Jet Propulsion System Research Articles

Analyzing the performance of hull and water jet propeller under mooring conditions: effects of shallow water depths and varying inflow speeds

PurposeWater jet propulsion is widely used in various military and civilian fields due to its advantages of simple structure and high propulsion efficiency. The process of mooring involves utilizing specially designed equipment to secure a ship at a designated berth. During the process of water jet propulsion, the single propeller operates within a complex and turbulent three-dimensional flow. Hence, studying the coupling between the water jet propeller and the hull is critical to comprehending the characteristics of the device and the distribution of the flow field in detail.Design/methodology/approachFirstly, we conducted computational fluid dynamics (CFD)-based self-propulsion calculations to evaluate the interaction between the hull and the propeller. We subsequently analyzed the propeller's performance and the forces acting on the hull to understand how the presence or absence of the hull influenced the water jet propeller. Finally, we performed calculations and analysis of the cavitation characteristics of the coupling between the hull and the water jet propeller, considering different rotational speeds and water depths at the bottom of the pool.FindingsThe study demonstrated that the presence of the hull boundary layer under the hull-propeller coupling condition led to reduced uniformity of propeller inlet flow and lower efficiency of the propulsion pump. However, it also increased the bias toward low-flow conditions. Additionally, increasing the impeller speed led to a gradual increase in the cavitation volume within the water jet propeller, resulting in a gradual decrease in the propeller's performance.Originality/valueThis research provides the technical support required for effective design and operation of water jet propulsion systems. This paper involves studying and analyzing the performance and flow field of the coupling between the hull and propeller under mooring conditions with a specified hull model.

Laser assisted Powder Bed Fusion of pure Molybdenum using ultrashort laser pulses

Refractory metals are used in applications requiring extreme high temperature resistance, e.g. jet propulsion systems in aerospace applications or for controlling nuclear reactions. However, the traditional manufacturing of these metals is demanding and expensive, especially if fine structures are required. Here, we report on the laser assisted powder bed fusion of pure Molybdenum. The high melting point and thermal conductivity together with high susceptibility to solidification fractures of Molybdenum make it difficult to identify a suitable parameter window for the laser based melting process. Thus, we apply an ultrashort pulse laser system operating at a center wavelength of 1030 nm and a repetition rate of 32 MHz with a pulse width of 270 fs for the additive processing. Using the additional parameter field provided by the pulsed laser source we are able to fabricate thin-walled structures well below 100 µm as well as volumetric parts with a relative density close to 100 %.

The Optimization Design of the Nozzle Section for the Water Jet Propulsion System Applied in Jet Skis

The Optimization Design of the Nozzle Section for the Water Jet Propulsion System Applied in Jet Skis

Hydrogen hypersonic combined cycle propulsion: Advancements, challenges, and applications

In the progress toward net zero, two propulsion systems are attracting increasing interest, one based on energy stored in batteries, and the other based on energy stored in hydrogen. In between the applications where hydrogen energy storage has more advantages, there is hypersonic propulsion, which is the object of this perspective. Hypersonic vehicles are aircraft or missiles able to travel at speeds above Mach 5. There are four main types of hypersonic vehicles, spaceplanes, glide missiles, cruise missiles, and aircraft. While glide missiles generally do not need propulsion, cruise missiles, and aircraft are designed to sustain hypersonic speeds for extended periods. They use advanced propulsion systems, which include scramjets, relying on the forward motion of the vehicle to compress incoming air for combustion, and featuring supersonic combustion. While scramjets work well at hypersonic speeds, they must be integrated with other propulsion systems, such as ramjets, rockets, and turbojets, to move back and forth from zero speed. Spaceplanes have been designed so far by using only rockets or integrating rockets and turbojets for better operation in the atmosphere. Spaceplanes' operation in the atmosphere could also be further improved by using ram/scramjets. Point-to-point hypersonic travel for civil applications, which is the focus of this work, requires significant advantages in jet propulsion systems that have to work over different regimes, from subsonic to transonic to supersonic to hypersonic. The work reports on the challenges of hydrogen hypersonic combined cycle propulsion.

