Yes, why not?
I'm a little disappointed that I haven't gotten hardly any feedback on my work so far.
Nothing appears to be wrong here. You have been in the job for four months only, which isn't a long time. There's nothing wrong in not getting any feedback so far from the management.
Generally speaking, getting no feedback is better than getting a negative feedback. Most likely, things are going perfectly fine so far and you are performing as expected/or even better.
I believe there's always room to improve, and I'm sure there are things I am doing wrong.
If you think about it, there's always room for improvement and better way to do your work.
I'm open to hearing negative feedback so that I can work on those things and improve myself.
Good of you to have a welcoming attitude to constructive criticism.
How do I know what I am doing wrong if nobody is telling me?
You are most likely not. If you are working in a project managed by one of your managers, and there isn't any negative feedback, you are delivering as expected. If you concerned about technicalities, such as coding conventions, architecture, best practises, you can seek input from your colleagues in your team, other Stack Exchange resources such as Code Review and Software Engineering, by reading relevant books on Software Engineering and basically by learning from your mistakes over time. Learning and improving is a lifelong endeavour, especially in domains such as Software Development.
It also seems like they don't like it when I ask questions (and give me short responses), so I try to keep questions to a minimum.
That doesn't reflect anything against you. Maybe they don't like talking much. Maybe they are occupied with their tasks. Maybe you have not gotten enough opportunities to socialize with them so far. Also, don't forget, you have been with the company only for four months, which isn't a long period of time.
But I am wondering if it would be appropriate to ask for an evaluation?
Nothing wrong in asking about it. If you feel the managers may not be available for face to face meeting, you can simply put it in an email. Better to ask in an email if you feel they respond curtly due to time constraint/shyness.
It's been four months since I have been working on project ABC. While the work has been going fine so far, I can really use your feedback on it.
Can you share any comments/feedback that you may have in general, and let me know if there are any areas where there's scope for improvement? I am pretty open to receive constructive criticism and can use it to improve the quality of my output. It would be really helpful for me.
I get this feeling that they don't want to take time to sit down with me and do that.
They are not always obliged to review and share feedback for each and every piece of your work. Remember they too have their own work and responsibilities and are busy with that.
However, I feel like it is their responsibility as managers to tell me.
Their responsibility as managers is to make sure that you deliver as expected, and nothing less. They are answerable for that to their upper management. You generally hear from your managers if things are not working as expected and they will then try to identify cause(s) and resolve it.
Maybe you are thinking too much and are worrying about the quality of your output. Simply focus on your work, keep an eye out to learn from your experiences and you'll do absolutely fine.