China. The collaboration program includes co-production of certain components and a 37-unit order from CATIC over a 10-year period for marine and industrial applications.