Pressure Torque Research Articles

Influence of Rain Ingestion on the Endwall Treatment in an Axial Flow Compressor

The effects of water ingestion on the performance of an axial flow compressor are experimentally studied with and without endwall treatment. The background to the work is derived from the assessment of airworthiness for an aero-engine. The stability-enhancing effects with endwall treatments under rain ingestion are not previously known. Moreover, all the endwall treatments are designed under dry air conditions in the compressor. Water ingestion at 3% and 5% relative to the design mass flow proposed in the airworthiness standard are applied to initially investigate the effects on the performance under smooth casing (SC). Results show that the water ingestions are mainly located near the casing wall after they move through the rotor blade row. The pressure rise coefficient increases, efficiency declines, and torque increases under the proposed water ingestion. The increase of the inlet water increases the thickness of the water film downstream the rotor blade row and aggravates the adverse effects on the performances. Subsequently, three endwall treatments, namely circumferential grooves, axial slots, and hybrid slots–grooves, are tested with and without water ingestion. Compared with no water ingestion, the circumferential grooves basically have no resistance to the water ingestion. The axial slots best prevent the drop of the pressure rise coefficient induced by water ingestion, and hybrid slots–grooves are the second-best place owing to the contribution of the front axial slots. Therefore, the hybrid slots–grooves can not only extend the stall margin with less efficiency penalty compared with axial slots, but also prevent rain ingestion from worsening the compressor performance.

Analysis of mechanical parameters for asymmetrical strip rolling by slab method

An analytical model is proposed to analyze the asymmetrical cold strip rolling by the slab method, and used to easily determine the rolling pressure distribution, roll force, and torque. The effects of asymmetrical rolling conditions including roll speed, roll radius and friction coefficient on rolling pressure, roll force and torque are analyzed separately. The influences of different asymmetrical conditions on rolling pressure distribution are different and unrelated, but will superimpose each other when multiple asymmetrical conditions coexist. An appropriate combination of asymmetrical conditions can improve the non-uniform distribution of roll torques due to the unequal roll speed. The analysis results are in good agreement with experimental measurements and other studies, which verify the accuracy of the proposed model.

Torque model verification for the GOCE satellite

The modeling of torques acting on satellites is essential for the design of satellite attitude control systems. The GOCE satellite, equipped with accurate accelerometers, star trackers and GPS receivers, presents an opportunity to validate these models. Although the forces on GOCE and other accelerometer-carrying missions have been extensively analyzed in the past, a similar analysis has so far not yet been made for the torques.In this paper, we present a set of torque models for the GOCE satellite. It consists of six main parts: (1) magnetic torquer actuators, (2) aerodynamic torque, (3) gravity gradient torque, (4) solar radiation pressure torque, (5) thruster torque, and (6) passive magnetic torque. The magnetic properties of the payload are approximated using a parametrization, of which the parameters are estimated from the observation data.Based on data recorded during selected spacecraft events, the model for the control torques can be validated and error sources are identified in the other models. The models perform best in roll and pitch, where the standard deviation is reduced to 15.2% and 2.1% of the standard deviation of the control torque around those axes respectively. In yaw the standard deviation is significantly larger at 30.5%. The remaining differences between models and observations show magnetic signatures due to electric currents and signatures of aerodynamic model errors. The latter correspond well with an increase in thermosphere density and wind speed with increased geomagnetic activity. The pitch torque is found to be a potential source of vertical wind data.

Asteroid de-spin and deflection strategy using a solar-sail spacecraft with reflectivity control devices

Various asteroid mitigation strategies have been proposed to avoid destructive impact events. In such a mission, the spinning motion of an asteroid can prevent a precise and effective deflection maneuver. To circumvent this problem, this study investigates a novel de-spin method using a solar sail spacecraft that is attached to the surface of an asteroid. In this approach, the solar radiation pressure torque induced by reflectivity control devices on the sail membrane is exploited to cancel out the spin rate of an asteroid without requiring fuel. In addition, once attitude control is achieved after the de-spin, the trajectory of the asteroid can be deflected by leveraging the solar radiation pressure force acting on the sail attached to the asteroid. This paper constructs general theories on the proposed asteroid de-spin and deflection methods and provides evidence that this novel strategy would be a feasible option for mitigating small and slow-spinning asteroids.

