Trim Control Research Articles

Hydrodynamic Analysis of Integrated Interceptor-Stern Flap for Trim Control on High-Speed Planing Vessel

Hydrodynamic Analysis of Integrated Interceptor-Stern Flap for Trim Control on High-Speed Planing Vessel

Analysis of the Impact of Disposal of Oil-Contaminated Ballast Water on Marine Pollution in MT. Bull Kangean

Abstract Ballast water refers to water containing substances, materials, or goods necessary for ship stability, trim control, list (tilt), or pressure. According to the shipping terms dictionary, ballast can also include waste or refuse stored on board. This study aims to analyze the environmental impact of oil-contaminated ballast water disposal on marine pollution in MT. Bull Kangean. Oil spills at sea typically occur due to two reasons: accidental leaks caused by damage to the ship hull or oil tanks (e.g., collisions with coral reefs or sunken objects), and deliberate discharge of used oil from manufacturing equipment, which can lead to environmental contamination and harm to areas designated for oil disposal. The research methodology involves collecting primary data through observations, interviews, and document reviews to understand the impact of oil-contaminated ballast water disposal on marine pollution. Qualitative descriptive methods are employed for data analysis. The findings of this research indicate that the disposal of oil-contaminated ballast water does result in marine pollution. Observations reveal that inadequate supervision by the deck crew regarding ballast water disposal leads to the mixing of oil with the water during the disposal process.

Trim Analysis and Structured H-Infinity Control of Wing-Docked Multibody Aircraft

A wing-docked multibody aircraft is a novel configuration being explored as a balanced solution between efficiency and structural resilience for very long-endurance aviation. The presence of wingtip hinges complicates the dynamics and control of this class of aircraft but has thus far only been analyzed in specific cases. In this work, we make a comprehensive exploration of parameter space of the multibody trim problem and stability and demonstrate the treatment of the control problem using the robust H∞ synthesis technique. We propose a simplified simulation approach to the static trim analysis and demonstrate key observations relating to the configurations and open-loop dynamic stability of multibody aircraft in general. An interpolated parameter-scheduling model using the hinge angle as a scheduling parameter is established, based on which the structured multimodel H∞ synthesis method is employed to synthesize the robust flight controllers. Simulation results show that the designed controllers are capable of configuration control within the range of possible trim solutions and have also achieved good control effectiveness in path following and disturbance rejection. The proposed trim analysis and control techniques serve to provide a systematic benchmark study on wing-docked multibody aircraft dynamics, which is valuable to the development of this research area.

First Report of Clover yellow vein virus Infecting Senna septemtrionalis (Arsenic bush).

