Propellant Engine Research Articles

Large Two-Stroke Marine Diesel Engine Operation with a High-Pressure SCR System in Heavy Weather Conditions

Abstract The transient performance of a direct-drive large two-stroke marine diesel engine, installed in a vessel operating in a seaway with heavy weather, is investigated via simulation. The main engine of the ship is equipped with a selective catalytic reduction (SCR) aftertreatment system for compliance with the latest International Maritime Organization (IMO) rules for NOx reduction, IMO Tier III. Because of limitations of exhaust gas temperature at the inlet of SCR systems and the low temperature exhaust gases produced by marine diesel engines, in marine applications, the SCR system is installed on the high-pressure side of the turbine. When a ship sails in heavy weather, it experiences a resistance increase, wave-induced motions, and a time-varying flow field in the propeller, induced by ship motions. This results in a fluctuation of the propeller torque demand and, thus, a fluctuation in engine power and exhaust gas temperature, which can affect engine and SCR performance. To investigate this phenomenon and take into account the engine–propeller interaction, the entire propulsion plant was modeled, namely, the slow-speed diesel propulsion engine, the high-pressure SCR system, the directly driven propeller, and the ship’s hull. To simulate the transient propeller torque demand, a propeller model was used, and torque variations due to ship motions were taken into account. Ship motions in waves and wave-added resistance were calculated for regular and irregular waves using a 3D panel code. The coupled model was validated against available measured data from a shipboard propulsion system in good weather conditions. The model was then used to simulate the behavior of a Tier III marine propulsion plant during acceleration from low to medium load, in the presence of regular and irregular waves. The effect of the time-varying propeller demand on the engine and the SCR system was investigated. Introduction The effect of waves on a marine propulsion system is a complex phenomenon involving interactions between different subsystems of the propulsion plant, i.e., the prime mover, the propeller, and the ship’s hull. Ships sailing in heavy weather conditions experience a resistance increase, wave-induced motions, and a time-varying flow field in the propeller. This leads to a fluctuation of the propeller torque demand which results in a fluctuation in engine-produced power and exhaust gas temperature.

An energy efficiency practice for coastal bulk carrier: Speed decision and benefit analysis

This study puts forward an optimal speed decision-making method for a coastal bulk carrier as an important energy efficiency practice. Firstly, the ship resistance model is established considering the impact of multiple environmental factors, such as wind, waves and shallow water; on this basis, according to ship–engine–propeller interaction mechanism, the ship energy consumption model is established. Then, the ship speed optimisation model is established and the multi-objective genetic algorithm is applied to obtain the most fuel-efficient speed set. Finally, a coastal bulk carrier is selected for a case study to implement the proposed method, and the fuel saving as well as the economic and environmental benefits are analysed. The results indicate that the proposed speed optimisation method can calculate the optimal speed for each leg of shipping line and that the total fuel consumption of the target ship can be reduced by 8.47% through increasing the sailing time and expanding the low-load operational range of the main engine. This study can help the crew members to improve the energy efficiency management of ships.

The Concept and Theoretical Performance of Vertical Rocket Launcher Aircraft

A concept of a new type of military aircraft called rocket launcher aircraft (RLA) is presented. RLA is effectively a reusable first stage of a two-stage military rocket. The second stage called drone launched short range rocket (DLSRR) is disposable. DLSRR is discussed in author’s previous work and the present work can be viewed as a sequel to afore article. The function of an RLA is to raise one or more DLSRR to an altitude of up to 100 km and to supply them with initial velocity of up to 2,355 m/s. The DLSRRs are fired at high initial velocity and altitude. This enables them to reach targets at the distances of hundreds of kilometers at much lower cost than conventional short range rockets. RLA returns to the base within 6.5 to 8 minutes of its launch. It should be able to perform two to four sorties per hour and 30 to 50 sorties per day. RLA has one or more primary rocket engines for liftoff and acceleration. Most RLAs have one or more auxiliary propeller engines for landing. Some RLAs use their primary rocket engines for landing. Light RLAs may be able to land using only a parachute. A great variety of RLAs with liftoff mass ranging from 1 ton to over 1,000 tons is possible. Some RLAs have disposable fuel tanks. In this work we calculate performance of a light (10 tons), medium (55 tons) and heavy (390 tons) RLAs. Every RLA should be capable of both vertical and forward-leaning trajectories. In this work, we focus on vertical ones. We hope that, Rocket Launcher Aircraft hold a great promise for the future.

