GAS TO GAS ASPIRATOR WITH IMPROVED ENTRAINMENT EFFICIENCY
An eductor type gas to gas aspirator having improved entrainment efficiency includes a motive gas nozzle configured with a distal tip having an arcuate internal profile that converges in a downstream direction. The arcuate internal profile preferably has sinusoidal convergence curvature. In a preferred embodiment, the length L s of the nozzle tip is between 2D and 4D where D is the diameter of said outlet orifice, and the distance L d between nozzle outlet orifice and the upstream end of and out let barrel passage is between 0 and D.
1 . A gas to gas eductor aspirator comprising:
an interaction region having a converging downstream end;
a nozzle for receiving a motive gas under pressure and issuing a jet of motive gas into the downstream end of said interaction region;
an entrainment gas inlet passage in flow communication with said interaction region such that the entrainment gas is entrained into said interaction region by said motive gas jet;
a barrel passage having an upstream end for receiving the motive gas jet and the entrained entrainment gas;
wherein said nozzle is configured with a distal tip having an arcuate internal profile that converges in a downstream direction and terminates in an outlet orifice from which said jet is issued.
2 . The aspirator of claim 1 wherein said arcuate internal profile of said nozzle tip has a generally sinusoidal convergence curvature.
3 . The aspirator of claim 2 wherein said sinusoidal convergence curvature is represented by L s sin θ, where L s is the length of nozzle tip and θ is the axial length of the nozzle tip 16 defined in angle units between 90° and 270°.
4 . The aspirator of claim 2 wherein the length L s of the nozzle tip is between 2D and 4D where D is the diameter of said outlet orifice.
5 . The aspirator of claim 4 wherein the distance L d between said nozzle outlet orifice and the upstream end of barrel passage is between 0 and D.
6 . The aspirator of claim 5 wherein the minimum internal diameter D e of said barrel passage is between 3.5D and 4D.
7 . The aspirator of claim 6 wherein the barrel passage has a divergence angle Ω w between 0° and 2°.
8 . The aspirator of claim 1 wherein the length L s of the nozzle tip is between 2D and 4D where D is the diameter of said outlet orifice.
9 . The aspirator of claim 1 wherein the distance L d between said nozzle outlet orifice and the upstream end of barrel passage is between 0 and D where D is the diameter of said outlet orifice.
10 . The aspirator of claim 1 wherein the minimum internal diameter D e of said barrel passage is between 3.5D and 4D where D is the diameter of said outlet orifice.
11 . The aspirator of claim 1 wherein the barrel passage has a divergence angle Ω w between 0° and 2°.
12 . The aspirator of claim 1 wherein said outlet orifice is rectangular with a width W and a height H, and wherein W>>H.
13 . The aspirator of claim 1 wherein said nozzle is internally subdivided into plural motive gas nozzles in side by side relation with respective outlet orifices arranged to issue plural respective parallel motive gas jets into said interaction region and said barrel passage for entraining said entrainment gas.
14 . The aspirator of claim 13 wherein said arcuate internal profile of said nozzle tip has a generally sinusoidal convergence curvature.
15 . The aspirator of claim 1 wherein said nozzle is internally subdivided into three motive gas nozzles in side by side relation with respective outlet orifices arranged to issue three respective parallel motive gas jets into said interaction region and said barrel passage for entraining said entrainment gas.
16 . The aspirator of claim 15 wherein said arcuate internal profile of said nozzle tip has a generally sinusoidal convergence curvature.
17 . The aspirator of claim 1 wherein said arcuate internal profile of said nozzle tip has a generally sinusoidal convergence curvature, and wherein said barrel passage has a length between 19D and 26D, where D is the diameter of said outlet orifice.
18 . The aspirator of claim 17 wherein the diameter D I of the interior of said nozzle upstream of the nozzle tip is in the range from 2D to 3D.
19 . The aspirator of claim 18 wherein the length L s of the nozzle tip is between 2D and 4D and the distance L d between said nozzle outlet orifice and the upstream end of barrel passage is between 0 and D.
20 . The aspirator of claim 1 wherein said arcuate internal profile of said nozzle tip has a generally sinusoidal convergence curvature and said aspirator has an entrainment efficiency ν greater than 3.