The Rolls-Royce WR-21 is a

gas turbine A gas turbine or gas turbine engine is a type of Internal combustion engine#Continuous combustion, continuous flow internal combustion engine. The main parts common to all gas turbine engines form the power-producing part (known as the gas gene ...

marine engine An inboard motor is a marine propulsion system for boats. As opposed to an outboard motor, where an engine is mounted outside the hull of the craft, an inboard motor is an engine enclosed within the hull of the boat, usually connected to a prop ...

, designed with a view to powering the latest naval

surface combatant Surface combatants (or surface ships or surface vessels) are a subset of naval warships which are designed for naval warfare, warfare on the surface of the water, with their own weapons and armed forces. They are generally ships built to fight oth ...

s of the partner nations.

History

Developed with government funding input from the United Kingdom, France and the United States, the WR-21 was designed and manufactured by an international consortium led by

Northrop Grumman Northrop Grumman Corporation is an American multinational Aerospace manufacturer, aerospace and Arms industry, defense company. With 97,000 employees and an annual revenue in excess of $40 billion, it is one of the world's largest Arms industry ...

as prime contractor. The turbine itself was designed primarily by

Rolls-Royce Rolls-Royce (always hyphenated) may refer to: * Rolls-Royce Limited, a British manufacturer of cars and later aero engines, founded in 1906, now defunct Automobiles * Rolls-Royce Motor Cars, the current car manufacturing company incorporated in ...

with significant marine engineering and test facility input from DCN, with Northrop Grumman responsible for the

intercooler An intercooler is a heat exchanger used to cool a gas after compression. Often found in turbocharged engines, intercoolers are also used in air compressors, air conditioners, refrigeration and gas turbines. Internal combustion engines Mo ...

, the

recuperator A recuperator (electro- end carbogidro-) - is a special purpose countercurrent exchange, counter-flow energy recovery heat exchanger positioned within the supply and exhaust air streams of an air handling system, or in the exhaust gases of an in ...

and

system integration System integration is defined in engineering as the process of bringing together the component sub-systems into one system (an aggregation of subsystems cooperating so that the system is able to deliver the overarching functionality) and ensuring ...

. WR-21 development draws heavily on the technology of the successful

Rolls-Royce RB211 The Rolls-Royce RB211 is a British family of high-bypass turbofan engines made by Rolls-Royce Holdings, Rolls-Royce. The engines are capable of generating of thrust. The RB211 engine was the first production turbofan#Three-spool, three-spool e ...

and Trent families of gas turbines. The original design and development of the WR-21 was carried out by

Westinghouse Electric Corporation The Westinghouse Electric Corporation was an American manufacturing company founded in 1886 by George Westinghouse and headquartered in Pittsburgh, Pennsylvania. It was originally named "Westinghouse Electric & Manufacturing Company" and was ...

(later Northrop Grumman Marine Systems) under a

US Navy The United States Navy (USN) is the naval warfare, maritime military branch, service branch of the United States Department of Defense. It is the world's most powerful navy with the largest Displacement (ship), displacement, at 4.5 millio ...

contract placed in December 1991. Later the

Royal Navy The Royal Navy (RN) is the naval warfare force of the United Kingdom. It is a component of His Majesty's Naval Service, and its officers hold their commissions from the King of the United Kingdom, King. Although warships were used by Kingdom ...

and the

French Navy The French Navy (, , ), informally (, ), is the Navy, maritime arm of the French Armed Forces and one of the four military service branches of History of France, France. It is among the largest and most powerful List of navies, naval forces i ...

became interested in the WR-21, leading to Rolls-Royce and DCN involvement. The WR-21 is the propulsion system of Royal Navy

Type 45 destroyers The Type 45 destroyer, also known as the D or ''Daring'' class, is a class of six guided-missile destroyers built for the United Kingdom's Royal Navy in the early 21st century. The class is primarily designed for anti-aircraft and anti-missile ...

