April 11, 2018

A Kilo Submarine's Impeller Tunnels (Internal Thrusters) Diagram Revealed *

Diagram 1. (Courtesy sourmasov(dot)eu) indicates the openings of the the starboard impeller tunnel in a Kilo 877's or 636's light hull.

Diagram 2. A Kilo 877 or 636 turned vertically to display its main and "economical" motors and propeller. Of greater interest is the two impeller tunnels (labelled "Auxiliary Propeller) port and starboard. This may be the first appearance of this diagram on the English Internet *. (Foreign source). * but every piece of information or diagrams that seem especially "new" need more evidence to verify their accuracy...

From two Anonymous sources, early April 2018, propulsion information for Kilo submarines have been put together. Kilos are equipped with a main propulsion propeller served by one main propulsion motor of around 5.5 MW up to 500 rpm. 

At high speeds, the main propulsion motor is connected to the shaft. The shaft speed (propeller speed) is reduced by the main propulsion motor’s reduction gear (eg. max speed of 500 rpm is significantly higher than propeller speed, eg. max speed 250 rpm). 

At very low speeds (perhaps less than 3 knots) <3 knots="" nbsp="" span="">the main propulsion motor is not connected to the shaft and the main propeller is driven only by a small ("Economical Prop Motor in Diagram 2.) propulsion motor to achieve "economical" (less battery use) and silent operation.

Kilos (both the 877s and 636s) also use two small pump impellers (can also be called internal thrusters but for submarine) in two tunnels (see the two diagrams below especially Diagram 2.). These can be for:

i)             for very low speed manoeuvring,
ii)           or staying still in a current (eg. while releasing or retrieving special forces divers).

The pump impellers are set inside tunnels in the Kilo submarines light, external, hull. Kilo submarines have a double hull structure consisting of the external light hull and the inner pressure hull. * but this impeller information and Diagrams that seem especially "new" needs more evidence to verify accuracy...

It is not known how common pump impellers are in Western and Northeast Asian (Japanese, South Korean and Chinesesubmarines. Perhaps the impellers are advanced features of the Kilos?

As reduction gear vibrates at high speed, the Improved Kilo 636.3 (built only for the Russian Navy) seems to have a louder acoustic fingerprint than more modern submarines (designed by TKMS, Naval Group, KHI-MHI or Saab) driven by PSMS or DC motor without reduction gear. 

The Kilo appears to be too old in many respects. A new Russian conventional submarine design with modern technologies such as PSMS, AIP, LIBs and higher power diesels is needed. However with most of Russia’s submarine design budget going to Russia’s nuclear propelled submarines there is insufficient money to bring Russian conventional submarines up to Western or Northeast Asian  standards.

Anonymouses and Pete


Anonymous said...

An IUSSS article said on the 636.3 the reduction gear ratio is greater than 2, likely 2.5 to 3. At 4kts, the propeller will be running at 45rpm only so there is essentially zero cavitation noise.

Ztev Konrad said...

Regarding the rear hull design, even western style single hull designs have the pressure bulkhead well before the tail cone and fin structures, so the rear outer casing is effectively a second outer hull. Quite possible to have tunnels for auxiliary propulsors inside this rear casing.
This story describes in detail how composites have replaced the rear hydrodynamic fairing structure on Virginia class submarines. The bow dome is composite as well.

Peter Coates said...

Thanks very much Ztev

The impeller, with reference to the Virginia SSN, likely relates to one part of the Virginia's pump jet

So scrolling 3/4s down of the reference https://www.compositesworld.com/articles/composite-solutions-cutting-cost-of-nuclear-powered-subs you provided, states:

"Low-cost composite impeller

The third component is a composite centrifugal pump impeller (a vaned, rotating disk which forces fluid in one direction under presssure). It replaces a tight-tolerance part cut from a large forged ingot of titanium by 5-axis machining. The high material cost was escalating and volatile; the machining process was very expensive, complex and generated a lot of waste. The ManTech objective was a low-cost composite alternative with no reduction in performance. Osborn explains, “When we moved to composite, we were able to net-shape fabricate, using a mold without additional machining.” Impeller parts wee resin transfer molded using carbon- and glass-fiber reinforcements with vinyl ester resin, which were then assembled and overwrapped with filament-wound fiberglass. The program reduced part cost by roughly $550,000 per submarine and shortened its build schedule from nine to three months. It has also led to a more complex impeller development program, slated for implementation on the [Virginia-class submarine (VCS)] as well."



Anonymous said...

Hi Pete

Length of the 877 submarine (4 propulsion motors, two diesels) was compared with that of the 212A submarine (one PMSM, one diesel, FC=fuel cell) : i) total length 73.8m (212A, 56.0m), ii) hull length 56.1m (40.0m), iii) propulsion motor section length15.3m (6.8m), iv) diesel section lenght 9.5m (10.0m), and v) FC section lenght 0m (2.8m). Prolusion motor section of the 877 is much longer than that of the 212A.

As length of ecomic motor + main motor (4.1MW) of the 877 is ca.7m and length of PMSM (2MW) of the 212A is 1.7m, miniaturization and simplification of propulsion motor system is needed in Russian convensional submarine.

This video (https://www.youtube.com/watch?v=-gqZF5mtzgc) shows the inside of Iranian submarine TAREGH (Kilo-class). We can understand toughness of maintaince and monitoring of LABs. In accident of Argentine submarine, the LAB section was flooded resulting hydrogen explosion.

2:31-2:48/5:25 : A crew measures the specific density of sulfuric acid in LABs. This density reduces with discharge.
2:31 : A crew is cheking LABs on the keel, because heights of right and left hand sides of LABs are same.
2:40 : Other LABs are left hand side. They are also checked.


Peter Coates said...

Thanks Anonymous [at 13/4/18 11:01 AM]

Much of your data inspired me to draw up a Table, find Diagrams and display the Youtube that you identified.

see new article at http://gentleseas.blogspot.com.au/2018/04/comparing-kilo-877s-with-tkms-type-212a.html