Optimal Pressure Distribution Research Articles

Математичне моделювання руху автобронетанкової техніки з колісною формулою 4×4 при зміні тиску в шинах коліс на прикладі КрАЗ-Спартан

The authors proposed a study of the passability of trucks and armored vehicles of the National Guard of Ukraine with a 4x4 wheel formula. The movement of armored vehicles (AMT) of the National Guard of Ukraine involves movement both on public roads and off-road. The possibility of increasing cross-country ability by ensuring optimal pressure distribution in the tires of the wheels is being considered. The increase in bearing capacity in difficult operating conditions can be estimated with the help of modern mathematical tools. This allows the vehicle equipment of the National Guard of Ukraine to study the cross-country ability and select optimal parameters when performing service and combat tasks with a certain ratio of technical characteristics in different operating conditions. As a result of the full-scale war of the Russian Federation against Ukraine, more serious technical requirements are imposed on the vehicles of the Armed Forces of Ukraine (AFU) and the National Guard of Ukraine (NGU) than in peacetime. Among these requirements, maneuverability is in the first place - controllability is ensured by the ability to move at high speed over rough terrain. The patency of the AMT of the National Guard of Ukraine depends on many factors, the main ones of which are: the type and quality of the surface on which movement takes place, the pressure in the tires of the wheels, the weight of the vehicle, the order of passing the route of the convoy, etc. The central air pressure control system in wheel tires (SRPRS) is widely used in various variants of automotive equipment with high traffic intensity, but the main disadvantage of such systems is the need to minimize tire pressure to improve cross-country ability on load-bearing surfaces with low load-bearing capacity. This tolerance can cause the tire to slip off the rim, overheat or burst. This is due to the fact that the maximum speed is limited due to the risk of system failure. It is recommended to determine the influence of various factors in order to ensure the required level of support patency and analyze it using the example of the KrAZ-SPARTAN armored car with a 4×4 wheel formula.

Experimental Investigation and CFD Analysis of Wind Turbine Blades with Different Attack Angles

The escalating global demand for energy coupled with escalating environmental concerns has underscored the imperative of efficacious energy conversion from renewable reservoirs. Among these, wind energy has ascended as a pragmatic and ecologically conscientious solution. Its ascent, outpacing conventional fuels such as coal, underscores the necessity to comprehend its performance intricately. This study zeroes in on an airfoil model, subjecting it to a dual scrutiny encompassing empirical investigation and computational simulation. Employing Computational Fluid Dynamics (CFD) analyses executed in ANSYS software, the study prognosticates pressure and velocity patterns for the 2D iteration of the Model 1 airfoil by the National Advisory Committee for Aeronautics (NACA). This exhaustive scrutiny spans across velocities of 10 m/s and diverse angles of attack (-5°, 2°, and 8°). Remarkably, a robust 90% correlation manifests between the outcomes of empirical experimentation and computational simulation. Within the aerodynamic schema of the Horizontal Axis Wind Turbine (HAWT), the 8° angle of attack emerges as the vanguard, distinctly illustrating the pinnacle of optimal pressure distribution and velocity gradient. Noteworthy is the consistent augment in airfoil performance as the blade angle escalates, substantiated by elevated apex velocities and pressures in juxtaposition to the -5° and 2° angles. The findings of this inquiry engender a significant stride in airfoil refinement for the optimization of wind turbine blades, thereby conferring invaluable insights in the realms of blade design, aerodynamic contemplations, and the augmentation of wind turbine performance.

Framework of nacelle inverse design method based on improved generative adversarial networks

Nowadays, inverse design has been widely used in aerodynamic design. However, the traditional inverse design method is limited to ensure the optimality, accuracy, and reality of the target distribution, which restricts the further development of the inverse design. To address these issues, the framework of nacelle inverse design based on improved Generative Adversarial Networks (GAN) is firstly proposed in this paper. The pressure distribution database obtained by CFD is used for training the GAN model, and the well-trained generator producing a large number of samples is employed for searching the optimal pressure distribution. Especially, in order to enhance the optimization ability of the traditional GAN model, an improved GAN model is proposed by modifying the loss function of the generator and discriminator. Pressure distribution-aerodynamic parameters ANN model and pressure distribution-geometry ANN model are established to evaluate the aerodynamic performance of the target distribution and obtain the nacelle geometry corresponding to the target distribution. The inverse design of the nacelle profile is carried out using the traditional GAN model and the improved GAN model and applied for the spin-forming and non-spin-forming nacelles, respectively. The results show that the inverse design framework with the improved GAN model achieves better optimal results.