Digital model of the drag force of the Earth’s upper atmosphere for the design of low-orbit spacecraft

A digital model is described for estimating the drag force of the Earth's upper atmosphere acting on a low-orbit spacecraft. Unlike the classical model of aerodynamic force, the digital model is the result of a computer algorithm. This algorithm calculates the field of aerodynamic force values, taking into account changes in the flight altitude, aerodynamic coefficient and the area of the spacecraft midsection over time. The calculations also use a digital model of the dynamic density of the Earth's upper atmosphere. The digital model of the drag force of the Earth's upper atmosphere is useful in the design of low-orbit spacecraft with a low-thrust jet propulsion system (thrust order – millinewtons). On the basis of the calculated values of the aerodynamic force, it is possible to form requirements for the geometry of the spacecraft, attitude modes and arrangement of low-thrust jet engines (for example, electric jet engines). With the accumulation of big data in the form of tabular functions of aerodynamic force from the space of various design and ballistic parameters of low-orbit spacecraft, it is possible to create a machine model (ML-model). It will make forecasts of the values of the design characteristics for the low-orbit spacecraft being developed according to a limited set of initial requirements.

Determination of Optimum Parameter Space of a Fluidic Thrust Vectoring System based on Coanda Effect Using Gradient-Based Optimization Technique

In the realm of aviation, jet propulsion systems serve to provide enhanced maneuverability and to make sure that the aircraft thrust is accurately and precisely regulated during take-off and landing operations. The movement of aerodynamic control surfaces (flaps, slats, elevators, ailerons, spoilers, wing attachments) determines the mobility of practically all aircraft types. Recognized as dependable components in the aviation world for take-off and landing tasks, these control surfaces are being replaced by fluidic thrust vectoring (FTV) systems, especially in small unmanned aerial vehicles (UAVs) and short or vertical take-off and landing aircraft. The FTV system is capable of directing thrust in any preferred direction without the need for any movable components. This paper numerically examines the FTV system by utilizing computational fluid dynamics (CFD) and an optimization technique based on gradients of the system components to understand the physics of the Coanda effect in FTV systems. This research employs gradient-based optimization for nozzle design in order to optimize the parameter space for different velocity ratios (VR) by calculating the moment around the upper Coanda surface, which is used to represent the jet deflection angle. In that context, four different Coanda surface-pintle pair designs for four different VRs are produced. The parameter space shows significant improvement in all four configurations, and results reveal that all output parameters successfully delay separation on the thrust vectoring system's upper Coanda surface. Finally, four optimum design suggestions are tested at various VRs, and the most efficient and proper design is recommended based on output parameters.

Impact of jet velocity profile on the propulsive performance and vortex ring formation of pulsed jet propulsion

A squid-inspired jet propulsion system that indudes a deformable body and a nozzle exit attached to it is numerically studied. By prescribing the body deformation during a single discharge, we examine the impact of jet speed profiles on the vortex ring formation and propulsion performance of the system. Our results show that a secondary vortex ring following the leading vortex ring can be produced by the reverse cosine jet speed pattern at a given maximum stroke ratio, and for the other profiles (i.e., constant, cosine, reverse cosine, half cosine and rever half cosine styles) only distributed vortices are seen behind the leading vortex ring. The constant jet speed produces the largest time-averaged thrust due to jet momentum flux related thrust associated with its large jet speed. Except for the constant speed style, the largest mean thrust production and propulsion factor are obtained by the reverse cosine profile among the other four styles attributed to the formation of the secondary vortex ring. Nevertheless, this secondary vortex ring would not be produced at a small maximum stroke ratio for the reverse cosine speed fashion. We also find that the mean thrust production can reach a maximum under a specific maximum stroke ratio (Γm = 7.60) when two vortex rings are produced. This work may provide insight into the mechanical and control design of jet-based biomimetic propellers and robots.

Design of CRMC non-adiabatic supersonic nozzle with frictional effect

The design and function of nozzles are critical to various applications such as steam turbines, gas turbine jet engines, and jet propulsion systems. In certain applications, an advanced nozzle increases fluid speed from subsonic to supersonic or even hypersonic velocities. This is achieved by controlling the flow characteristics of the fluid and producing the necessary thrust under specific design and operational conditions. This study focuses on analyzing the shape and flow parameters of the nozzle and its length. The developed 1-D gas dynamic equations with the real gas equation assume that the momentum rate remains constant to calculate the geometry and flow parameters. The constant rate of momentum change theory (CRMC) accounts for the frictional effect and heat addition, aiding in the computation of nozzle coordinates with identical flow parameters at any distance, such as 0.5 mm in the present case. The results were confirmed using computational fluid dynamics (C.F.D.) with ANSYS Workbench2022R2. At design conditions, the numerical results were found to agree with the present CRMC theory.

