The most powerful Han emperor, known for his administrative centralization and imperial expansion, was

Emperor Wu, also known as Wudi or Liu Che.

Explanation:

Emperor Wu (141-87 BCE) expanded the influence and the power of the Chinese empire under the Han dynasty as no previous ruler had. He adopted Confucianism as the official state ideology, a decision that had profound and lasting consequences for the culture and history of China, because Confucianism continues to influence and mold Chinese mentality and social life until today, the year 2020. He also incorporated southern China and Vietnam into his lands, and reconquered Korea. He strengthened the empires's security by attacking and punishing the nomads Xiongnu, a permanent threat to his kingdom.