The May 12 issue of Aviation Week, has some interesting articles on various advanced engine technologies under development in Europe (Paid Subscription Required) under the sobriquet Newac (new aeroengine core technology).
As opposed to some of the other initiatives, such as P&W’s geared fan, this is focusing on increasing the efficiency of the core, not the fan.
A basic description of the technologies that they are looking at are very aggressive active clearance management between the case and the turbine blades to minimize losses, the use of intercooling (blue in picture above) and heat exchangers (green in picture above) increase turbine inlet temperatures while keeping flame temperatures lower (less NOx, also called “exhaust heat recuperation”), and aggressive management of cooling air to minimize losses.
The intercooling and recuperation are actually not new technology, they have been used in stationary turbines for years, but its application to aero engines is new.