Static Pressure Data Research Articles

Development of Cyclic Pressure Offloading Insole for Diabetic Foot Ulcer Prevention.

Introduction. The likelihood of developing a diabetic foot ulcer (DFU) during one's lifetime for individuals with diabetes mellitus is around 19% to 34%. Continuous and repetitive loading on soft tissues are the major causative factors for DFU. This paper introduces an air cell array insole designed for cyclically offloading pressure from plantar regions to reduce repetitive stress and loading on foot. Materials and Methods. The insole comprises an air cell array insole and a pneumatic control unit. The interface pressure was evaluated in static and dynamic conditions at 3 different air cell internal pressures (6.9, 10.3, and 13.8 kPa). Plantar interface pressure was measured using a commercial pressure system, and data were analyzed using paired t test. Average interface pressure and peak pressure (PP) were studied to evaluate the functionality and effectiveness of the insole. Results. The analysis of static pressure data revealed that cyclic offloading significantly (p < .05) reduced PP in 4 tested cells corresponding to big toe, metatarsal heads, and heel areas with the maximum mean difference of 12.9 kPa observed in big toe region. Similarly, dynamic pressure data analysis showed that cyclic offloading significantly (p < .05) reduced PP in these areas, with the highest mean PP reduction of 36.98 kPa in the big toe region. Discussion. Results show the insole's capability to reduce plantar pressure through cyclic offloading. Internal pressure of air cells significantly affects the overall pressure reduction and must be chosen based on the user's weight. Conclusion. Results confirm that the insole with offloading capabilities has the potential to reduce the risk of developing DFUs by alleviating the plantar stress during both static and dynamic conditions.

Analysis of static plantar pressure data with capsule networks: Diagnosing ataxia in MS patients with a deep learning-based approach

In this study, it was aimed to detect ataxia in patients with Multiple Sclerosis (MS) by utilizing static plantar pressure data and capsule networks (CapsNet), one of the deep learning (DL) architectures. CapsNet is also equipped with a robust dynamic routing mechanism that determines the output of the next capsule. MS is a chronic nervous system disease that shows its effect in the central nervous system and manifests itself with attacks. One of the most common and challenging symptoms of MS is known as ataxia. Ataxia causes loss of control of limb muscle tone or gait disorders, leading to loss of balance and coordination. The diagnosis of ataxia in MS is applied employing the standard Expanded Disability Status Scale (EDSS) score. However, due to reasons such as physician misconception, diagnosis differences among physicians, and incorrect patient information, more unbiased solutions are required for the diagnosis. The results included Sensitivity at 96.34 % ± 1.71, Specificity at 98.11 % ± 2.04, Precision at 98.08 % ± 2.16, and Accuracy at 97.13 % ± 0.33. The main motivation of the study is to show that these deep learning methods can successfully detect ataxia in MS patients using static plantar pressure data. The high-performance measurements of sensitivity, specificity, precision and accuracy emphasize that the proposed system can be an effective tool in clinical practice. In addition, it was concluded that the proposed autonomous system would be a support mechanism to assist the physician in the detection of ataxia in patients with MS.

Injury of flexor halluics longus tendon in amateur marathon runners results in abnormal plantar pressure distribution: observational study

ObjectiveTo analyze the changes of plantar pressure in amateur marathon runners with flexor halluics longus (FHL) tendon injury using the Medtrack-Gait plantar pressure measurement system, and to explore whether the plantar pressure data can be used as an index for the diagnosis of injury.MethodsA total of 39 healthy amateur marathon runners without any ankle joint symptoms were recruited. Dynamic and static plantar pressure data were measured using the pressure plate of Medtrack-Gait. According to MRI imaging findings, whether the FHL tendon was injured or not was judged, and the dynamic and static data were divided into the injury group and control group. The data with statistically significant differences between the two groups were used to make the receiver operating characteristic (ROC) curve.ResultThe maximum contact area (PA) of the first metatarsal(M1) region, the maximum load-bearing peak value (PW) and the time pressure integral (PMPTI) of the second metatarsal(M2) region in the injury group were lower than those in the control group, respectively (P < 0.05). The maximum contact area (PA) of the fifth metatarsal(M5) region was higher than that in the control group (P < 0.05). The area under curve (AUC) value of the ROC curve of the PA of M1 region, the PW and PMPTI of M2 region were statistically (P < 0.05).ConclusionFHL tendon injury resulted in decreased PA in M1, decreased PW and PMPTI in M2, and increased PA in the M5 region, suggesting that FHL tendon injury resulted in a force shift from the medial to the lateral side of the foot. The PA of M1, PW and PMPTI of M2 have certain diagnostic value for early FHL injury in amateur marathon runners.

Estimation of Initial Oil in Place for Buzurgan Oil Field by Using Volumetric Method and Reservoir Simulation Method

The estimation of the initial oil in place is a crucial topic in the period of exploration, appraisal, and development of the reservoir. In the current work, two conventional methods were used to determine the Initial Oil in Place. These two methods are a volumetric method and a reservoir simulation method. Moreover, each method requires a type of data whereet al the volumetric method depends on geological, core, well log and petrophysical properties data while the reservoir simulation method also needs capillary pressure versus water saturation, fluid production and static pressure data for all active wells at the Mishrif reservoir. The petrophysical properties for the studied reservoir is calculated using neural network technique from 13 cored and logged wells. The results showed that the reservoir simulation method gave a value of Initial Oil in Place that agrees and close to the value of Initial Oil in Place obtained from the volumetric method with a percentage different around 2%. However, the estimation of Initial Oil in Place by reservoir simulation method offered accurate results during good history matching with observed data as well as making appropriate adjusting for Pc vs. Sw values for the whole reservoir from October 1976 until December2020. MB21 unit own most Initial Oil in Place equal to 525*106 SM3 while MB12 has lowest IOIP equal to 2*106 SM3. Finally, the calculation of Initial Oil in Place by both volumetric and simulation methods presented good results while comparing with previous study at 2013 with discovered different around 1.5% and 0.6% respectively.

