Patent Publication Number: US-11660621-B2

Title: Reduced precipitation rate nozzle

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
     This application is a divisional application of U.S. application Ser. No. 16/692,868, filed Nov. 22, 2019, which is incorporated by reference herein in its entirety. 
    
    
     FIELD 
     This invention relates generally to irrigation nozzles and, more particularly, to an irrigation nozzle with a relatively low precipitation rate and uniform fluid distribution. 
     BACKGROUND 
     Efficient irrigation is a design objective of many different types of irrigation devices. That objective has become increasingly important due to concerns and regulation at the federal, state and local levels of government regarding the efficient usage of water. Over time, irrigation devices have become more efficient at using water in response to these concerns and regulations. However, there is an ever-increasing need for efficiency as demand for water increases. 
     As typical irrigation sprinkler devices project streams or sprays of water from a central location, there is inherently a variance in the amount of water that is projected to areas around the location of the device. For example, there may be a greater amount of water deposited further from the device than closer to the device. This can be disadvantageous because it means that some of the area to be watered will be over watered and some of the area to be watered will receive the desired about of water or, conversely, some of the area to be watered will receive the desired amount of water and some will receive less than the desired about of water. In other words, the distribution of water from a single device is often not uniform. 
     Two factors contribute to efficient irrigation: (1) a relatively low precipitation rate to avoid the use of too much water; and (2) relatively uniform water distribution so that different parts of the terrain are not overwatered or underwatered. The precipitation rate generally refers to the amount of water used over time and is frequently measured in inches per hour. It is desirable to minimize the amount of water being distributed in combination with sufficiently and uniformly irrigating the entire terrain. 
     Some conventional nozzles use a number of components that are molded separately and are then assembled together. For example, U.S. Pat. No. 5,642,861 is an example of a fixed arc nozzle having a separately molded nozzle base for mounting the nozzle to a fluid source, base ring, and deflector for directing the fluid outwardly from the nozzle. Other nozzles are complex and have a relatively large number of parts. For example, U.S. Pat. No. 9,776,195 discloses a nozzle that uses a number of inserts and plugs installed within ports. As an alternative, it would be desirable to have a nozzle having a simple one-piece, molded nozzle body that may reduce the costs of manufacture. 
     Accordingly, a need exists for a nozzle that provides efficient irrigation by combining a relatively low precipitation rate with uniform water distribution. Further, many conventional nozzles include a number of components, such as a nozzle base, nozzle collar, deflector, etc., which are often separately molded and are then assembled to form the nozzle. It would be desirable to reduce the cost and complexity of nozzles by reducing the number of separately molded components. It would be desirable to be able to form a one-piece, molded nozzle body that would avoid the need for separate component molds and the need for assembly after component molding. 
     Further, it has been found that irrigation may be especially non-uniform at the boundary edges of an irrigation pattern. More specifically, an excessive amount of fluid may be concentrated at these boundary edges, and a nozzle may distribute fluid either too far or not far enough along these boundary edges. Accordingly, there is a need to improve the irrigation uniformity at the boundary edges relative to other portions of the irrigation pattern. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG.  1    is a bottom perspective view of an embodiment of a nozzle embodying features of the present invention; 
         FIG.  2    is a top perspective view of the nozzle of  FIG.  1   ; 
         FIG.  3    is a cross-sectional view of the nozzle of  FIG.  1   ; 
         FIG.  4    is an exploded view of the nozzle of  FIG.  1   ; 
         FIG.  5    is a bottom plan view of the nozzle of  FIG.  1    (with the filter removed); 
         FIG.  6    is a top plan view of the nozzle of  FIG.  1   ; 
         FIG.  7    is a side elevational view of the nozzle of  FIG.  1    (with the filter removed); 
         FIGS.  8  and  9    are detailed perspective views of some of the ribs on the underside of the deflector portion of the nozzle of  FIG.  1   ; 
         FIG.  10    is a schematic representation of the port of the nozzle of  FIG.  1    showing the geometry of the port; 
         FIG.  11    is a fluid distribution diagram showing the fluid distribution of a conventional nozzle; and 
         FIG.  12    is a fluid distribution diagram showing the fluid distribution of the nozzle of  FIG.  1   . 
