referring now to the exploded view of fig1 , the spa nozzle includes a main housing 10 which has an external threaded portion 11 for below the waterline securement or mounting by a gland nut ( not shown ) in the wall w of a spa , an air inlet barb 12 and a main water inlet barb 13 . the air inlet 12 is connected to a valve ( not shown ) for on / off control . the upstream end 14 of subhousing 15 has a cutout 16 ( fig2 a ) that aligns with the flow inlet 13 to control water flow rate from full to about 30 %. subhousing 15 has a flared or bell - shaped section 15 b and an annular rib 15 r which engages the inner wall of main housing 10 . the downstream end of the subhousing 15 has a hook element chm which will be described later in connection with the securement thereto of the escutcheon 40 . the fluidic oscillator element 20 includes an annular dam member 21 that receives an o - ring member 22 which engages the inner wall 23 of the upstream end 14 of subhousing 15 ( see fig2 a and 2 b ). this forms a water chamber wcp for feeding water into the fluidic itself . the fluidic oscillator per se is shown in silhouette form in fig2 b and includes a plug p , a power nozzle pn for projecting a jet stream of water past a pair of control ports cp 1 , cp 2 through an interaction region ir which has sidewalls sw 1 and sw 2 which diverge or flare outwardly toward ambient and top tp and bottom bt walls . top and bottom inertance plates 25 and 26 , respectively , are mounted on the top and bottom walls and have inertance loop forming grooves ilg ( only one shown in fig1 ) formed in the faces thereof . one inertance loop coupling aperture is shown in the view taken in fig1 and designated as ilc for inertance loop connection passage to interconnect the control ports cp 1 and cp 2 . a similar passage or opening is formed in the opposite control passage cp 1 , but in the opposite sidewall thereof . ( see exploded view shown in fig1 . ) the opposing ends of the inertance grooves and the inertance loops themselves are juxtaposed over a pass - through passage ptp so that the inertance loop extends between the two control ports cp 1 , cp 2 and controls the frequency of oscillation of the fluidic oscillator . thus , the inertance loop between the two control ports cp 1 and cp 2 is comprised of inertance loop coupling passages ilc ( one for each control port ), two inertance loop grooves ilg ( one in each of plates 25 and 26 ) which are connected by the passthrough passage ptp . the fluidic oscillator operates in a conventional fashion as follows : the water jet issues through power nozzle pn and passes across the control ports adjacent thereto and due to some perturbance , the jet will be closer to one or the other control port cp 1 or cp 2 . this produces a pressure gradient across the jet at the control ports to switch the let to one side or the other and then the process repeats . as noted earlier , the length and size of the inertance loop plates attached to the control ports of the fluidic element set the oscillating frequency . the frequency oscillation or sweeping of the water jet into the spa tub per se can be changed by adjusting the length and size ( area ) of the inertance loops formed on the inertance loop plates . an air passage or groove ag is formed in the top and bottom inertance plates for matching with other holes all in the body of the fluidic for air entrainment admission to air entrainment hole ah . in this embodiment the air entrainment hole ah is located downstream of the power nozzle pn . the fluidic interaction region ir has sidewalls sw 1 , sw 2 that diverge downstream of the power nozzle pn to form a “ v ” shape . to obtain sufficient air entrainment , the air entrainment hole must be located close to the power nozzle where the jet is still focused . if the air entrainment hole ah is moved further downstream , the moving ( sweeping ) jet is not over the hole for a sufficient period of time to allow sufficient air to be drawn in . when the air entrainment hole ah is positioned close to the power nozzle pn to optimize air entrainment , some quantity of air would be drawn into the inertance loop constituted by the groove ag in inertance plates 25 , 26 . air is sufficiently less dense than water so its inclusion in the inertance loop would first raise the oscillating frequency , and then as more air contaminates the inertance loop , the oscillations would stop . to solve this problem , a water ingestion port wip is added to the inertance loop . in addition to slowing the frequency ( desirable in this application ), the key benefit of the water ingestion port wip is to provide water to purge the air contamination from the inertance loop . without the water ingestion port wip , the air entrainment hole ah would need to be placed further downstream and less air would be entrained into the exiting water ( undesirable ). air entrainment may be enhanced by a slot structure slo extending downstream of air entrainment port or hole ah , as is disclosed in thurber et al application ser . no . 