Wake Field Research Articles

ACCELERATING OF THE ELECTRONS OF ELECTRON BUNCHES IN A WAVEGUIDE LOADED DIELECTRIC STRUCTURE

The paper presents some results of experimental studies of the excitation of wake fields and the acceleration of electrons in waveguide-dielectric structures (DS) upon injection of a sequence of electron bunches into them. Exper-iments have shown an increase in the amplitude of the wake wave and the acceleration of a small fraction of elec-trons when the wavelength of the excited field is equal to the doubled bunch length. A simple physical model of the observed phenomenon is given. Also, the paper proposes a method for accelerating a part of each electron bunch in the steady-state mode of the resonator dielectric structure. Some of the electrons are “cut out” by the collimator and enter the accelerating phase of the previously excited wake wave. The wave is displaced due to the difference in the distances traveled by the wave and the accelerated part of the electrons.

Effect of ionization waves on dust chain formation in a DC discharge

An interesting aspect of complex plasma is its ability to self-organize into a variety of structural configurations and undergo transitions between these states. A striking phenomenon is the isotropic-to-string transition observed in electrorheological complex plasma under the influence of a symmetric ion wake field. Such transitions have been investigated using the Plasma Kristall-4 (PK-4) microgravity laboratory on the International Space Station. Recent experiments and numerical simulations have shown that, under PK-4-relevant discharge conditions, the seemingly homogeneous direct current discharge column is highly inhomogeneous, with large axial electric field oscillations associated with ionization waves occurring on microsecond time scales. A multi-scale numerical model of the dust–plasma interactions is employed to investigate the role of the electric field in the charge of individual dust grains, the ion wake field and the order of string-like structures. Results are compared with those for dust strings formed in similar conditions in the PK-4 experiment.

Comment to the paper I. Papp et al.: Laser wake field collider [Phys. Lett. A 396 (2021) 127245

• The proposal of Papp et al. (2021) [1] to use laser wake field for ion acceleration is wrong because only electrons can be accelerated this way. • The probability of fusion reaction in counter propagating beams is so small that no energy surplus can be obtained. • Even if all colliding ions will fuse, the energy gain of ∼20 MeV per colliding pair is 500 times smaller than the energy of two colliding ions of 10 GeV. • The numerical simulations of the proposal do not show either laser wake field generation or ion acceleration.

Delayed detached eddy simulation method for breaking bow waves of a surface combatant model with different trim angle

Sailing attitudes vary with different loading conditions for ships sailing in open sea, and the trim angle, either by bow or by stern, exerts considerable impact on the flow field around the ship. Currently, attention has primarily been focused on hull resistance and wave patterns while few studies have touched upon breaking bow wave under different trim conditions. This study aims to analyze the breaking bow wave of a surface combatant model with a length of 5.72 m DTMB (name of a surface combatant model) under different sailing attitudes at Fr = 0.35. The Delayed Detached Eddy Simulation (DDES) approach was adopted to study the breaking bow wave features such as plunging jet and air entrainment. The interface-compression algebraic Volume Of Fluid (VOF) method in OpenFOAM was used to capture the free surface. The Computational Fluid Dynamics (CFD) approach was firstly validated by comparing hull resistance and wave contour with the available experimental data. The study then delves into the influence of trim angles on breaking bow waves through simulations of the different conditions, i.e., 1 deg trim by bow, test condition and 1 deg trim by stern. The wave contour, breaking wave profile, vorticity field and the wake field at several transverse sections are then compared in three trim conditions, followed by an analysis of the initial evolution of bow wave breaking based on the turbulent kinetic energy and the vorticity field at four cross sections. The results suggest that trim by bow makes free surface sharper and wave amplitude larger in the breaking bow wave region. The reason is that trim by bow enlarges the attack angle of the bow, thus energizing the bow wave and generating a more violent free surface of bow wave breaking.