     
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     In one form, the exemplary drawings show a nozzle  100  that improves efficiency of irrigation by combining a relatively low precipitation rate with relatively uniform fluid distribution. The nozzle  100  includes a small inflow port  106  (or central channel) to allow a relatively small volume of water through the nozzle  100 , i.e., to provide a low precipitation rate. The spray nozzle  100  further includes a deflector  112  with a profile including rib structures forming different types of flow channels that separate fluid into different streams in order to improve the overall water distribution, i.e., to provide relatively uniform fluid distribution. Many conventional irrigation nozzles have deflectors with a series of similarly shaped radial flutes that distribute one type of fluid spray. In contrast, the deflectors of the preferred embodiments have a series of ribs with structures disposed in the flow paths of the fluid resulting in different streams having different characteristics. The different sprays combine to provide a relatively uniform water distribution pattern. 
     As described further below, the nozzle  100  preferably includes one or more of the following features to improve uniformity of fluid in the irrigation pattern: (1) vent holes to normalize air pressure behind the water streams emerging from the nozzle  100  to facilitate uniform fluid distribution at the boundary edges of the irrigation pattern; (2) a rear wall offset a certain distance to facilitate uniform fluid distribution at the boundary edges of the irrigation pattern; and (3) a port aperture with a cross-section defining a complex geometry of compound radii to improve distribution uniformity. The vent holes and the rear wall offset help reduce heavy precipitation along the boundary edge of the irrigation pattern and help reduce overthrow beyond the intended throw radius. The geometry of the port aperture helps decrease precipitation at the boundary edges and achieve uniform distribution throughout the irrigation pattern. 
     One embodiment of a nozzle  100  is shown in  FIGS.  1 - 8   . In this form, the nozzle  100  generally comprises a compact unit, preferably made primarily of lightweight molded plastic, which is adapted for convenient thread-on mounting onto the upper end of a stationary or pop-up riser (not shown). The nozzle  100  preferably includes a one-piece nozzle body  102  and a flow throttling screw  104 . In operation, fluid under pressure is delivered through the riser to the nozzle body  102 . The fluid preferably passes through an inflow port  106  controlled by the throttling screw  104  that regulates the amount of fluid flow through the nozzle body  102 . The nozzle  100  also preferably includes a filter  107  to screen out particulate matter upstream of the inflow port  106 . Fluid is directed generally upwardly through the inflow port  106 , along a generally conical transition surface  108 , and then along ribs  110  formed in the underside surface of a deflector  112 . 
     As can be seen, the nozzle body  102  is preferably generally cylindrical in shape. It includes a bottom mounting end  114  forming an inlet  115  and with internal threading  116  for mounting of the nozzle body  102  to corresponding external threading on an end of piping, such as a riser, supplying water. The nozzle body  102  also defines a central bore  118  to receive the flow throttling screw  104  to provide for adjustment of the inflow of water into the nozzle body  102 . Threading may be provided at the central bore  118  to cooperate with threading on the screw  104  to enable movement of the screw  104 . The nozzle body  102  also preferably includes a top deflecting end defining a distal wall  120  relative to the inlet  115  and defining the underside surface of the deflector  112  for deflecting fluid radially outward through a fixed, predetermined arcuate span. Further, the nozzle body  102  includes a recess  122  defined, in part, by a boundary wall  124  and with the conical transition surface  108  disposed within the recess  122 . 
     As can be seen in  FIGS.  1  and  2   , for the half-circle nozzle  100 , the inflow port  106  generally extends about 180 degrees in order to cover a 180 degree irrigation pattern. The inflow port  106  is preferably disposed in a plate  126  located downstream of the internal threading  116  and is preferably located adjacent the central bore  118  that receives the throttling screw  104 . Although in this embodiment the threading is shown as internal threading  116 , it should be evident that the threading may be external threading instead. Some risers or fluid source are equipped with internal threading at their upper end for the mounting of nozzles. In this instance, the nozzle may be formed with external threading for mounting to this internal threading of the riser or fluid source. 
