Effect of working parameters on performance characteristics of hydrostatic turntable by using FSI-thermal model

Effects of working parameters on performance characteristics of hydrostatic turntable are researched by applying the fluid-structure-thermal coupled model.Fluid-structure interaction(FSI)technique and computational fluid dynamics(CFD)method are both employed by this new model,and thermal effects are also considered.Hydrostatic turntable systems with a series of oil supply pressures,various oil recess depth and several surface roughness parameters are studied.Performance parameters,such as turntable displacement,system flow rate,temperature rise of lubrication,stiffness and damping coefficients,are derived from different working parameters(rotational speed of turntable and exerted external load)of the hydrostatic turntable.Numerical results obtained from this FSI-thermal model are presented and discussed,and theoretical predictions are in good agreement with the experimental data.Therefore,this developed model is a very useful tool for studying hydrostatic turntables.The calculation results show that in order to obtain better performance,a rational selection of the design parameters is essential.

Effects of working parameters on the performance of cyclone separator for rapeseed combine harvester based on CFD

Existing development for cyclone separation cleaning components of the rapeseed combine harvester,which employs the suspending airflow to separate the rapeseeds from the materials other than grain(MOG),has the challenge to figure out the optimal working parameters,highlighting a need for exploration of the invisible airflow based on Computational Fluid Dynamics(CFD).The airflow status was mainly affected by the air velocities of the inlet,and the outlet for the MOG.The single factor and response surface experiments were carried out.It could be found that the inlet and MOG outlet velocities affected the air velocities through the change in the air quantity.Furthermore,the mathematical model of the relationship between the air velocities inside the cyclone and the working parameters was built,and the optimal combination of working parameters was obtained by multi-objective optimization.The inlet and outlet velocities of the optimal combination were 4.25 m/s and 29.87 m/s,respectively.Under this condition,the cleaning ratio and loss ratio of the cleaning device was 94.62%and 5.39%,respectively,as validated by the field experiment.The findings provide references for the improvement of cleaning systems for rapeseed combine harvesters.

Development and evaluation of power consumption model for no-till planter based on working parameters

In order to fully understand the relationships of power consumption of no-till planter among tractor,soil properties and working parameters which affect the field operation,the power consumption model for no-till planter applied to overcome the coupling difficulties was developed in the study.Based on operation depth of no-till planter and soil properties as constraints in accordance with a certain distribution,the relationship data among traction force,forward speed and power output shaft by field test were collected and analyzed.The results showed that the relationship between traction power and power-take-off(PTO)power was negatively correlated.Under the same power consumption condition,the relationship between traction force and the PTO torque was linearly correlated,and the slope was basically consistent.Different power consumptions corresponded to different intercepts.When the forward speed was 6-7 km/h and PTO shaft rotational speed was 370-450 r/min,lower power consumption with higher working efficiency can be achieved.There was a direct correlation between total power consumption and the square of rotational speed multiplied by forward speed.The maximum correlation coefficient was found around 0.82.The findings set up a foundation for designing control system of no-till planter.

Sufficiently diffused attachment of nitrogen arc by gasdynamic action

For realizing diffused anode attachment in pure nitrogen arcs, a special arc plasma generator was designed and combined with suitable working parameters such as gas flow rate and arc current. The anode has a flow-restrictor channel of 2.8 mm diameter and downstream expansion half-angle of 8°, with the purpose of creating a dispersed nitrogen-arc column by strong gasdynamic expansion effect. Results show that, when thermal blocking condition existed in the flow restrictor and the cathode cavity pressure was higher than that in the exit chamber by at least 9 kPa, the action due to gasdynamic expansion could be much stronger than the self-magnetic contraction effect of the arc and the nitrogen arc column could be effectively dispersed to form a sufficiently diffused attachment on the water-cooled anode surface.

Experiment and Simulation of Large Capacity Air-guns in Deep Structure Exploration

The air-gun source has important applications as a new, environmentally, green active source in regional scale deep exploration. In the past, the air gun source was used mainly in smallscale, high-resolution shallow oil exploration, but has a lack of adequate research in deep exploration. In order to study the selection of work parameters and field conditions of the air gun source in deep exploration, this paper does the following work： （1） analyze the characteristics of the air gun source using air gun experiments; （2） simulate the air gun signal and air gun-array signal based on the theory of free bubble oscillation to analyze the influence of bubble oscillation and study the wavelet energy and spectrum characteristics needed in deep exploration; （3） on the basis of theoretical simulation, study the influence of work parameters, such as air-gun capacity, work stress and depth on air gun signal and analyze the influence of air-gun array inspired moment and spacing of different air guns on air gun-array signals; and （4） study energy reflection and transmission coefficients for different underwater interfaces, which is very useful for choosing suitable field conditions.