Effect of piezoelectric material on vibration of vessel of marine transportation

The drive arrangement of normal marine vessels involves a propeller coupled to a progression of shafts and diary orientation which is at last associated with a push bearing which sends the propeller pivotal power into the frame of the boat through a push block coupled to the mass head. For effortlessness, the framework is improved to a propeller, a solitary shaft, diary bearing and a push bearing. As the vessel travels through the sea, a wake is produced. This non-uniform wake field is the inflow to the propeller. The power produced by the propeller is additionally non-uniform. The impetus arrangement of a marine vessel is the principle supporter of commotion emanated from the vessel. It is along these lines important to diminish the commotion sent from the propeller into the sea and consequently the vibration that is created by the propeller that is thus communicated into the body. The inspiration for lessening commotion and vibration remembers diminishing mechanical wear for segments, expanding secrecy limit of military vessels, improving traveler and group solace, and decreasing the effect on marine conditions. The point of this theory is to dissect the shaky power created by the propeller, the power transmission ways, and techniques to quantify the power transmission through the push bearing continuously.

A curved surface representation method for convolutional neural network of wake field prediction

The goal of this study is to develop a prediction method to recognize the wake field behind a ship using a convolutional neural network (CNN) model. First, a new representation method for a 3D curved surface is proposed suitable for the CNN, called an image-based hull form representation (IHR). The advantages of the proposed method are the high fidelity of its hull form representation using more than 20,000 input data points and its fast prediction speed, which requires less than 0.01 s for a task that traditionally took more than an hour to estimate by physics-based simulation. The IHR regards that a two-dimensional grid formed on the 3D curved hull surface, which is used for structured-grid-based CFD, as a data set with the same data structure as the image data. Because CNNs recognize image data at accuracy rates higher than humans, a CNN is also be expected to recognize 3D surface characteristics with higher accuracy than humans. The image data are represented by three primary colors (cyan, magenta, yellow) in vertical and horizontal (i × j) pixels. The hull-form-structured grid can also be expressed as an i × j structure data with (x, y, z) coordinates that have the same data structure as the three primary colors in the image data. A CFD calculation data set of 2730 ship types with different stern shapes was constructed to verify the proposed method. The validation results proves that the root mean squared error of the proposed model is 0.005 to predict axial wake velocity on a propeller plane, and the coefficient of determination R2 achieves 0.986. In addition, the estimation speed for each hull-form prediction is 100,000 times faster than are physics-based simulations. The results lead to the conclusion that the representation method of a curved surface and the proposed prediction method of the stern wake field is a promising tool in the initial hull form design.

Analysis of Trailing Vortex Structure and Turbulent Features of High-Speed Train in Vacuum Pipeline

Through the improved delay-detached eddy simulation (IDDES), this paper establishes a 1:1 model for a high-speed train, and simulates the transient state of the train running 600km/h in a vacuum pipeline with the pressure of 1,000Pa. The results show that, following the Ω criteria, a pair of counterrotating vortexes can be captured, which alternatively shed near the tip of the last carriage, and propagate over a long distance along the flow direction. The motion and expansion of the vortexes are clearly three-dimensional (3D). Judging by the physical meaning of vortexes, the high vorticity vortexes mainly concentrate near the tip of the last carriage, while the low vorticity vortexes scatter across the wake zone. The latter vortexes have a low dissipation rate and are dominated by rotation. The turbulent energy and Reynolds stress of the wake field are very obvious near the tip of the last carriage, and attenuate quickly along the flow direction. This means the vortexes near the tip of the last carriage face a strong shear effect, and undergo apparent dissipation. Low turbulent energy and Reynolds stress are distributed in the downstream far from the tip of the last carriage, i.e., the interaction zone between vortexes and the ground / inner pipe wall.

The mean wake model and its novel characteristic parameter of H-rotor VAWTs based on random forest method

Using the random forest (RF) algorithm, this study presented a key parameter to characterize the mean wake of H-rotor VAWTs while modelling the wake. First, the RF algorithm was used to establish the regression relationship between the average wake velocity distribution and the rotor features. Next, the feature crosses method was combined with the RF algorithm to analyze the interaction and importance of the inputs. It was found that the normalized importance of a synthetic feature in wake modelling occupied a considerable significance, reaching 0.884 out of 1. The RF wake model with this parameter as the only input feature could successfully reconstruct the wake. It was found that this feature may reflect the ability of incident wind passing through the operating rotor and played a decisive role in the wake velocity distribution, including initial velocity deficit and wake recovery rate. The universality of this parameter was proved through cases analysis of wind turbines under different sizes and operating conditions. The study of the wake field is important for the modelling of the H-rotor VAWT wake field, and hence affects the optimal configuration of the wind farm.