Analysis of analytical attitude propagators for spin-stabilized satellites

In this paper, analytical attitude propagators for spin-stabilized satellites are analyzed. For this purpose, external torques are introduced in the motion equations such as solar radiation pressure torque, aerodynamic torque, gravity gradient torque, and magnetic residual and eddy current torques. For the magnetic torques, it used both the dipole and quadripole Earth’s magnetic field models. The obtained analytical solution is applied and compared with actual data for Brazilian data collection satellites SCD1 and SCD2. The results, when a daily data update is applied, based on the INPE-Brazilian Institute for Space Research supplied data, show a good agreement of all involved parameters with the actual deviations in the parameter values within the precision required for the satellite mission. This permits to conclude that the used theory is suitable for the studied problem. Thus, the propagators presented in this work can be applied to predict the rotational motion of spin-stabilized artificial satellites, particularly for SCD1 and SCD2 satellites over the considered time period.

Attitude Control of a Flexible Solar Sail in Low Earth Orbit

Launching solar sails to low Earth orbit can provide cheap and frequent opportunities for test missions, orbit raising from low Earth orbit, or deorbiting space debris. This Paper considers the problem of attitude dynamics and control of a flexible solar sail under solar radiation pressure, aerodynamic forces, and gravity gradient torque. A geometrically nonlinear finite element method was used to study the effects of solar radiation pressure and aerodynamic forces on a flexible membrane, including the deformation-induced disturbance torque and changes of center of pressure. Then, an analytical method was applied to estimate the deformation of the membrane, and consequently the generated disturbance torque. The results showed that the analytical method could estimate the sail deformation very accurately. The problem of controllability of a sliding mass control mechanism in low Earth orbit was studied, and the controllable attitude regions were defined according to the mass of the sliding masses. A robust servomechanism linear quadratic regulator optimal control approach was applied to control the attitude of a flexible sail in low Earth orbit under the disturbance torques. The simulation results showed the efficacy and robustness of the controller in dealing with deformation-induced torques during orbit raising and deorbiting.

Effect of gasoline/n-butanol blends on gaseous and particle emissions from an SI direct injection engine

N-butanol has shown potential as an alternative fuel to mitigate the energy crisis and reduce emissions. The emission and combustion characteristics of a spark ignition (SI) engine fed with gasoline/n-butanol blends under direct injection are studied in this paper. The experiments are conducted using different excess air ratios (λ) and n-butanol blending volume ratios (NBr). The results indicate that the indicated mean effective pressure (IMEP) and engine torque (Ttq) show small changes following n-butanol addition. The NOx and CO emissions decline continuously with increasing NBr. The n-butanol addition can help reduce HC emissions compared to neat gasoline when the NBr is below 40%; specifically, the HC emissions reach the lowest value at 20% NBr. As for particle emissions, the addition of n-butanol shows a very significant effect on the reduction of accumulation mode particle number, especially at rich-fuel mixture conditions, for which a decrease by about 52% is achieved. On the contrary, the nucleation mode particle number and peak particle diameter increase constantly with increasing NBr. Overall, the addition of 20% NBr to the blends reduces both particle and gaseous emissions. This work therefore presents a procedure to optimize the control of particle and gaseous emissions from gasoline/n-butanol blends, thus reducing the impact of the use of fossil fuel.

Method of load calculation of electrical drives of rolling mills during heavy plate manufacturing

During manufacturing of heavy strips and plates from difficult-to-form steel grades on sheet and wide-strip rolling mills there is a problem of exact calculation of power parameters of rolling. It is pointed out that known methods do not provide required precise information at high deformation zones in a stand. An improved calculation method for rolling pressure and load torque of electrical drive engine is suggested further. This method considers peculiar strain of product in high deformation zones and its accelerated motion in reverse mode. Improved analytical dependences for rolling pressure and load torque of electrical drive are reviewed. Control flow chart and main screen of developed software for calculation of wide- strip rolling parameters are presented. Comparative analysis of calculation data and experimental results of engine equivalent currents during tube steels rolling is made. As a result improved precision of calculation method is justified.

