US 2379551 A
Description (OCR text may contain errors)
July 3, 1945.
Filed Oct. 6, 1944 IIIII Patented July 3, 1945 UNITED STATES PATENT OFFICE Henry Alfred Ernest Talley, London, England 2 Claims.
This invention relates to improvements in means for mixing two gases (which term is intended to include atmospheric air) comprising essentially a jet and Venturi or diffuser tube its object being to provide a device of this nature which will ensure that any proportion of an entrained gas which has been decided upon and the ratio of entrainment of such portion to the primary supply of gas passing through the jet, remains constant at all rates of flow of gas through the said jet.
The principle of a'jet and Venturi tube is well known but in order to attain the object sought by this invention it is essential that the jet, Venturi or diffuser tube, vacuum chamber and entrainment orifice shall have relative proportions and a particular construction without which accuracy in the mixing of the two gases may not be consistent and may vary with the rate of flow of the primary gas through the jet.
According to the present invention the orifices of the jet, Venturi or diffuser tubeand the engitudinal axis. Themouth B f the Venturi tube trainment orifice must be of the pur orifice type passage is coned or tapered at an included angle of degrees. This jet enters the mouth of the Venturi or difiuser tube which has a converging throat of 60 degrees included angle followed by a straight or parallel portion half an inch in length in turn followed by a diverging outlet of 6 degrees included angle. A further essential feature is that the tip or ultimate orifice of the jet must be in the exact transverse plane where the commencement of the passage of the Venturi tube has its smallest cross-sectional area.
The jet and Venturi or diffuser tube are fitted to or housed in a vacuum chamber which ensures that these parts retain their relative positions to obtain the desired result. The vacuum chamber has an inlet orifice which is of the pure orifice type like that of the jet and through which a predetermined volume of secondary gas is entrained by the flow of the primary gas through the jet.
In some instances it is desirable to vary the volume of entrained gas for which purpose the inlet orifice of the vacuum chamber is provided or fitted with a tapered or conical pin suitably operated sothat with the inlet orifice closed by the base portion of the said pin no entrainment of secondary gas can take place whilst with the pin fully withdrawnirom the said inlet orifice maximum entrainment will occur with the possibility of infinite variations between these two positions.
has an included angle 0 of 60 degrees, a straight parallel passage d one-half inch in length and a flaring or divergent outlet C having an included angle 6 of 6 degrees to the longitudinal axis.
The jet A and Venturi tube B are mounted in a vacuum chamber D in such a manner that the tip or ultimate orifice f of the jet lies in, the exact transverse plane $:c where the passage of the Venturi tube B has its smallest cross sectional area. i
The vacuum chamber B has an inlet orifice E likewise of the pure orifice type through which a pre-determined volume of secondary gas can be entrained by the flow of the primary gas through the jet D. This inlet orifice E may however be controllable or variable by providing a tapered pin F or the like which can be adjusted by any appropriate means such as G in order that the pin F can be set to completely close or fully open the inlet E or be set at any intermediate position. In using a conical pin the inlet orifice E would have to be a straight bore in order that the ultimate orifice between it and the conical pin shall be a pure orifice with no land at the cross section.
1. An improved jet and Venturi tube construction which ensures that the ratio of any pre-determined proportion of an entrained gas shall remain constant at all rates of flow of the primary gas passing through the jet characterised by a jet of the pure orifice typ whose external included angle is exactly degrees toits longitudinal axis and theinternal angle is exactly 30 tudinal axis and a vacuum chamber housing the I jet and Venturi tube, said vacuum chamber hav- I ing an inlet orifice for the entrained gas likewise of the pure orifice type. I
2..In an improved jet and Venturi-tube construction as claimed in'claim 1 an adjustable tapered pin for infinitely varying the inlet orifice.
HENRY ALFRED ERNEST TALLEY.