Fluid pressure amplifier

A housing defining a duct for fluid flow contains a cylinder arrangement - mounted in or at an outlet end of the duct. An input piston is exposed to the fluid flow through the duct and an obturator member is mounted in the duct and arranged to periodically close the duct downstream of the input piston such that the body of fluid flowing through the duct applies an increased pressure to the input piston. Resulting movement of the input piston can be used to directly provide mechanical power, generate electricity, or provide compression of a volatile fluid which, when ignited, provides thrust through rapid exit of combustion products.