Acoustic and Thermoacoustic Jet Propulsion

This manuscript bridges the fields of jet propulsion, synthetic jets and thermoacoustic engines. We introduce the case that synthetic jets in air can be considered a consistent approach for propulsion systems. To date, studies on synthetic jet propulsion have been scattered and rather subsidiary. Furthermore, investigating the perspective of propulsion can provide new insights into the field of synthetic jets and the physics of propulsion. In this work, synthetic jet propulsion in air is demonstrated and studied for acoustic and thermoacoustic cases. We developed synthetic jet systems and characterized the resulting propulsion regarding several relevant parameters such as geometric factors and the frequency and power of acoustic jets electromechanically and thermally produced. We demonstrated the 10.4-mN and 2.7-mN thrust in the acoustic and thermoacoustic modes, respectively, using compact tabletop assemblies. The physical mechanism of the jets has been modeled, simulated, verified with Schlieren imaging and laid in the perspective of adherent literature. Similarities and differences regarding traditional jet propulsion systems are discussed. Synthetic jet propulsion in air using a thermal cycle is experimentally demonstrated for the first time.

Novel processing route for design and manufacturing of metal toughened nanoceramics: Al–Al2O3 nanocermets

Monolithic alumina is a highly brittle ceramic with a very low fracture toughness, making it an unreliable material for mechanical and structural applications. Ceramic-metal composites (cermets) are the subject of intensive interest to obtain materials which can address the intrinsic brittleness of ceramics without compromising their high strength and light weight. In the present investigation, aluminium-alumina (Al–Al 2 O 3 ) nanocermets were developed. The nanocermets possessed the toughness of Al phase and the strength of reinforced nano Al 2 O 3 particles. The nanocermets green bodies were prepared such that upon sintering each adjacent Al 2 O 3 grain was conformally coated with a continuous Al film. Mechanical milling via a combination of cryo-milling and ball-milling was used to prepare Al–Al 2 O 3 nano-powder mixture. Spark plasma sintering was used to consolidate the green nanocermets. Results show that specimens prepared from 35 h milled powders exhibited superior mechanical properties as compared to other nanocermets, with an improvement in microhardness, elastic modulus, compressive strength, and flexural strength by 88%, 78%, 69% and 40% with respect to sintered pure Al. The indentation toughness of 35 h milled nanocermet showed an increment of 12.5% with respect to sintered pure Al 2 O 3 . Characterization techniques such as XRD, SEM, HR-TEM, X-ray tomography were employed to investigate the phase evolution and structural morphology, while FEM simulations were performed for understanding the crack propagation mechanisms in nanocermets. Figure Description: A novel processing route devised from the combination of cryo-milling and ball-milling of elemental Al and Al 2 O 3 powders, followed by spark plasma sintering (SPS) for the development of toughened and strengthened Al–Al 2 O 3 nanocermets (metal-ceramic nano-systems). An attempt has been made to utilize the favourable physical and mechanical attributes of ductile metal phase and brittle ceramic phase to fabricate nanocermets with enhanced mechanical properties. These nanocermets will find use in structural applications requiring components with high strength to weight ratio, such as automotive parts, ballistic armours and jet propulsion systems. • Al 0.2 -(Al 2 O 3 ) 0.8 nanocermets possessing the toughness from ductile Al and strength from brittle Al 2 O 3 are developed. • A combination of cryo-milling and ball-milling is used for the preparation of nanosized Al-Al 2 O 3 powder mixtures. • An optimized cryo-milling of 10 h transforms micron-sized Al particles into nanometric thin sheets. • Enhanced wettability of Al and Al 2 O 3 at the grain boundary interface is achieved for metal-ceramic nano-systems. • Toughening of brittle Al 2 O 3 by metallic Al phase transforms the inter-granular fracture into trans-granular mode.

