In order to ensure constant pressure and constant flow rate of compressed air what should we put between the compressor and end user?

The answer is in your school book. Pressure regulator is the answer.

Just my two cents. You are young, and more interested in finding the answer on the internet than taking the time to do things correctly by learning through your schooling and books. Do know that by "cheating" in this way, you will never have the feeling of self worth that it takes to make it in the real world.

Learn from your instructors, learn through your studies, and when you enter the real life workforce, learn from your mistakes.

Don't cheat, don't take the easy route. Hard work combined with good ethics and integrity will take you further than you could ever imagine.

I agree with you completely mygirlsdad77. Thank you for all your help on the boards. It gets harder every day for me to answer just one or two questions anymore since I get tired real easy.