Clover yellow vein virus (ClYVV) is a member of the genus Potyvirus, family Potyviridae and was reported to infect many plant species, such as Ammi majus L., Phaseolus vulgaris L., Vicia faba L., Lens culinaris L., Borago officinalis L., Cicer arietinum L., Gladiolous gandavensis L., Glycine max L., Trifolium repens L., and Dendrobium sp. (Irey et al. 2006; Ortiz et al. 2009; Park et al. 2014; Yoon et al. 2022). Senna septemtrionalis (Viv.) H.S.Irwin & Barneby (arsenic bush), a species in the subfamily Caesalpinioideae, is widely distributed in tropical and subtropical regions (Datiles et al. 2022). In June 2021, virus-like symptoms of mosaic, chlorosis, and leaf-curling were observed in arsenic bush in Kunming, Yunnan province, China. Symptomatic leaves were collected from four arsenic bush (SS1-4), and asymptomatic leaves were collected from 3 additional arsenic bush plants (SS5-7) (eXtra S1). To identify the putative causal virus, sap of symptomatic leaves (SS1) was stained with 1 % phosphotungstic acid and observed under a transmission electron microscope (TEM). Potyvirus-like particles (about 750-800 nm  13 nm) were observed from the sample (eXtra S1). Total RNA was extracted from sample SS1 using TRIzol Reagent (Invitrogen, USA) and subjected to the Illumina NovaSeq platform for RNA-Seq. After trimming and quality control of raw data, 24,125,963 high-quality clean reads were assembled into 72,835 Unigenes using Trinity software. BLAST searches indicated that the nucleotide sequence of Unigene c29731 (10,893 nt) and its deduced amino acid sequence shared 82.62% to 96.45% and 92.60% to 99.19% identity with several ClYVV isolates, respectively. Unigene c29731 had the highest coverage ratio (88%) and the highest nucleotide sequence identity (96.45%) with ClYVV isolate IA-2016 (GenBank accession No. MK292120.1). The complete genome of ClYVV SS1 isolate (ClYVV-SS, GenBank accession No. OP868578) was determined using RT-PCR and 5' and 3' rapid amplification of cDNA ends (RACE) (Chen et al. 2001). A total of 224,936 out of 24,125,963 reads were mapped to the ClYVV-SS1 genome, yielding an average depth of coverage of 3,056.823 (min=1, max=7,859) at nucleotides from 1 to 9,324 of ClYVV genome (eXtra S2). BLASTN results indicated that the complete genome of ClYVV-SS1 shared 96.45% nucleotide sequence identity and 99% coverage ratio with ClYVV isolate IA-2016 genome. Phylogenetic analysis showed that ClYVV-SS1 and other ClYVV isolates clustered together (eXtra S2). RT-PCR was performed on samples (SS2-7) using a pair of primers of the coat protein gene (5'- TCCGACAAAGATAAGTTGAATGCTGGTG-3' and 5'-GAATCGTGCTCCAGCAATGTGA-3') designed from multiple sequences alignment (MSA). Using SS1 sample as positive control, amplicons of ~813 bp were obtained from three symptomatic samples (SS2-4) but not the asymptomatic ones (SS5-7). A total of 17 of 20 arsenic bushes developed symptoms of mosaic and leaf-curling approximately two weeks after mechanical inoculation with arsenic bush (SS1) sap, with 10 uninoculated plants used as control (eXtra S1). RT-PCR was performed for all tested plants. 17 symptomatic arsenic bushes tested positive for ClYVV, while all other samples tested negative. This confirmed that the symptomatic arsenic bushes were infected with ClYVV. To our knowledge, this is the first report of ClYVV infecting arsenic bush.

Numerical Investigation of Interceptor Bulb to Improve Trim Control

Numerical Investigation of Interceptor Bulb to Improve Trim Control

Numerical Investigation of Extended Stern to Reduce Resistance of Planing Hull

The attributes of a high-speed vessel depend on various factors, such as trim angle, speed, center of gravity, and deadrise angle. The ship's trim angle will affect the ship's drag performance. Attempts to control trim have been made by adding stern appendages and modifying the hull. This study aims to analyze the performance of deep-V planing-hull ship drag by modifying the ship's stern. The stern modification investigation was carried out by adding length to the stern based on angles of 100, 200, and 300. This investigation evaluates resistance, trim, and heave while ignoring changes in ship displacement. The prediction of resistance and ship movements was simulated using the Reynold Averaged Navier-Stokes (RANS) equations to solve the problem. Numerical simulation applied the Computational Fluid Dynamics (CFD) based on finite volume method with an overset of techniques. Validation studies ensured numerical simulations have good accuracy based on comparisons with experimental model tests conducted by previous researchers. The pressure distribution caused by the extended stern affected the ship's drag, further demonstrating a better trim control. The results of the stern modification simulation revealed that the resistance was reduced at Fr 0.58–0.87. Extended sterns with an angle of 30° indicated the best results, with a resistance reduction percentage of 26% at Fr 0.58. However, drag increased at Fr speeds > 1.45 as the ship's speed increased.

