With an increasing instability and cost fluctuation in the world energy markets, it has become more important to increase the US Navy fleet’s overall fuel efficiency. The Navy’s Energy Program for Security and Independence sets forth goals to reduce its overall consumption of energy and decrease its reliance on petroleum. One way that helps accomplish these goals is through the use of hybrid electric drive systems to replace gas turbine engines to accomplish lower ship speeds. Although gas turbines are power dense and fairly efficient at full load, their fuel efficiency decreases drastically at the lower power levels used when slower speeds are required to accomplish the ship’s mission. It is in this lower speed range where operating gas turbine generators closer to their optimum efficiency levels and powering an electric motor saves a significant amount of fuel. This paper will discuss two in-service systems developed for various US Navy ships: the Hybrid Electric Drive (HED) system for DDG 103 and the Auxiliary Propulsion System (APS) for LHD 8 and LHA 7. It will describe each of the two configurations and their histories, how they are implemented and increase the capability of the ship, and the resulting fuel efficiencies that have been realized with their use.

U.S. Navy marine gas turbine engines serve as primarye and auxiliary power sources for several current classes of ships. Early observations noted in the 1960s and 1970s revealed severe corrosion attack on the first stage blade and vane components of a shipboard marine gas turbine engine that caused engine failure after only several hundred hours. In gas turbine development, there is always a drive and need to enhance the performance and life of engines. The virtues of using Ni-base superalloys in hot-section components has been well recognized and practiced as a means of substantial increase in turbine-inlet temperature, resulting in improvements in thermal efficiency, durability, and performance of engines. The USN shipboard environment (the marine environment) is high in salt laden air and water, coupled with air and fuel sulfur species that cause aggressive corrosion in gas turbine hot sections. Materials that can function in this environment are considered to be “Marinized”. Higher engine power density and pressure ratios for new engine designs will increase maximum blade, vane, and rotor metal temperatures from a mainly Low Temperature Hot Corrosion (LTHC) regime into both the High Temperature Hot Corrosion (HTHC) and Oxidation Corrosion regions. It is expected that future increased surface combatant loads and operational changes will require increased gas turbine operating temperatures and change the associated operating environment to one where Type I and Type II hot corrosion AND oxidation will be prevalent in newly anticipated operational profiles. The advanced gas turbine upgrade package will include better corrosion and oxidation resistant capability and/or higher temperature capable materials and their associated component overhaul methodologies. New materials need to be created and developed for use in more aggressive environments and higher temperature operations. The main cause of the shorter time between overhauls is the materials deterioration of the engine components associated with the hot section of the engine, e.g. turbine airfoils. The deterioration mechanisms are hot corrosion, with Type 1 hot corrosion mechanism becoming operative at the higher temperatures. The goal of this paper is to evaluate methods to enable running the engine at high power while getting back to the longer mean time between overhauls. The method to achieve the longer time is to evaluate and propose for implementation materials, which can withstand the higher temperatures and at the same time mitigate the operative corrosion mechanisms associated with marine environments.

The United States Navy (USN) 501-K Series Radiological Controls (RADCON) Program was launched in late 2011, in response to the extensive damage caused by participation in Operation Tomodachi. The purpose of this operation was to provide humanitarian relief aid to Japan following a 9.0 magnitude earthquake that struck 231 miles northeast of Tokyo, on the afternoon of March 11, 2011. The earthquake caused a tsunami with 30 foot waves that damaged several nuclear reactors in the area. It was the fourth largest earthquake on record (since 1900) and the largest to hit Japan. On March 12, 2011, the United States Government launched Operation Tomodachi. In all, a total of 24,000 troops, 189 aircraft, 24 naval ships, supported this relief effort, at a cost in excess of $90.0 million. The U.S. Navy provided material support, personnel movement, search and rescue missions and damage surveys. During the operation, 11 gas turbine powered U.S. warships operated within the radioactive plume. As a result, numerous gas turbine engines ingested radiological contaminants and needed to be decontaminated, cleaned, repaired and returned to the Fleet. During the past eight years, the USN has been very proactive and vigilant with their RADCON efforts, and as of the end of calendar year 2019, have successfully completed the 501-K Series portion of the RADCON program. This paper will update an earlier ASME paper that was written on this subject (GT2015-42057) and will summarize the U.S. Navy’s 501-K Series RADCON effort. Included in this discussion will be a summary of the background of Operation Tomodachi, including a discussion of the affected hulls and related gas turbine equipment. In addition, a discussion of the radiological contamination caused by the disaster will be covered and the resultant effect to and the response by the Marine Gas Turbine Program. Furthermore, the authors will discuss what the USN did to remediate the RADCON situation, what means were employed to select a vendor and to set up a RADCON cleaning facility in the United States. And finally, the authors will discuss the dispensation of the 501-K Series RADCON assets that were not returned to service, which include the 501-K17 gas turbine engine, as well as the 250-KS4 gas turbine engine starter. The paper will conclude with a discussion of the results and lessons learned of the program and discuss how the USN was able to process all of their 501-K34 RADCON affected gas turbine engines and return them back to the Fleet in a timely manner.