Equilibrium of an arbitrary bunch train with cavity resonators and short range wake: Enhanced iterative solution with Anderson acceleration

This paper continues the work of two previous treatments of bunch lengthening by a passive harmonic cavity in an electron storage ring. Such cavities, intended to reduce the effect of Touschek scattering, are a feature of fourth generation synchrotron light sources. The charge densities in the equilibrium state are given by solutions of coupled Ha\"issinski equations, which are nonlinear integral equations. If the only wake fields are from cavity resonators, the unknowns can be the Fourier transforms of bunch densities at the resonator frequencies. The solution scheme based on this choice of unknowns proved to be deficient at the design current when multiple resonators were included. Here we return to the conventional formulation of Ha\"issinski equations in coordinate space, the unknowns being charge densities at mesh points on a fine grid. This system would be awkward to solve by the Newton method used previously, because the Jacobian matrix is very large. Here a new solution is described, which is both Jacobian-free and much simpler. It is based on an elementary fixed point iteration, accelerated by Anderson's method. The scheme is notably fast and robust, accommodating even the case of extreme over-stretching at current far beyond the design value. The Anderson method is promising for many problems in accelerator theory and beyond, since it is quite simple and can be used to attack all kinds of nonlinear and linear integral and differential equations. Results are presented for ALS-U, with updated design parameters. The model includes harmonic and main r.f. cavities, compensation of beam loading of the main cavity by adjustment of the generator voltage, and a realistic short range wake field (rather than the broad-band resonator wake invoked previously).

An experimental investigation into model-scale installed jet–pylon–wing noise

A model-scale experimental investigation of an installed jet–pylon–wing configuration was conducted at the University of Southampton, with the scope to study the effect a pylon has on noise generation and to clarify its impact on the fluctuating wall-pressure load. The set-up consisted of two single-stream nozzles, a baseline axisymmetric annular nozzle and a partially blocked annular pylon nozzle. The nozzles were tested first isolated and then installed next to a NACA4415 aerofoil ‘wing’ at a single nozzle–wing position. The jet Mach number was varied between $0.5 \leq M_{{j}} \leq 0.8$ and measurements were performed both under static and in-flight ambient flow conditions up to ${M_{{f}} = 0.2}$ . The jet flow-field qualification was carried out using a single-velocity-component hot-wire anemometer probe. The pressure field on the wing surface was investigated using two miniature wall-pressure transducers that were flush-mounted in the streamwise and spanwise directions within the pressure side of the wing. A linear ‘flyover’ microphone array was used to record the noise radiated to the far field. The unsteady pressure data were analysed in both time and frequency domains using multi-variate statistics, highlighting a far-field noise reduction provided by the presence of the pylon only in the installed case. Furthermore, the wake field generated behind the pylon is seen to significantly modify the wall-pressure fluctuations, particularly at streamwise locations close to the pylon trailing edge.

Determining Actuator Requirements for Cyclic Varying Pitch Propeller for Ships

In marine applications, a cyclic varying pitch (CVP) propeller is a propeller in which the propeller blade can be cyclic-pitched. This cyclic pitching of the propeller blades is used to adapt to the local flow conditions in the non-uniform wake field that the propeller operates in, behind the ship hull. This has the potential to improve the performance of the propulsion system relative to a propeller which has fixed pitch for each revolution. The potential performance improvements include increasing the propulsion efficiency and reducing the cavitation, pressure pulses, vibrations and noise problems. However, the CVP propeller is not on the market today, and several challenges have to be addressed before the CVP propeller may be realized. One of these challenges is how to design the individual cyclic pitch mechanism for the propeller. However, before the cyclic pitch mechanism can be designed, it is necessary to know the requirements for it, such as the required pitching power and torque. The focus of the current paper is therefore to present a model for the propeller, by which it is possible to determine the loads acting on the CVP propeller blades during the cyclic pitching, and hence the actuator force/torque and power requirements. To illustrate the usefulness of the model, an example is presented, in which the loads on a CVP propeller are determined, together with the requirements for the individual cyclic pitch mechanism. The efficiency results presented are, however, not representative of the efficiency improvement that may be obtained, as neither the propeller nor the pitch trajectory has been optimised. The results do, however, serve to show the benefit and validity of the model.