     The cross-section of the inflow port  106  may be modified in different models to match the precipitation rate. In one preferred form, for example, the cross-section of the inflow port  106  may be configured for a maximum throw of 8 feet with a low precipitation rate that is less than 1 inch per hour, preferably about 0.9 inches per hour. The cross-section of the inflow port  106  may be increased for nozzles intended to have a longer maximum throw radius (such as, for example, 15 feet) while maintaining the matched precipitation rate of about 0.9 inches per hour. As should be evident, the dimensions of inflow ports of other models may be configured for different intended throw distances while preferably matching this precipitation rate. In one straightforward example, the cross-section of the port may be in the shape of a regular semi-circle. However, in another form, the cross-section of the port  106  extends 180 degrees but is preferably defined by compound radii, as shown in  FIG.  10    and as addressed further below. 
     Further, as addressed below, the shape of the inflow port  106  may be modified to achieve different fixed arcuate spans. For example, the cross-section of the inflow port may extend 90 degrees for quarter-circle (or 90 degree) irrigation, or two opposing 180 degree inflow ports may be used to achieve close to full circle (or 360 degree) irrigation. Alternatively, two inflow ports (one extending 180 degrees and the other extending 90 degrees) may be used to achieve roughly three-quarter circle (or 270 degree) irrigation, or two inflow ports of approximately the same size may be formed to achieve this three-quarter circle irrigation. Again, these models with different arcuate spans would preferably have matched precipitation rates of about 0.9 inches per hour. 
     As can be seen in  FIGS.  1  and  2   , once fluid flows through the inflow port  106 , it then flows along the conical transition surface  108  to a water distribution profile on the underside of the deflector  112 . The transition surface  108  is intermediate of the port  106  and the profile, which includes a plurality of ribs  110 , and guides flow directed through the port  106  to the flutes  140  defined by successive ribs  110 . The transition surface  108  is aligned with and expands smoothly outwardly in the direction of the plurality of ribs  110  and reduces energy loss experienced by fluid flowing from the port  106  to the flutes  140 . The transition surface  108  is generally conical in shape having a vertex  134  disposed near the port  106  expanding into smoothly curved sides  136  having increasing curvature in the direction of the deflector  112  and terminating in a base  132  near the plurality of ribs  110 . For the half-circle nozzle  100 , the conical transition surface  108  is preferably in the shape of an inverted half-cone with a generally semi-circular base  132  on the underside of the deflector  112  and a vertex  134  offset slightly from the boundary wall  124 . The conical transition surface  108  is preferably curved to smoothly guide upwardly directed fluid radially and outwardly away from the central axis of the nozzle body  102  to the ribbed deflector surface. The portion of the cone near the vertex  134  is preferably inclined closer to vertical with less curvature, and the portion of the cone near the base  132  preferably has greater curvature. Various different forms of curvature may be used for the conical transition surface  108 , including catenary and parabolic curvature. Also, as should be evident, the surface  108  need not be precisely conical. 
     The dimensions of the conical transition surface may be modified in different models to provide different flow characteristics. For example, the vertex may be located at different vertical positions along the boundary wall, the semi-circular base may be chosen with different diameters, and the curved edge surface may be chosen to provide different degrees of curvature. These dimensions are preferably chosen to provide a more abrupt transition for shorter maximum throw radiuses and a gentler transition for longer maximum throw radiuses. For instance, for an 8-foot nozzle (in comparison to the 15-foot nozzle  100 ), the vertex  134  may be located higher along the boundary wall  124 , the semi-circular base  132  may be smaller, and the curved edge surface  136  may have less curvature. Thus, for an 8-foot nozzle, the upwardly directed fluid strikes the underside surface of the deflector  112  more squarely, which dissipates more energy and results in a shorter maximum throw radius than the 15-foot nozzle  100 . 
     Further, as with the inflow port  106 , the shape of the conical transition surface  108  may be modified to accommodate different fixed arcuate spans, as addressed further below. For example, the conical transition surface may be in the shape of an inverted quarter conical portion with a vertex and a quarter-circle base for quarter-circle (or 90 degree) irrigation. Alternatively, the nozzle body may include two inverted half-conical portions facing opposite one another to achieve close to full circle (or 360 degree) irrigation. Further, the nozzle body may include one inverted half-conical portion and one inverted quarter-conical portion facing opposite one another for three-quarter circle (or 270 degree) irrigation, or the nozzle body may include two conical portions of approximately the same size for this three-quarter circle irrigation. 
