Propulsion System Performance Research Articles

The importance of the engine-propeller model accuracy on the performance prediction of a marine propulsion system in the presence of waves

The shipping industry is the heart of international trading activities and the global economy. Maritime transport contributes to environmental pollution through the emission of greenhouse gases. New mandatory regulations aim at improving the environmental performance of ships by encouraging power reduction and alternative fuels. These requirements drew attention to the estimation of the ship performance in the presence of waves considering unconventional combustibles. Investigating the effects of waves on untraditional propulsion plants could help to design more environmentally friendly ships. The purpose of this paper is to determine the importance of the time-varying wake field, ship motions, propeller emergence, and engine response on the performance in waves of a marine propulsion system powered by a medium-speed LNG engine. This is performed by comparing the engine-propeller performance estimated by modelling the propulsion plant at three different levels of complexity. The results illustrated the poor prediction accuracy of the propulsion system performance in waves when the time-varying wake field, ship motions, and propeller emergence are neglected. The influence of the engine response on the performance prediction of the engine-propeller system was negligible. The outcomes of this paper demonstrate the importance of considering the effects of the waves on the propulsion system of a ship during the optimization phase.

Efficacy Analysis of Thickness and Camber Size of Cross Section of the Stator on Hydrodynamic Parameters in Linear Jet Propulsion System

The linear jet propulsion system, unlike pump-jets which are widely used in underwater bodies, is installed inside a tunnel under the vessel and can be used for high-speed crafts, tugs, and service boats. However, this system has not received adequate attention by researchers, which is the subject of the current study. In the present paper, hydrodynamic performance of the linear jet propulsion system is numerically investigated. Accordingly, the Ansys-CFX software is utilized and RANS equations are solved using the SST turbulent model. The results of the proposed numerical model, in the form of thrust and torque coefficient as well as efficiency, are compared with available experimental data for a ducted propeller, and good compliance is achieved. Considering the importance of stator cross section on the performance of the linear jet propulsion system, the influence of thickness and camber size of the stator on linear jet propulsion systems are examined. Based on the numerical findings, it is determined that at constant advance ratio, with increasing thickness of stator, the efficiency increases. It is also observed that as the span length increases, the maximum and minimum of the pressure coefficient increase for different thicknesses. Furthermore, it is seen that positive and negative pressure coefficients decrease with an increase in foil thickness.

Development of a hybrid method in a 3-D numerical burn-back analysis for solid propellant grains

This study was performed to analyze the performance of a solid propulsion system quickly and accurately. Systems that are currently in operation use a propellant with a complicated configuration to satisfy the performance requirements. Multi-dimensional internal ballistics analysis is essential in this case. The propellant's burning surfaces move in all directions, and the local burning velocity changes, so a 3-D analysis technique is necessary for the moving boundary. Previous research focused on improving the accuracy of the combustion configuration analysis using new methods, but it is difficult to apply them because user convenience was not considered. Therefore, the problems of the analysis methods were analyzed, and a hybrid burn-back analysis method was developed. The method's accuracy was improved by selectively using the minimum distance function (MDF) manipulation method, which has fast calculation speed, as well as a level set method for regions where the configuration of the propellant grains is complicated. The results verified that the accuracy was increased, and the calculation time was reduced.

ANALYSIS OF UNSTEADY CAVITATION FLOW OVER HYDROFOIL BASED ON DYNAMIC MODE DECOMPOSITION

Cavitation is a special flow phenomenon with strong unsteadiness that often occurs in propeller of ships and underwater vehicles. The occurrence of cavitation often affects the hydrodynamic performance and efficiency of propulsion systems. In order to study the unsteady cavitation flow field structure around hydrofoil, numerical prediction and flow field structure analysis of unsteady cavitation flow around two-dimensional hydrofoil are investigated by using Schnerr-Sauer cavitation model and SST $k$-$\omega $ turbulence model. The validity of the established numerical method is verified by comparing the numerical prediction of cavitation evolution and pressure data with experimental results. The velocity field of the cavitation flow field is analyzed by using Dynamic Mode Decomposition (DMD). The results show that the first-order mode is 0Hz, which represents the average flow field. The second-order mode is about the frequency of cavitation shedding, which reveals the cavities grow and shed periodically at the leading edge of the hydrofoil. The third-order mode has a corresponding frequency about 2 times of the second order mode, which reveals that the fusion behavior of two large-scale vortices behind the hydrofoil. The fourth-order mode has a corresponding frequency about 3 times of the second order mode, which characterizes the fusion behavior of some small-scale eddies in the flow field. Finally, the modal decomposition analysis of the cavitation flow field under different cavitation numbers was carried out. It was found that the vortex structure of the shedding cavities increased with the decrease of the cavitation number, and the second-order mode frequency decreases with decreasing cavitation number.

