CFM International's (CFMI) TECH56 new technology effort for the CFM56 is moving to the next phase following completion of full-scale rig tests of a low-parts-count, high-pressure compressor (HPC).
The latest tests were key to developing and validating a range of design advances for the engine family. CFMI continues to seek potential applications for TECH56 hardware in the current engine series, while studying combining the advanced elements into a next-generation CFM56 engine.
Tests were conducted on "Build II" of the HPC, which comprises only six stages, compared with nine on the present design. Although tests in 2000 of "Build I" showed "outstanding operability" with a 24% high-speed stall margin, component efficiency was lower than expected. Build II incorporates newly contoured aerofoils and minor "tweaks", says CFMI, but is otherwise identical to Build I, with forward-swept rotors, bowed and swept stators, stronger blade tips and blisks in the first and second rotor stages. Pressure ratio (PR) was also increased to 14:1, a 29% improvement over the 11:1 PR of the current engine.
CFMI says tests on Build II "confirmed a substantial efficiency improvement with no compromise in operability", and adds that, in more than 335h of tests at General Electric's compressor test site in Lynn, Massachusetts, the HPC "proved its robustness for the real engine environment".
CFMI plans further component validation tests this year, including the evaluation of a "Build III" HPC rig. Other tests include full-scale blade-out and cross wind tests of a 1.7m (68in) diameter, hollow, wide-chord, swept fan. A modified low-pressure compressor that can operate without variable bleed valves is also set to continue tests.
Source: Flight International
