Australian Future Subs Diesel Generator Requirements PART 0.5

This article is a necessary Prequel, which, in retrospect, I should have written before I wrote Australian Future Subs Diesel Generator Requirements PARTs ONE and TWO

Basically greater definition of the diesel problems are required before assessments of diesel remedies can be made.

In the beginning Australia was well served, from 1967 to 1999 by the long UK developed military-off-the-shelf (MOTS) Oberon class submarine. This included the mature, (used since 1959?) Admiralty Standard Range V16 diesel. The Oberon's diesels were apparently used long enough on submarines to detect and resolve deficiencies. Comments from readers who actually worked with Oberon diesels are welcome.

Without the benefit of long UK experience Australia embarked from the late 1970s, on studies and then development of locally built Collins class submarines. The UK Royal Navy had long experience of operating submarines in Indian and Pacific Ocean conditions while the Swedes had not. 

There begins the unhappy tale of the Garden Island-Hedemora (GI-H) diesel and most of the other components of the Collin's drive-train. 

The UK headquartered, but international Royal Institute of Naval Architects (RINA) have published  a very useful  paper titled "Technical Meeting - 3 February 2016" which is partly on the GI-H, see https://www.rina.org.uk/iqs/dbitemid.1665/rp.2/sfa.view/Section_News1.html

In 1987, Australia, hoping for a “off-the-shelf or low-risk” diesel for the Collins submarine, selected the Hedemora V18B14SUB diesel. At that time, nothing else was judged to have met Australia’s stringent, high power, diesel specifications. Unfortunately the Swedish Hedemora Diesel company declined and Australia's Hedemora diesels became Australia Only orphan technology.

"Now [Australia has] all of the 19 Hedemora V18B14SUB engines in the world [just for all 6 of Australia's Collins subs]! The V indicates the vee configuration, the 18 is the number of cylinders, the B is the larger bore (210×210 mm), the 14 is the speed (1400 rpm), and the SUB category is the monolithic engine (not bedplate mounted) for submarines." 

“Hedemora had demonstrated the V12B configured for snorting, and promised that the V18B would work as well giving 1.4 MWe. However, they had never actually built a turbocharged V18B14SUB, but had built lots of V18B engines for industrial power and marine generator sets, and had tested a V12B against submarine-type conditions. They had built a number of V12A (smaller bore) submarine engines for the Royal Swedish Navy, the latest examples being turbocharged."

"Therefore the V18B14SUB was accepted as an off-the-shelf design, which it really wasn’t. But then, nothing else seems to have met the specification either [no MAN, MTU diesels met Australia's criteria and Japan was nowhere near contemplating exporting arms].”

Looking to the Australian future submarine the paper goes on to comment:

"Safety Issues
With fuel supply at around 2000 bar (200 Pa), containment is critical. All components, including pumps, need to be safely contained. MTU have developed (or are developing) a submarine variant of their 4000 series engine (it is mentioned on their website). However, many in the submarine community remain nervous of such high pressure systems.

Performance Issues

Such an engine would require significant work on the control system and turbocharging arrangements. The control system would need load control, not just the conventional speed control. MTU are well capable of this, but one would need to be reassured that they were applying it to cope with open-ocean sea states. Likewise for the Pielstick engines, which may be favoured by a French supplier, although Pielstick is now back in the MAN stable after many years in French hands."

So several issues need to be kept in mind: 

1.  What is a military-off-the-shelf (MOTS) submarine diesel? 

2.  Is MOTS the structure of a still unmodified diesel?

3.  Must a MOTS diesel be proven by being used for years in submarines? Is prior use on a

     locomotive or surface ship beneficial?

4.  Can turbocharging or supercharging a diesel disrupt the reliability or other 
     characteristics of the diesel?

5.  How extensive can modifications to the structure or use of a MOTS diesel be before it is
     no longer MOTS? Hence becoming risky?

Reader comments made here January 5 to 10, 2018, will be added to two "Australian Future Subs Diesel Generator Requirements PART..." per week.

Pete