Modeling the flow curve of hot deformed austenite under industrial rolling conditions

A 0.02%C plain carbon steel and a 0.11%C Nb-modified steel were tested in compression in the austenite temperature range.The critical strains for the initiation of dynamic recrystallization were determined from the 41 stress-strain curves obtained,using the double differentiation method.The work hardening behavior up to the critical strain was analyzed with the aid of a dislocation density model and the work hardening parameters r and h were derived in this way.These parameters were used to model the austenite flow curves beyond the critical strain, i.e.in the absence of dynamic recrystallization.The net softening attributable to dynamic recrystallization was defined as the difference between the calculated work hardening curve and the experimental flow curve.The softening data are expressed in the form of Avrami kinetics.Using the dependences of the work hardening parameters and Avrami kinetic parameters on Z,the Zener-Hollomon parameter,it is shown how the flow curves pertaining to industrial rolling conditions can be modeled.

Describing failure in geomaterials using second-order work approach

Geomaterials are known to be non-associated materials. Granular soils therefore exhibit a variety of failure modes, with diffuse or localized kinematical patterns. In fact, the notion of failure itself can be confusing with regard to granular soils, because it is not associated with an obvious phenomenology. In this study, we built a proper framework, using the second-order work theory, to describe some failure modes in geomaterials based on energy conservation. The occurrence of failure is defined by an abrupt increase in kinetic energy. The increase in kinetic energy from an equilibrium state, under incremental loading, is shown to be equal to the difference between the external second-order work,involving the external loading parameters, and the internal second-order work, involving the constitutive properties of the material. When a stress limit state is reached, a certain stress component passes through a maximum value and then may decrease. Under such a condition, if a certain additional external loading is applied, the system fails, sharply increasing the strain rate. The internal stress is no longer able to balance the external stress, leading to a dynamic response of the specimen. As an illustration, the theoretical framework was applied to the well-known undrained triaxial test for loose soils. The influence of the loading control mode was clearly highlighted. It is shown that the plastic limit theory appears to be a particular case of this more general second-order work theory. When the plastic limit condition is met, the internal second-order work is nil. A class of incremental external loadings causes the kinetic energy to increase dramatically, leading to the sudden collapse of the specimen, as observed in laboratory.

Analysis and experiment on cutting performances of high-stubble maize stalks

In the cold areas of Northeast China,maize high-stubble cutting is a novel stalk conservation tillage method,in which the maize stalks are under a unilaterally-fixed no-support cutting status.Thus,reducing the cutting resistance and power consumption of maize stalks under this status is very significant for the development of high-efficiency high-stubble cutting devices.Based on a self-designed testing system that highly restored the maize high-stubble cutting conditions and by means of experimental design and mathematic statistics,the effects of working parameters(blade angle,blade shape,cutting speed and cutting angle)on the maximum cutting resistance and power consumption were studied.By analyzing stress conditions during the stalk cutting process,six mathematic models were built to express the relationships between individual factors and the maximum cutting resistance or cutting power consumption.Through model optimization,the parameter combination for optimal cutting performance of maize stalks under unilaterally-fixed no-support cutting status was obtained:blade angle is 18°,blade shape is isosceles triangle,cutting speed is 9.5 m/s,and cutting angle is 75°.Field validation experiments under this parameter combination showed that the maximum cutting resistance was(55.23±3.50)N(declined by 11.04%),and power consumption was(11.41±1.04)J(declined by 16.65%).The research findings can be a reference for the design and development of maize high-stubble cutting devices.

Performance test and process parameter optimization of 9FF type square bale straw crusher

In order to solve the problem of low productivity,unqualified segment length and high energy consumption during the process of crushing square bale straw caused by improper operation parameters,a 9FF square bale straw crusher was developed.In this study,by taking maize straw as the test material,the feeding speed,spindle speed of the crushing device and the state of the crushing device were taken as influence factors,and standard straw length rate,productivity per net working hour(hereinafter referred to as NWH)and energy consumption per ton of product as test indicators,the influence of the factors on the indicators were studied,and tests were carried out on the process of square bale straw crushing.By adopting the single factor test on the effect of the feeding speed,the spindle speed of the crushing device and the state of the crushing device on the test indicators,the suitable range of each factor was determined,respectively.Using the orthogonal test method,range method,variance method and comprehensive balance method,the experiment analyzed the significance of the influence of the three factors on various indicators and the order of priority.The test results showed that:the feeding speed was 5 m/min,spindle speed was 3000 r/min,and the state of the crushing device was a mixing cutter hammer,which was the best parameter combination(A1B1C1)for the processing technology of the square bale forage crusher.The standard straw length rate was 93.7%,and the productivity per NWH was 2.80 t/h,with energy consumption per ton of 4.72 kW·h/t,in which the standard straw length rate and productivity per NWH reached optimal values,and the energy consumption per ton of product was slightly higher than the optimal value in the experiment.The research results can provide a reference for the optimal design of the special crusher for square bale straw.