• FUJIMURA Tetsuji, OBA Yoshinori,IKEDA Shuji

The research and development of environmentally compatible engine for small aircraft (ECO engine project) was started in 2003. The objective of this project is to improve engine system integration capability and to establish the advanced technologies required for next generation small aircraft engines, which are environmentally friendly and economically viable. To satisfy these requirements, a large number of advanced component technologies has been developed and incorporated in the engine system design. The total number of stages has been reduced by half from current same class engines. This paper describes the outline of the engine system design, which satisfies the ECO engine project goal.

• MIZUTA Ikuhisa, MUROOKA Takeshi,GOTO Shinya, KODAMA Hidekazu

To reduce the direct operating cost of environmentally compatible engines for small aircraft, a new concept of aerodynamic design technology "Zero Hub to Tip Ratio Fan ( ZH fan )" was developed, which is expected to increase the mass flow rate at the fan inlet without increasing the case diameter and to increase the fan's inner total pressure ratio. Three dimensional aerodynamic design was conducted using Computational Fluid Dynamics, and each target for flow rate, efficiency, and pressure ratio was achieved in performance rig tests.

• KATO Dai, GOTO Shinya, KATO Takaya, WAKABAYASHI Tsukasa, OCHIAI Hiroyuki

To reduce the direct operating costs of environmentally compatible engines for small aircraft, highly loaded aerodynamic design technology was developed for the compressor, which could reduce the number of stages considerably while maintaining performance. Three dimensional aerodynamic design was employed using Computational Fluid Dynamics, and the target pressure ratio was obtained from performance rig tests. Diffuser Passage Compressor technology was introduced to suppress tip clearance leakage flows and expand the operating range of small compressors. Effectiveness was demonstrated by low-speed model tests. Linear friction welding and Micro Spark Coating technologies were developed to realize low cost and simple production of the compressor blisks, a term for integrated bladed disks.

• TANIMITSU Haruyuki, NAKAMATA Chiyuki, FUJIMOTO Syu, AOKI Yasuhiro, ISHIZAKI Masato

To reduce direct operating costs of environmentally compatible engine for small aircraft, higher loading turbine without performance decrement was studied. The study was carried out for shock wave control and feasibility of counter-rotation turbine system. The aerodynamic performance was verified by the rig tests. Another outstanding advancement was novel cooling technologies. There were two key technical features: multi-slot internal cooling system and newly-developed film cooling hole to improve film effectiveness. These new cooling systems were validated in the cascade rig tests. To evaluate the applicability of Japanese single crystal superalloys to low cost HPT blades, studies of ingot, casting and heat treatment processes of the superalloys were conducted for the HPT blades. The laser-CVD process was studied as the coating method of the top layer of TBC. Trial coating on turbine blades was carried out, and the technical problems of the method for application were explained.

• NAKAKITA Tomofumi, KAWASUMI Akio, HIRONISHI Nobuyuki

In recent years, on-condition maintenance has been generally applied to aircraft engines. On-condition maintenance is the methodology to repair the equipment only when the maintenance is actually necessary by observing the state of the system periodically. Aiming at the further reduction of maintenance costs, engine health monitoring technology was developed to evaluate the deterioration of the engine and to isolate the fault module if any failure is detected. The engine electronic control unit module utilizing multifunctional electronic devices was also developed to reduce the cost increase associated with this additional monitoring function. This article introduces these technologies.

• OISHI Tsutomu, OBA Yoshinori

The objectives of the ECO engine project are improvement of engine system integration capability and establishment of advanced technologies required for the next-generation of small aircraft engines that are environmentally friendly and economically viable. Technologies for low noise engines in the ECO engine project are described. The aircraft noise reduction is targeted to achieve the new chapter 4 standard with 20 dB cumulative margin in ICAO Annex 16. Research and development of low noise technology was conducted for fan noise reduction and exhaust jet noise reduction, which are the major noise sources of jet engines. In the fan noise research targeting 3 dB reduction, a swept blade and integrated outlet guide vanes were investigated under weight limit and structural restrictions. In the jet noise research targeting 2 dB reduction, the notched nozzle as a new concept was investigated for simple nozzle design. 3.8 dB reduction for fan noise and 2.2 dB reduction for jet noise were demonstrated through several model rig tests.

• HOSOI Jun, HIROMITSU Nagayoshi, RIECHELMANN Dirk, FUJII Atsushi, SATO Junichi

A gas-turbine combustor was developed for environment-friendly and economical aircraft engines adaptable to 50-seat class jet planes. The combustor has a simple structure and low NOx emission characteristics. The target level of NOx reduction was 50% or less, which corresponds to the requirements of ICAO CAEP 4. A special simple structure swirler, named a cross jet swirler, was developed. The test results revealed a significant reduction of NOx emissions, to 56.3% of the present ICAO CAEP 4 requirements for the LTO cycle. Furthermore, CO emissions were reduced by 19%, and total hydrocarbons by 59% compared with the reference values of the ICAO requirements.