Chinese Marine Propulsion
On most commercial vessels, such as those built in China, the main propulsion engines are 2-stroke, low speed diesel engines. Auxiliary engines on the other hand are 4-stroke high to medium speed marine diesel engines with power outputs in the range of 30-3000 kW. The main engines are usually used while at sea, while the auxiliary engines can operate in all modes of ship operation during transiting, maneuvering and hotelling. Category 3 marine diesel engines range in size from about 2,500 to 70,000 kilowatts (3,000 to 100,000 horsepower). These are very large marine diesel enginesused for propulsion power on ocean-going vessels such as containerships, oil tankers, bulk carriers, and cruise ships. Category 1 and Category 2 marine diesel engines range in size from about 500 to 8,000 kilo-watts (700 to 11,000 horsepower). These engines are used to provide propulsion power on many kinds of vessels including tugboats, pushboats, supply vessels, fishing vessels, and other commercial vessels. They are also used as stand-alone generators for auxiliary electrical power on many types of vessels.
In the past ships were powered by steam or diesel engines. As the gas turbine has higher power, lighter weight, smaller size, and good starting capability, fewer accessories, high reliability and low noise, its application was rapidly extended from aircraft to marine ships. It is reported that by the end of the Cold War there were more than 40 countries using gas turbines as the powerplant for their Navy ships. There are several combinations of the ship powerplant, such as the gas-diesel combination (i.e. using gas turbine for high speed and diesel for low speed and cruising); gas turbine combination, (i.e. all power provided by the gas turbine).
From the mid 1970s through the mid-1980s, in more than 1,300 frigates above 1,000 ton class newly built or to be build by various countries, about 88% used one of these powerplant combinations using gas turbines. Operation has proved that tactical and technical performances of the ships are greatly improved by using gas turbines. For newly designed and built ships such as frigates, destroyers etc., the adoption of gas turbines as their powerplant is an important mark of powerplant modernization.
As Gabriel Collins and Michael C. Grubb note : "Within the larger group of ship subcomponent technology, marine propulsion is worthy of particular note. It is an area in which Chinese industry has struggled to develop indigenous technology, but more significantly, marine propulsion is perhaps the dual-use technology most directly transferable between commercial and military shipbuilding. Commercial diesel engines are common in naval auxiliary vessels worldwide, but whereas U.S. Navy combatants are predominantly driven by high-performance gas turbine engines or nuclear reactors, Chinese surface combatants and submarines also rely heavily on diesels derived from the commercial sector. Medium-speed (300-1,000 rpm) diesels offer high power at a reasonable size and weight, and they typically have lower initial and fuel-consumption costs than higher-powered gas turbines. Larger low-speed diesels offer high thermal efficiency and ideal fuel economy, but their mammoth size and weight make them ill suited for naval applications (with the exception of a few large auxiliary vessels).Medium-speed diesels are further attractive for many navies specifically because of their high commercial commonality; examples are the SEMT-Pielstick PA- and PC-series diesels on fifty-three Chinese-built commercial ships and seventy-two PLAN naval vessels (including forty-seven combatants)."
" ... no indigenous marine gas turbine has been fielded to date, and the few PLAN units using gas turbine propulsion have thus far relied on imported engines. The lead unit of the Type 052 Luhu class of destroyers is equipped with two General Electric LM2500 gas turbines, but U.S. sanctions imposed following the Tiananmen Square incident forced all following Luhu, Luhai, and Luyang I units to use Zorya-Mashproekt DA-80 gas turbines imported from Ukraine."
The gas turbine engine's main rivals are the diesel engine or the steam turbine. Due to the innate superiority of naval gas turbine power systems, they are more consistent with military performance requirements for main surface combat ships. Gas turbines have become the power system of choice for naval powers such as the U.S. Navy, British Navy, Japanese Maritime Self-Defense Force.
- The first advantage is the gas turbine significantly superior power density. In general, the same volume of gas turbine power is one-third to one-fifth of the diesel engine and about one-fifth to one-tenth a steam turbine. This is because the gas turbine itself is a continuous rotating compact structure. The small size, and high power is very suitable for small ships where the speed requirement is high.
- A second advantage of gas turbine startup speed. Although the gas turbine's rotational speed is the highest of three power systems, because the rotor is very light it takes only 1-2 minutes to achieve maximum speed. The diesel engine piston reciprocating motion accelerate slower. The steam turbine is unresponsive and the highest power output of the system may take up to an hour. The start speed acceleration and deceleration performance has a direct impact on warships deployed during war and anti-submarine warfare.