A Method to Increase the Permissible Torque of the Friction Force in Steering Units of Liquid Propellant Engines

A Method to Increase the Permissible Torque of the Friction Force in Steering Units of Liquid Propellant Engines

Effect of Main Engine Placement and Propeller Shaft Inclination on Ship Performance

P lacement of the ship propulsion system components might also affect the value of the ship's resistance and thrust. Included in the placement of the ship's propulsion system components are the placement of the main engine and propeller shaft inclination. Changes in the placement of the main engine will affect the location of the center of gravity of the ship which affects the trim and the amount of resistance of the ship. While propeller shaft inclination will affect the direction of thrust produced by the propeller. In this research, an analysis of how big the effect of the placement of the main engine and the propeller shaft inclination on various angles for the 60 GT fishing vessel on the ship's performance by using simulation. Simulations were performed with Numeca Fine Marine software using the Actuator Disk Propeller method. Propeller shaft inclination variations are 1⁰, 2⁰, 3⁰, and 4⁰. At each propeller shaft inclination, there are two variations of the placement of the main engine at a distance of 4m-6.5m from the AP and 5.5m-8m from the AP. Based on the results of the simulation that has been done, the greater the angle of the propeller shaft inclination, the more resistance value will be even smaller, and the thrust produced is also smaller. When the main engine is shifted towards FP, the resistance value will be greater, and the thrust generated is also greater. The most optimal conditions are on the rake of the propeller shaft 4⁰ and the main engine position 4m-6.5m from the AP, the total resistance value of the ship = 9648.97 N and the thrust = 16520.66, torque = 1867.46, KT = 0.1569, KQ = 0.0177, J = 0.2827 and propulsion efficiency = 0.3991. This configuration was chosen because to make the ship move at the same speed, the configuration requires less power.

Rotating acoustic source localization: A power propagation forward model and its high-resolution inverse methods

The rotating-acoustic source localization has played an important role in rotary machine fault diagnosis, engine noise reduction and propeller recognition etc. To achieve high-resolution localization of fast rotating sources, this paper proposes an improved power propagation forward model of rotating acoustic source based on the equivalent source hypothesis. Then the ill-posed inverse problem derived from the forward power model is solved robustly by proposed two sparsity-based methods: the Least Absolute Shrinkage and Select Operator for Rotating-acoustic Sources (LASSO-RS) and Least Angle Regression for Rotating-acoustic Sources (LAR-RS). The contributions of this paper are that, at one hand, the improved forward model is indeed time-invariant for the fast-rotating source owing to the time-domain de-Doppler technique; at the other hand, high-resolution acoustic maps can be obtained by proposed LASSO-RS and LAR-RS thanks to the sparsity-based regularization, even under very low signal-to-noise ratio (SNR). Moreover, the proposed LAR-RS is the data-driven method, rather than the parameter-dependent method such as the LASSO-RS with careful selection of regularization parameter. In simulations and experiments, the proposed methods can robustly localize rotating monopoles in the condition of 3000 RPM rotation speed (50 Hz), −5 dB SNR, and 2500 Hz working frequency.

Analysis of the interaction of a supersonic gas flow with a solid low melting polymer as a ramjet engine propellant