Numeričko istraživanje utjecaja zakrilaca krmenog praga na hidrodinamičke performanse glisiranja

The trim tab and interceptor have been utilized to optimize the running trim and motion control of planing boats at varying speeds in calm water. Increasing the height of the interceptor can create excessive drag and bow-down trim. The effectiveness of the interceptor can be increased by integrating it with a horizontal flap. This research focuses on the impact of the influence caused by interceptor flaps on the pressure distribution and fluid flows around the vessel. To simulate trim and sinkage measurement, the environment was modeled in the two-degree of freedom condition. Variation of integrated interceptor flaps has been analyzed with Finite Volume Method (FVM) based on RANS (Reynolds-Averaged Navier-Stokes) equation using overset mesh. The turbulent K- ε and VOF (Volume of Fluid) models are used to model the water and air phases. The grid convergence study is performed to establish the parallel solver’s grid independence. To confirm the accuracy of the test in the bare hull condition, the numerical approach was tested experimentally. The result of drag, trim, and sinkage was calculated and it has been proved that the added flaps into interceptors are very useful in drag reduction and trim control. The percentage of interceptor height is directly proportional to the resulting lift force. Higher lift force can more effectively improve trim and reduce drag. Overall, this study shows an improvement in ship performance when using an interceptor and interceptor flap. One of the model configurations in the study has been shown to reduce drag by up to 33.3% at Froude number 1.45 when compared to ships without an interceptor.

Using trim Control to Improve energy Efficiency on High-Speed Marine Vehicles (HSMV): A Review

Using trim Control to Improve energy Efficiency on High-Speed Marine Vehicles (HSMV): A Review

Reinforcement Learning Based Aircraft Controller Enhanced By Gaussian Process Trim Finding

Abstract This work presents mathematical and practical frameworks for designing deep deterministic policy gradient (DDPG) flight controllers for fixed-wing aircraft. The aim is to design reinforcement learning (RL) flight controllers and accelerate training by substituting the six degrees-of-freedom aircraft models with linear time-invariant (LTI) dynamic models. The initial validation flight tests of the DDPG RL flight controller exhibited poor performance. Post-flight test investigation revealed that the unsatisfactory performance of the RL flight controller could be attributed to the high reliance of the LTI model on accurate control trim values and the substantial errors observed in the predicted trim values generated by the engineering-level dynamic analysis software. A complementary real-time learning Gaussian process (GP) regression was designed to mitigate this critical shortcoming of the LTI-based RL flight controller. The GP estimates and updates the trim control surfaces using observed flight data. The GP regression method incorporates real-time corrections to the trim control surfaces to enhance the performance of the flight controller. Flight test validation was repeated, and the results show that the RL controller, bolstered by the GP trim-finding algorithm, can successfully control the aircraft with excellent tracking performance.

Stealth performance evaluation of helicopter against airborne early warning radar considering trimming control

Airborne pulse Doppler radar is a key threat to the military helicopter, and assessing the stealth performance of helicopter against airborne early warning radar is helpful to the helicopter’s stealth design and operational planning. In this paper, the Shooting and Bouncing Ray (SBR) and Uniform Theory of Diffraction (UTD) based high-frequency algorithms are used to calculate the Radar Cross Section (RCS) of helicopter, and the radar range equations are used to evaluate the stealth performance. In order to account for the effects of rotor flapping motions during actual flight, the aerodynamics model of whole helicopter is established and the attitudes and controls of helicopter at different flight states are trimmed and input into the RCS calculation module. The effects of helicopter flight speed, flying direction and operational environment on radar stealth performance are studied in focus. It is demonstrated by the results that the trimming control does have a great influence of more than 5 dB on the RCS of helicopter, and the introduction of the trim calculation brings the helicopter’s returns calculation closer to the reality. Variations in flight speed lead to the changes in the stealth performance of helicopter against Early Warning Aircraft (EWA), and the helicopter flight speed can be planned according to the operational requirements to minimize exposure distance or exposure time. Variations in flying direction mainly affect the detection properties of helicopter returns, and flying in the same direction with EWA usually gives the helicopter better low-observability than flying head-on. Variations in operational environment mainly affect the radar detection performance and the sensitivity of the detection performance to external factors; the same amount of change in some external factor causes a different amount of change in the helicopter’s detectability in different environments.