밀착 의복 개발을 위한 원단의 방향에 따른 부위별 변화량 및 의복압 연구

It is a generally accepted fact that % fabric stretch of the stretch fabric differs depending on the direction of the grainline. Subtle differences in the direction of the grainline would affect the performance of compression garments. In this study, compression garments, which have the same pattern size, were made by 4 types of grainline combinations. Then, clothing pressure was measured directly on the human body and the mannequin used, and an air-pack type sensor was used to determine whether different grainlines of patterns affect the clothing pressure of four compression garments. Also, fabric strain, load, and displacement were compared with real clothing pressure to investigate their relationships. In the results, it was noted that an accurate % fabric stretch of each grainline direction should be ascertained to design a compression garment that has an optimal pressure distribution.

Development and validation of a hybrid aerodynamic design method for curved diffusers using genetic algorithm and ball-spine inverse design method

The inverse design is one of the aerodynamic design methods, in which the pressure distribution along the wall is known, and the duct geometry is unknown. To obtain the best geometry by the inverse design, the target pressure distribution along the walls should be optimum. This paper presents an aerodynamic design of diffusers by optimizing the wall pressure distribution and applying it to the ball-spine inverse design method. A code was first developed to solve the boundary layer equations using the integration method, and then incorporated into a genetic algorithm to optimize the wall pressure distribution to achieve the maximum pressure recovery without separation occurrence. Depending on the type of the duct, a series of constraints was applied to the wall pressure distributions during the optimization process. The optimized pressure distribution was considered as the target pressure distribution for the inverse design problem. The duct geometry changes during the inverse design process to reach one satisfying the target pressure distribution. An offline connection was observed between the ball-spine inverse design method and the genetic algorithm. The boundary layer code was the medium for this offline connection. The optimized wall pressure distribution and inverse design process were evaluated for a straight diffuser and three S-shaped diffusers with different height to length ratios. The results revealed the robustness of the offline link of the inverse design and the genetic algorithm for the optimal aerodynamic design of ducts.

Proper orthogonal decomposition assisted inverse design optimisation method for the compressor cascade airfoil

Inverse design is by far the most physically explicit method in the turbomachinery field for designing a cascade airfoil shape for a prescribed distribution of aerodynamic parameters on the airfoil surface. However, a vital drawback of the available inverse design methods for cascade airfoils is the lack of effective techniques to specify optimal target aerodynamic parameters, particularly optimal pressure distribution on the airfoil surface. This drawback hinders the wide application of inverse design optimisation methods in the turbomachinery field. To overcome this vital drawback, we proposed a proper orthogonal decomposition (POD) assisted inverse design optimisation method for cascade airfoils, in which an optimal pressure distribution on airfoil surface was automatically obtained by solving a direct design optimisation problem and accurately parameterised via the POD method. The effectiveness of the proposed inverse design optimisation method was demonstrated using the inverse designs of a compressor cascade airfoil with two different optimisation objectives. Results highlighted the proposed inverse design method's capability to significantly improve the aerodynamic performance of the compressor cascade. The POD method can provide an adequate and flexible description of airfoil surface pressure distribution with a small number of POD modes. This work is valuable for the further development of inverse design optimisation methods for advanced compressor blades.

Design and Development of a New Press for Grape Marc

The purpose of this research was to determine the optimal geometry of a variable pitch conical helicoid to be used in a pressing machine for grape pomace, also known as grape marc. This study attempted to understand if the optimized geometry of the considered helicoid after every pitch resulted in volume decrease DVc, equal to that obtained during the pressing phase of grape pomace DVp, using an optimized membrane press. The conical helicoid with variable pitch was replaced in a machine that offered continuous pressing of grape pomace using a cylindrical helicoid with constant pitch (constant pressure distribution, not optimized, along the cochlea axis). As this was a machine already available in the market, the overall dimensions were already established—5.95 m in length and 1.5 m in width. The pressure distribution p1 and volume change DVp, obtained during the grape pomace pressing phase in the optimized membrane press (producing high-quality wine) was taken into consideration in this research. Furthermore, the optimized pressure distribution p1 was applied in seven phases during the pressing process, and a consequent volume change value DVp was obtained for each phase. Therefore, this study determined the geometry of the variable pitch conical helicoid, which, after every pitch, resulted in volume changing DVc that was similar to the volume changing DVp obtained by the optimized membrane press. For this scope, calculations were realized using the Mathematica 10 program code, which, on being assigned the overall dimensions, slope angle of the helicoid, and volume for the first pitch value, determined the radius and pitch values of the helicoid, total volume, and volume change DVc. It was also noted that by appropriately varying the geometric parameters (taper and pitch of the helicoid), different options of pressure distribution on grape pomace can be obtained, thus enabling improvement and optimization of product quality.