The performance of ramjet engines with a supersonic combustion is one of the main directions of hypersonic aircraft development research is studied. Researchers around the world create special experimental facilities for testing engine models, investigate fuels for ramjet engines and classify new scientific data. Since the ambient temperature and the oxidizer flow temperature in engine air duct are low at the flight altitude of a hypersonic aircraft, low melting materials can be used as a fuel agent in a solid propellant. The main purpose of this work is analysis of heat and mass exchange processes associated with the motion of a supersonic gas flow in an axisymmetric duct described as a combustion chamber of a ramjet engine with a solid polymer. The mathematical model of the problem consists of the unsteady Reynolds-averaged Navier-Stokes equations and the equations of a semiempirical turbulence model. The stated problem was solved by the finite volume method. Initial and boundary conditions are identical to experimental conditions and this makes it possible to verify the results of the numerical solution directly during aerodynamic tests. Gas dynamic parameters for the gas flow in an air duct of a ramjet engine are described, pressure profiles at the gas-solid interface are plotted, and a transient pressure behavior is considered. The results of the solution of a coupled heat transfer problem allow analyzing a dynamic heat exchange pattern in a solid polymeric material (caprolone, polyethylene and polyoxymethylene). It has been found that the effect of a supersonic flow on the surface of a low melting material within one second leads to temperature changes in a solid to a depth of 20% of its total thickness.

A novel framework for liquid propellant engine’s cooling system design by sensitivity analysis based on RSM and multi-objective optimization using PSO

One of the challenges of combustion chamber and nozzle design in a Liquid Propellant Engine (LPE) is to predict the behavior and performance of the cooling system. Therefore, while designing, the optimization of the cooling system is always of great importance. This paper presents the multi-objective optimization of the LPE’s cooling system. To this end, a novel framework has been developed, resulting from the application of the Response Surface Method (RSM) and the correlation coefficients matrix, sensitivity analysis and the The Particle Swarm Optimization (PSO). based on this method, the input variables, constraints, objective functions, and their surfaces were identified. In terms of multi-optimization algorithms, RSM and PSO are utilized to get global optimum. In conclusion, the methodology capability is to optimize the LPE’s cooling system, 6 percentage increase in total heat transfer and 7 bar decrease cooling system pressure loss, which resulted in a 1.2-seconds increase in the specific impulse of the engine.

Rico and the jets: Direct numerical simulations of turbulent liquid jets

This paper is associated with a poster winner of a 2019 American Physical Society's Di- vision of Fluid Dynamics (DFD) Milton van Dyke Award for work presented at the DFD Gallery of Fluid Motion. The original poster is available online at the Gallery of Fluid Motion, https://doi.org/10.1103/APS.DFD.2019.GFM.P0020 The breakup of an interface into a cascade of droplets and their subsequent coalescence is a generic problem of central importance to a large number of industrial settings. Examples of these applications include the atomisation of propellants in engines, the formation of droplets in injectors, mixers, separators, and the generation of droplets in multiphase flow regime transitions [2, 3, 12]. In all of these situations, it is important to predict the evolving droplet size distribution that results from a competition between breakup and coalescence, which are influenced by a range of multi-scale physics; this includes the interaction of turbulence with interfaces, capillarity, viscosity, and gravity. Therefore, it is unsurprising that the breakup of liquid jets during injection (i.e. atomisation) has received great scientific interest [4, 8, 10, 11, 13]. To the best of our knowledge, the transient dynamics of turbulent liquid/liquid systems have not been reported in the literature. Temporal instabilities and the resulting spatio-temporal interfacial structures are predicted by solving the full three-dimensional two-phase Navier-Stokes system in the context of a hybrid front-tracking/level-set method [14-16].