     As shown in  FIGS.  1  and  2   , the deflector  112  is generally semi-cylindrical. The deflector  112  has an underside surface that is contoured to deliver a plurality of fluid streams generally radially outwardly therefrom through a predetermined arcuate span. In the half-circle nozzle  100 , the arcuate span is preferably about 180 degrees, although other predetermined arcuate spans are available. As shown in  FIGS.  1 ,  2 ,  7 , and  8   , the underside surface of the deflector  112  preferably defines a water distribution profile that includes an array of ribs  110 . The ribs  110  subdivide the water into multiple flow channels for a plurality of water streams that are distributed radially outwardly therefrom to surrounding terrain. As addressed further below, the ribs  110  form flow channels that provide different trajectories with different elevations for the water streams. These different trajectories allow water distribution to terrain relatively close to the nozzle  100  and to terrain relatively distant from the nozzle  100 , thereby improving uniformity of water distribution. 
     In view of this deflector configuration, the nozzle  100  shown in  FIGS.  1 - 8    is a multi-stream, multi-trajectory nozzle. As can be seen in  FIG.  7   , the deflector  112  is contoured to create flow channels for water streams having at least three different types of trajectories: (1) a distant trajectory with a relatively high elevation (A); (2) an intermediate trajectory with an intermediate elevation (B); and (3) a close-in trajectory with a relatively low elevation (C). These three different water trajectories allow coverage of terrain at different distances from the nozzle  100  and thereby provide relatively uniform coverage. 
     A variety of different rib configurations are possible. In one form, as shown in  FIGS.  1 ,  2 ,  7 , and  8   , the deflector  112  includes a plurality of radially-extending ribs  110  that form part of its underside. Flutes  140  for water are formed between adjacent ribs  110  and have rounded bottoms  162  coinciding with the underside of the upper deflector surface  158 . The ribs  110  are each configured to divide the fluid flow through the flutes  140  into different channels for different sprays directed to different areas and thereby having different characteristics. A similar rib structure is described in U.S. Pat. No. 9,314,952, which description is incorporated herein by reference in its entirety. 
     As the ribs  110  are each generally symmetric about a radially-extending line, only one of the sides of a representative rib  110  will be described with it being understood that the opposite side of that same rib  110  has the same structure. With reference to  FIGS.  8  and  9   , the rib  110  has a first step  166  forming in part a first micro-ramp and a second step  168  defining in part a second micro-ramp. The first step  166  is generally linear and positioned at an angle closer to perpendicular relative to a central axis of the deflector  112  as compared to the bottom  162  of the upper deflector surface  158 , as shown in  FIGS.  8  and  9   . The second step  168  is segmented, having an inner portion  168   a  that extends closer to perpendicular relative to the central axis as compared to an outer portion  168   b , which has a sharp downward angle. 
     The geometries of the ribs  110  and the bottom  162  of the of the upper deflector surface  158  cooperate to define a plurality of micro-ramps which divide the discharging water into sprays having differing characteristics. More specifically, the first and second steps  166  and  168  divide the sidewall into four portions having different thicknesses: a first sidewall portion  163  disposed beneath an outward region of the bottom  162  of the upper deflector surface  158 ; a second sidewall portion  165  disposed beneath the first sidewall portion  163  and at the outer end of rib  110 ; a third sidewall portion  167  disposed beneath the first sidewall portion and radially inward from the second sidewall portion  167 , and a fourth sidewall portion  169  disposed beneath the first and second sidewall portions  165  and  167 , as depicted in  FIGS.  8  and  9   . As addressed further below, these four sidewall portions result in fluid flow along the ribs  110  in multiple water streams that combine to provide relatively uniform fluid distribution. 
     In this form, the half-circle nozzle  100  preferably includes 15 ribs  110 . These ribs  110  produce water streams in three sets of general flow channels having general trajectories for relatively distant, intermediate, and short ranges of coverage. More specifically, and with reference to  FIG.  7   , there is a distant spray A, a mid-range spray B, and a close-in spray C. However, rather than being distinct trajectories, these secondary and tertiary streams (B and C) are deflected or diffused from the sides of the relatively distant, nominal streams (A). Accordingly, this type of nozzle  100  is a multi-stream, multi-diffuser nozzle. Of course, the number of streams may be modified by changing the number of ribs  110 . 
