A fuel/air premixing system, comprising: a fuel nozzle, comprising: a center body configured to receive a first portion of air and to deliver the air to a combustion region; and a single swirler configured to receive a second portion of air and to deliver the air to the combustion region, wherein the swirler comprises: an outer shroud wall; an inner hub wall comprising multiple fuel injection ports; and multiple swirl vanes with a radial swirl profile at a downstream edge of each swirl vane, wherein the radial swirl profile comprises a first region extending from the outer shroud wall to a transition point and a second region extending from the transition point to the inner hub wall, and the first region is substantially straight and the second region is arcuate, wherein the radial swirl profile forms a first swirl angle at the outer shroud wall and the radial swirl profile forms a second swirl angle at the inner hub wall, and the first swirl angle is greater than the second swirl angle and wherein each swirl vane further comprises multiple fuel outlet ports in fluid communication via a fuel plenum in the swirl vane with fuel injection ports. a fuel nozzle, comprising: a center body configured to receive a first portion of air and to deliver the air to a combustion region; and a single swirler configured to receive a second portion of air and to deliver the air to the combustion region, wherein the swirler comprises: an outer shroud wall; an inner hub wall comprising multiple fuel injection ports; and multiple swirl vanes with a radial swirl profile at a downstream edge of each swirl vane, wherein the radial swirl profile comprises a first region extending from the outer shroud wall to a transition point and a second region extending from the transition point to the inner hub wall, and the first region is substantially straight and the second region is arcuate, wherein the radial swirl profile forms a first swirl angle at the outer shroud wall and the radial swirl profile forms a second swirl angle at the inner hub wall, and the first swirl angle is greater than the second swirl angle and wherein each swirl vane further comprises multiple fuel outlet ports in fluid communication via a fuel plenum in the swirl vane with fuel injection ports. a center body configured to receive a first portion of air and to deliver the air to a combustion region; and a single swirler configured to receive a second portion of air and to deliver the air to the combustion region, wherein the swirler comprises: an outer shroud wall; an inner hub wall comprising multiple fuel injection ports; and multiple swirl vanes with a radial swirl profile at a downstream edge of each swirl vane, wherein the radial swirl profile comprises a first region extending from the outer shroud wall to a transition point and a second region extending from the transition point to the inner hub wall, and the first region is substantially straight and the second region is arcuate, wherein the radial swirl profile forms a first swirl angle at the outer shroud wall and the radial swirl profile forms a second swirl angle at the inner hub wall, and the first swirl angle is greater than the second swirl angle and wherein each swirl vane further comprises multiple fuel outlet ports in fluid communication via a fuel plenum in the swirl vane with fuel injection ports. an outer shroud wall; an inner hub wall comprising multiple fuel injection ports; and multiple swirl vanes with a radial swirl profile at a downstream edge of each swirl vane, wherein the radial swirl profile comprises a first region extending from the outer shroud wall to a transition point and a second region extending from the transition point to the inner hub wall, and the first region is substantially straight and the second region is arcuate, wherein the radial swirl profile forms a first swirl angle at the outer shroud wall and the radial swirl profile forms a second swirl angle at the inner hub wall, and the first swirl angle is greater than the second swirl angle and wherein each swirl vane further comprises multiple fuel outlet ports in fluid communication via a fuel plenum in the swirl vane with fuel injection ports.