АКУСТИЧНА ПОМІТНІСТЬ БЕЗПІЛОТНИХ ЛІТАЛЬНИХ АПАРАТІВ З СИЛОВОЮ УСТАНОВКОЮ, ЩО МІСТИТЬ ЕЛЕКТРОДВИГУН І ПОВІТРЯНИЙ ГВИНТ

The presence in operation of many prototypes of UAVs with propeller propellers, the use of such devices at relatively low altitudes and flight speeds makes the problem of reducing the noise generated during UAV flights urgent both from the point of view of acoustic visibility and ecology.The main source of the UAV's acoustic signature is its power plant, which includes the engine and propeller.The tasks of this work, the solution of which requires the implementation of experimental studies, include the determination of the power, spatial and spectral characteristics of the acoustic fields of propeller driven power plants of UAVs with an electric drive. The propeller is one of the main sources of acoustic radiation produced by the power plant. The influence on the acoustic characteristics of the power plant was investigated: changes in the diameter of the propellers with a constant pitch, changes in the number of blades and the number of revolutions (peripheral speeds of the propeller). The possibility of reducing the noise produced by the propeller by changing the nature of the noise spectrum was considered. The rotor rotation noise, especially of its five first harmonics, is one of the most noticeable parts in the noise spectrum of a propeller engine installation. Therefore, a hypothesis was considered and put into practice to reduce the acoustic signature of UAVs by reducing the noise of these components due to their shift to the region of higher frequencies, at which sound vibrations in the air decay faster. A comparison technique is proposed. The measurements were carried out under static conditions, in the KhAI anechoic chamber. Note that the propellers involved in the experiments operated at Reynolds numbers (Re0.75 <1*105), which can significantly affect its aerodynamic and acoustic characteristics. An empirical formula was obtained for the 11 × 6" «Aero-naut» propeller, which makes it possible to estimate the noise produced by this propeller when designing for a given flight mode in a given direction. The possibility was considered in the future to have a database of frequently used propellers. The contribution of harmonic noise components was considered propeller in the direction of its radiation. The contribution of the brushless electric motor to the intensity of acoustic radiation of the UAV power plant is determined. It is noted that the main contribution to the noise of a power plant with a brushless electric motor is made by the propeller. At the same time, the noise of a brushless electric motor can significantly increase in the range of 2 ... 3 kHz with wear of rolling bearings.

Analysis of Engine and Propeller Selection for Unmanned Aircraft LSU-05 NG

This research focuses on analyzing the selection of engine and propeller for the propulsion system of LSU-05 NG by calculating the aircraft power needs. The aircraft power is evaluated in two loading conditions, namely heavy loading with regard to minimum take-off speed and light loading with regard to maximum cruise speed. Furthermore, from the five engine recommendations available, propeller rotation efficiency, thrust generated, and engine weight that meets the aircraft DRO (Design Requirment and Objective) are analyzed. The results of this research provide recommendations for using an engine with a minimum power of 16.5 hp with the main candidate is DLE 170 and a 32x10 size propeller as the LSU-05 NG propulsion system.

Study of Soderholm Erosive Burning Model in Internal Ballistic Analysis of Solid Rocket Motors

In this study, the Saderholm erosive burning model is presented as a comprehensive model. Types of propellant (double-based or composite), the need for experimental coefficient for each engine, are the most important limitations of erosive burning models. These require a lot of propellant characteristics and also limitations on the application of some models for high length-to-hydraulic Diameter ratios motors (over 40). In this study, it has been shown that the Saderholm erosive burning model simulates the internal ballistics behavior of a solid propellant engine with an acceptable approximation. Two types of engines with different propellant and length-to-hydraulic Diameter ratios about 30 and 40, the quasi-one dimensional quasi-steady ballistics is solved by using generalized flow equations based on the Saderholm and Greatrix erosive burning models. Finally, it was demonstrated that the Saderholm model is comprehensive for design and numerical work (where there is not much propellant coefficient) and simulates the behavior of the engine with very good approximation.

Pseudo-boiling and heat transfer deterioration while heating supercritical liquid rocket engine propellants

Heating of liquid propellants used as the coolant in rocket engines may lead to undesired phenomena such as pseudo-boiling or heat transfer deterioration under specific conditions. This can be an issue for propellants characterized at the same time by relatively low critical pressure and temperature. Light hydrocarbons, as for instance methane, belong to this family. In the present paper, a critical review is made of the main results obtained by Authors and their coworkers for the present application. Focus is on the correlations and trends inferred by their numerical simulations mainly carried out considering methane as the coolant, perhaps the most challenging one.