Joint optimisation for improving ship energy efficiency considering speed and trim control

Operational optimisation is one of the most important methods for reducing energy consumption and emissions related to ships. In this study, a speed-trim joint optimisation method is proposed. First, the propulsion power for various operating conditions was estimated by numerical simulation, two-dimensional method, and ship-engine-propeller principle. Second, the obtained data, consisting of ship power, draft, trim angle, and speed, were further expanded to form a joint optimisation decision database using the artificial neural network method. Subsequently, a dynamic programming algorithm was used to calculate the optimal speed for each segment of the voyage. The optimal trim angle corresponding to the speed was obtained based on the joint optimisation decision database. Finally, a 7500 ton inland bulk carrier was chosen as the case ship to validate the proposed method. The results showed that the method could reduce the total ship power consumption by up to 7.64%.

CFD based prediction on hydrodynamic effects of Interceptor and flap combination on planing hull

It has been a continuous effort for long years by high-speed vessel designers to achieve its optimal hydrodynamic performance. Few studies were made on the impact of interceptor and flap combination on high speed hulls in recent years. Interceptors are blades which extend vertically downwards at the transom of the vessel and a flap is attached to its end. The installation of interceptor near the vessel transom a change in pressure distribution around the hull and more significantly observed at the transom. The present study investigates on the hydrodynamic quality of 20deg deadrise high-speed planing hull mounted with interceptor-flap combination using computational fluid dynamics (CFD). Planing hull model was analyzedusing CFD based Finite Volume method with dynamic mesh. The height of the interceptor and angle of flap plays an important role on the efficiency of the vessel. Experiments were carried out in the towing tank at Indian Institute of Technology Madras for the planing hull and CFD studies were extended with interceptor-flap. The validation studies serve to authenticate the use of the interceptor on the basis of comparison with simulations using model tests. The pressure variation that is caused due to integrated interceptor-flap has an effect on the resistance of the vessel which further showed better control of trim. The numerical study on planing hull with interceptor-flap showed an increased waterline length which leads to reduced Froude number. The hydrodynamically improved underwater form was observed leading to resistance reduction of upto 25% on the vessel and significant reduction of trim upto 57% at the design speed.

INTERCEPTOR EFFECTS ON A 3D RECTANGULAR PLATES IN A CALM WATER BY USING COMPUTATIONAL FLUID DYNAMICS (CFD)

Interceptor is an additional device designed to improve boat efficiency by altering its running attitude. Interceptors are recently used for trim control during the boat’s trip which give a significant reduction in water resistance, resulting in improved efficiencies. This paper focused on the hydrodynamics effects on resistance and trim of 3D rectangular plate in addition of interceptors in calm water by using CFD. Investigation has been carried out by using OpenFoam code. The results of this study meet a good agreement with most of previous works related to interceptor’s study. This study found that Angle of Attack (AoA) employment at the interceptor with typical blade depth height shows better lift to drag ratio in comparison with interceptor without AoA employment. Moreover, those configurations also produced better trim angle reduction which resulting better running attitude. This study also shows that the efficiency of the interceptor is related to the boundary layer thickness.