Performance investigation of an innovative Vertical Axis Hydrokinetic Turbine – Straight Blade Cascaded (VAHT-SBC) for low current speed

Research on the development and innovation of Vertical Axis Hydrokinetic Turbine (VAHT) to improve performance has been done. One of the important indicator that affects VAHT’s performance is Coefficient of Performance (Cp). Theoretical Cp value for the VAT (Darrieus) turbine is 0.45. This paper presents the results of a performance investigation for an innovative Vertical Axis Hydrokinetic Turbine – Straight Blade Cascaded (VAHT-SBC) by modifying the number and the arrangement of blades using CFD simulation. Symmetrical NACA 0018 is used for this study, each model is simulated with current speed variation (U - m/s) of 0.5, 1 and 1.5. An increase in Cp value is shown in variation of 9 blades (3 blades cascaded in each arm) with Cp value of 0.396 at TSR of 2.27 which is reach 88% of the theoretical value. Furthermore, the streamline velocity of the pressure contour, velocity streamline and torque fluctuations are also presented in this paper to gain in deep information.

Dynamic transmission of oil film in soft-start process of HVD considering surface roughness

PurposeThe purpose of this paper is to study the dynamic transmission of the oil film in soft start process of hydro-viscous drive (HVD) between the friction pairs with consideration of surface roughness, and obtain the distribution law of temperature, velocity, pressure, shear stress and viscous torque of the oil film.Design/methodology/approachThe revised soft-start models of HVD were derived and calculated, including average Reynolds equation, asperity contact model, load force model and total torque model. Meanwhile, a 2D model of the oil film between friction pair was built and solved numerically using computational fluid dynamics (CFD) technique in FLUENT.FindingsThe results show that the maximum temperature gradually reduces from the intermediate range (z = 0.5 h) to the inner side of the friction pair along the direction of oil film thickness. As the soft-start process continues, pressure gradient along the direction of the oil film thickness gradually changes to zero. In addition, tangential velocity increases and yet radial velocity decreases with the increase of the radius.Originality/valueIn this paper, it was found that the viscous torque calculated by the numerical method is smaller than that by the CFD model, but their overall trend is almost the same. This also demonstrates the effectiveness of the numerical simulation.

A Continuum Model for Fiber-Reinforced Soft Robot Actuators

Fiber-reinforced elastomeric enclosures (FREEs) generate sophisticated motions, when pressurized, including axial rotation, extension, and compression, and serve as fundamental building blocks for soft robots in a variety of applications. However, most modeling techniques employed by researchers do not capture the key characteristics of FREEs to enable development of robust design and control schemes. Accurate and computationally efficient models that capture the nonlinearity of fibers and elastomeric components are needed. This paper presents a continuum model that captures the nonlinearities of the fiber and elastomer components as well as nonlinear relationship between applied pressure, deformation, and output forces and torque. One of the key attributes of this model is that it captures the behavior of FREEs in a computationally tractable manner with a minimum burden on experimental parameter determination. Without losing generality of the model, we validate it for a FREE with one fiber family, which is the simplest system exhibiting a combination of elongation and twist when pressurized. Experimental data in multiple kinematic configurations show agreement between our model prediction and the moments that the actuators generate. The model can be used to not only determine operational parameters but also to solve inverse problems, i.e., in design synthesis.

Torque coordination control strategy in engine starting process for a single motor hybrid electric vehicle

To troubleshoot the oversized output torque ripple during engine starting process of parallel hybrid electric vehicle (HEV), the engine starting process is divided into cranking phase, speed synchronisation phase and after-ignition phase. In this paper, the expressions of the vehicle jerk are derived from the vehicle dynamic formula in each phase, and the influences of various parameters on the jerk are analysed. The coordinated control strategy between the clutch pressure and motor torque, and that between the motor torque and engine torque are proposed. The simulation for the single shaft HEV model is carried out through MATLAB/SIMULINK by which rationality of the control algorithms was checked. Finally, a bench test is implemented whose results prove the determined change rate of clutch pressure, motor torque, and engine torque can effectively coordinate to meet the need of vehicle ride performance in engine starting in-motion process.

Research on the torque characteristics of a seawater hydraulic axial piston motor in deep-sea environment

Seawater hydraulic axial piston motor (SHAPM) is an elemental component in underwater tool system. The pressure flow model and torque model of the SHAPM was derived and the deformation of the piston guide and rear/front sliding bearings in the deep-sea environment was analyzed by ANSYS Workbench, in which the change of fit clearances have a great effect on the working performance of the SHAPM. Therefore, the simulations on the deformation of the piston guide and rear/front sliding bearings in different seawater depths were achieved and different fit clearances with varying depths were obtained. The results indicated that the clearances on the piston/cylinder bore pair and rear/front sliding bearings decreased with the increase of sea depth and the effective sea depth suiting for normal work was got. Meanwhile, the torque efficiency of the SHAPM in deep sea environment is lower. The results revealed that with the increase of the sea depth, the clearances of the piston/cylinder bore pair and rear/front sliding bearings decreased correspondingly. Meanwhile, the torque efficiency of the SHAPM decreased to a certain extent. Last, the suitable sea depth range for the normal working of the SHAPM was obtained.