Study on Torsional Vibration Characteristics of Cross Shaft Universal Coupling

In this work, the ship propulsion shaft system with cruciform universal coupling is studied. First, based on the analysis of the structure and characteristics of the cross-axis universal coupling, the motion relations and expressions between the components of the universal coupling are established by using the coordinate transformation method. Second, the characteristics of the four submodels of the head mass point element, the end mass point element, the universal coupling mass point element, and other mass point elements are discussed, and the corresponding torsional vibration differential equations of the four submodels are established. On this basis, the mathematical model of the propulsion shafting system and the differential equations of torsional vibration are established by using the modularization method and lumped parameter method. Finally, the torsional vibration modes and response characteristics of the shafts are calculated and analyzed by using the system matrix method when the external load driving torques of the universal coupling, propeller, and diesel engine are considered. At the same time, the correctness of the mathematical model and calculation method is verified by the test and comparative analysis of ship propulsion shafts. It lays a theoretical foundation for further research on torsional vibration characteristics and mechanisms of the ship propulsion shafting system based on universal coupling. Introduction Universal coupling is a common connection component of mechanical shaft system transmission. It is a common mechanism that can be used to transfer motion and torque. Universal coupling has no requirement for neutrality between the two axes connected. It can be used for intersecting, parallel or staggered multiposition relations, and can still ensure the continuous rotation of the two axes connected. Compared with the belt drive and chain drive, universal coupling has the advantages of large transmission range, compact transmission, high transmission efficiency, and convenient maintenance. Therefore, it is widely used in ships, automobiles, lifting and transportation (Avrigean et al. 2015; Chang et al. 2017), engineering machinery, and other equipment. Because of the manufacturing error, assembly error, and the failure to keep synchronous rotation between the driving shaft and the driven shaft in the working process, additional inertia moment of the universal coupling is generated, which causes the vibration of the system and even leads to the fracture of the universal coupling in serious cases.

Nutation control strategy through state feedback: application to a spin-stabilized autonomous system

This research relies on nutation control strategy through state feedback with its application to a spin-stabilized autonomous system such as spacecraft. The key subject behind the investigation is to present a new formulation in the area of attitude control to be able to handle the rotational angles in connection with angular rates, while the system under control is in a predefined mission operation plan. In a word, the main contribution of the research is to cope with the nutation in the process of spin-stabilized attitude control approach in association with the y, z-axis rotational angles to be desirable, at each instant of time. With this goal, the x-axis spin up mode of the system under control is first handled, while the y, z-axis rotational angles of such a system can instantly be adjustable to guarantee the performance of the aforementioned mission operation plan with high accuracy. And then the nutation and angular rates of the system are appropriately controlled in the presence of large disturbances, as long as the propellant engine on mode is addressed to complete the maneuvers in the predefined space mission. The novelty of this research with respect to state-of-the-art materials in this filed is briefly taken in the unique system’s integration and its investigated outcomes. The aforementioned ones are finally considered with regard to some measurable techniques in a number of different cases to indicate that the proposed control approach is well resulted, tangibly.

Using information processing algorithms that factor in the effect of secondary modulation of radar signals

The article provides an assessment of the impact the dynamic structures of power systems of aircraft systems have on the spectrum of the reflected radar signal. In the conditions of autonomous actions of the fighter, the tasks of long-range detection of airborne targets are assigned directly to the onboard radar station. It is necessary to resolve the contradictions associated with increasing the detection range without changing the energy indicators of the onboard radar station. This is possible by optimizing the processing of many spectral components of the signal reflected from the propeller and turboprop engine of airborne targets. The location of propeller reflections in the spectrum of the reflected signal is determined by the technical parameters of the power plant and its mode of operation. The percent of the total energy of the reflected signal spectrum outside the main spectral component is comparable with the energy reflected from the airframe of the aviation complex, most of which is the energy reflected from the rotating elements of power plants. Therefore, the development of an algorithm for detecting a signal with a complex spectral structure that maximizes the probability of detection under time and computational resources restrictions is a very relevant scientific task. The scientific novelty lies in the development of an algorithm for detecting a signal with a complex spectral structure and its detection characteristics taking the effect of secondary modulation into account as well as in the development of practical recommendations for optimizing algorithms for detecting airborne targets. Using the developed algorithm in the fighter’s pulse-Doppler radar station will increase the detection range of an air target against the background of interfering reflections from the water surface.

