Shalom ,Thank you for your insights regarding saying the name of Hashem in Zemirot. Regarding Mizmor L’David ,psalm 23 singing the melody by Ben Tzion Shenker ,most people seem to articulate "Hashem". I personally prefer to articulate A-do-nai. The last sentence however is repeated [including a repetition of G-d’s name ], therefore I sing A-do-nai the first time and Hashem for the repetition. Would you kindly tell me if this is acceptable or recommend an alternate method.

I generally do the same thing. If the entire verse is repeated it is OK to say A-do-nai again, but I think its preferable not to. All the best.