how can i use a set of node points
 

I have a 2D triangular mesh generator that takes in a 2d image with an object of interest inside (like an airfoil or profile of a car) and outputs x and y coordinates for all of the node points. It can also output the three vertices for each triangle. Aside from a plot of these coordinates connected with lines, that's all I have for a mesh. There is a defined rectangle around the object in the image which could serve as boundaries.

Is there any way I can import that to a mesh generation software that will allow me to apply boundary conditions and output something useful to a solver like fluent or OpenFOAM?

If you have the locations of the nodes and the connectivity of the triangle, it will be fairly easy to write a small code to create a file that can be read by Fluent for example. You can find a description of the Fluent .msh format online to guide you.