Experimental study on the characteristics of wind turbine wake field considering yaw conditions

AbstractThis paper explores the wake of a wind turbine yaw and its influence on the output power of the downstream wind turbine. A wind turbine model (hub height and diameter of 1.2 m and 1.0 m, respectively) was used in the experiments, and the yaw angle of the upstream wind turbine was successively varied through values of 0°, 15°, and 30°. The wind speed and the intensity of turbulence in the wake region were measured using a hot‐wire anemometer. The measuring positions were changed to 3, 5, and 7 rotor diameters behind the upstream wind turbine. In addition, the output power of the downstream wind turbine model was measured using the rotational speed torque meter. The results show that, in the case of large‐angle yaw of the upstream wind turbine, the recovery of the wind speed in the wake area was greatly improved, and up to 30% recovery was achieved. The power output of the downstream wind turbine was also significantly increased. Under the yaw conditions of 15° and 30° for the upstream wind turbine, the average output power of the downstream wind turbine increased by 17.6% and 21.6%, respectively.

Wake field, impedance and collective instability

The first mention of the impedance concept appeared on November 1966 in the CERN internal report Longitudinal instability of a coasting beam above transition, due to the action of lumped discontinuities by V.G. Vaccaro. Then, a more general treatment of it appeared in February 1967 in the CERN yellow report Longitudinal instabilities of azimuthally uniform beams in circular vacuum chambers of arbitrary electrical properties by A.M. Sessler and V.G. Vaccaro. The concept of wake field came two years later, in 1969, in the paper The wake field of an oscillating particle in the presence of conducting plates with resistive terminations at both ends by A.G. Ruggiero and V.G. Vaccaro. This was the beginning of many studies, which took place over the last five decades, and today, impedances and wake fields continue to be an important field of activity, as concerns theory, simulation, bench and beam-based measurements. Building a reliable impedance or wake field model of a machine is the first necessary step to be able to evaluate the machine performance limitations, identify the main contributors in case an impedance reduction is required, and study the interaction with other mechanisms such as optics nonlinearities, transverse damper, noise, space charge, electron cloud, beam-beam (in a collider), etc. Beam collective instabilities, and their mitigation, cover a wide range of effects in particle accelerators and they have been the subjects of intense research. As the machines performance was pushed new mechanisms were revealed and nowadays the challenge consists in studying the interplays between all these intricate phenomena, as it is very often not possible to treat the different effects separately. With the increasing power of our computers this becomes easier but the need to continue and develop theories remains, to have a better understanding of the interplays between all these effects: the subject of impedance and beam instabilities in particle accelerators is far from being exhausted, as testified by the many new instability and stabilizing mechanisms which have been recently explained or discovered. Furthermore, in the context of the studies for possible future accelerators, some uncharted territories remain such as, for instance, the collective instabilities during the necessary ionization cooling for a muon collider.

Numerical Investigation of the Shallow Water Effect on the Total Resistance, Vertical Motion and Wave Profile of a Container Ship Model

A ship sailing in shallow water is affected by the interaction between the moving hull and the seabed in different forms such as: significant increase in total resistance, increase in the sinkage and trim that may result in squatting effect, a change in wave pattern and increased wave amplitude, a change in the propeller wake field and an altered propeller and manoeuvring performance. In order to investigate the influence of shallow water on a container ship that is assumed to be subjected to work in different water depths, the KRISO container ship model is analysed in both deep and shallow water, with a special focus on the change in resistance, vertical motion and wave profile. A viscous flow simulation is performed first to predict the ship performance in deep water and the results are compared with the experimental data that are available in the public domain. Then, the critical shallow water condition is investigated and the obtained results are compared against those formerly obtained in deep water. The numerical simulations are performed using the viscous flow solver ISIS-CFD of the FINETM/Marine software provided by NUMECA. The solver is based on the finite volume method to build the spatial discretization of the transport equation in order to solve the Reynolds-Averaged Navier-Stokes (RANS) equations. Closure to turbulence is achieved using the Menter Shear Stress Transport (K-ω SST) model, while the free-surface is captured through an air-water interface based on the Volume of Fluid (VOF) method. The comparison between the numerically obtained results and the available EFD data showed a satisfactory congruence.