     The flow channels for the relatively distant streams (A) are formed primarily by the uppermost portion of the flutes  140  between successive ribs  110 . More specifically, these streams (A) flow within the uppermost portion of the flute  140  defined by the rounded bottoms  162  at the underside of the upper deflector surface  158  and extending downwardly to the first steps  166 . As can be seen in  FIGS.  8  and  9   , this uppermost portion is generally curved near the base of the flute  140 , such as in the shape of an arch. There is one stream (A) between each pair of ribs  110  and between the two edge ribs  110  and the boundary wall  124 . 
     The flow channel for the mid-range spray (B) is defined generally by the side of each rib  110  between the first step  166  and the second step inner portion  168   a . More specifically, these streams (B) flow within an intermediate portion of the discharge channel  140  and have a lower general trajectory than the distant streams (A). These mid-range streams (B) may be deflected laterally to some extent by the second step outer portion  168   b . There is one stream (B) corresponding to the side of each rib  110 . 
     The flow channels for the close-in streams (C) are formed generally by the lowermost portion of the flute  140  on each side of rib  110 . More specifically, these streams (C) flow beneath the second step  168  and along the lowermost portions of the ribs  110 . These streams (C) generally have a lower trajectory than the other two streams (A and B) and impact and are directed downwardly by the second step outer portion  168   b . The sharply inclined end segment  168   b  is configured to direct the water spray more downwardly as compared to the spray from the first micro-ramp. There is one stream (C) corresponding to the side of each rib  110 . 
     As addressed above, these three general trajectories are not completely distinct trajectories. The relatively distant water stream (A) has the highest trajectory and elevation, generally does not experience interfering water streams, and therefore is distributed furthest from the nozzle  100 . However, the secondary and tertiary streams (B and C) are deflected or diffused from the sides of the ribs  110 , have lower general trajectories and elevations, and experience more interfering water streams. As a result, these streams (B and C) fill in the remaining pattern at intermediate and close-in ranges. 
     The positioning and orientation of the first and second steps  166  and  168  may be modified to change the flow characteristics. It will be understood that the geometries, angles and extent of the micro-ramps can be altered to tailor the resultant combined spray pattern. Further, in some circumstances, it may be preferable to have less than all of the ribs  110  include micro-ramps. For instance, the micro-ramps may be on only one side of each of the ribs  110 , may be in alternating patterns, or in some other arrangement. 
     In the exemplary embodiment of a nozzle  100 , the ribs  110  are spaced at about 10 degrees to about 12 degrees apart. The first step  166  is preferably triangular in shape and between about 0.004 and 0.008 inches in width at its outer end from the sidewall of the adjacent portion of the rib  110 , such as about 0.006 inches. It preferably has a length of about 0.080 inches and tapers downwardly about 6 degrees from a horizontal plane defined by the top of the nozzle  100 . The second step  168  may be between about 0.002 inches in width, an inner portion  168   a  may be about 0.05 inches in length, and an angle of the inner portion  168   a  may be about 2 degree relative to a horizontal plane. The angle of the bottom portion  170  of rib  110  may be about 9 degrees downwardly away from a horizontal plane coinciding with the top of the nozzle  100 . While these dimensions are representative of the exemplary embodiment, they are not to be limiting, as different objectives can require variations in these dimensions, the addition or subtraction of the steps and/or micro-ramps, and other changes to the geometry to tailor the resultant spray pattern to a given objective. 
     Other rib features and configurations are described in U.S. Pat. No. 9,314,952, which description is incorporated herein by reference in its entirety. The rib features and configurations disclosed in U.S. Pat. No. 9,314,952 may be incorporated into the nozzle embodiments disclosed in this application. More specifically, the deflector surface and water distribution profile including rib features of that application may be used in conjunction with the inflow ports, conical transition surfaces, and other parts of the nozzle embodiments disclosed above. 