Experimental Study on the Internal Pressure Pulsation Characteristics of a Bidirectional Axial Flow Pump Operating in Forward and Reverse Directions

A bidirectional axial flow pump can realize bidirectional pumping, which has a wide application prospect in coastal low-head pumping stations and water jet propulsion systems. In this paper, a typical bidirectional axial flow pump is taken as the research object, and the hydraulic model of the bidirectional axial flow pump is manufactured. The hydrodynamic characteristics of the bidirectional axial flow pump are tested on the high-precision hydraulic mechanical test bench, including the positive and negative directions. In the experiment, multiple pressure pulsation monitoring points were arranged in the impeller chamber, and the pressure fluctuations in the pump under a total of 42 flow conditions were measured by a micro pressure pulsation sensor, involving 21 working conditions of forward operation and 21 working conditions of reverse operation. According to the experimental results, the hydrodynamic characteristics, especially the pressure pulsation characteristics in the pump, of the two-way axial flow pump under positive and negative operation are comprehensively compared and analyzed, and the energy characteristics and the propagation law of pressure pulsation of the two-way axial flow pump under positive and negative operation are revealed. The research results provide an important reference for the safe and stable operation of coastal bidirectional axial flow pump stations.

Двухзазорный СВЧ ионный двигатель и его исследование аэродинамическим методом

The article contains the authors’ research in the field of jet propulsion systems with low energy consumption of small spacecraft of the class of nanosatellites. The paper presents a microwave ion engine with double acceleration of ionized gas in the gaps formed by the end surfaces of cylindrical resonators. The results of an experimental study of the pressure force of a jet set of ionized gas by the aerodynamic double angle method are presented. A stand for determining the power parameters of week plasmajet is presented. The design of the prototype is presented. The total energy consumption of the prototype is 5 watts, the accelerated gas flow rate is up to 200 km/s, the jet pressure force on the sensing element of the stand is 0,1 μN. The working body of the prototype is nitrogen at a pressure in a vacuum chamber of 18 Pa.

SLIDING MODE BASED PREDICTIVE CONTROLLER OF A SPHEROIDAL UNDERWATER VEHICLE

This paper focuses on hydrodynamic modeling and control of spheroidal underwater vehicle. The vehicle considered in this paper is appendage free and unstable. Water jet propulsion system is used in this vehicle. The dynamics of the vehicle is highly unstable due to munk moment. The spheroidal shape underwater robot is used in nuclear reactor inspection, port security inspection, defence and ocean surveillance where external appendages are not required. A new and innovative control technique, Sliding mode based model predictive control is introduced in this paper. Sliding mode control technique is used to stabilize the vehicle and once the vehicle model is stabilized it is easy to apply Model Predictive Control (MPC). Model Predictive control technique is used to control the heading of spheroidal underwater vehicle. Simulation results show that the Sliding mode based predictive control performance is better than simple PD control and state feedback controller.

Застосування «зеленого» палива в системах реактивних керуючих двигунів малої тяги