A nonlinear optimization tool to simulate a marine propulsion system for ship conceptual design

An optimization tool is developed to simulate the performance of a marine propulsion system of a fishing trawler for ship conceptual design. It consists of two modules implemented in Matlab. The first optimization module simulates the performance of a high speed turbocharged four-stroke marine diesel engine along the engine load diagram. It couples 1D engine simulation tool and a nonlinear optimizer to minimize the BSFC of the marine engine and to verify the limitations of emissions defined by international organizations, by optimizing turbocharger and injection parameters. The second module assists in the selection of a suitable fixed pitch propeller from Wageningen B-series at the ship design speed at engine operating point with minimum fuel consumption and by verifying the propeller cavitation, strength and noise issues, instead of only maximizing the propeller efficiency or minimizing the BSFC as considered in previous researches.Then, the objective of the propeller optimization module is changed to compute the propeller performance by (1) maximizing the propeller efficiency (2) minimizing the BSFC, for the purpose of comparison with the current study. The current case shows a significant reduction in the amount of fuel consumed by around 30% in comparison with the other two cases.

Aero-Propulso-Elastic Analysis of a Supersonic Transport

An aeroelastic modeling capability of a flexible aircraft with gas turbine engines is developed using a computational fluid dynamics tool as an integration platform. The new modeling capability allows for the typical aeroelastic analysis to include a nonlinear dynamic model of the turbomachinery that is capable of capturing relevant gas dynamics. An example case of the aero-propulso-elastic (APE) modeling capability is explored for a supersonic transport vehicle with turbofan engines. An overview of the methodology for integrating the propulsion system and elastic vehicle is provided. This is followed by a study to explore coupling sensitivities compared against typical aeroelastic analysis. Dynamic and static vehicle responses are considered across key flight conditions and vehicle-level angles of attack, where the inclusion of the propulsion system has a 10% increase in vehicle wing tip deformations. It is found that the propulsion system is stable at various operating conditions, with structural oscillations having little impact on propulsion system performance. Perceived loudness, a key performance metric for a supersonic transport, is investigated using the APE model. Results lead to an approximately 4 dB increase in noise over a rigid body analysis that neglects the propulsion system. The greatest impacts are shown during off-nominal conditions.

Experimental Investigation of Spherical Tank Slosh Dynamics with Water and Liquid Nitrogen

Understanding, predicting, and controlling fluid slosh dynamics is critical to safety and improving the performance of liquid propulsion systems for space missions. Computational fluid dynamics simulations can be used to predict the dynamics of slosh. Experimental and numerical studies of water slosh have been conducted; however, cryogenic slosh data relevant for validating computational fluid dynamics are lacking. This paper presents the results of slosh experiments with a spherical tank without and with a ring baffle using both water and liquid nitrogen. The experiments were designed to measure forces from continuous excitation over a relevant range of frequencies and amplitudes, natural frequency, and damping parameters. Analytical models and empirical correlations for slosh damping are constructed and compared to the experimental results. An established analytical model for slosh forces is compared to the experimental results for verification purposes. Experiments with a ring baffle installed show increased damping and attenuation of maximum slosh forces. To provide the greatest utility of these data for future rocket and spacecraft missions, the results are presented in a fully nondimensional framework.

Predictive Modeling of Aerospace Fuel Properties Using Comprehensive Two-Dimensional Gas Chromatography with Time-Of-Flight Mass Spectrometry and Partial Least Squares Analysis

