PULSE COMUBSTION INSTALLATIONS

1432344 Combustion apparatus of the periodic combustion type UNIVERSITY OF BATH and R D PEARSON 5 April 1973 [30 March 1972] 15147/72 Heading F1L A combustion apparatus of the periodic combustion type suitable for heating water, includes a tubular combustion chamber 2 with a coaxial exhaust duct 12 spaced from a sharp-edged orifice 20 of the chamber, an air inlet duct 8 communicating with the space 22 between the orifice and exhaust duct with an aerodynamic valve arrangement at its inflow end inhibiting the outflow of air therefrom, and the combustion chamber, inlet duct and outlet duct are of such length as to produce resonant conditions upon combustion of fluent fuel in the chamber. As shown, the inlet duct 8 is coaxial with the exhaust duct 12 and is separated therefrom by a frusto-conical water jacket 16. A blanked-off frusto-conical sleeve 28 aligned with the inlet duct 8 forms the aerodynamic valve. Alternatively, the lip 26 on duct 8 may be directed inwardly. Radial vanes 31 in the inlet duct divide it to form longitudinal passages. A pressure jet atomizing burner nozzle 34 is supplied with fuel via a valve 44 during start-up when air is provided from a fan 32. Upon successful ignition, the rise in pressure is sensed by a probe 42 to open a valve 46. The valve 46 is similarly closed upon cessation of combustion. The fuel supply may be pulsed in phase with the resonant vibrations. Again, Fig. 3 (not shown), the combustion chamber (52) has a re-entrant orifice (54). The air inlet is formed as two pairs of perpendicular ducts (70), (72) swept back through 180 degrees parallel to the combustion chamber axis and of rectangular section diverging to circular cross-section at their inlet ends (74), (76). They have a common cylindrical outlet end (56) coaxial with the combustion chamber axis. One pair of ducts (72) are vertical and have an in-turned lip (80) at their inlet ends. The other pair have out-turned lips (78), and all have Helmholtz resonators (84), (86) aligned with them and the whole is positioned in a windbox (82) having a Venturi intake (90). A start-up fan (88) delivers air to ducts (72). The exhaust gases are used to heat water by passing through a helical smoke tube in an annular water chamber, or by passing through annular smoke ducts alternating with annular waterways in a cylindrical vessel.