DE9403330U1 - jet - Google Patents

Description

Joh. Vaillant GmbH u. Co. GM 1241

The innovation relates to a nozzle for a premixing atmospheric gas burner.

In the known nozzle designs of this type, the nozzle has an essentially circular outlet cross-section. A gas jet emerging from such a nozzle can entrain a certain amount of air from the surroundings. However, it has been shown that in many cases only insufficient air is entrained by the escaping gas jet, i.e. that the induction ratio is too low. In order to increase the induction ratio, it was proposed in accordance with GB-PS 17 709 and US-PS 1 794 869 to create a vortex and thus achieve a better admixture of air by means of bluff bodies arranged in the gas jet.

The aim of the invention is to propose a nozzle of the type mentioned at the beginning, which enables a larger air flow rate to be entrained by the escaping gas jet even without a bluff body and is therefore characterized by a simple structure.

According to the innovation, this is achieved by the nozzle having a non-circular outlet opening.

The premixture in atmospheric burners can be changed not only by a corresponding design of the nozzle but also by the geometry of the outlet opening on the nozzle. The premixture, or generally the ratio of the moving air-gas mixture V _x to the injected gas flow V is called the induction ratio.

For a circular nozzle outlet for a round isothermal free jet, an induction ratio I ₀ results according to the following relationship:

_ _2m

- 2m

For a rectangular isothermal free jet, an induction ratio I _Q results from the following relationship:

V _x &khgr;

I _n = -|- = 2m . -

Here, &khgr; is the distance between the outlet opening of the nozzle and any location in the horizontal direction in front of the nozzle, m is a mixing number, and A is the cross-section of the outlet opening.

This results in an induction ratio of

&idiagr;_&agr;&igr;

^{&idiagr;&ogr;} &ggr;?

1.13

higher than that of a circular outlet opening.

The proposed geometry of the outlet opening makes it possible to increase the premixing within certain limits, e.g. by approx. 13%, not only in the development of new atmospheric burners but also in existing heating systems.

Depending on the application, both aspects of emission reduction and flame stability may be in the foreground.

According to a further feature of the invention, it can be provided that the outlet opening of the nozzle is square.

This results in a very simple structure.

The invention will now be explained in more detail with reference to the drawing.

It shows:

Fig. 1 shows a cross section through a nozzle with flow path, Fig. 2 shows a front view of the nozzle and Fig. 3 shows further nozzle front views.

The same reference symbols indicate the same details in all figures.

The nozzle 1 of an atmospheric premix gas burner has an outflow opening 2 through which gas flows out at a second quantity V ₀ , the gas entraining air from the environment in a mixing zone 3 extending over a distance &khgr;, so that a second quantity V _x of an air-gas mixture enters a mixing tube (not shown) of the burner at the end of the distance &khgr;.

As can be seen from Fig. 2, the outflow opening 2 has, for example, a rectangular or square cross-section whose long sides b and h have a certain cross-section, resulting in a higher induction ratio than with a circular outflow opening.

In addition to square or rectangular nozzle openings, a variety of other non-circular opening geometries can be used, as shown in Figure 3.

The mixing behavior when using non-circular nozzle openings is changed compared to that when using round openings in such a way that disturbances are already imposed on the gas jet in the nozzle 1, which lead to turbulence in the free jet and thus to increased air intake.

The following opening geometries are shown in Figure 3 with consecutive numbering:

Designation

11 wide ellipse

12 narrow ellipse

13 Parallelogram

14 equilateral triangle

15 equilateral pentagon

16 equilateral hexagon

17 equilateral heptagon

18 equilateral octagon

19 three-star

20 four-star

21 Five Star

22 Six-pointed star

23 Five-beam

24 Eight-beam

25 equilateral triangle

26 right-angled triangle

27 isosceles triangle

28 like No. 14 with inward angled side

2 9 diamond

3 0 Dragons
31 trapeze

Dimensions

large axis: 10 mm small axis: 5 mm large axis: 10 mm small axis: 2 mm

Area: 33 mm ² Area: 59 mm ² Area: 63 mm ²

Leg: 7 mm Hypotenuse: 10 mm Legs: 10 + 5 mm Legs: 10 mm Hypotenuse: 5 mm

large diagonal: 10 mm small diagonal: 5 mm

large side: 10 mm small side: 5 mm

Height: 5mm

two touching right-angled triangles house square with inward-angled side half house (see no. 33) arrow max.

broad cross

narrow cross T-shape

&Egr;-shape (like No. 39 with two additional arms)

H-shape

C-shape (like No. 40 without middle arm)

two isosceles triangles isosceles triangle and quadrilateral isosceles triangle and quadrilateral Height + width: 10 mm Bar width: 3 mm Bar length: 10 mm Bar width: 10 mm Bar length: 1 mm Bar width: 1 mm Bar length: 10 mm

or 5 mm

Bar width: 1 mm Bar length: 10 mm

or 5 mm Bar width: 1 mm Bar length: 10 mm

or 5 mm Bar width: 1 mm Bar length: 10 mm

or 5 mm

46 isosceles triangle and wide rectangle

47 isosceles triangle and circle

48 Square and circle

49 two touching rectangles

50 narrow rectangle with circle in the middle

51 dumbbell

52 two circles, separated

53 two circles, lying together

54 Lemniscate 55 Quarter circle 56 semicircle 57 horn 58 Wing profile 59 Bell jar 60 drops

Rectangle: 3 x 10 mm
Circle diameter: 5 mm

Circle diameter: 5 mm Square: 5 x 5 mm

Rectangle: 1 x 10 mm

Circle diameter: 3 mm Distance between centers: 7 mm
Circle diameter: 3 mm Distance between centers: 4 mm

Claims (1)

Joh. Vaillant GmbH u. Co GM 1241 EXPECTATIONS Nozzle for a premixing atmospheric gas burner, characterized in that the nozzle (1) has a non-circular outlet opening (2). Nozzle according to claim 1, characterized in that the outflow opening (2) of the nozzle (1) is square.