The combined gas turbine and gas turbine power propulsion device (COGAG power propulsion device) is an advanced combined power system, which uses multiple gas turbines as the main engine to drive propellers to propel the ship. COGAG power propulsion device has high power density, excellent stability and maneuverability, it receives more and more attention in the field of ship power at home and abroad. This article takes the COGAG power propulsion device as the research object, uses simulation methods to study its steady-state operating characteristics, and conducts a ship-engine-propeller optimization matching analysis based on economy and maneuverability. The research work carried out in this article is as follows. Firstly, according to the structural relationship between the various components and the system thermal cycle mode of the COGAG power propulsion device, establish the controller, main engine, gear box, clutch, shafting, propeller, ship and other components and simulation models of the system with the modular modeling idea. Secondly, divide the gears according to ship speed. For the four working modes of single-gas turbine with load, dual-gas turbine with load, three-gas turbine with load, and four-gas turbine with load, analysis the ship-engine-propeller optimization matching of the COGAG power propulsion device based on economy and maneuverability, and calculate the best shaft speed and propeller pitch ratio in each gear, so as to obtain the steady-state operation characteristics of the COGAG power propulsion device based on the ship-engine-propeller matching, which provides a basis for determining the target parameters of the dynamic process.

Gas turbines are typically selected for propulsion or power generation on marine vessels because of their excellent power-to-weight ratio, fuel flexibility, long maintenance intervals, and reliability. These machines are operating in challenging conditions that are linked to salty and humid air, constant vessel movement, or lack of rigid foundation. This paper presents a novel gas turbine installation on the top deck of a shuttle tanker ship and its innovative integration into the vessel’s power generation system, and discusses the technical solutions that were developed to comply with the latest safety and environmental regulations.

sCO 2 power cycles offer improved cycle efficiencies compared with traditional steam Rankine cycles. However, the turbomachinery required to support such a cycle does not exist at a commercial scale and requires development. This paper describes a new 10 MWe scale sCO 2 turbine was developed and demonstrated in an sCO 2 closed-loop recompression Brayton cycle. Since this turbine was developed for Concentrating Solar Power (CSP) applications, a target inlet temperature of over 700°C was chosen using funding from the US DOE SunShot initiative and industry partners. However, it can be applied to traditional heat sources such as natural gas, coal, and nuclear power. Traditional Rankine steam cycle thermal efficiencies are typically in the 35–40% range, but can be as high as 45% for advanced ultra-supercritical steam cycles. The sCO 2 cycle can approach 50% thermal efficiency using externally fired heat sources. Furthermore, this cycle is also well suited for bottoming cycle waste heat recovery applications, which typically operate at lower temperatures. The high-power density and lower thermal mass of the sCO 2 cycle results in compact, high-efficiency power blocks that can respond quickly to transient environmental changes and transient operation, a particular advantage for solar, waste heat, and ship-board applications. The power density of the turbine is significantly greater than traditional steam turbines and is comparable to liquid rocket engine turbo pumps. This paper describes the design and construction of the turbine and provides additional testing of the 10 MWe turbine in a 1 MWe test facility including a description of rotordynamics, thermal management, rotor aero and mechanical design, shaft-end and casing seals, bearings, and couplings. Test data for the turbine is included, as it achieves its operational goal of 715°C, 250 bara, and 27,000 rpm.