     As can be seen from  FIGS.  6 ,  8 , and  9   , the nozzle  100  also includes features to increase the uniformity of distribution at the boundary edges, i.e., at each 180 degree boundary edge. The nozzle  100  includes vent holes  172  to normalize air pressure behind the water streams emerging from the nozzle  100 . These vent holes  172  preferably extend vertically through the distal wall  120 . They are generally disposed at two positions at each arcuate end of the deflector, these two positions corresponding to each boundary flute  174  defining each of the two boundary edges of the irrigation pattern. In this preferred form, there are six vent holes  172  disposed about each boundary flute  174 . More specifically, as can be seen, in this preferred form, two of the vent holes  172 A are disposed behind the boundary flute  174  (adjacent the rear wall  176 ), two of the vent holes  172 B are disposed above the boundary flute  174  (vertically above the water stream exiting this flute  174 ), and vent holes  172 C are disposed in front of the boundary flute  174  (vertically above the rib  110  and flute  140  adjacent the boundary flute  174 ). It is believed that the positioning of the two vent holes  172 A between streams exiting the boundary flutes  174  and the rear wall  176  provide air flow that help produce crisp boundary edges, regardless of the pressure of the exiting water streams. The vent hole pattern may only include one or more holes  172 A. Further, as can be seen, the boundary flute  174  is not the same size as the other flutes  140  but is instead about half of the diameter of the other flutes  140 . 
     It is believed that, without vent holes  172 A, fluid distributed at the boundary edges will tend to cling to the boundary wall  124  and/or the rear wall  176 . In other words, when this fluid exits at the boundary edges, it tends to wrap around the corners and adhere to one or both walls  124 ,  176 . When fluid is exiting the vent holes  172 A, air is generally drawn downward into the space between the exiting water stream and the rear wall  176 . By normalizing the air pressure behind the exiting water stream, a more uniform irrigation pattern is formed. This result is generally true regardless of the fluid pressure, fluid flow, and fluid velocity. It is believed that, without vent holes  172 A, low flow and low velocity conditions may especially result in non-uniform and uneven irrigation patterns. 
     As should be understood, the number and arrangement of vent holes  172  may be modified. It is generally believed that several vent holes  172  may be desirable for redundancy to make the vent holes  172  more grit resistant. Further, the vent holes  172  may define any of various cross-sectional shapes, including circular, oval, rectangular, triangular, etc. It is believed that the two vent holes  172 A closest to the rear wall  176  may provide the most benefit, and they may prevent impact with and/or clinging to the rear wall  176 . It is also believed that some or all of the vent holes  172  help prevent impact of the exiting water streams with the distal wall  120 . 
     As mentioned above, and as can be seen in  FIGS.  1 ,  2 ,  7 ,  8 , and  9   , the two boundary flutes  174  are half flutes, i.e., they each have about half of the cross-section of the other flutes of the deflector  112 . It is believed that boundary flutes  174  of the same size as the other flutes results in too much water at the boundary edges of the irrigation pattern, and it is believed that the water streams at the boundary edges tends to draw in more water. These two truncated flutes  174  therefore reduce the amount of water at the boundary edges of the pattern. 
     Further, in one form, the rear wall  176  may be preferably offset from the boundary wall  124  by a minimum distance of about 0.010 to 0.015 inches. This minimum offset helps limit the water streams deflecting off of the rear wall  176  and reduce the amount of friction resulting from the rear wall  176 . As stated, such water streams impacting or adhering to the rear wall tend to contribute to heavy precipitation along the boundary edges of the irrigation pattern and/or contribute to overthrow beyond the intended throw radius. It is believed that the offset must have a minimum distance to provide a certain amount of separation to allow air to flow into the space between the exiting water stream and the rear wall  176 . However, too much offset may lead to a decrease in performance because it may lead to air flow in the wrong direction, i.e., not primarily downward but also including some lateral components. 
     In addition, the cross-section of the port  106  is preferably shaped in a certain manner to increase the uniformity of the entire irrigation pattern. More specifically, the port  106  is preferably formed of a complex geometry of arc segments with different/compound radii to improve distribution uniformity. In other words, the port  106  extends about 180 degrees but is not precisely semi-circular in cross-section. The lateral edges (the left and right sides) of the port  106  are preferably symmetrical, and each lateral edge preferably defines a shorter leg/radius relative to a longer leg/radius relative to the forward edge. As stated above, fluid tends to accumulate and overthrow at the boundary edges, resulting in a less uniform pattern. By adjusting the shape of the port  106  in this manner, less fluid is directed to the boundary edges of the irrigation pattern and more fluid is directed to the forward portion of the irrigation pattern. In one straightforward example, the port  106  may be formed of arc segments with two distinct radii: a shorter radius to the lateral edges and a longer radius to the forward edge. 
