Andrzej Jeziorski/MUNICH
BMW Rolls-Royce is examining the development of a new high pressure (HP) compressor for its BR700 engine family, which will allow it to produce lighter engines at the top of the family's thrust range.
Under an agreement with shareholder Rolls-Royce, the company is restricted to the thrust range of 62-103kN (14,000-23,000lb). Despite this, senior sources close to the programme say that the new compressor could allow BMW R-R to compete directly in future with CFM International's CFM56 family, which now covers a thrust range of 82-150kN.
The new compressor will increase the BR700's core pressure ratio from 17 to 20, allowing higher thrusts than those of the 82-103kN BR715 to be generated by a lighter engine, provisionally named the BR700-7XX. The higher pressure-ratio core will allow the removal of the BR715's two booster compressor stages without any loss of thrust.
The pressure ratio will be achieved by replacing the current HP compressor blading with an advanced blade design now under development. The core will still have 10 HP compressor stages and two HP turbine stages.
According to BMW R-R research and development director Günter Kappler, it may even be possible to achieve a core pressure ratio of 22 with the new blades.
Kappler says that the company is performing three-dimensional fluid dynamics work on such a compressor, although no hardware programme has yet been launched.
BMW R-R is designing the HP compressor for the R-R Trent 500, and Kappler says that this development work "-will carry over" into any new compressor programme for the BR700 .
The Trent 500 compressor is due to be tested by early 1999, and the results of these tests will demonstrate the potential for reblading the BR700 HP compressor, says Kappler.
Source: Flight International