This paper proposes a novel cogeneration system based on Kalina cycle and absorption refrigeration system to meet the design requirements of China State Shipbuilding Corporation, which is efficiently satisfy the power and cooling demands of a maritime ship at the same time. Unlike most of the combined systems, this cogeneration system is highly coupled and realizes cogeneration without increasing the system complexity too much. The basic ammonia mass fraction of this novel system is increased, so that the ammonia concentration of ammonia-water steam from the separator can be higher, which contributes to lower refrigerating temperature and thus less heat loss in the distillation process. In addition, higher ammonia concentration solution makes overheating easier, which improves the thermal efficiency. Moreover, the system has two recuperators to make further improvement of the thermal efficiency. Thermodynamic models are developed to investigate the system performance and parametric analysis is conducted to figure out the effects of including working fluid temperature at the outlet of the evaporator, working fluid temperature at superheater outlet, mass fraction of ammonia in basic solution, turbine inlet pressure, temperature of cooling water at the inlet of condensers and the refrigeration evaporation temperature on the system performance. Furthermore, the cogeneration system is optimized with genetic algorithm to obtain the best performance, which achieves 333.00kW of net power output, 28.83 kW of cooling capacity and 21.81% of thermal efficiency. Finally, the performance of the proposed system is compared with an optimized recuperative organic Rankine cycle (ORC) system and an optimized Kalina cycle system 34 (KCS34) using the same heat source. The results show that the thermal efficiency and power output of the novel cogeneration system is 3.89% and 1.05% higher than that of the recuperative ORC system and KCS34 system respectively.

Navies worldwide are increasingly considering and adopting propulsion plants with electric propulsion for cruise and ship silent operation, and gas turbines for boost propulsion for high speed. These propulsion plants, often referred to as hybrid propulsion, utilize water jets, controllable pitch propellers, or fixed pitch propellers, and have design and overall configuration to fit into naval ships with various size hulls such as would be the case with corvettes, frigates, destroyers, cruisers, etc. Therefore, size, weight, and space of the propulsion plant is important, but equally important is limiting associated machinery which must be used with a particular hybrid propulsion plant design selected. In addition, propulsion design engineers, in conjunction with naval architects, shipyards and navies, must consider fuel efficiencies, machinery efficiencies, weight of all the associated machinery, placement in the hull, first time cost, and life cycle maintenance with associated cost when selecting the configuration of the propulsion system’s associated machinery. Manning levels are dictated by these parameters and in the end, it must be realized that the purpose of the ship mission can be compromised if reliability is not high and premature failures occur. This paper is a more in depth analysis of hybrid propulsion systems for naval ships of various sizes, and analysis of the associate machinery emphasizing ship weight and space savings, fuel savings, cost savings, mean time between failures and mean time to repair which results in lower manning requirements and increased mission readiness. By the time this paper is published, more than 250 SSS Clutches will be installed in US Navy Arleigh Burke Destroyers, 32 are operating in low speed propeller shafts of British Navy Type 23 ships, 2 in the Japanese Navy’s Asuka Class and 16 in low speed propeller shafts of Royal Korean Navy FFX Batch II frigates. At the time of abstract submission, all three programs referenced above have cumulatively had zero defects attributable to SSS Clutch material, function, design, or quality. While the US Navy are given occasional reminders of why alternative clutch designs remain ineffective, unreliable and remarkedly inefficient, other nations’ vertically tiered supply chains and inexperienced engineers are shielded from similar issues.

The present study aims to develop prediction method of turbocharger’s turbine wheel temperature at working conditions. To take fluid-solid heat transfer physics into account, CHT (Conjugate Heat Transfer) based approach is introduced. The model mesh comprises turbine wheel, rotor shaft, and stationary parts of the turbine side together with internal fluid region. Remaining parts, compressor or surrounding atmosphere are not included in the calculation mesh yet boundary conditions at contact surface of the outer mesh region were carefully considered and coupled into CHT. An actual ship board turbocharger was selected to investigate presented calculation method. Multiple point thermal measurement was conducted both for the turbine wheel and the stationary parts to obtain verification data. CHT calculation for this model case was demonstrated and results were compared. The results, especially at the rotor wheel surface shows fairly good agreement with the measured temperatures within the range of ± 5degC. Stationary part temperatures showed larger discrepancy yet high/low relationship of temperatures from parts to parts was agreed with the experiment. The reason for temperature discrepancy was considered to come from too simplified modeling of heat transfer path and this can be improved in future work.