     An exemplary form of a port  106  with more compound radii, e.g., four compound radii, is shown in  FIG.  10   . As can be seen, in this form, the lateral edge points  178  of the port  106  define sides  179  having shorter legs than the center  180  of the forward edge  181 . More specifically, in this particular example, the shorter legs are preferably about 0.058 inches from the midpoint  182  of the base  184 , and the longer leg to the center  180  of the forward edge  181  is about 0.063 inches (although it should be understood that other dimensions are possible). In this form, the cross-sectional shape of the port  106  includes a base  184  with a midpoint  182 , two lateral edge points  178  disposed at equal distances from the midpoint  182 , and a forward edge  181  spaced from the midpoint  182  and connecting the two lateral edge points  178 . Further, in this form, the distance from the midpoint  182  to each lateral edge point  178  is less than the distance from the midpoint  182  to the center  180  of the forward edge  181 . 
     Additional radii have been added to fine tune fluid distribution within the irrigation pattern. More specifically, as can be seen, in this particular form, the cross-section of the port  106  is defined by arcuate segments having four different radiuses/curvatures. In this particular example, starting from one lateral edge point  178 , the first arcuate segment  186  preferably has a radius of about 0.045 inches and extends about 25 degrees; the second arcuate segment  188  preferably has a radius of about 0.713 inches and also extends about 25 degrees; the third arcuate segment  190  has a radius of about 0.040 inches and extends about 18 degrees; and the fourth arcuate segment  192  has a radius of about 0.072 inches and extends about 22 degrees. As can be seen, in this form, the port  106  generally has a bulging forward portion so as to fill in forward portions of the irrigation pattern, i.e., the port  106  is oblong in cross-sectional shape in the forward direction. The dimensions and shape of the port  106  may be scaled and adjusted, as desired, to fill in various sizes and shapes of irrigation patterns. 
     In this form, the cross-section of the port  106  is symmetrical about the line from the midpoint  182  to the center  180  of the forward edge  181 . In addition, in this form, the cross-section of the port  106  is preferably offset slightly from the boundary wall  124 . In other words, the base  184  of the port  106  is spaced slightly from the boundary wall  124 , and in one form, it may be spaced about 0.002 inches from the boundary wall  124 . 
     As should be understood, other arrangements of the number, curvature, and extent of arcuate segments are possible. For example, and without limitation, there may be three, five, or more arcuate segments with any of various arcuate curvatures and that extend any of various arcuate lengths. It is generally contemplated that at least two arcuate segments having different radii are used. By adjusting the number and arrangement of arcuate segments, fluid distribution within the irrigation pattern may be adjusted in a desired manner and the uniformity of fluid distribution in the irrigation pattern may be correspondingly adjusted. The use of compound radii therefore provides flexibility in adjusting fluid distribution within the irrigation pattern. The dimensions and shape of these arcuate segments may be scaled and adjusted, as desired, to fill in various sizes and shapes of irrigation patterns. 
     An optional feature of the nozzle  100  is a pinch angle defined by the boundary wall  124  at the deflector  112 . More specifically, this pinch angle is preferably formed at the top of the boundary wall  124  and preferably defines one side of each boundary flute  174 . It is oriented such that the boundary wall  124  extends in a direction away from the rear wall  176 . In other words, as shown in  FIG.  9   , the top portion  124 A of the boundary wall  124  preferably defines an inwardly inclined angle of about six degrees (or preferably within the range of two to twelve degrees) with respect to the remainder of the boundary wall  124 . It is believed that this pinch angle helps limit the boundary water stream from impacting or adhering to the rear wall  176 , reduce precipitation along the boundary edges of the irrigation pattern, and/or limit overthrow beyond the intended throw radius. Further, it is believed that different pinch angles may be desirable for different arcuate spans, e.g., 90 degrees, to fine tune the edges, given lower or higher flow conditions. 