- The third advantage of the gas turbine is that the low-frequency noise component is very low. As the gas turbine itself is turning at high-speed, it produces more high-frequency whistling noise. The reciprocating piston engine produced a large amount of low-frequency mechanical vibration and noise, resulting in easy detection by enemy warship sonar. So diesel power is particularly inappropriate for anti-submarine warship power systems.
China started research and development of Gas Turbine late. In 1958, China started to develop a plan for organizing gas turbine implementation, decided to set up the two joint design teams, initially to study the feasibility of large, medium and small unit demonstration and program design. The end of 1959, the Soviet Union transfered Gas Turbine technology so that China had the technology to the training unit for the purpose of copying the work. In just 11 months, the Shanghai Turbine Works completed the first of this type of gas turbine prototype manufacturing. However, for various reasons, after three years of imitation, the prototype manifested a large number of failures in acceptance tests. Later this type of gas turbine was used in a high-speed gunboat in tests. In 1964 the design of the 6,000 horsepower fired unit was completed. For the first time a ship with aa gas turbine was designed and developed in China, but due to the long development cycle, it was not deployed. The rest of the world mainly depended on different gas turbine aircraft engines, but China lagged behind in aviation engines. China has made continuous attempts in Marine Gas Turbines, but has failed to come up with a mature and reliable gas turbine.
China commenced study and development of modifying the aeroengine into marine powerplant from the beginning of the 1970s. ZEF worked in conjunction with the Harbin Marine Boiler and Turbine Engine Research Institute to develop the powerplant for hovercraft by modifying the WJ6 engine. It passed the ground test and by the mid-1980s came to the stage of being tested on hovercraft. XEF also converted the WS9 engine into a 11,000 kW (15,000 hp) marine powerplant.
The aviation industry in recent years has undertaken the development of four gas turbines: the QD128, QC185, QC70, R010. The R010 is a heavy duty gas turbine, the QD128 and QC185 are mid-range power gas turbines, and QC70 is a low-power gas turbine. The engine numbers reflect the power rating of the engine, hence the QC185 would have a nominal power rating of 18.5 MW. Because of the volume and large weight, the R010 only suitable for land-based power generation. The domestic QC185 gas turbine was first exhibited at the Zhuhai Airshow in 2004. The engine was based on improvements from core machine of the WS10 "Taihang" turbofan engine, but its output can not meet the needs of China's large surface ships. The QC185 Gas Turbine, based on the Type A WS-10A aeroengine, has an output of 17,800kw (24,180hp), a thermal efficiency of 36%, and weighs 5,800kg. The QC185 can be used in power plants, mechanical drives in oil and chemical industry, and warships. The output power level, variously reported as less than 17 MW or as much as 18,500 kilowatts, did not match China's need for the development of larger surface ships.
The QC280 / QD280 [GT25000] Gas Turbine stood the test of the Gulf of Aden to escort operations, showing a reliable performance installed in the 052B-type destroyer of 6,000 tons. The Chinese imitation of Ukraine's GT25000 Gas Turbine is rated at a power of 28-29 MW, but the actual output power is about 23 MW, and four GT25000 Gas Turbines have an actual total power of about 90 MW. The Chinese Navy fleet the Gulf of Aden implemented a long escort mission, each batch of vessels had continuous overseas performance for months, and never had engine problems. This showed that domestic GT25000 gas turbine's reliability and economy were adapted to China's needs. The power system based on the GT25000 could continue to improve its technology and performance deficiencies.
According to the "China Aviation News" reports, the QC185 medium power gas turbines achieved first ignition on 29 August 2010, and idle state to achieve stable operation. The QC70 low-power gas turbine completed the first phase of reliability testing, which lasted 13 months, on 22 August 2010. From both the volume and power perspective, both can be used for naval power, QC185 can be used for large destroyers, QC70 can be used in hovercraft. This showed that China had developed and manufactured equipment Gas Turbine, a key step forward in the road.
China's gas turbine technology has been unable to break through bottlenecks because the gas turbine industry itself faces institutional problem. The most important reason was the lack of a long-term engine development plan for China's aviation industry. Due to a late start, lack of experience and industrial base, China has failed to come up with the core of a large-scale practical machine model.
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