Removal of fuel sulfur assumes that hot corrosion events will subsequently end in shipboard and aero gas turbine engines. Most papers in the literature since the 1970s consider Na 2 SO 4 and SO 3 as the primary reactants causing hot corrosion. However, several geographical sites around the world have relatively high pollutant levels (particulate matter, SO 2 , etc.) that have the potential to initiate high-temperature corrosion. The deposit chemistry influencing hot corrosion is more complex consisting of multiple sulfates and silicates with the addition of chlorides in a marine environment. Sulfur species may still enter a ship combustion chamber as contaminants via air intake or with seawater entrained in air entering through the ship air intake. High levels of impurities (SO 2 ) above 2 ppm can lead to hot corrosion attack. Research is needed to determine how sulfate salt mixtures and air impurities influence hot corrosion in marine and non-marine conditions. Other impurities such as phosphorus, lead, chlorides, sand, and unburned carbon may lower salt melting temperatures, alter the sulfate activity, or change the solution chemistry and acidity/basicity that leads to accelerating hot corrosion. Other issues need to be considered in non-metallic materials system.

Hybrid marine ship propulsion systems are currently being used, and many more are being considered worldwide, including for commercial ships as well as for navies worldwide. These hybrid propulsion systems offer extended ship range and potentially quiet operation with propulsion on propeller shaft line electric motors. When high power and / or speed may be required, the main engines or turbines can be quickly started, and propeller shaft line clutches provide quick and reliable transition from or back to the electric motors. In the naval marine sector, several ship programs currently use “Combined Diesel Electric or Gas Turbine” (CODELOG) or “Combined Diesel Electric and Gas Turbine” (CODELAG) propulsion. Some utilize Synchronous Self-Shifting Clutches, and some utilize other types of non-automatic friction clutches. Many navies worldwide are considering this type of hybrid propulsion, but variations in machinery arrangements and components can result in significant differences in fuel efficiency, weight, space, first time cost, ship performance, and propulsion machinery lifecycle maintenance with associated cost. Therefore, serious investigation of the alternatives early in the ship design phase is important and accessing the experience of these existing systems with these components is vital, before settling on a machinery arrangement and its components for a future ship program. As the old cliché says, “The Devil is in the Details!” Like any system, the success, the reliability, and the ultimate capability often come down to design details and the components chosen. Naval ships are designed to operate, even when damaged or when control or oil supply systems fail. Simplicity and the ability to improvise is often the key to mission success or failure. Synchronous Self-Shifting Clutches, or SSS Clutches, have proven to be “fit and forget” in these propulsion systems, have performed without fail in battle conditions, and this paper will describe the systems, explore the alternatives for propulsion clutches, provide advantages and disadvantages, and will provide experience of SSS Clutches in hybrid propulsion systems.

When the concept of aircraft derivative marine gas turbines were originally proposed, one of the selling points was the engine was going to be easy to remove and replace thereby minimizing the operational impact on the ship. Anticipated Mean Time Between Removal (MTBR) of these engines was expected to be approximately 3000 hours, due mostly to turbine corrosion damage. This drove the design and construction of elaborate removal routes into the engine intakes; the expected time to remove and replace the engine was expected to be less than five days. However, when the first USN gas turbine destroyers started operating, it was discovered that turbine corrosion damage was not the problem that drove engine maintenance. The issues that drove engine maintenance were the accessories, the compressor, combustors and engine vibration. Turbine corrosion was discovered to be a longer term affect. This was primarily due to the turbine blade and vane coatings used and intake air filtration. This paper discusses how engine design, tooling development, maintenance procedure development and engine design improvements all contributed to extending the MTBR of USN propulsion and electrical power generation gas turbines on the DD 963, CG 47, DDG 51 and FFG 7 classes to greater than 20,000 hours. The ability to remove the gas turbine rapidly or in most cases repair the engine in-place has given the USN great maintenance flexibility, been very cost effective and not impacted operational readiness.

