Should I consult my professor before sending my newly written research paper to a journal?
Unless the professor should be a co-author or you need their permission to include their name in acknowledgements, there is no need to have it reviewed. If the work is yours, you can decide to submit it. 

But if you have any doubts about it or any part of it, having a review by a professor can be worth it. You may get advice that results in a revision or you may get advice that is worthless. But again, you are in control. 

Don't worry about people stealing your ideas. While it happens, it is rare and not something that reputable people do. If you have doubts about the ethics of someone, don't send it to them, but that is obvious. 

If you send it, you will get feedback from independent referees. It is to your advantage to start out with the best product you can create, but the review process itself can lead to some improvement. 

If you don't have a particular journal in mind then a professor might be able to give advice on that, just from reading an abstract. Lots of possibilities. 

But the work is yours. You choose.