09 / 899 , 547 , filed jul . 6 , 2001 , entitled spa nozzles with air entrainment , incorporated herein by reference . integrally molded with the fluidic is an annular ring 29 which receives a rotatable or movable mode change disc 30 which has tabs 31 , 32 that are fitted into arcuate guide slots 33 , 34 . mode change disc member 30 is also retained in position by a snap - on escutcheon member 40 . snap - on escutcheon member 40 has a cooperating latch member clm which engages a cooperating hook member chm on the downstream end of housing 15 . mode change disc 30 has an elongated slot 35 . the important feature about mode - change disc 30 is the slot 35 and its orientation relative to the downstream end of the interaction region or chamber ir . as illustrated , the mode disc 30 is generally round and has a generally rectangular slot 35 therein . the slots 33 , 34 and tabs 31 , 32 allows the mode disc 30 to be rotated up to about 90 ° to change the outlet geometry and thus the sweep of fluid stream . at 0 ° rotation ( fig3 a - 3 b ), the slot 35 is aligned with the diverging ends of the fluidic oscillator . as shown in fig2 b , the slot 35 is aligned with the width of the diverging end of sidewalls sw 1 and sw 2 of the interaction region ir , thus allowing the water jet to sweep . thus at 0 ° rotation , the slot 34 provides a continuation of the exit geometry of the interaction region ir and allows the submerged jet to sweep or oscillate back and forth in the water of the spa tub . at 90 ° rotation , the slot 34 is perpendicular to the fluidic exit geometry . this results in the edges of the oscillating wave being backloaded , and the output is a straight focused jet . the rectangular slot 34 can be made larger with a generally round section to control the field of the straight jet in the jet mode . the disc 30 can be adjusted to angles from between 0 ° and 90 ° to achieve progressively narrower sweeping oscillations . the mode control disc 30 has a pair of side slots or depressions f 1 , f 2 to each side of the slot in the mode disc 30 to enable easy , ergonomic and firm grasping between the user &# 39 ; s fingers . in the straight jet mode , the jet may have a pulsating sensation , depending on the size of the opening chosen . this pulsation feels twice as quick as the oscillations in oscillating mode due to the jet passing through the center twice per oscillation . in the straight jet mode , the water is concentrated in a smaller area than the oscillation mode . therefore , the momentum flux and intensity , is greater . control of the flow rates can be accomplished by rotating the sleeve valve formed in the subhousing and discussed briefly above . air can be routed through the central control valve on the spa nozzle to a manifold , and an air line ( not shown ) from this manifold is connected to each spa nozzle housing via air barb fitting 12 . air enters the rear of the housing and is separated from the water passages by the rear o - ring ro . the air passes through the two channels hc 1 and hc 2 on either side of the water chamber wcp . air passages then turn 90 ° through aperture app to the top and bottom inertance plates 25 , 26 of the fluidic , and each of the inertance plates 25 , 26 have an air channel ag in them to carry the air to the pass - through hole ah downstream of the power nozzle pn . the fluidic oscillator can be set in any angular position . as illustrated in the drawings , the fluidic oscillator is constrained in its fore and aft position by being retained between the housing and the escutcheon . it is constrained from rotating by the friction of the rear o - ring . while the invention has been described in relation to preferred embodiments of the invention , it will be appreciated that other embodiments , adaptations and modifications of the invention will be apparent to those skilled in the art .
there is disclosed a fluidic spa tub nozzle having a fluidic oscillator with diverging sidewalls and a cooperating mode - change member for changing the mode from an oscillatory swept jet mode to a straight jet mode and positions thereinbetween . the fluidic oscillator has an inertance loop formed by groove plates secured to the top and bottom walls of the fluidic oscillator .