An insertion-type flowmeter adapted for removable insertion into a fluid conduit comprising: (a) an elongate body having an elongate body axis for insertion into fluid conduits of different diameters, the elongate body including a flow opening defined by a top wall, a bottom wall, and a pair of side walls (226, 228) extending between the top and bottom walls, the flow opening extending from an opening entry to an opening exit perpendicular to the elongate body axis and completely through the elongate body, the size of the flow opening being independent from the different diameters of the fluid conduits; (b) a vortex-generating element disposed within the flow opening for generating substantially uniform vortices and directing said vortices to impinge on said top wall and said bottom wall in an alternate fashion, the vortex generating element being disposed at distance from the opening entry that is correlated to the size of the flow opening to define a flow conditioning space in the flow opening between the opening entry and the vortex-generating element; (c) a first pressure element disposed within said elongate body and adjacent said top wall; (d) a second pressure element disposed within said elongate body and adjacent said bottom wall, so that said first and second pressure elements are operative to sense said vortices impinging on said top wall and said bottom wall, respectively; and (e) output means associated with each of said first and second pressure elements for generating an output signal indicative of the force applied to each of said first and second pressure elements, wherein preferably the vortex-generating element includes a forward face plate perpendicular to the opening direction and a tail piece disposed rearwardly of the face plate and wherein the tail piece includes a curved portion (314, 316) and a straight, tapering portion (310, 312), the curved portion being between the forward face plate and the straight, tapering portion. (a) an elongate body having an elongate body axis for insertion into fluid conduits of different diameters, the elongate body including a flow opening defined by a top wall, a bottom wall, and a pair of side walls (226, 228) extending between the top and bottom walls, the flow opening extending from an opening entry to an opening exit perpendicular to the elongate body axis and completely through the elongate body, the size of the flow opening being independent from the different diameters of the fluid conduits; (b) a vortex-generating element disposed within the flow opening for generating substantially uniform vortices and directing said vortices to impinge on said top wall and said bottom wall in an alternate fashion, the vortex generating element being disposed at distance from the opening entry that is correlated to the size of the flow opening to define a flow conditioning space in the flow opening between the opening entry and the vortex-generating element; (c) a first pressure element disposed within said elongate body and adjacent said top wall; (d) a second pressure element disposed within said elongate body and adjacent said bottom wall, so that said first and second pressure elements are operative to sense said vortices impinging on said top wall and said bottom wall, respectively; and (e) output means associated with each of said first and second pressure elements for generating an output signal indicative of the force applied to each of said first and second pressure elements,