Increasingly stringent requirements for aerospace propulsion system performance, reliability, and operability motivate quantitative connections between fuel composition, physical characteristics, and system performance. Chemically accurate assessment of aviation turbine fuels (Jet-A, JP-8, etc.) and kerosene-based rocket propellants (RP-1 and RP-2) is requisite to mature these models. Comprehensive two-dimensional gas chromatography with time-of-flight mass spectrometry (GC × GC–TOFMS) is an excellent analytical tool for measuring detailed chemical information contained in complex fuels. Additionally, multivariate data analysis methods, referred to as chemometrics, are ideally suited to relate detailed chemical information contained within the GC × GC–TOFMS data to fuel properties and performance in a predictive manner. Herein, we apply these techniques to a chemically diverse set of 74 distillate and multicomponent aerospace fuels, resulting in an improved understanding of the chemical compositional basis for physical and thermochemical behavior. Informed by GC × GC–TOFMS data, highly reliable partial least squares (PLS) models are developed and employed in the prediction of physical properties (measured separately using conventional test methods). Root-mean-square errors of cross-validation (RMSECV) were relatively low: values of 0.0450 cSt, 41.3 Btu/lbm, 0.130 mass %, and 0.0064 g/mL were obtained for viscosity, heat of combustion, hydrogen content, and density, respectively. The corresponding normalized root-mean-square errors of cross-validation (NRMSECV) were 6.01, 10.3, 8.71, and 7.12%, respectively. Investigation of the linear regression vectors (LRVs) provides valuable insight into the relationship between the chemical composition and physical properties, enabling, in principle, the model-informed selection of fuel chemical composition to achieve desired performance criteria.

Tip to End Analysis of Air Breathing Rotating Detonation Engine System

A discovery was made recently that the heat release would be very efficient if it is associated with detonation phenomenon. A detonation wave imparts high pressure to the products of combustion which in turn produces large propulsive power as a result of expansion through the propulsive element. This kind of pressure gain combustor is a new idea which is going to be incorporated in the futuristic propulsive devices. A representative air breathing propulsive system configuration powered by the continuous detonation wave engine is chosen for the present investigation. This includes understanding of various processes occurring in the air intake, isolator, rotating detonation wave engine and flow expansion system. A detailed numerical modelling and simulation based on steady 1-D flow have been carried out. This analysis gave insight into the overall propulsion system performance taking into consideration of the interaction between various sub systems.

Direct measurement of 1-mN-class thrust and 100-s-class specific impulse for a CubeSat propulsion system.

This paper presents the development of a thrust stand to enable direct measurement of thrust and specific impulse for a CubeSat propulsion system during firing. The thrust stand is an inverted pendulum and incorporates a mass balance for direct in situ mass measurement. The proposed calibration procedure allows precise performance characterization and achieves a resolution of 80 μN thrust and 0.01 g mass loss, by taking into account the drift of the thrust-stand zero caused by propellant consumption. The performance of a water micro-resistojet propulsion system for CubeSats was directly characterized as a proof of concept of the thrust stand. Continuous profiles of thrust, specific impulse, and mass consumption were acquired under various conditions in a single firing test. A thrust from 1 mN to 10 mN and a specific impulse from 45 s to 100 s with a maximum measurement uncertainty of ±15.3% were measured for the throat Reynolds number in the range 100-400.

Information and analytical system to monitor operating processes and environmental performance of vehicle propulsion systems

The article describes the peculiarities of using the information and analytical system to study the operating processes of vehicle propulsion systems and to assess their environmental performance, particularly fuel consumption and harmful emissions under operating conditions. The study provides the functional structure of the information and analytical system. It contains the subsystems that enable to obtain and analyze data about the operating process in the cylinder, the subsystem for obtaining data from the engine control system, the subsystem for obtaining data about the operating mode of the propulsion system, the subsystem of data analysis and forecasting the vehicle propulsion system indicators in different operating modes. The case of using the information and analytical system has been shown to study the influence of exhaust gas recirculation on fuel efficiency and environmental performance indicators of the vehicle propulsion system in separate modes and under operating conditions.

Experimental verification of performance of tip-jet helicopter propulsion system

This paper presents the methodology for estimation of power delivery and efficiency of the tip-jet helicopter propulsion system. The main advantage of the tip-jet helicopter is the absence of heavy transmission and tail rotor, but if compared to conventional helicopters, it has significantly lower efficiency. The crucial parameter that impacts the performances of the tip-jet helicopter is a propulsion force at the end of the blade. The analytical and numerical calculations with results for prediction of this propulsion force are presented in this paper. The case study is the ATRO-X tip-jet helicopter. Its propulsion system is driven by the gas-generator Phoenix-100, as a power source, which generates propulsion force by ejecting the hot combustion products through the nozzles at the blades tips.

