Automotive Ceramic Gas Turbine Research Articles

Research and Development of the Automotive Ceramic Gas Turbine

To demonstrate the advantageous potential of ceramic gas turbines for automotive use, the 7–year R&D programme conducted by the Petroleum Energy Centre in Japan, is under way. The basic engine is a 100 kW, single–shaft regenerative engine having a turbine inlet temperature of 1350°C and a rotor speed of 110,000 rpm. The engine components were designed, experimentally evaluated and improved in the individual and various assembly test rigs, and an assembly test including rotating and stationary components was performed under the condition of turbine inlet temperature of 1200°C.

Development of Low-Emission Combustor for a 100kW Automotive Ceramic Gas Turbine (2nd Report, Emissions of a Pre-vaporization Pre-mixing Lean Combustor)

Development of Low-Emission Combustor for a 100kW Automotive Ceramic Gas Turbine (2nd Report, Emissions of a Pre-vaporization Pre-mixing Lean Combustor)

Development of Low-Emission Combustor for a 100 kW Automotive Ceramic Gas Turbine. 1st Report, Combustion Performance of a Pre-vaporization Pre-mixing Lean Combustor.

A low emission combustor, which uses a pre-vaporization pre-mixing lean combustion system for a 100 kW automotive ceramic gas turbine (CGT), has been designed, developed and subjected to performance tests. In the early stages of the tests, flashback and auto-ignition caused by extremely high combustor inlet temperature were major problems of the development. Introducing air to the boundary layer of the mixture flow, was one of the measures which effectively prevented flashback. Auto-ignition characteristic was described by a semi-experimental equation. Requirements needed to achieve CGT performance, such as operation range due to combustion characteristics, pressure loss and temperature distribution were fully satisfied.

The application of ceramic-matrix composites to the automotive ceramic gas turbine

A Japanese 100 kW automotive ceramic gas turbine (CGT) project was started in 1990 and was concluded successfully in 1997. This project was supported by the Ministry of International Trade and Industry and was conducted by the Petroleum Energy Center to achieve the targets of this project such as higher thermal efficiency over 40% at a turbine inlet temperature of 1350°C, lower exhaust emissions to meet Japanese regulations, and multi-fuel capabilities. Ceramic-matrix composites (CMCs) are expected to become one of the most reliable materials for high-temperature use to make up for the deficient properties of monolithic ceramics and heat-resistant alloys. Carbon fiber, silicon nitride fiber, silicon carbide fiber, silicon carbide whisker, in situ silicon nitride, TiB 2/milled carbon fiber were used as reinforcements for silicon carbide, SiNC, SiAlON and silicon nitride matrix composites. Higher mechanical properties tested by the developed testing standards, and reliability against thermal shock, particle impact damage and creep resistance were confirmed to apply these CMCs for engine components. Several screening test steps were performed before the engine tests and these confirmed that CMC had strong potential for actual engine components.

Radial Turbine Development for the 100 kW Automotive Ceramic Gas Turbine

The development of turbine components for the automotive 100 kW ceramic gas turbine has entered the final stage of the seven-year project and is making satisfactory progress toward the goals. We have attained the interim targets of the aerodynamic performances and have been carrying out tests to further improve efficiency. As for ceramic parts, we have changed the material of the turbine rotor to a new one that is excellent in long-sustained and high-temperature strength properties, and have confirmed substantial strength at high temperature through hot-spin tests. After evaluating blade-vibration stress through analyses and experiments, we completed an endurance evaluation at 1200°C (1473 K) TIT (Turbine Inlet Gas Temperature) and a rated speed of 100,000 rpm. We are now carrying out endurance tests at 1350°C (1623 K) TIT. For ceramic stationary parts, we already finished the evaluations at 1200°C TIT and are also conducting an endurance test at 1350°C TIT. Using these parts in a full-assembly test, together with other elements, we confirmed that they cause no functional problem in tests performed at 1200°C TIT level up to the rated speed (100,000 rpm), and are evaluating their performances.

Ceramic Matrix Composites Application in Automotive Gas Turbines

We are conducting the development of ceramic matrix composites (CMC) and components made of CMC for a 100 kW automotive ceramic gas turbine (CGT) as shown in Fig. 1. When compared to monolithic ceramics (MC), CMC that we have developed demonstrate superior strength characteristics in terms of resistance to particle impact and thermal shock. We have conducted evaluation tests on the strength of CMC components in which MC such as silicon nitride and silicon carbide were used as a reference for comparison with CMC in the same testing process as employed for components made of MC such as silicon nitride and silicon carbide. It was confirmed that actual components made of CMC realized approximately the same strength as the test pieces. Furthermore, some CMC components have already passed screening tests that evaluated the strength of the components. It was therefore confirmed that the potential exists for the possibility of testing these components in high-temperature assembly tests and engine tests.

97/04090 Evaporation characteristics of fuel spray and low emissions in a lean premixed-prevaporization combustor for a 100 kW automotive ceramic gas turbine

97/04090 Evaporation characteristics of fuel spray and low emissions in a lean premixed-prevaporization combustor for a 100 kW automotive ceramic gas turbine

Evaporation characteristics of fuel spray and low emissions in a lean premixed-prevaporization combustor for a 100 kW automotive ceramic gas turbine

A lean premixed-prevaporization combustor (PPL-1) for a 100 kW automotive ceramic gas turbine has been developed to meet the Japanese emission standards for passenger cars without using an aftertreatment system. The design of a fuel injector and a prevaporization-premixing tube (PP-tube) in the PPL-1 combustor is a key subject for promotion of evaporation of fuel spray. The Sauter mean diameter and the non-evaporated mass fraction of fuel spray in the PP-tube were measured employing a phase Doppler particle analyzer varying inlet air temperature, air pressure, air velocity and swirl number. The evaporation of the fuel spray in the PP-tube was promoted by higher swirl number, air velocity, air temperature and increased atomization of the fuel injector, but was suppressed by higher air pressure and fuel properties such as distillation in high temperature. The characteristics of NO x , CO and HC emissions were measured with a combustor test rig and discussed influences of the evaporation characteristics of fuel spray. Results show that a mass fraction of non-evaporated fuel of less than 10% and lean fuel-air mixtures, i.e. having equivalence ratios from 0.15 to 0.5, reduce the PPL-1 combustor emissions of NO x and CO.