     The features described above help improve the uniform distribution of fluid, especially at the boundary edges of the irrigation pattern.  FIG.  11    shows an example of the fluid distribution of a conventional nozzle with heavy precipitation and overthrow along the boundary edges of the irrigation pattern. As seen from above, fluid distribution appears relatively heavy along the boundary edges (shown by the dark portions) and appears to overthrow these boundary edges (extending beyond points  194 ).  FIG.  12    shows an example of the fluid distribution of nozzle  100 . Fluid distribution is more uniform within the irrigation pattern, and there is little (if any) overthrow at the boundary edges (overthrow beyond points  194 ). 
     Several features have been described above to facilitate the uniform fluid distribution and improve fluid distribution at the boundary edges, including vent holes, rear wall offset, port with compound radii, and a pinch angle. It is contemplated that various embodiments of nozzles may include one or more of these features, either in combination or alone. It should therefore be understood that this disclosure does not require the inclusion of any one or more of these features. In certain circumstances, and depending on the nature of the irrigation pattern and other requirements, it may be desirable to exclude one or more features from an embodiment. 
     Further, the shape of the deflector may be modified to accommodate different fixed arcuate spans, i.e., 90, 270, and 360 degrees. For example, the deflector may include ribs disposed within 90 degrees for quarter-circle irrigation. Additionally, the nozzle body may include two 180 degree deflector surfaces facing opposite from one another to achieve close to full circle (or 360 degree) irrigation. The nozzle body may also include a 90 degree deflector surface combined with a 180 degree deflector surface to achieve 270 degree irrigation. Alternatively, the nozzle body might include two deflector surfaces of approximately the same size to achieve this three-quarter circle irrigation. For these modified embodiments, it may be preferable to have edge flutes to provide a more distant trajectory for water streams at the edges of the pattern. 
     The nozzle  100  also preferably includes a flow throttling screw  104 . The flow throttling screw  104  extends through the central bore  118  of the nozzle body  102 . The flow throttling screw  104  is manually adjusted to throttle the flow of water through the nozzle  100 . The throttling screw  104  includes a head  148 , is seated in the central bore  118  and may be adjusted through the use of a hand tool. The opposite end  150  of the screw  104  is in proximity to the inlet  115  protected from debris by a filter (not shown). Rotation of the head  148  results in translation of the opposite end  150  for regulation of water inflow into the nozzle  100 . The screw  104  may be rotated in one direction to decrease the inflow of water into the nozzle  100 , and in the other to increase the inflow of water into the nozzle  100 . In one preferred form, the screw  104  may shut off flow by engaging a seat of the filter. As should be evident, any of various types of screws may be used to regulate fluid flow. 
     In operation, when fluid is supplied to the nozzle  100 , it flows upwardly through the filter and then upwardly through the inflow port  106 . Next, fluid flows upwardly along the conical transition surface  108 , which guides the fluid to the ribs  110  of the deflector  112 . The fluid is then separated into multiple streams, flows along the rib structures and is distributed outwardly from the nozzle  100  along these flow channels with different trajectories to improve uniformity of distribution. A user regulates the maximum throw radius by rotating the flow throttling screw  104  clockwise or counterclockwise. 
     Although the nozzle  100  distributes fluid in a fixed 180 degree arc, i.e., nozzle  100  is a half-circle nozzle, the nozzle may be easily manufactured to cover other predetermined water distribution arcs. Figures showing nozzles with other fixed distribution arcs are easily configured. These other nozzles may be formed by matching the arcuate size of the inflow port with the arc defined by the boundary walls (and with ribs extending therebetween). Further, although the nozzle  100  addressed above includes a one-piece, unitary nozzle body, other embodiments may have a nozzle body that includes several components to define the nozzle body. Various embodiments are described in U.S. Pat. No. 9,314,952, and the patent disclosure is incorporated herein by reference in its entirety. 
     It will be understood that various changes in the details, materials, and arrangements of parts and components which have been herein described and illustrated in order to explain the nature of the nozzle may be made by those skilled in the art within the principle and scope of the nozzle and the flow control device as expressed in the appended claims. Furthermore, while various features have been described with regard to a particular embodiment or a particular approach, it will be appreciated that features described for one embodiment also may be incorporated with the other described embodiments.