The Rolls Royce 501-K34 gas turbine engine serves as the prime mover in the Ship Service Gas Turbine Generators (SSGTGs) of the U.S Navy’s USS ARLEIGH BURKE (DDG 51) Class Flight I and Flight II ships. At the time of this writing, there are 65 ships and 195 shipboard 501-K34 turbine engines which operate a total of about 400,000 hours per year. Engines periodically require removal from ships for depot repair. This paper discusses the guidelines that govern the removal process then discuss the 156 engine removals that occurred between January 2008 and November 2018.

Considering the increasing development of naval destroyers and the obvious advantages of marine gas turbine, this paper designs a novel COGAG (Combined Gas-turbine And Gas-turbine) propulsion system which mainly consists of four GT25 marine gas turbines and one CCG (Cross Connection Gears) for the large destroyer. Firstly, the overall configuration and key devices of COGAG propulsion system are introduced briefly. Then, the typical operating patterns of COGAG propulsion system under different condition are discussed in detail. Finally, many experimental information are further presented. All the results show that the developed COGAG propulsion system not only has higher flexibility and reliability, but also can effectively improve the fuel economy of marine ships.

Naval applications require various modes of operation from a combination of driving sources to different ship propulsion systems. Various gear configurations are available for these applications. The driver types and operating modes generate different requirements for the selected clutch design. In this paper the application of different types of clutches will be compared for their specific applications, advantages and disadvantages.

The combined diesel-electric and gas turbine (CODLAG) plant is a new type of ship power plant combining the advantages of electric propulsion system and mechanical propulsion system. The requires about ship power grid is lower than full electric propulsion mode, at the same time it can gain the quiet of electric propulsion in the low working conditions and increase the mobility of the ship in the high working conditions. Unlike traditional mechanical propulsion methods and forward-looking all-electric propulsion methods, the CODLAG plant has a coupling between mechanical propulsion and electric propulsion mode. The cooperative working characteristics of two different nature systems is still need further research. For the in-depth research of CODLAG device’s characters, this study built a simulation model of CODLAG device based on Matlab/Simulink and C/C++ platform. A kind of torque-shaft speed double closed-loop control strategy based on PID was used on the CODLAG device. And the typical work condition of CODLAG, including merging, merging off and variable work condition, was simulated in this study. Through the simulation, the dynamic response of main parameters at typical condition have been got. Then, characters of CODLAG device with CPP was simulated at variable condition. And the thrust response was compared with FPP’s. Through comparative analysis, the effectiveness of integrated simulation method specifying to CODLAG device was verified, and some useful conference was provided for the future research.

Intake and exhaust system is one of the important parts of power systems of the ships, because the resistance performance will influence the whole performance of the main propulsion engine. Therefore, the performance of the intake and exhaust systems are always studied in advance inside laboratories before they are built as the real ship system. In this paper, both CFD and experiment methods are employed to investigate the pressure loss performance of intake and exhaust systems. The RANS simulation with k-ε turbulence model is done by the commercial code ANSYS Fluent. Firstly, sixteen different intake and exhaust models were calculated with the proper boundary conditions according to the former research experience. The resistance performance of the real ship intake and exhaust models was obtained. Then a simplified geometric model was proposed to simulate the performance of the complex real ship intake and exhaust system effectively and efficiently. This kind of novel simplified model can reproduce the geometrical structures of the real ship under lab environments, which can easily adjust the angle of the resistance simulators. Additionally, a low speed wind tunnel system with a kind of small-scale aerodynamic model has been made and its pressure loss performance was measured under laboratory conditions in the experiment. Finally, the simulation results are compared with the experimental data. The results show that the simulation method employed in this paper is suitable to do such research work with high accuracy. And the simplified model can be used to mimic the resistance performance of the real ship intake and exhaust systems.