Analysis of hull, propeller and engine interactions in regular waves by a combination of experiment and simulation

The goal of this study is to investigate ship propulsion system dynamics under sea wave conditions by including the interaction of hull, propeller, and engine. A mathematical ship propulsion system model was made and the related computer code was developed. To get the results as close as possible to real conditions, measured data for physical models, including the ship’s resistance in calm and sea waves and propeller performance, were implemented in the model. For a diesel engine, performances provided by the manufacturer were used. The wave force time series, as exciting force, changed the propulsion system state from steady to transient. It activated system variables including ship’s speed, advance number, propeller and engine torque, propeller and engine rotational speeds, effective and generated powers, and net thrust. The analysis was performed for a container ship for two regular waves. Using the developed computer code, the ship’s speed and system variables, as well as the consumed fuel and the voyage distance, were calculated and compared with the calm water condition. The voyage mode was set on constant rotational engine speed implementing a P-action governor with fuel rate and engine torque limiters. The outcomes of the research explain the influence of the governor and its limiters on fuel consumption, identify the nonlinear impact of sea waves on propeller characteristics, and underline the effect of voyage mode on system response and the consumed fuel. The results also show that the conventional method for calculating speed reduction based on the added resistance is not capable of justifying the system’s dynamic behaviour.

Multicompartment Tubular Micromotors Toward Enhanced Localized Active Delivery

A tubular micromotor with spatially resolved compartments is presented toward efficient site-specific cargo delivery, with a back-end zinc (Zn) propellant engine segment and an upfront cargo-loaded gelatin segment further protected by a pH-responsive cap. The multicompartment micromotors display strong gastric-powered propulsion with tunable lifetime depending on the Zn segment length. Such propulsion significantly enhances the motor distribution and retention in the gastric tissues, by pushing and impinging the front-end cargo segment onto the stomach wall. Once the micromotor penetrates the gastric mucosa (pH ≥ 6.0), its pH-responsive cap dissolves, promoting the autonomous localized cargo release. The fabrication process, physicochemical properties, and propulsion behavior are systematically tested and discussed. Using a mouse model, the multicompartment motors, loaded with a model cargo, demonstrate a homogeneous cargo distribution along with approximately four-fold enhanced retention in the gastric lining compared to monocompartment motors, while showing no apparent toxicity. Therapeutic payloads can also be loaded into the pH-responsive cap, in addition to the gelatin-based compartment, leading to concurrent delivery and sequential release of dual cargos toward combinatorial therapy. Overall, this multicompartment micromotor system provides unique features and advantages that will further advance the development of synthetic micromotors for active transport and localized delivery of biomedical cargos.

Resistance moment of a rotation surface of liquid rocket engines turbomachines elements

The research elaborates the main characteristics of the liquid propellant engines; it determines that some turbo pump units have got the frequency of rotor spinning up to 100 000 and even 120 000 r.p.m. The authors analyse the current methodologies to specify losses connected with disc friction. The methodologies determining disc friction coefficient often obtain criterion-empirical character, and due to increasing a number of rotor spinning of turbo pump unit of the liquid propellant engines, they reflect the specification reliability inaccurately. The research demonstrates equations to determine disk friction coefficients based on considering the theory of three-dimensional boundary layer to a rotational flow taking into account the turbulent process of velocity distribution. The authors give recommendations on determining an index of velocity distribution degree depending on Reynolds rotation criterion of a disc and plug flow.

Disc friction to specify power balance of a turbopump unit of LPE

The research elaborates the main characteristics of the liquid propellant engines; it determines that some turbopump units have got the frequency of rotor spinning up to 100 000 and even 120 000 r.p.m. The authors analyse the current methodologies to specify losses connected with disc friction. The methodologies determining disc friction coefficient often obtain criterion-empirical character, and due to increasing a number of rotor spinning of turbopump unit of the liquid propellant engines, they reflect the specification reliability inaccurately. The research demonstrates equations to determine disk friction coefficients based on considering the theory of three-dimensional boundary layer to a rotational flow taking into account the turbulent process of velocity distribution. The authors give recommendations on determining an index of velocity distribution degree depending on Reynolds rotation criterion of a disc and plug flow.