Electric sail phasing maneuvers for constellation deployment

The aim of this work is to investigate heliocentric phasing maneuvers performed by a spacecraft propelled by an Electric Solar Wind Sail, that is, an innovative propellantless propulsion system that consists of a spinning grid of charged tethers that uses solar wind momentum to produce thrust. It is assumed that the Electric Solar Wind Sail may be controlled by varying its attitude with respect to a classical orbital reference frame, and by switching the tether grid off to obtain Keplerian arcs along its phasing trajectory. The analysis is conducted within an optimal framework, the aim of which is to find both the optimal control law and the minimum-time phasing trajectory for a given angular drift along the (assigned) working orbit. A typical phasing scenario is analyzed, by considering either a drift ahead or a drift behind maneuver on a circular, heliocentric orbit of given radius. The paper also investigates the possibility of using an Electric Solar Wind Sail-based deployer to place a constellation of satellites on the same working orbit. In that case, the optimal flight time is obtained in a compact, semianalytical form as a function of both the propulsion system performance and the number of the sail-deployed satellites.

Experimental evaluation of a hybrid electric propulsion system for small UAVs

PurposeThis paper aims to experimentally evaluate the performance of a parallel hybrid propulsion system for use in small unmanned aerial vehicles (UAVs).Design/methodology/approachThe objective is to combine all the individual components of the hybrid electric propulsion system (HEPS) into a modular test bench to characterize the performance of a parallel hybrid propulsion system, and to evaluate a rule-based controller based on the ideal operating line concept for the control of the power plant. Electric motor (EM) designed to supplement the power of the internal combustion engine (ICE) to reduce the overall fuel consumption, with the supervisory controller optimizing ICE torque.FindingsThe EM was able to supplement the power of the ICE to reduce fuel consumption, and proved the capability of acting as a generator to recharge the batteries drawing from ICE power. Furthermore, the controller showed that it is possible to reduce the fuel consumption with a HEPS when compared to its gasoline counterpart by running simulated representative UAV missions. The findings also highlighted the challenges to build and integrate the HEPS in small UAVs.Originality/valueThe modularity of the test bench allows each component to be changed to assess its impact on the performance of the system. This allows for further exploration and improvements of the HEPS in a controlled environment.

Optimal Design of Inlet Passage for Waterjet Propulsion System Based on Flow and Geometric Parameters

As an important overcurrent component in a waterjet propulsion system, the inlet passage is used to connect the propulsion pump and the bottom of the propulsion ship. The anticavitation, vibration, and noise performance of the waterjet propulsion pump are significantly affected by the hydraulic performance of the inlet passage. The hydraulic performance of the inlet passage directly affects the overall performance of the waterjet propulsion system, thus the design and optimization method of the inlet passage is an important part of the hydraulic optimization of the waterjet propulsion system. In this study, the hydraulic characteristics of the inlet passage in the waterjet propulsion system with different flow parameters and geometric parameters were studied by a combination of numerical simulation and experimental verification. The model test was used to verify the hydraulic characteristics of the waterjet propulsion system, and the results show that the numerical results are in good agreement with the test results. The numerical results are reliable. The hydraulic performance of the inlet passage is significantly affected by the inlet velocity ratio. There is a certain correlation between the hydraulic performance of the inlet passage and ship speed, and the hydraulic performance of the inlet passage is limited by ship speed. The geometric parameters of the best optimization case are as follows: the inflow dip angleαis 35°, the lengthLis 6.38D0, and the upper lip angle is 4°. The optimal operating conditions are the conditions of IVR 0.69–0.87.

Study on Ignition Delay Time of Al/Mg Fuel-rich Propellant under Tangential Air Flow

Solid propellant, as the power source of propulsion system, has obvious influence on the internal ballistic characteristics of ramjet. The ignition and combustion charac-teristics of solid propellant help to reveal the combustion mechanism and have im-portant guiding significance for estimating the performance of propulsion system. In this paper, the ignition and combustion characteristics of Al/Mg fuel-rich propellant under tangential air flow were studied. Laser ignition experiment was carried out on the Al/Mg fuel-rich propellant at different tangential air flow rates and tangential air flow components. The results show that the air flow rate and air flow composition can affect the flame shape and the brightness of the propellant. At the same time, with the increase of air flow rate, the more obvious the erosion combustion effect on the pro-pellant burning surface. The air flow rate also affects the ignition delay time. When the air flow rate is low, the ignition delay time decreases with the increase of air flow rate. When air flow rate is 0.8L/min, the ignition delay time is reduced to the mini-mum of 350ms, but with the air flow rate continues to increase, the ignition delay time is increasing. As the oxygen content in the air flow increases, the ignition delay time increases. However, when the oxygen content is less than 14% or higher than 21%, the effect of oxygen content on the ignition delay time is weakened.