The aim of this work is to analyze the state of the art in the development and use of pollution-free (“green”) propellants in low-thrust jet engines used as actuators of spacecraft stabilization and flight control systems and to adapt computational methods to the determination of “green”-propellant engine thrust characteristics. The monopropellant that is now widely used in the above-mentioned engines is hydrazine, whose decomposition produces a jet thrust due to the gaseous reaction products flowing out of a supersonic nozzle. Because of the high toxicity of hydrazine and the complex technology of hydrazine filling, it is important to search for its less toxic substitutes that would compare well with it in energy and mass characteristics. A promising line of this substitution is the use of ion liquids classed with “green” ones. The main components of these propellants are a water solution of an ion liquid and a fuel component. The exothermic thermocatalytic decomposition of a “green” propellant is combined with the combustion of its fuel component and increases the combustion chamber pressure due to the formation of gaseous products, which produces an engine thrust. It is well known that a “green” propellant itself and the products of its decomposition and combustion are far less toxic that hydrazine and the products of its decomposition, The paper presents data on foreign developments of “green” propellants of different types, which are under test in ground (bench) conditions and on a number of spacecraft. The key parameter that governs the efficiency of the jet propulsion system thrust characteristics is the performance of the decomposition and combustion products, which depends on their temperature and chemical composition. The use of equilibrium high-temperature process calculation methods for this purpose is too idealized and calls for experimental verification. Besides, a substantial contribution to the end effect is made by the design features of propellant feed and flow through a fine-dispersed catalyst layer aimed at maximizing the monopropellant-catalyst contact area. As a result, in addition to the computational determination of the thrust characteristics of a propulsion system under design, its experimental tryout is mandatory. The literature gives information on the performance data of “green”-propellant propulsion systems for single engines. However, in spacecraft control engine systems their number may amount to 8–16; in addition, they operate in different regimes and may differ in thrust/throttling characteristics, which leads to unstable propellant feed to operating engines. To predict these processes, the paper suggests a mathematical model developed at the Institute of Technical Mechanics of the National Academy of Sciences of Ukraine and the State Space Agency of Ukraine and adapted to “green”-propellant engine systems. The model serves to calculate the operation of low-thrust jet engine systems and describes the propellant flow in propellant feed lines, propellant valves, and combustion chambers. To implement the model, use was made of the results of experimental studies on a prototype “green”-propellant engine developed at Yuzhnoye State Design Office. The analysis of the experimental results made it possible to refine the performance parameters of the monopropellant employed and obtain computational data that may be used in analyzing the operation of a single engine or an engine system on this propellant type in ground and flight conditions

MODELLING OF THE UNMANNED AERIAL VEHICLES FLIGHT CONTROL SYSTEM

The article is an independent work containing the author’s ingenious research methodology and the model of the control system of Unmanned Aerial Vehicles. Furthermore a unique and world first mathematical model of an Unmanned Aerial Vehicle was developed, as well as a simulation program which enabled to investigate the control system of any Unmanned Aerial Vehicles in the tilt duct pitch (altitude), bank (direction), deviation and velocity, depending upon the variable values of the steering coefficient, reinforcement coefficient and the derivative constant. The research program was written in the language of the C++ as the MFC class, on the MS Visual Studio 2010 platform. The main issue resolved in the article is the pioneering research of the process of control during manual and semi-automatic guidance of the Unmanned Aerial Vehicle, with a jet propulsion system to the coordinates of preset points of the flight route. Modelling of the flight control system takes into account: the logical network of operations of the simulation program, the pilot-operator model, the set motion and control deviations as well as the flight control laws. In addition, modeling of the control system takes into account the drive model, engine dynamics, engine thrust, the model of steering actuators and the model of external loads. In contrast, the external load model takes into account the external forces acting on the unmanned aircraft, including gravitational forces and moments, aerodynamic forces and moments, aerodynamic drag, aerodynamic lateral forces, aerodynamic lift forces, aerodynamic heeling moment, mechanism of local angle of attack from damping torque and forces and moments from the engine.

Empirical estimation of engine-integration noise for high bypass ra-tio turbofan engines

To investigate the impact of installation on jet noise from modern high-bypass-ratio turbofan engines, a model-scale noise experiment with a jet propulsion system and a fuselage model in scale was conducted in the anechoic wind tunnel of ONERA, CEPRA 19. Two area ratios (an area of the secondary nozzle over an area of the primary nozzle), 5 and 7, and various airframe configurations such as wing positions relative to the tip of the engine nacelle and flap angles, were considered. Based on the analysis of experimental data, an empirical model for the prediction of engine installation noise was proposed. The model comprises two components: one is the interaction be-tween the jet and the pressure side of the wing, and the other is the interaction between the jet and the flap tip. The interaction between the jet and the pressure side of the wing contributes to the noise at the low frequencies (≤ 1.5 kHz), and the interaction between the jet and the flap tip con-tributes to the noise at the high frequencies. The proposed model showed a good agreement with the experimental data.

Transient analysis of the influence of gap size of the rotor from stator on hydrodynamic performance of the linear jet propulsion system

ABSTRACT Hydrodynamic coefficients including thrust, torque and efficiency at different advance ratios are investigated for all components of a Linear-Jet propulsion system. Ansys-CFX software is utilised and URANS equations are solved by the SST turbulent model. Pressure on high- and low-pressure sides of the stator at different spans is computed based on different axial gap size between stator and rotor as well as chord of the rotor in the propulsion system. The computed thrust and torque coefficient as well as efficiency are validated by available experimental data for a ducted propeller. The obtained pressure distribution indicates different fluctuations caused by the interaction of rotor and stator. These oscillations and vibrations are the main cause of damage to the ship hull and the propulsion system. To study these phenomena, unsteady forces applied on the stator at different distances between the rotor and the stator for various time steps are investigated.