EVALUATION OF INTERCEPTOR DESIGN TO REDUCE DRAG ON PLANING HULL

A planing hull is a high-speed craft with relatively complex hydrodynamic characteristics. An increase in speed can induce a significant change in trim angle with an increment in ship drag. One solution to reduce ship resistance is to use an interceptor. This research aimed to analyze the hydrodynamics of a planing hull vessel by applying an interceptor. The fundamental aspects reviewed included the analysis of drag, trim, heave, and lift force. The interceptor would be investigated on the basis of its integrated position at its height. This research also used the computational fluid dynamic (CFD) method in calm water conditions. All simulations were conducted with the same mesh structure, which allowed the performance evaluation of the interceptor in calculating turbulent air–water flow around the ship. Numerical calculations used the Reynolds-averaged Navier–Stokes (RANS) equation with the k–ε turbulence model to predict the turbulent flow. The vertical motion of the ship was modeled using dynamic fluid–body interaction (DFBI) in the fluid domain through an overset mesh technique. The numerical approach was compared with the experimental test results of Park et al. to ensure the accuracy of the test results. The interceptor was designed at the transition phase, which showed the highest trim angle followed by high drag. The interceptor would experience negative trim at high speeds; thus, it was not recommended. The research results indicated that the most effective use of the interceptor was at Froude number 0.87 close to the chine position with a height of 100%. This interceptor could reduce a maximum of 57% drag, 17% heave, 8.48% trim, and 0.12% lift force. The interceptor could increase excessive drag and trim at Froude numbers over 1.16. The interceptor proved to be remarkably useful in trim control and ship drag reduction, but selecting the wrong dimensions and positions of the interceptor could endanger the ship. This simulation was performed on Aragon-2; thus, the interceptor performance may possibly change if a different hull geometry is used.

Ship Bow Wings with Application to Trim and Resistance Control in Calm Water and in Waves

Flapping foils for augmenting thrust production have drawn attention as a means of assisting ship propulsion in waves due to their high efficiency rate compared to traditional screw propellers. However, they can also offer substantial resistance reduction when used as stabilizers. In this work, the aim is to investigate the feasibility of a symbiotic concept combining the ship’s propeller with a foil arranged at the ship’s bow at a fixed position operating as a trim-pitch stabilizer. The work presents results obtained from experiments conducted in the towing tank of the Laboratory of Ship and Marine Hydrodynamics of the National Technical University of Athens (LMSH NTUA), as well as results from an in-house CFD solver. The test cases focused on the resistance and the dynamic behavior of the wing–vessel configuration in calm water conditions and in head waves. All results were compared against the performance of a bare hull (without foil). The findings of this work are based both on numerical and experimental data and indicate that a bow wing in static mode can be used for trim-control of a vessel by altering the angle of attack leading to a possible drop in wave resistance both in calm water and in waves. In the latter case, utilizing the wing in head waves results in a significant reduction in the pitching and heaving responses of the vessel, which may lead to substantial enhancement of the propulsion performance.

Nonlinear Aeroelastic Analysis for Highly Flexible Flapping Wing in Hover

Aeromechanics of highly flexible flapping wings is a complex nonlinear fluid–structure interaction problem and, therefore, cannot be analyzed using conventional linear aeroelasticity methods. This paper presents a standalone coupled aeroelastic framework for highly flexible flapping wings in hover for micro air vehicle (MAV) applications. The MAV-scale flapping wing structure is modeled using fully nonlinear beam and shell finite elements. A potential-flow-based unsteady aerodynamic model is then coupled with the structural model to generate the coupled aeroelastic framework. Both the structural and aerodynamic models are validated independently before coupling. Instantaneous lift force and wing deflection predictions from the coupled aeroelastic simulations are compared with the force and deflection measurements (using digital image correlation) obtained from in-house flapping wing experiments at both moderate (13 Hz) and high (20 Hz) flapping frequencies. Coupled trim analysis is then performed by simultaneously solving wing response equations and vehicle trim equations until trim controls, wing elastic response, inflow and circulation converge all together. The dependence of control inputs on weight and center of gravity (cg) location of the vehicle is studied for the hovering flight case.