Torque coordinated control in engine starting process for a single-motor hybrid electric vehicle

To tackle the excessive output torque ripple during engine starting process of parallel hybrid electric vehicles, the engine starting process is divided into three phases in this study: engine cranking phase, speed synchronization phase, and after synchronization phase. The expressions of the vehicle jerk are derived from the vehicle dynamic formula in each phase, and the influences of various parameters on the jerk are analyzed. The coordinated control strategy for the clutch pressure and motor torque and that for the motor torque and engine torque are proposed. The simulation model for the single-motor parallel hybrid electric vehicle is established using MATLAB/Simulink, and the effectiveness of the proposed control algorithms is verified. Besides, a bench test is conducted and the test results show that the selected change rates of clutch pressure, motor torque, and engine torque can effectively coordinate the relation between clutch, motor, and engine. It can be concluded that the proposed control strategy satisfies the requirement of vehicle ride performance in engine starting in-motion process.

ADRC‐based transient air/fuel ratio control with time‐varying transport delay consideration for gasoline engines

This paper presents a fuel injection controller based on the modified active disturbance rejection control (ADRC) algorithm to maintain the air/fuel ratio (AFR) at the stoichiometric value in the presence of a transport time delay. The factors affecting the dynamics of the AFR include the variations of the intake manifold pressure, engine speed, and load torque, as well as uncertain parameters existing in the fuel film evaporation and the oxygen sensor aging, which are viewed as the 'total disturbance' to the AFR system and estimated by the extended state observer (ESO). Thus, based on the Lyapunov–Krasovskii functional stability theory, the ADRC fuel injection controller is designed with the gain matrices of the controller and observer and solved by employing linear matrix inequalities. Considering the time‐varying transport delay, a time delay block is added to the ESO. By synchronizing the input signals of the ESO, the performance in terms of the timely compensation for the disturbance is improved. The effectiveness of the proposed control strategy is validated through simulation of a V6 spark ignition engine model developed by the Society of Instrument and Control Engineers (SICE) Research Committee on Advanced Powertrain Control Theory. © 2017 Institute of Electrical Engineers of Japan. Published by John Wiley & Sons, Inc.

Modeling and Finite Element Analysis of Load-Carrying Performance of a Wind Turbine Considering the Influence of Assembly Factors

In this work, a wind turbine shrink disk is used as the research object to investigate load-carrying performance of a multi-layer interference fit, and the theoretical model and finite element model are constructed. According to those models, a MW-level turbine shrink disk is designed, and a test device is developed to apply torque to this turbine shrink disk by hydraulic jack. Then, the circumferential slip between the contact surfaces is monitored and the slip of all contact surfaces is zero. This conclusion verifies the reasonability of the proposed models. The effect of the key influencing factors, such as machining deviation, assembly clearance and propel stroke, were analyzed. The contact pressure and load torque of the mating surfaces were obtained by building typical models with different parameters using finite element analysis (FEA). The results show that the minimum assembly clearance and the machining deviation within the machining range have little influence on load-carrying performance of multi-layer interference fit, while having a greater influence on the maximum assembly clearance and the propel stroke. The results also show that the load-carrying performance of a multiple-layer interference fit can be ensured only if the key factors are set within a reasonable design range. To avoid the abnormal operation of equipment caused by insufficient load torque, the propel stroke during practical assembly should be at least 0.95 times the designed propel stroke, which is significant in guiding the design and assembly of the multi-layer interference fit.

