This document describes a 1957 patent for an oscillating column combustion apparatus. The apparatus has a combustion chamber and pulsating tube that form an acoustic resonator. It is an improvement over prior designs by introducing the combustion mixture tangentially into the cylindrical combustion chamber through a mixing tube. This causes the mixture to circulate and thermally prepare along the hot chamber walls before igniting, overcoming issues with deposits clogging inlet throats in previous models. The pulsating tube can be arranged coaxially to induce better vortexing for ignition.

1. * GB780148 (A)
Description: GB780148 (A) ? 1957-07-31
Improvements in or relating to oscillating column combustion apparatus
Description of GB780148 (A)
PATENT SPECIFICATION
Date of Application and filing Complete Specification: Nov. 15, 1955.
780,148 No.32652/55.
htA1 1 Application made in Germany on Nov. 15, 1954.
Complete Specification Published: July 31, 1957.
Index at acceptance:-Class 51(1), A1B2.
International Classification:-F23f.
COMPLETE SPECIFICATION
Improvements in or relating to Oscillating Column Combustion Apparatus
We, HEIZMOTOREN GESELLSCHAFT MIT BESCHRANKTER HAFTUNG, a limited
liability Company organised under German law, of Franziskanerstrasse,
Uberlingen/Bodensee, Germany, do hereby declare the invention, for
which we pray that a patent may be granted to us, and the method by
which it is to be performed, to be particularly described in and by
the following statement:-
This invention is concerned with improvements in or relating to
oscillating column combustion apparatus whose combustion chamber and
pulsating tube-,,form a Helmholtz resonator in the usual manner, and
in which also several pulsating tubes can be used.
In such apparatus it is known to introduce the combustion mixture to
the combustion chamber through an inlet throat. This inlet throat has
the purpose of preparing the combustion mixture for ignition. This
preparation for ignition is generally effected thermally, in that the
combustion mixture is chemically changed (cracked). In order to
improve this thermal preparation, in many cases, a part of the inlet
throat has been extended into the combustion chamber, so that then the
end of inlet throat projects freely into the combustion chamber. In
this way a very good preparation of the combustion mixture is obtained
and the latter becomes highly ignitable, but after long operating
periods.difficulties arise which make an alteration in this

2. construction desirable. In particular it has been observed that with
fuels which readily deposit carbon there is an increase in size of the
inlet throat. Since this inlet throat has a relatively small cross
section compared with the combustion chamber, considerable changes in
the characteristics of the apparatus can be caused as a result and
indeed the operation can be adversely affected.
It is an object of this invention to overcome the above mentioned
disadvantages.
The removal of these disadvantages cannot [Price 3163 however be
achieved by removing the inlet throat. Even if the thermal preparation
of the fuel in the inlet throat were to be dispensed with, this inlet
throat is still of importance to protect the valve from the effects 50
of the hot combustion gases. Rather must the solution be sought by
transferring the thermal preparation into the combustion chamber
itself. In this connection however, care must be taken that the
explosion properties and the characteristics of the device as a
Helmholtz resonator are not altered.
This problem has been solved according to this invention which
provides an oscillating column combustion apparatus for the 60
production of periodic explosions in an acoustic resonator
characterised by the provision of an at least partly cylindrical
combustion chamber into the cylindrical part of which a mixing tube
having air and fuel inlets opens tangentially, and to which there is
connected, axially thereof, an open exhaust tube, which with the said
combustion chamber forms the acoustic resonator.
With such an arrangement the inlet throat 70 itself or the mixing tube
remains cold, because it is no longer inside the combustion chamber.
The combustion mixture however, upon entering the combustion chamber
obtains a speed of circulation around the axis 75 of the combustion
chamber. As a result the portion of the mixture which is mechanically
prepared and finely divided in the mixing tube and is thus ready for
ignition collects at the axis of the combustion chamber, whilst 80 the
coarser drops of liquid which are less well mechanically prepared for
ignition move to the walls of the combustion chamber. The rotary
movement causes this portion to flow over the hot walls of the
combustion chamber whereby it is heated and thermally prepared for
ignition. Deposits of carbon on the walls of the relatively large
combustion chamber do not cause any difficulties.
If the combustion chamber is reduced in 90 780,148 diameter or tapered
in the direction of the pulsating or exhaust tube the inlet throat
will open into the part of the combustion chamber having the largest
diameter. It is also particularly advantageous to reduce the diameter
of the combustion chamber stepwise so that the various parts of the
combustion chamber and the pulsating tube are formed as cylinders

