English term (edited): design science research methodology

The expression "design science research methodology" is a layered expression with three levels of modification, as follows:

1. The word "research" modifies the noun "methodology." In other words, the methodology in question is not just any kind of methodology, but a "research methodology," or منهجية بحثية or منهجية أبحاثية (both are used, but منهجية بحثية is better).

2. The word "science" modifies the noun "research," so that the research in question is not just any kind of research, but "science research" (بحث علمي). Therefore the methodology in question is not just any kind of "methodology" or "research methodology," but "science research methodology," or منهجية بحثية عليمة or منهجية البحث العلمي

3. The word "design" modifies the noun phrase "science research," so that the science research in question is not just any kind of science research, but "design science research" (بحث علمي تصميمي), and the methodology" in question is not just any kind of science research methodology, but specifically "design science research methodology," or منهجية البحث العلمي التصميمي

As you can see from the Wikipedia article that you included in your question, the phrase "design science" is not commonly used as a stand alone phrase as if it were a regular noun phrase. It is used mainly to characterize a particular type of methodology, more specifically, a particular kind of research methodology. You can see that in the very title of the article.

We can, of course, translate "design science" by itself, but it would be what we call a red herring. It would throw the reader off completely. But when taken in its context, its meaning comes out clearly.

"This study follows a design science research approach."
تتبع هذه الدراسة مقاربة المنهجية البحثية العلمية التصميمية

"design science project"
مشروع يتبع المهجية العلمية التصميمية

Notice that the Arabic language does not use noun modifiers, so we have to resort to using attributive adjectives instead of noun modifiers, but that is a separate topic of discussion, and a very long one at that. It would not be appropriate to address it here.