Jet propulsion of a squid-inspired swimmer in the presence of background flow

Inspired by recent studies of a squid-like swimmer, we propose a three-dimensional jet propulsion system composed of an empty chamber enclosed within a deformable body with an opening. By prescribing the body deformation and jet velocity profile, we numerically investigate the jet flow field and propulsion performance under the influence of background flow during a single deflation procedure. Three jet velocity profiles, i.e., constant, cosine and half cosine, are considered. We find that the maximum circulation of the vortex ring is reduced at a higher background flow velocity. This is because stronger interaction between the jet flow and background flow makes it harder to feed the leading vortex ring. Regarding thrust production, our analysis based on conservation of momentum indicates that with the constant profile the peak thrust is dominated by the time derivative of the fluid momentum inside the body, while momentum flux related thrust accounts for the quasi-steady thrust. For the cosine profile, its peak is mainly sourced from momentum flux associated with the unsteady vortex ring formation. No prominent thrust peak exists with the half cosine profile whose thrust continuously increases during the jetting. For all the three jet velocity profiles, added-mass related thrust attributed to body deformation enhances the overall thrust generation non-negligibly. Under the present tethered mode, the background flow has negligible influence on the thrust attributed to momentum flux and momentum change of the fluid inside the body. However, it indeed affects the over pressure-related thrust but its effect is relatively small. The overall thrust declines due to the significantly increased drag force at large incoming flow speed despite the rise of added-mass related thrust. Unsteady thrust involving vortex ring formation becomes more important in the overall thrust generation with an increased background flow velocity, reflected by larger ratios of the unsteady impulse to jet thrust impulse.

Influence of Inlet Duct Length on the Hydraulic Performance of the Waterjet Propulsion Device

This study uses a combination of computational fluid dynamics (CFD) and experimental research to explore the influence of the length of the inlet duct on the hydraulic performance of the water jet propulsion pump device. By extending the oblique, straight, and long pipe section of the inlet duct, six sets of schemes were designed. The research results show that as the length of the inlet duct increases, the head, thrust, and inlet duct efficiency of the water jet propulsion pump first increase and then decrease, reaching the maximum value in scheme 4, but it has little effect on the efficiency of the entire water jet propulsion system. In addition, after extending the obliquely straight long pipe section of the inlet flow channel, the velocity distribution of the outlet section of the flow channel is gradually uniform, and the absolute value of the vorticity first increases and decreases, but the uniformity of the velocity distribution and the weighted average angle change little. This research enriches the research theory of the inlet duct and also provides a reference for the selection of inlet duct length and its performance optimization.

Utilization of Open-Source OpenFOAM Code to Examine the Hydrodynamic Characteristics of a Linear Jet Propulsion System with or without Stator in Bollard Pull Condition

With the development of high-speed crafts, new propulsion systems are introduced into the marine industry. One of the new propulsion systems is linear jet which is similar to pump jet and has a rotor, a stator, and a duct. The main difference between this system and pump jet is the placement of linear jet system under the hull body and inside a tunnel. Since this system, like a water jet, is inside the tunnel, the design idea of this system is a combination of a water jet and pump jet. In this paper, hydrodynamic performance of linear jet propulsion system is numerically investigated. To this end, the OpenFOAM software is utilized and RANS steady equations are solved using a k - ε turbulent model. The linear jet geometry is produced by assembling a Kaplan rotor, stator with a NACA 5505 cross section, and a decelerating duct. The results of numerical solution in the form of thrust, torque coefficient, and efficiency are compared with available experimental data for a ducted propeller, and good agreement is displayed. Subsequently, the hydrodynamic parameters are computed in two conditions: with a stator and without a stator. By comparing the results, it is observed that the total thrust coefficient of the propulsion system with a stator at all advance ratios increases by at least 40%. It is further observed that addition of a stator also improves its efficiency.