Method for making cylindrical structures with cooling channels

A method for making double-wall structures having integral internal channels, comprising:

• assembling a double-wall assembly comprising an inner wall, channel forming means, sacrificial channel filling means and an outer wall, wherein the inner wall and the outer wall are complementary to one another and separated by the channel forming means that is placed between and in touching contact with them to define at least one channel, and wherein the sacrificial channel filling means is complementary to the channel forming means and placed into the channel forming means to fill the at least one channel, such that the double-wall assembly comprises a substantially solid structure;
• wherein the assembling the at least one channel further comprises forming at least one stepwise offset for promoting turbulent fluid flow through the at least one channel;
• hot pressing the double-wall assembly at a temperature and for a time sufficient to cause the inner wall, outer wall and channel forming means to become metallurgically bonded to one another;
• and
• removing the sacrificial channel filling means.