“…Four types of nozzles were investigated for their discharge characteristics and size effect in Reynolds numbers ranging from 3 × 10 2 to 8 × 10 3 . From the results [7,8], the pyramidal silicon nozzles possess good properties including thermal response, maximum sustainable pressure, and long-term stability. However, the pyramidal sonic nozzles have a divergent angle of 35.3°, much larger than the ISO-suggested 4°-6°.…”