LOADING RESPONSE OF STERN TAB MOTION CONTROLS IN SHALLOW WATER

The ride control systems of high-speed vessels frequently use active stern tabs for both motion control and maintenance of correct trim at various speeds and sea conditions. This paper investigates the effect of water depth on the lift force provided by stern mounted trim tabs, of the type fitted to INCAT high speed wave-piercer catamaran vehicle ferries and similar vessels. This investigation was carried out at model scale with the use of a test apparatus in a flume tank in the University of Tasmania hydraulics laboratory. The lift force magnitude and location were measured over a range of tab angles and flow depths. This was used to calculate the lift coefficient of the tab and asses the performance of the tab over the range of flow depths. It was found that the lift force increased and the force location progressed further forward of the hinge as flow depth decreased. The lift curve slope of the stern tab increased by a factor of over 3 relative to the deep water value when the water depth below the hull was approximately equal to the tab chord. The deep water lift curve slope appears to be approached only when the water depth exceeded 4 or more tab chord lengths. The centre of pressure of the lift force was more than two chord lengths ahead of the tab hinge, showing that most of the lift produced by the tab was under the hull rather than on the surface of the tab itself.

A trim problem formulation for maximum control authority using the Attainable Moment Set geometry

This paper presents a generic trim problem formulation, in the form of a constrained optimization problem, which employs forces and moments due to the aircraft control surfaces as decision variables. The geometry of the Attainable Moment Set (AMS), i.e. the set of all control forces and moments attainable by the control surfaces, is used to define linear equality and inequality constraints for the control forces decision variables. Trim control forces and moments are mapped to control surface deflections at every solver iteration through a linear programming formulation of the direct Control Allocation algorithm. The methodology is applied to an innovative box-wing aircraft configuration with redundant control surfaces, which can partially decouple lift and pitch control, and allow direct lift control. Novel trim applications are presented to maximize control authority about the lift and pitch axes, and a “balanced” control authority. The latter can be intended as equivalent to the classic concept of minimum control effort. Control authority is defined on the basis of control forces and moments, and interpreted geometrically as a distance within the AMS. Results show that the method is able to capitalize on the angle of attack or the throttle setting to obtain the control surfaces deflections which maximize control authority in the assigned direction. More conventional trim applications for minimum total drag and for assigned angle of elevation are also explored.

Identifikasi Pemeliharaan Vertical Garden di Fairmont Sanur Beach Bali

Maintenance Identification on Vertical Garden at Fairmont Sanur Beach Bali. Fairmont Sanur Beach Bali has a vertical garden with an area of 10 m x 4 m. The Hotel is able to maintain the plant condition. The purpose of this research is to identify the vertical garden maintenance system at the Fairmont Sanur Beach Bali. The research method uses survey and literature study methods. Data collection techniques are observation, interview, and literature study. Data analysis methods with descriptive methods and scoring tables. The results about the identification of vertical garden maintenance systems consist of watering, water disposal system, trimming, fertilizing, replanting plants, media replacement, sanitation, pest and disease control. Watering in 2 hours creating high humidity in the media. The volume of water released is not fully experienced evapotranspiration. The planting media do not experience drought during the day, so the plants keep fresh. In the calculation of plant suitability values, the corresponding values are Hemigraphis alternata. Plants with adequate value are Epipremnum aureum, Asparagus densiflorus, Ananas bracteatus tricolor, Schefflera Arboricola, and Portulaca grandiflora. In the maintenance process requires a fertigation system to facilitate fertilization. The use of automated systems such as timmers will simplify the maintenance and a more scheduled.

Investigation on trim control of semi-planing amphibious cargo truck using experimental and numerical approaches

Speed on water is a key indicator of amphibious vehicles. However, due to the inherent non-streamlined configuration, when reaching a certain velocity, the resistance acting on the vehicle hull is so large and the maximum speed on water is hard to be further enhanced. Moreover, the trim gets so larger that leads the stern submerged into water when speed up. In order to solve this problem of a semi-planing amphibious cargo truck, this paper proposed a method by installing interceptors, hydrofoils, and combination of them on the stern. Experimental tests and numerical studies were performed respectively, and the numerical results were in good agreement with experiment. In what continues, the effect of interceptors, hydrofoils, and combination of them on trim and resistance was investigated. The results showed that the interceptor had a better effect than hydrofoil when height is not so big, but the effect got more and more powerful with interceptor height increasing, finally lead to an excessive trim control. Combination of interceptor with hydrofoil in suitable size were beneficial to trim control and resistance reduction.