Anticipated but Unwelcome

This article provides the latest trends in the gas turbines market and their future outlook. The last three years of operation have generated more profit for the commercial airline industry than the previous 30 years combined. That money has led to new orders for commercial aircraft and as a result, production of commercial aviation gas turbines is in full swing. Engine manufacturers such as Pratt&Whitney, Rolls-Royce, General Electric, Safran, and others have taken this surge in orders as an incentive to develop new technology. The launch of a new jet engine by a manufacturer can be a multi-billion dollar effort. Financial projections and executive careers hang on a smooth roll-out of the new technology.

Assessing the capability of conventional in-cylinder insulation materials in achieving temperature swing engine performance benefits

Materials that enable wall temperature swing to follow the gas temperature throughout a reciprocating internal combustion engine cycle promise the greatest benefits from in-cylinder insulation without detriments to volumetric efficiency or fuel autoignition behavior. An anisotropic barium–neodymium–titanate insulation was selected as a promising off-the-shelf material to begin investigating temperature swing characteristics while maintaining adequate strength and adherence to the aluminum components it was applied to. Experimental analysis showed that permeable porosity within the barium–neodymium–titanate coating resulted in increased heat losses despite thermal insulation, fuel absorption losses, and a reduction in compression ratio. Additionally, the thickest coating suffered severe degradation throughout testing. Any potential benefits of temperature swing insulation were dominated by these losses, emphasizing the need to maintain a sealed coating surface.

Design of Sealing Structure and Analysis of the Flow Field in Micro Internal Combustion Swing Engine

A multistage groove sealing structure in Micro Internal Combustion Swing Engine (MICSE) was designed. By machining several grooves on the center-swing, it provides non-contacting control of internal leakage. The sealing principle of this structure may be described as follows. Gas at high pressure enters through the clearance of adjacent grooves to accelerate, then expands isentropically in the grooves. Once crossing several such grooves, gas emerges at the other end of the sealing structure at significantly reduced pressure. Numerical simulations were utilized to analyze the influences of pressure ratio and groove depth on leakage characteristics. The results demonstrate that at pressure ratio smaller than 2.0, turbulence eddy dissipation process in grooves cannot dissipate kinetic energy obtained during the throttling process completely, which results in poor sealing effect, at pressure ratio lager than 2.5, the two processes reach dynamic balance and sealing effect no longer changes. There is an optimal value in groove depth, undersize or oversize may lead to imperfect throttling effect or turbulence eddy dissipation process.