3. following one another.
The pulsating or exhaust tube is preferably arranged coaxially with
the combustion chamber. The pressure wave, which during the sub
pressure phase returns in the exhaust tube, then flows axiallv into
the combustion tube, and produces in it a particularly good inner
vortex action, which brings about the highest readiness for ignition
of the fuel. If desired two oppositely directed pulsating or exhaust
tubes can be connected to one combustion chamber.
If the combustion chamber, for instance in heating apparatus, is
strongly cooled, it may be that the combustion chamber wall would be
too cold for the thermal preparation of the fuel. In this case a heat
resisting cylinder can be provided on the inside of the wall of the
combustion chamber, into which heat resisting cylinder the inlet
throat opens. The preparation of the circulating mixture is then
carried out inside this heat resisting cylinder.
The source of ignition, e.g., an externally heated depression, a
sparking plug or aglowing wire is preferably disposed in the inlet
throat, and may be located slightly in front of the outlet therefrom
into the combustion chamber.
The inlet throat does not need to be arranged in a radial plane,
although this arrangement is, in general, preferable for the
circulation effect. The inlet throat can also be inclined to the
radial plane and preferably in such a direction that the circulating
mixture is given a component of movement in the direction of the
pulsating tube. From considerations of space it may be necessary to
mount the inlet throat with its axis parallel to that of the
combustion chamber, the two parts being then connected together by a
longitudinal slot, the opening of which gives a circulating component
of movement to the mixture about the axis of the combustion chamber.
In order that the invention may be well understood, some preferred
embodiments thereof will now be described with reference to the
accompanying drawings in which:Fig. 1 is a section through a
combustion chamber and its inlet throat:
Fig. 2 is a side view of Fig. 1; Figs. 3 and 4 are similar views of a
modified device having a stepped combustion chamber, and Figs. 5 and 6
are again similar views of another device in which the inlet throat is
parallel to the axis of the combustion chamber.
Referring to Figs. I and 2 an oscillating column combination apparatus
according to the invention comprises a combustion chamber l having a
conical portion 3, and a pulsating or exhaust tube 2. At the widest
part of the combustion chamber and adjacent the end 4, an inlet throat
5 opens tangentially into the combustion chamber at 6. An ignition
point is indicated at 7 on this inlet throat. 75 In the event of
strong cooling of the combustion chamber 1. an auxiliary cylinder 8 of

4. heat resistant metal. as shown in dotted lines, can be provided. into
which the inlet throat 5, which penetrates the wall of the comnbustion
tube, opens.
The arrangement could be made symmetrical with respect to the radial
plane in which the inlet throat lies. The inlet throat 5 would then
open tangentially into the centre of a 85 lone combustion chamber 1.
or cylinder 8.
To this would be connected at each end a conical portion 3 and a
pulsating or exhaust tube 2, which are tuned to the same frequency but
which do not need to have the 90 same cross section. The pulsating
tubes can be curved, so that their ends lie parallel to one another
beside the said radial plane.
In the embodiment according to Figs. 3 and 4 the change from the
combustion chamber to the pulsating or exhaust tube is effected in a
step by step manner rather than conically. The combustion chamber has
a part 10 of larger diameter and a part 11 of smaller diameter. The
pulsating or exhaust 100 tube 12 is connected to the part 11. The
inlet throat 13 opens into the larger part 10.
Whilst as shown in Figs. 1 to 4 the inlet throat 5 or 13 lies in a
radial plane to the common axis A of the reso jet tube arrangement,
the inlet throat in Figs. 5 and 6 has its axis parallel to this axis
A. The combustion chamber and the pulsating tube are constructed
similarly to those in Figs. 3 and 4 so that similar reference numerals
are used therefor. 110 The inlet throat 20 having its axis parallel to
axis A is disposed on the circumference of the larger part 10 of the
combustion chamber 10, 11, and the connecting slot 21 between 20 and
10 is so formed that when 115 the mixture flows in, a vortex is
produced here which also crosses the axis A.
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