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Reach new heights: Naval engines and marine propulsion system
As with everything else in its effort to achieve self-reliance in military equipment, India’s first stealth warship very nearly floundered on the shoals of an American embargo on the delivery of the General Electric LM-2800+ marine gas turbines.

Fortunately the embargo was short-lived and the engines were delivered and the Shivalik joined the Indian Navy just a couple of months behind schedule. As with every other military platform the engine is the heart of its capabilities.

It is around the thrust that the engine produces that the superstructure of the weapons platform is constructed with orientation either towards speed or carrying capacity of payload or maneuverability.

Hitherto, India has bought foreign vessels (largely from Britain and the former Soviet Union -now the Russian Federation) with integral foreign engines but as the years go by more and more of its indigenously designed and constructed naval craft will be powered with Indian engines.

Kaveri engine

India has just made a breakthrough in marine gas engine propulsion by converting the core of the Kaveri gas turbine - which was produced to power the other Indian venture the Light Combat Aircraft but failed to produce the required thrust-to a marine variant.

It has been tested to a sustained output of 12 megawatt and is being prepared to be fitted on the next batch of Rajput class (ex-Soviet Kashin-II class destroyers) being constructed at Mazagon Docks Limited, Mumbai.

The Rajput class of destroyers provide escort to aircraft carriers and sanitize the seas against enemy submarines and the air environment with anti-ship, anti-aircraft, anti-missile with onboard guns and missiles including the Russian Klub and the Indian supersonic vertical-launch Brahmos used in the land attack role.

Its speed of 35 nautical miles is considered fast and makes for great maneuverability. This is achieved by the four gas turbines it carries for propulsion. That the Kaveri engine is set to replace the Russian power plant is an incremental growth that India can be very proud about.

With the arrival of the Kaveri marine gas turbine India has three different kinds of power plants to choose for its next generation warships and submarines.

The public sector Bharat Heavy Electricals Limited is the cradle for diesel engines in India.

The Naval Dockyard in Mumbai has acquired the expertise in constructing a 60 megawatt power plant for the Arihant class of indigenous submarines, and now the Gas Turbine Research Establishment in Bangalore has brought forth the gas propulsion plant that makes for short-span, high-speed naval operations.

On all three types of propulsion-diesel, gas and nuclear-carry within themselves the potential for improvement in thrust given variations in materials and technologies that emerge over the years.

Thus, the Kaveri marine gas turbine has the potential for improvement to thrust beyond 12 megawatt.

In fact, that is how the US General Electric LM-2500 gas turbine has dominated the world market since it went into series production in 1970 with a rated output of 16 megawatts and every new variant of it which came approximately every ten years grew by between 3 to 4 megawatts in each new variant.

The current variant the LM-2500 plus (LM-2500+) has a capacity of 28.6 megawatt and is installed on the British super-liner Queen Mary II to supplement the four diesel generators that make up its main power unit.

Gas turbines in their several variations could become the power plant of the future given the kind of demands they are required to fulfill.

These could range from fast, long-range travel or in combination with diesel and steam caters to commercially viable marine transportation.

Now that the Indian Gas Turbine Research Establishment has got its foot in the marine propulsion door, it can, with due application, aspire to a larger share in the huge Indian maritime domain inclusive of both commercial shipping as well as the Indian Navy’s growing requirements for fast, maneuverable warships including aircraft carriers.

Growing industry

With the availability of three different types of propulsion-diesel, gas and nuclear-the burgeoning maritime industry could be spoilt for choice.

Each new type of warship or every mid-life upgradation opens up the possibility of a change in the type of propulsion to improve speed with carrying capacity.

Thus, when India began the design and construction of the Godavari class of frigates there was keenness to go for gas turbine technology but since Bharat Heavy Electricals had already made heavy investment in improvement of infrastructure in its factories it was decided to go in for steam turbines coupled with auxiliary systems.

The Godavari class is an evolution over the Leander class of frigates obtained from Britain in the 1960s. It is a stretched version of the Leanders and because of its larger bulk required a power system that would give speed to its additional weight.

The next in line are the Delhi class of destroyers the propulsion for which is provided by what in marine lingo is called CODAG or combined diesel and gas. Two Ukrainian Zorya Production Association M36E (E for Export) gas turbine plants coupled to four Russian reversible gas turbines in two pairs driving two propellers with respective gearboxes.

The successor Kolkata class ships also share the same power-plant system and twin propellers that give it more than 30 nautical miles per hour speed.

India’s first indigenously-built aircraft carrier now under construction in Cochin will be powered by four General Electric LM2500 gas turbines generating 88 megawatts giving the carrier a cruising speed of 28 knots.

LM-2500 is licence-built in India by Hindustan Aeronautics Ltd. It needs to be noticed that the published literature mentions only LM-2500 without the plus. This means that there is scope for upgradation even as the carrier is taking shape and is being prepared for sea trials.

It is just this possibility of upgradation that raises hopes that the indigenous Kaveri marine gas turbine will over the years (as in the case of the LM-2500 every decade) improve its thrust capabilities.

The LM-2500 has evolved from a 16 megawatt thruster in 1970 to a 28.6 megawatt LM-2500+ in the new millennium.

Now that a great deal has been learned from the failure of the Kaveri GTX gas turbine to adequately power the Tejas light combat aircraft, it is reworked in collaboration with Snecma of France and if India is able to acquire the single-crystal technology for the compressor blades it could have a beneficial outcome for the marine turbine version as well.

As stated earlier India has had multi-dimensional experience in diesel engines, gas turbine technology and nuclear propulsion.

Out of these only nuclear propulsion has the potential of a complete indigenous fuel cycle, the others being dependent on imports.

If India moves at a steady pace from pressured water reactors to fast-breeders based on plutonium to fast-breeders based on thorium drawn from the monazite sands of Kerala, the future of Indian maritime capabilities is rosy indeed.