Development of a Low-Emission Combustor for a 100-kW Automotive Ceramic Gas Turbine (II)

Performance tests were conducted on a low-emission combustor, which has a pre-vaporization–premixing lean combustion system and is designed for a 100 kW automotive ceramic gas turbine. The results of steady-state combustion tests performed at an inlet temperature of 1000–1200 K and pressure of 0.1–0.34 MPa indicate that the combustor would meet Japan’s emission standards for gasoline engine passenger cars without using an aftertreatment system. Flashback was suppressed by controlling the mixture velocity and air ratios. Strength tests conducted on rings and bars cut from the actual ceramic parts indicate that the combustor has nearly the same level of strength as standard test specimens.

Development of Low-NOx Combustor for Automotive Ceramic Gas Turbine. 2nd Report, Reliability Assurance.

The previous report in this series proposed the conceptual design of a prevaporization-premixing lean combustor for application to an automotive ceramic gas turbine. In the present report, two aspects of reliability assurance are discussed. First, this paper deals with the reliability design of the emissions under transient conditions. Optimization was carried out using the simulation results of the relationship between the response of the variable combustor geometry to follow load changes and the resulting air ratio changes for low-NOx level. The load-variation pattern used in this investigation was that of the Japanese l0-15 mode regulation. Second, this paper describes the validity of the reliability design prepared for the ceramic liner of the combustor. Service life of the liner was predicted on the basis of stress analysis results and fatigue parameters.

Low NOx Combustor for Automotive Ceramic Gas Turbine—Reliability Assurance

Two aspects of reliability assurance are discussed. First, this paper deals with the reliability design of emissions under transient conditions. The optimization was made from the simulation results of the relationship between the response of the variable combustor geometry to follow load changes and the resulting exhaust emission levels. The load variation pattern used in this investigation was that of the Japanese ten-mode regulation. Second, this paper describes the validity of the reliability design prepared for the ceramic liner of the combustor. A service life prediction was made for the liner on the basis of stress analysis results and fatigue parameters.

Status of the Automotive Ceramic Gas Turbine Development Program

A seven-year program, designated “Research and Development of Automotive CGT,” commenced in June 1990 with the object of demonstrating the potential advantages of ceramic gas turbine engines for automotive use. This program has been conducted by the Petroleum Energy Center (PEC) with the support of the Ministry of International Trade and Industry. The engine demonstration project in this program is being handled by a team from Japan Automobile Research Institute, Inc. (JARI). This paper describes the activities of the first year of the seven-year program, and includes the project goals and objectives, the program schedule, and the first-stage design of an experimental automotive ceramic gas turbine (CGT) engine and its components. The basic engine is a 100 kW, single-shaft gas turbine engine having a turbine inlet temperature of 1350°C and a rotor speed of 110,000 rpm. The primary engine components including the turbine hot flow path components have been designed using monolithic ceramics and are scheduled to be produced during the second year of the program.

Development of Low NOx Combustor for Automotive Ceramic Gas Turbine. 1st Report, Conceptual Design.

Three low NOx combustors, i.e., a lean premixing combustor, a rich-lean two-stage combustor and a lean diffusion flame combustor are tested in order to determine a suitable combustion design for an automotive ceramic gas turbine combustor. The prevaporization-premixing lean combustion is proposed as the most promising candidate to meet the Japanese l0·15 mode regulation for gasoline passenger cars. Droplet size for the atomizer, air-ratio range, air loading and other dimensional criteria in the lean primary combustion zone are proposed.

Current progress in Japan of advanced ceramics for high temperature application

The Ministry of International Trade and Industry (MITI) is currently promoting three national projects on high temperature structural ceramics. In the project of “Fine Ceramics” (1981-'92) part of “R & D of Basic Technologies for Future Industries”, silicon nitride and silicon carbide based ceramics are being developed for gas turbine components. This project puts emphasis on basic research on ceramic materials, particularly on the processing and is now in the final stages. The “Ceramic Gas Turbine (CGT) Project” (1988-'96) aims to establish 3 types of 300 KW CGT with turbine inlet temperature of 1350°C for industrial uses. “Automotive CGT Project” (1988-'96) is planned to develop an automotive CGT of 100 KW class and it is now in the stage of preliminary study for the first 2 years to be followed by 7 years full scale R & D. The engine type to be developed is presently under discussion. Those projects are carried on with close cooperation between industries and government research institutes. On application to ceramic gas turbine private sectors are carrying on their individual research work. Generally speaking, CGT research in Japan is at the stage of developing ceramic components. The fine ceramic market size is gradually increasing and it is expected that total production will be 6000 billion Yen in Japan by the year 2000. But the share of mechanical and high temperature ceramics is expected to be 10% of the total. However, as many users want high temperature structural ceramics for application to mechanical and thermal fields, it is thought that high temperature ceramic field will become more important in the future. However, many problems remain to be solved for industrial application of high temperature structural ceramics, such as improvement in strength, toughness, reliability, cost decrease, etc. One of the important future directions is considered to be research on ceramic composites by microstructural control with atomic and molecular level. And also we should consider applying the research results of other engineering fields and also use the results in general human activities.