Navy ship recuperator heat exchanger failure

Heat exchanger to preheat incoming air using stack gases on oil-fired surface ships, intended to raise cruise efficiency from ~10% to 30%, eliminating off-station refueling time. First built version lasted two minutes before tearing itself apart from transient thermal stresses. Eagar served on a Blue Ribbon panel investigating it.

This was ten years after that, and there have been some improvements in quality control in the mills, in understanding of the heat treatment and the water treatment, and in calculation of stresses. In some of the videos you're going to hear about the Navy's internally cooled recuperator on the surface ships, and how originally it was supposed to — this is just a big heat exchanger, take the stack gases from the oil-fired ships and preheat the incoming air so you get more efficiency. When you're just cruising along, a nice lazy stroll through the Pacific, you're operating at about ten percent efficiency because most of your heat's just going up the stack. You're not at full battle speed.

Billion-dollar Rolls-Royce / aerospace-company program for a fuel-economy heat exchanger on surface ships. Designed in Southern California, tested in England. Supposed to last 100,000 hours; lasted ~100 seconds. Failure cause: one-dimensional thermal model instead of full 3D, no transient startup analysis. Twisted like a pretzel within two minutes. Tom served on the failure review board.

The Navy has similar problems. I worked on a recuperator for surface ships. The carrier actually has the fuel for all the frigates and destroyers and cruisers. When you're being deployed, because you're concerned about the threat of a nuclear blast up in the atmosphere, you actually deploy for a hundred miles or more. So your small ships are out there 100 miles away from the carrier, and they have to come back to the carrier to refuel. The small ships burn diesel fuel, and they've got to come back. It turns out they can spend thirty percent of the time just going off station, okay.

$100 million Navy program (early 1990s), Rolls-Royce-built room-sized brazed stainless steel heat exchanger for preheating destroyer/frigate combustion air. Designed for 100,000 hours; failed in two minutes. Cause: 2D finite element model assumed symmetric gas flow; asymmetric heating snapped six-inch hardened-steel tie bars. Tom served on the post-mortem team. Teaching point: "wishful thinking is not good engineering."