Aircraft

Scramjet could generate electricity

A way of generating electricity to drive systems on a scramjet-powered aircraft will be tested this month. A magnetohydrodynamic (MHD) generator, using the interaction of magnetic fields with the scramjet's electrically conducting exhaust flow, will be ground tested at Mach 8 for up to 12s in a bid to produce 20-50kW.

The tests are the culmination of the US Air Force Research Laboratory's five-year Hypersonic Vehicle Electric Power Systems (HVEPS) programme. Conventional gas turbines mechanically drive generators to produce electricity to power aircraft systems, but scramjets have no rotating parts, and the programme's goal is to obtain power for on-board systems using MHD technology.

The tests will be conducted at United Technologies Research Center's scramjet cell in Connecticut. The scramjet has been modified with an MHD generator located downstream of its combustor. The generator uses a liquid helium-cooled superconducting magnet.

"We hope to get more funding for the next stage to develop the scramjet and MHD together," says John Lineberry, president of HVEPS participating engineering company Lytec.

General Atomics, Pratt & Whitney Rocketdyne and NASA Marshall Space Flight Center are also partners in the HVEPS project.

The next stage would involve design of a scramjet and MHD system optimised to work together. The scramjet used for the tests and the MHD unit obtained from NASA Marshall were designed for other purposes.

The scramjet was tested at Mach 8 in March, achieving 80% combustor efficiency, and the MHD generator was delivered to the test cell in September.