Machine Learning Validation Set
The validation set is there to stop you from using the test set until you are done tuning your model. When you are done tuning, you would like to have a realistic view of how the model will perform on unseen data, which is where the test set comes into play. 

But tuning the model is not only hyperparameters. It involves things like feature selection, feature engineering and aslo the choice of algorithm. Even though it seems like you are already decided on a model, you should consider alternatives as it might mot be the optimal choice.