Study of Stage-wise Pressure Pulsation in an Electric Submersible Pump under Variable Frequency Operation at Shut-off Condition

Pressure pulsation causes vibration in the Electric Submersible Pump (ESP) and affects the life and performance of its system. ESP systems are installed at depths ranging from a few meters to several hundred meters. Unlike pumps used on the surface, once they are installed they become inaccessible for maintenance or for any kind of diagnostic measurement that might be taken directly on them. Therefore a detailed knowledge of mean and fluctuating pressures is required to achieve an optimal pressure distribution inside the ESP. This paper presents the results of an experimental investigation of the stage-wise pulsating pressure in ESP at shut-off condition at different speeds. Experiments were conducted on a pump having five stages. A variable frequency drive was used to operate the pump at five different speeds. Piezoresistive transducers were mounted at each stage of ESP to capture the unsteady pressure signals. Fast Fourier Transformation was carried out on the pressure signals to convert into frequency domain and the spectra of pressure pulsation signals were analyzed. The obtained results indicated the existence of fundamental frequency corresponding to the speed of rotation times the number of impeller blades and of the whole series of harmonics of higher frequencies.

Determination of optimal shape of a moving punch with friction taken into account

The optimization problem for the contact interaction between a rigid punch and an elasticmediumis considered. It is assumed that that the punch is under the action of some prescribed forces and momenta and moves along a surface bounding a half-space filled with an elastic medium. It is also assumed that themotion is quasistatic and the friction forces arising in the region of contact are taken into account. The punch shape is considered as the desired design variable, and the integral functional characterizing the discrepancy between the pressure distribution in the region of contact that corresponds to the optimized shape of the punch and a given goal distribution of pressure is taken as the minimizing criterion. The optimal shape can be determined efficiently by solving the following two problems: first, to obtain the optimal pressure distribution and then to solve a boundary value problemfor the elastic half-space under the action of the obtained normal pressure and friction forces. By way of example, the optimal shape is analytically determined for a punch of rectangular shape in horizontal projection.

Design of a Free-Floating Polycarbonate-Urethane Meniscal Implant Using Finite Element Modeling and Experimental Validation

The development of a synthetic meniscal implant that does not require surgical attachment but still provides the biomechanical function necessary for joint preservation would have important advantages. We present a computational-experimental approach for the design optimization of a free-floating polycarbonate-urethane (PCU) meniscal implant. Validated 3D finite element (FE) models of the knee and PCU-based implant were analyzed under physiological loads. The model was validated by comparing calculated pressures, determined from FE analysis to tibial plateau contact pressures measured in a cadaveric knee in vitro. Several models of the implant, some including embedded reinforcement fibers, were tested. An optimal implant configuration was then selected based on the ability to restore pressure distribution in the knee, manufacturability, and long-term safety. The optimal implant design entailed a PCU meniscus embedded with circumferential reinforcement made of polyethylene fibers. This selected design can be manufactured in various sizes, without risking its integrity under joint loads. Importantly, it produces an optimal pressure distribution, similar in shape and values to that of natural meniscus. We have shown that a fiber-reinforced, free-floating PCU meniscal implant can redistribute joint loads in a similar pattern to natural meniscus, without risking the integrity of the implant materials.

Three-Dimensional Inverse Method for Turbomachinery Blading Design

An iterative procedure for three-dimensional blade design is presented, in which the three-dimensional blade shape is modified using a physical algorithm, based on the transpiration model. The transpiration flux is computed by means of a modified Euler solver, in which the target pressure distribution is imposed along the blade surfaces. Only a small number of modifications is needed to obtain the final geometry. The method is based on a high-resolution three-dimensional Euler solver. An upwind biased evaluation of the advective fluxes allows for a very low numerical entropy generation, and sharp shock capturing. Non-reflecting boundary conditions are applied along the inlet/outlet boundaries. The capabilities of the method are illustrated by redesigning a transonic compressor rotor blade, to achieve, for the same mass flow and outlet flow angle, a shock-free deceleration along the suction side. The second example concerns the design of a low aspect ratio turbine blade, with a positive compound lean to reduce the intensity of the passage vortices. The final blade is designed for an optimized pressure distribution, taking into account the forces resulting from the blade lean angle.

Effects of Central Conducting Pole and Choking Current on Confinement of Spheromak with Flux Hole

Stability against internal modes is investigated by use of the Mercier criterion. The flux hole was known to enhance stability of the spheromak by previous investigations. Introduction of a central conducting pole to the spheromak with the flux hole does not show always a stabilizing effect, i.e., it depends on the current profile in the plasma. Effect of a choking magnetic field is also studied and the flux hole is shown to disappear if a strong choking field is applied. The upper limits of the beta ratio on the magnetic axis are determined as functions of the choking current by use of a model pressure distribution and the optimized pressure distribution. For the latter pressure distribution, the Mercier criterion is marginally satisfied on all magnetic surfaces. The maximum value of them is shown to be 6%.