I am describing a part of literature in introduction of my paper with the following way(I studied on effect of blade thickness in CFD methods):
A few authors experimentally investigated the effect of blade thickness on the Wells turbine performance. They changed the blade thickness from hub to tip in their work.........((two authors investigated))
Despite prior authors, a few authors also kept blade thickness constant from hub to tip in their experimental study. Takao et al.  .....((three authors investigated))
As revealed above, in the past two decades, many investigations on blade thickness of the Wells turbine are performed by experimental studies. But there is a difficulty in the interpretation of experimental results because.......So, by using CFD methods, many efforts is performed in order to overcome ......[9, 16, 17]...((only two authors regarding the blade thickness investigated))
As described above, a few authors investigated the effect of blade thickness on Wells turbine performance by using CFD methods.
I think that I used "A few" too much. I am grateful for suggested ways to make it clearer and better. Could you please suggest some words to replace "A few" and "Despite"?