Assessment Of BLDC Drive For E-Bike Application

This paper describes about the need and the various architecture of Electric Bike (E-bike). Among the various electric propulsion sources available, the performance study of Brushless DC (BLDC) motor for an electrically assisted bicycle (E-Bike) is carried out under certain operating conditions. In order to determine the operating speed and to achieve a suitable gear ratio, the motor is operated at different duty ratios whereby the operating voltage and speed of rotation of the motor is varied. The motor is loaded during the various test speeds considered. Based on the performance of the motor and the norms set by Central Motor Vehicle Rules (CMVR) of India, the torque delivered by the motor is computed through experimentation. The characteristics graphs have been plotted against different parameters. Depending on the torque values at the recommended power, the motor operating speed, voltage and currents were identified. Suitable gear ratios have been identified to match the performance of the motor with the e-bike performance requisite leading to better performance of the E-Bike propulsion system.

Design, development, and performance of an ammonia self-managed vaporization propulsion system for micro-nano satellites

An ammonia self-managed vaporization propulsion (ASVP) system for micro-nano satellites is presented. Compared with a normal cold gas or liquefied gas propulsion system, a multiplex parallel sieve type vaporizer and related vaporization control methods are put forward to achieve self-managed vaporization of liquefied propellant. The problems of high vaporization latent heat and incomplete vaporization of liquefied ammonia are solved, so that the ASVP system takes great advantage of high theoretical specific impulse and high propellant storage density. Furthermore, the ASVP operation procedure and its physical chemistry theories and mathematical models are thoroughly analyzed. An optimal strategy of thrust control is proposed with consideration of thrust performance and energy efficiency. The ground tests indicate that the ASVP system weighs 1.8 kg (with 0.34-kg liquefied ammonia propellant) and reaches a specific impulse of more than 100 s, while the power consumption is less than 10 W. The ASVP system meets multiple requirements including high specific impulse, low power consumption, easy fabrication, and uniform adjustable thrust output, and thus is suitable for micro-nano satellites.

Investigation of Micro Gas Turbine Systems for High Speed Long Loiter Tactical Unmanned Air Systems

In this study, the on-going research into the improvement of micro-gas turbine propulsion system performance and the suitability for its application as propulsion systems for small tactical UAVs (<600 kg) is investigated. The study is focused around the concept of converting existing micro turbojet engines into turbofans with the use of a continuously variable gearbox, thus maintaining a single spool configuration and relative design simplicity. This is an effort to reduce the initial engine development cost, whilst improving the propulsive performance. The BMT 120 KS micro turbojet engine is selected for the performance evaluation of the conversion process using the gas turbine performance software GasTurb13. The preliminary design of a matched low-pressure compressor (LPC) for the proposed engine is then performed using meanline calculation methods. According to the analysis that is carried out, an improvement in the converted micro gas turbine engine performance, in terms of thrust and specific fuel consumption is achieved. Furthermore, with the introduction of a CVT gearbox, the fan speed operation may be adjusted independently of the core, allowing an increased thrust generation or better fuel consumption. This therefore enables a wider gamut of operating conditions and enhances the performance and scope of the tactical UAV.

Characteristics of hydrogen jet combustion in a high-enthalpy supersonic crossflow

The facilitation of a stable combustion process is of utmost importance for the realizability and performance of hypersonic propulsion systems. To elucidate the turbulent combustion characteristics, wall-modeled large eddy simulations of a transverse jet injection into a heated supersonic flow are conducted employing a detailed reaction mechanism. The computation framework utilizes an adaptive central-upwind weighted essentially nonoscillatory (WENO-CU) scheme to achieve the sixth-order accuracy in smooth flowfields, while keeping a good shock-capturing ability. The reacting zones agree well with experimental measurements in terms of the instantaneous distribution of OH radicals. And the flame penetration height has been predicted with an error of less than 17%. It is found that the turbulent reacting flow is dominated by nonpremixed combustion mainly taking place in the near-wall region and jet windward shear-layer. Moreover, the autoignition process, which plays a critical role in stabilizing supersonic combustion, shows to favor a fuel-lean or not very fuel-rich environment of a high enthalpy. Local scalar dissipation induced by turbulence gives rise to a rapid fuel mixing with the surrounding air. However, this effect may also lead to the decrease in local temperature.