CFD analysis of a multiplatform catamaran by means of a web-based application: Experimental data comparison for a fully automated analysis process

The recently introduced LincoSim Web Based High Performance Computing (HPC) Cloud Platform for Automatic Virtual Towing Tank Analysis, which is based on open-source Reynolds Averaged Navier-Stokes (RANS) solvers (Salvadore & Ponzini, 2019), is herein applied to the hydrodynamic assessment of a catamaran vessel. An experimental data campaign was used to assess the effect of the demihull separation distance on the catamaran's resistance for a given demihull shape. The results of the comparison between the experimental and the automatically generated numerical ones are presented and discussed in the present work. The comparison is quite rich including data for a reference monohull, three demihull separations and two displacements conditions, each with the Froude number ranging from 0.145 to 0.904. The set of the experimental data acquired for the model scaled catamaran are the total resistance, the sinkage and the dynamic trim. Nevertheless, also the wave fields at three given locations are considered in the towing tank experiments in order to assess not only the effect on the hull, but also on the catamaran's wake field. The agreement between computational and experimental quantities is good for both the hull-related and flow-related ones, confirming the ability of the developed automated tool to discern between favorable and detrimental fluid dynamic conditions and to efficiently rank performances also for multihulls. Notably, thanks to the availability of numerical data for both model and full scale, also the effectiveness of the extrapolation process has been assessed.

LiDAR and SCADA data processing for interacting wind turbine wakes with comparison to analytical wake models

This study is a follow up on a previous one carried out within the frame of the French project SMARTEOLE, during which, a ground-based scanning LiDAR measurement campaign was conducted in the onshore wind farm of Sole du Moulin Vieux. That previous study focused on the wakes of two wind turbines that experienced different degrees of interaction depending on the incoming wind direction, through the processing of LiDAR measurements. The measurement duration (7 months) ensured the statistical convergence of the ensemble-averaged flow fields obtained after holding a categorisation process based on the wind speed at hub height, wind direction, and atmospheric stability, where only near-neutral stability conditions were considered. The present study focuses on integrating the operational data of the wind turbines through SCADA processing to complement the LiDAR wake field observations and to be used as an input for analytical wake models. First, the correlation between the atmospheric stability, deduced from MERRA-2 dataset, and the free-stream turbulence intensity, measured by the wind turbines’ anemometers, is studied for different wind speed ranges. It is observed that the turbulence intensity tends towards a consistent value as the atmospheric stability approaches near-neutral stability conditions, giving confidence into the applied strategy of data categorisation based on MERRA-2 outputs. The influence of the degree of wake interaction on the wake added turbulence, the velocity and power deficits between both turbines is assessed. Clear trends between the wake added turbulence and both the velocity and power deficits are detected. Consequently, two fitting laws are proposed. Then, different analytical wake models and wake superposition methods are fed with the operational data deduced from the processed SCADA data, and are used for predicting the evolution of the velocity deficit within the wake. Some statistical metrics are used for error quantification of the different engineering wake models compared to the scanning LiDAR measurements, used as reference, and Blondel and Cathelain produces the closest results to the field measurements.

Probabilistic estimation of the Dynamic Wake Meandering model parameters using SpinnerLidar-derived wake characteristics

Abstract. We study the calibration of the Dynamic Wake Meandering (DWM) model using high-spatial- and high-temporal-resolution SpinnerLidar measurements of the wake field collected at the Scaled Wind Farm Technology (SWiFT) facility located in Lubbock, Texas, USA. We derive two-dimensional wake flow characteristics including wake deficit, wake turbulence, and wake meandering from the lidar observations under different atmospheric stability conditions, inflow wind speeds, and downstream distances up to five rotor diameters. We then apply Bayesian inference to obtain a probabilistic calibration of the DWM model, where the resulting joint distribution of parameters allows for both model implementation and uncertainty assessment. We validate the resulting fully resolved wake field predictions against the lidar measurements and discuss the most critical sources of uncertainty. The results indicate that the DWM model can accurately predict the mean wind velocity and turbulence fields in the far-wake region beyond four rotor diameters as long as properly calibrated parameters are used, and wake meandering time series are accurately replicated. We show that the current DWM model parameters in the IEC standard lead to conservative wake deficit predictions for ambient turbulence intensities above 12 % at the SWiFT site. Finally, we provide practical recommendations for reliable calibration procedures.