Design

The WR-21 is the first aeroderivative

to incorporate

gas compressor A compressor is a mechanical device that increases the pressure of a gas by reducing its volume. An air compressor is a specific type of gas compressor. Many compressors can be staged, that is, the gas is compressed several times in steps or ...

and

exhaust heat recovery system An exhaust heat recovery system turns waste heat energy in exhaust gases into electric energy for batteries or mechanical energy reintroduced on the crankshaft. The technology is of increasing interest as car and heavy-duty vehicle manufacturers ...

technologies that deliver low specific fuel consumption across the engine's operating range. It offers a reduction in fuel burn of 30% across the typical ship operating profile. *The

cools air entering the high-pressure compressor, reducing the amount of energy required to compress the air. *The

preheats the combustion air by recovering

waste heat Waste heat is heat that is produced by a machine, or other process that uses energy, as a byproduct of doing work. All such processes give off some waste heat as a fundamental result of the laws of thermodynamics. Waste heat has lower utility ...

from the exhaust, improving cycle efficiency and reducing fuel consumption.

Specifications

* Rated power: 25.2 MW * Specific fuel consumption: approximately * Main module wet weight: * Twin-spool gas generator and free-rotating power turbine ** Low-pressure (LP) spool with six-stage

compressor A compressor is a mechanical device that increases the pressure of a gas by reducing its volume. An air compressor is a specific type of gas compressor. Many compressors can be staged, that is, the gas is compressed several times in steps o ...

and single-stage

turbine A turbine ( or ) (from the Greek , ''tyrbē'', or Latin ''turbo'', meaning vortex) is a rotary mechanical device that extracts energy from a fluid flow and converts it into useful work. The work produced can be used for generating electrical ...

at 6,200 rpm ** High-pressure (HP) spool with six-stage compressor and single-stage turbine at 8,100 rpm ** Five-stage free power turbine 3,600 rpm (60 Hz) *

Intercooler An intercooler is a heat exchanger used to cool a gas after compression. Often found in turbocharged engines, intercoolers are also used in air compressors, air conditioners, refrigeration and gas turbines. Internal combustion engines Mo ...

between LP and HP compressors * Nine radial combustors * Exhaust heat recuperator to combustor inlet air

Operational issues

In 2009 it was discovered that the

intercooler as fitted in the WR-21, on Type 45 destroyers, had a major design flaw, failing to operate in water temperatures beyond 30C. The intercooler of the first Type 45 destroyer, , failed in the mid-Atlantic in 2010 and had to be repaired in Canada, with further repairs for intercooler failure in 2012 in Bahrain. The Type 45's pioneering integrated electric propulsion (IEP) system uses two WR-21s and two Wartsila 2-MW diesel generators to power everything on board, including weapons systems in addition to propulsion and other functions, leaving the ships vulnerable to "total electric failure". The

Ministry of Defence A ministry of defence or defense (see American and British English spelling differences#-ce.2C -se, spelling differences), also known as a department of defence or defense, is the part of a government responsible for matters of defence and Mi ...

said: "The Type 45 was designed for world-wide operations, from sub-Arctic to extreme tropical environments, and continues to operate effectively in the Gulf and the South Atlantic all year round." The WR-21 engines will have to be supplemented by one or two additional diesel generators, fitted by cutting open the hull in

dry dock A dry dock (sometimes drydock or dry-dock) is a narrow basin or vessel that can be flooded to allow a load to be floated in, then drained to allow that load to come to rest on a dry platform. Dry docks are used for the construction, maintenance, ...

. Former First Sea Lord Admiral Philip Jones clarified that "WR-21 gas turbines were designed in extreme hot weather conditions to what we call “gracefully degrade” in their performance, until you get to the point where it goes beyond the temperature at which they would operate... we found that the resilience of the diesel generators and the WR-21 in the ship at the moment was not degrading gracefully; it was degrading catastrophically, so that is what we have had to address." The Admiral still argued that despite the problems, the Royal Navy has been able to deploy Type 45 destroyers in nine-month cycles to the Gulf region where temperatures are high with little fault. The Royal Navy has also been able to maintain at least two Type 45s at operational readiness.

References

External links

Rolls-Royce WR-21 Marine gas turbine page
(archived 2013-11-08) * {{DEFAULTSORT:WR-21 Aero-derivative engines Marine gas turbines