Development of a real-time two-stroke marine diesel engine model with in-cylinder pressure prediction capability

The in-cylinder pressure is an important parameter for the diesel engine but it fails to be used in the common scenes, like the control, hardware in loop, and virtual reality, for its lack of real-time capability. In order to have this capability, the conventional diesel engine models are ameliorated (named as MG model, the merged diesel engine model). These parameters that exclude the in-cylinder pressure and indicator torque are calculated by mean value model, the widely used model for real-time applications, to keep on its speed. The other parameters are calculated by the 0D model. To improve the in-cylinder pressure calculation speed, the simplification and asychronization are used. The compression, combustion, and expansion processes are calculated the same as 0D assumption but the exhausting and scavenging processes are simplified by two linear functions. Its calculation time saves about 33.3% comparing to the conventional 0D approach. The boundaries of cylinder model are asynchronous with the scavenging and exhausting manifolds by abandoning cylinder cycles at reasonable intervals so that the time can be reduced further. In practical coding, the in-cylinder pressure needs to be calculated by a parallel thread to realize asychronization. In the case that abandons 4 cycles every 5 cycles the calculation time saves nearly 80% further. Only during the dynamic process, is the reduced time positively correlated with the number of abandoned cycles. The proposed model is calibrated against shop test data, whose predicting accuracy is comparable to the 0D model. The maximum relative errors of steady MG model and steady 0D model are 3.96% and −3.23%, and the mean relative errors are 1.38% and 2.18%. In the case that abandons 4 engine cycles, the maximum relative error of explosion pressure is 0.363% during the dynamic process. This model can be used in real-time HIL, controller design, engine analysis, and simulator.

Characterization and performance analysis of a new type of a high water-based hydraulic motor with a self-balanced distribution valve mode

High water-based hydraulic motors (HWBHMs) with advantages including higher specific power and shorter acceleration and braking time can be used to directly drive loads. In particular, low speed and high torque high water-based hydraulic motors work well in limited space and for special applications (open flame areas). However, traditional structure and flow distribution mechanisms cause serious leakage and lower work efficiency for low speed and high torque high water-based hydraulic motors. Thus, a new structure and flow distribution mechanism with self-balanced distribution valve groups for a high water-based hydraulic motor need to be developed to work in high pressure, low speed, and high torque conditions. In this paper, a high water-based hydraulic motor was theoretically analyzed and the working principle behind a high water-based hydraulic motor was briefly introduced. Numerical simulations were performed to examine the effects of the distribution valve parameters on the distribution performance. An orthogonal test method was used to determine the optimized structure parameters. A simulation model of a high water-based hydraulic motor was established using the AMESim simulation method to validate the feasibility of the optimized structure parameters. This research has laid a foundation for the further development of a high water-based hydraulic motor with low speed and high torque.

Large-eddy simulation analysis of turbulent flow over a two-blade horizontal wind turbine rotor

Unsteady turbulent flow characteristics over a two-blade horizontal wind turbine rotor is analyzed using a large-eddy simulation technique. The wind turbine rotor corresponds to the configuration of the U.S. National Renewable Energy Laboratory (NREL) phase VI campaign. The filtered incompressible Navier-Stokes equations in a non-inertial reference frame fixed at the centroid of the rotor, are solved with centrifugal and Coriolis forces using an unstructured-grid finite-volume method. A systematic analysis of effects of grid resolution, computational domain size, and time-step size on simulation results, is carried out. Simulation results such as the surface pressure coefficient, thrust coefficient, torque coefficient, and normal and tangential force coefficients are found to agree favorably with experimental data. The simulation showed that pressure fluctuations, which produce broadband flow-induced noise and vibration of the blades, are especially significant in the mid-chord area of the suction side at around 70 to 95 percent spanwise locations. Large-scale vortices are found to be generated at the blade tip and the location connecting the blade with an airfoil cross section and the circular hub rod. These vortices propagate downstream with helical motions and are found to persist far downstream from the rotor.

Preliminary design of pressure torque separation sensor for drilling bit

The working state of drilling bit is a critical issue in the drilling process. The preliminary design of pressure and torque separation sensor for drilling bit is expatiated herein. The sensor unit is composed of the elastic unit and the Wheatstone full bridge. Under composited load, the theoretical analysis about separating the axial force and torque of drilling bit is discussed firstly. The separation has been achieved by using the Wheatstone full bridge pasted onto the elastic unit. Then the transversal and axial strains distribution of elastic unit has been calculated and analyzed by ANSYS software, when the bit is under axial force and torque. Based on the calculation and analysis results, the sensitivity and accuracy of the sensor’s whole measurement chain can be reckoned. Meanwhile, the calculation and analysis results can also give good suggestion about the positions where the strains gauge should be pasted. Finally, it has been proved that this solution can meet the preset requirements very well.