Vízügyi Közlemények, 1962 (44. évfolyam)

4. füzet - IX. Könyvismertetés

(47)* II. THE SPRAY DISTRIBUTION WITH DIFFERENT NOZZLE PATTERNS IN SPRINKLING IRRIGATION By F. Lipták (For the Hungarian text see pp. 369) The advantages of sprinkling irrigation cannot be realized fully unless the sprinkling equipment is hydraulically and mechanically well designed, the nozzles are arranged in the correct pattern'and operated suit ably. The basic requirement of proper sprinkling irrigation is to obtain a possibly uniform spray distribution. Different nozzle patterns are investigated, and nozzle patterns are suggested, which ensure in practice the most uniform spray distribution. A nozzle design, having an г —JR diagram, which ensures an appreciably more uniform spray distribution than the present ones is further proposed for the manifacturers. Index numbers published so far in the literature are discussed, and the introduction of some new, more representative ones, is suggested. The notations used are : i — the spray intensity, I = the average spray intensity R = the spraying distance, Rh = the useful spraying distance, ß = the uniformity coefficient, у = the area coefficient, a — the distance of nozzles on the same pipeline, m = the spacing of branch pipes. Values relatirg loa single r.< zzle are indicated by a comma ,', as e.g. i', whereas seveial nozzles are di noted by the simple symbol, e.g. i. Quantities obtained for a radial, or any other section are distinguished by the exponent x, as e.g. i

x, whereas the x is omitted from values relating to area. Various nozzle patterns are illustrated and compared on the basis of the average characteristic curve of the nozzle MR —

50 (Fig. 1). Inasmuch as the area irrigated by a single nozzle has the shape of a circle, or a sector thereof, and the nozzles are arranged in a square, triangular, or rectangular pattern, the irrigated areas will obviously overlap to a certain extent. Since irrigation is always carried out with several nozzles, the investigation of the spray distribution over the irrigated area should include, besides the characteristics applying to the operation of a single nozzle (e.g., the i—R diagram itself, or I

х,, г'гпах), the mutual effect of individual nozzles on each other. It is common practice in the literature, to specify the nozzle distance (a) and the spacing of the branch pipes (m) in terms of the spraying distance. Tbus for instance, in the case of a simple quadratic pattern a = m = 1.41 R. Although the quantity involved in the formulae is usually R, actually it should be considered as Rh. In fact, there is an essential difference between the two, since the radius of the intersecting circles is in the first case R, whereas in the second Яц, and Rh < R, so that the interaction between the nozzles, and consequently also the spray distribution, will be different. Nozzles and branch pipes cannot be spaced arbitrarily, but only gradually, in keeping with the length of the pipe sections. Thus for instance, if the pipeline consists of 6 m long sections, the distances a and m can be varied in 6 m steps only. The disturbing effect of wind is neglected here, and the conclusions apply to calm weather only. A square nozzle pattern is shown is Figs. 3 to 6, a triangular one in Figs. 7 to 10 a full-overlap square pattern in Fig. 11, a lull-overlap triangular in Fig. 12, while a rectangular pattern in Figs. 13 to 15, all for the ease of full-circle spraying. A rectangular and a triangular pattern is shown in Figs. 16 and 17, for 240 degree sector spraying, while a triangular pattern is shown in Fig. 18 for 120 degree sectorspraying. Labour requirements of various nozzle patterns are illustrated in Table I, while the characteristic values obtained on the basis of the i—R diagram of the MR—

50 type nozzle have been compiled in Table II. An entirely true picture about the spray distribution is offered by the spray pattern and the value of the coefficient y. Spray patterns and effectively irrigated