Predicting the Radiated Noise of a Submarine Propeller with Different Types of Control Surfaces

_ The objective of this paper is to predict the noise radiated from submarine propellers with different control surface types (the cross- and X-type). When the propellers are free from cavitation, such as those of submarines at a diving depth, the radiated noise dominate, due to unsteady propeller forces. A well-known submarine model (DARPA SUBOFF) is taken as the computing sample. Simulations for hydrodynamics, including stern wakes and unsteady propeller forces, are carried out by using CFD (Computational Fluid Dynamics) technology, and the results are compared with the experimental data. The accuracy of the predicted noise depends on the CFD results. Comparisons between the CFD results and the experimental data are in good agreement. The CFD results are treated as dipole strengths in the linear wave theory to predict the radiated noise caused by the unsteady forces of the propeller. It is found that, when the control surface is of the X-type, the propeller inflow is more uniform, and the radiated noise can be decreased by about 5 dB compared to the cruciform control surface. Introduction When submarines are at diving depth, the noise generated by unsteady propeller forces (i.e., dipole strengths) will dominate. Because the juncture vortex caused by the sail makes the propeller inflow more nonuniform, the dipole strength will be enhanced and the radiated noise will be more noticeable. The uniformity of the wake field at the stern should be controlled well in order to restrain the radiated noise.

On the performance improvement of a flutter based energy harvester by introducing additional wake field

ABSTRACT This work experimentally investigates dynamics of flutter oscillation of a plane structure under the presence of an additional wake field and is motivated to improve performance of a flutter based energy harvester. Flutter instability is a potential future source to harvest abundant ambient energy, although, such harvesters are still in developing stage due to requirement of a flow velocity higher than the available ambient wind speed. The present work primarily proposes a viable means to reduce the critical velocity of flutter and so enhance the efficiency of the flutter-based energy harvester. Here, two groups of experiments are conducted. First, the effect of wake from an upstream body on the flutter is studied, and then, energy harvesting performance, using piezoelectric elements, are analyzed. Moreover, to understand flow dynamics, numerical studies are also performed. Tests are performed in a wind tunnel and the vibrations are visualized by a high-speed camera and sensed by piezoelectric transducer. The results obtained confirm a notable reduction of critical velocity, an upstream bluff body of 20 mm reduces the critical velocity by 38% when compared with the original flutter speed of sheet alone. Inline to this, a higher output of 1.46 V/6.81 µW than 1.42 V/6.46 µW is observed. Computational study shows that circulation over the plane structure plays an important role and its downstream extension relates to the level of reduction of critical velocity.

Numerical investigation of tip-vortex cavitation noise of submarine propellers using hybrid computational hydro-acoustic approach

In this study, the hybrid computational hydro-acoustics (CHA) method is applied to predict hydrodynamic noise due to tip vortex cavitation (TVC) of underwater submarine propellers. The hybrid CHA approach consists of two sequential methods: Delayed Detached Eddy Simulation (DDES) technique with adaptive mesh refinement method and the Ffowcs Williams and Hawkings (FW–H) equation. The former is utilized for accurate prediction of TVC of underwater propellers, and the latter is used for efficient prediction of hydro-acoustic pressure due to cavitating flow. The target submarine and propeller are the DARPA suboff submarine and two high skew propellers with skew angles of 17 and 38°. The propellers are designed to investigate the effects of skew angle on TVC and its noise. The corresponding experiments are performed in the Large Cavitation Tunnel (LCT) of the Korea Research Institute of Ships and Ocean Engineering (KRISO). The two preliminary simulations are carried out to confirm the close reproduction of the experimental conditions in the main simulations. First, the flow through the LCT test section is simulated to confirm the accurate reproduction of the wall boundary layer. Its validity is confirmed by comparing the predicted boundary layer profiles with the measured results. Second, the flow over the DARPA suboff submarine without a propeller in the LCT test section is simulated to confirm the accurate prediction of the inflow distortion originating from the boundary layer flow of the submarine body. Its validity is also confirmed by comparing the predicted nominal wake field with the measured one. After the close reproduction of these two effects is confirmed, the cavitating flow of the propellers installed to the DARPA suboff submarine body is simulated by using the DDES technique combined with adaptive mesh refinement, and the TVC noise is predicted by applying the quadrupole-corrected FW-H equation to the surfaces enclosing the propellers. The predicted TVC of the propeller closely follows the measured one. The numerical and experimental results capture the TVC induced by the wake flows due to the submarine body's rudders and sail. The predicted hydro-acoustic pressure spectra due to the propellers' cavitating flow also show excellent agreements with the predicted ones. Besides, both the numerical and experimental results confirm that the lower noise is generated by the propeller with a higher skew angle.