This paper will discuss the development and testing of an electric drive option designed for the propulsion system of the US Navy’s DDG 51 Class ships. It will briefly explain the history of the Hybrid Electric Drive (HED) program, including that of its predecessor, Proof of Concept (PoC), and the HED’s planned shipboard installation schedule. Operating at lower ship speeds, in a range where the currently installed propulsion gas turbines are less fuel efficient, the HED is expected to increase the ship’s fuel economy, allowing the ship to remain on station accomplishing its mission for a longer period of time. This paper will discuss how the gas turbine propulsion system, in concert with the HED, will be used to provide the most fuel efficient drive combination for various operating scenarios. Also covered will be a description of the major stakeholders involved in the HED’s development and implementation along with some of the constraints and challenges that were encountered in the testing phase of the program, both at the OEM facilities and at the US Navy’s Land Based Engineering Site (LBES) in Philadelphia PA. Planned fuel economy testing results obtained at the LBES facility will also be presented, intended to determine an estimate of the fuel savings that can be expected when the system is first placed in service on USS TRUXTUN (DDG 103) July 2018.

The Marine Corps Systems Command is evaluating alternative propulsion systems to achieve high water speed for the future USMC Amphibious Combat Vehicle (ACV). A gas turbine engine is one of the propulsion systems evaluated. The primary risk of operating a gas turbine engine in the ACV is power loss due to the ingestion of marine contaminants such as saltwater mist in the air, saltwater spray generated from the vehicle operation, green water wash caused by the operation of the vehicle in the surf zone or in rough seas, and hard particles such as sand present in the marine environment. The Auxiliary Ships and New Acquisition Support Branch (Code 425) of the Naval Surface Warfare Center, Philadelphia Division conducted a study to assist the Marine Corps Systems Command in assessing the feasibility of using a gas turbine engine as a propulsion system on future USMC ACVs. The study was focused on developing and testing a gas turbine intake solution for the ACV that can remove saltwater from the intake airstream of the notional 3,000 horsepower ACV engine. Code 425 developed a two-part solution for the intake of the ACV. The first part of the solution is the Combustion Air Protection Shroud (CAPS) located at the entrance of the engine intake and designed to protect the ACV engine from green water wash by elevating the intake above the ACV deck. The second part of the solution is a gas turbine intake filtration system located downstream of the intake shroud and designed to remove marine contaminants that enter the intake shroud. A reduced-scale model of the CAPS was designed by Code 425 in conjunction with Gibbs & Cox and tested at the Davidson Laboratory High Speed Test Basin at the Stevens Institute of Technology to determine the optimum extension height of the CAPS to protect the engine intake. This paper covers the design and testing of the CAPS. The results showed that a 2.67 ft. tall CAPS with selectively closeable air intake louvers is sufficient to keep out saltwater from the ACV gas turbine engine.

In the last years, the increased demand of the energy market has led to the increasing penetration of renewable energies in order to achieve the primary energy supply. However, natural gas is expected to still play a key role in the energy market, since its environmental impact is lower than other fossil fuels. It is mainly employed as gaseous fuel for stationary energy generation, but also as liquefied fuel, as an alternative to the diesel fuel, in vehicular applications. Liquefied Natural Gas is currently produced mainly in large plants directly located at the extraction sites and transported by ships or tracks to the final users. In order to avoid costs and environmental related impact, in previous studies Authors developed a new plant configuration for liquefied natural gas production directly at filling stations. One of the main issues of the process is that in various sections the working fluid needs to be cooled by external fluids (such as air for compressor inter and after-cooling or chilling fluids), in order to increase the global performances. As a consequence, an important amount of heat could be potentially recovered from this Liquefied Natural Gas production process. Thus, based on the obtained results, in this study the integration between the liquefaction process and an organic Rankine cycle is proposed. In fact, the heat recovered from the Liquefied Natural Gas production process can be used as hot source within the organic Rankine cycle. The aim of the work is the identification of the optimal integrated configuration, in order to maximize the heat recovery and, as a consequence, to optimize the process efficiency. With this purpose, in this study different configurations — in terms of considered organic fluid, architecture and origin of the recovered heat — have been defined and analyzed by means of a commercial software. This software is able to thermodynamically evaluate the proposed process and had allowed to define the optimal solution.