Impact of Asthma on Plantar Pressures in a Sample of Adult Patients: A Case-Control Study.

Based on the high prevalence of asthma in the population, and its relationship with various musculoskeletal and postural disorders, the aim of this study was to evaluate the plantar pressures in asthmatic patients compared to a control group. A case-control study involving 90 participants was conducted, consisting of 45 asthma patients and 45 healthy paired controls. Static plantar pressure data were recorded using a portable pressure sensor platform. Statistically significant differences were shown in the body weight on the left heel (p = 0.031), and the right forefoot maximum peak pressure was lower in the case group (p = 0.042). The findings of this study show alterations in static plantar pressures in asthmatic patients compared to healthy individuals. Specifically, the subjects with asthma showed less maximum pressure in the right forefoot and less weight on the left heel, which appear to be associated with the asthma disease.

Concurrent characterization of compressibility and viscosity in extrusion-based additive manufacturing of acrylonitrile butadiene styrene with fault diagnoses

Compressibility and viscosity of polymer feedstock are critical to their volumetric flow rate, weld strength, and dimensional accuracy in material extrusion additive manufacturing. In this work, the compressibility and viscosity of an acrylonitrile butadiene styrene (ABS) material is characterized with an instrumented hot end design. Experiments are first performed with a blocked nozzle to characterize the compressibility behavior. The results closely emulate the pressure-volume-temperature (PVT) behavior of a characterized generic ABS. Experiments are then performed with an open nozzle over a range of volumetric flow rates and temperatures. The static pressure data is fit to power-law, Ellis, and Cross viscosity models and the dynamic melt pressure data is then used to jointly fit material constitutive models for compressibility and viscosity. The results suggest that the joint fitting substantially improves the fidelity relative to the separately characterized viscosity and compressibility. The implemented methods support material extrusion process simulation and control including real-time identification of process faults such as (1) limited melting capacity of the hot end, (2) skipping (grinding) of the extruder drive gears, (3) low initial nozzle temperature, (4) varying flow rates associated with the intermeshing gear tooth velocity profile, and (5) delays and reduced melt pressures due to drool prior to extrusion. The ability to monitor the printing process for faults in real time, such as that presented in this work, is critical to born qualified parts. Additionally, these approaches can be used to screen new materials and identify optimal processing conditions that avoid these process faults. • Detailed design of an instrumented hot end is provided. • Two-stage compression is used to characterize compressibility with a blocked nozzle. • Power law, Ellis, and Cross models are fit to apparent viscosity data generated with a stock nozzle having a diameter of 0.4 mm. • Viscosity and compressibility models are fit by minimizing the error between the input mass flow rate and the modeled fluid capacitance and outlet mass flow rate. • Dynamic melt pressure data reveals significant faults occurring during extrusion.

Research on Pressure Comfort of Yoga Suit and Optimization Scheme of Pattern Based on CLO 3D Software

Based on the improvement of yoga clothing pressure comfort, this paper used Fuyi CAD garment system to make 2d clothing pattern, then, the 3D virtual fitting experiment of the main part of this paper was carried out. In the experiment, the static and dynamic pressure data of the virtual model were collected by using ClO 3D software, and the experimental data were analyzed by using the comparative experimental method. After analysis, the optimization was carried out in the garment piece, and then the same method was adopted to conduct data acquisition again, and it turned out to be that the overall virtual pressure reduces 247.93Kpa. Finally, the optimization effect of each garment piece was evaluated. The results showed that the sample can be optimized and the pressure comfort can be improved through the virtual pressure test method of CLO 3D platform.

Swirling effect on thermodynamic performance in a solid fueled ramjet with paraffin-polyethylene

In this work, systematic firing tests have been conducted to evaluate the thermodynamic performances and combustion behaviors of Solid Fuel Ramjet (SFRJ) fueled by paraffin-polyethylene blends fuel. The experiments are carried out via connected pipe facility. And three key parameters are identified, i.e. 1) fuel paraffin concentration, 2) swirl intensity (denoted by swirling number), and 3) solid fuel ramjet combustor geometry. These parameters are experimentally investigated one at a time. To characterize the propulsion system performance, the static temperature, pressure, and engine thrust data are logged in real-time. The time-averaged regression rate is obtained via a three dimensional scanner. A high-speed camera is employed to capture the flame shapes. The acquired pressure data from the engine is further analyzed by using Fast Fourier Transform to obtain its frequency spectrum and acoustical energy distribution over the frequency range of interest. The present results show that increasing the swirl number can increase the regression rate, combustion efficiency, and total thrust. However, increasing the paraffin concentration has a positive effect on the regression rate, but negative effect on the combustion efficiency. In addition, the regression rate is found to be inversely proportional to the inlet diameter and port diameter. In general, the present work shed lights on the thermodynamic performances of a SFRJ fueled by paraffin-polyethylene blends.

CFD modelling of physical velocity and anisotropic resistance components in a peaked stored grain with aeration ducting systems

Modelling airflow in large stored grain silos has been dealt with superficial velocities and with uniform airflow resistance across the bulk. However, superficial velocities are always lower than physical velocities in an isotropic medium. Besides, due to varying grain properties, there is a high potential of variation in airflow resistances along the vertical and horizontal directions.Thus, a 3D CFD model was developed considering physical velocity in an anisotropic porous media to predict airflow and static pressure distribution from a V-shaped aeration floor. Varying airflow resistances along the horizontal direction of an element were incorporated into the model to account for the variation in grain properties. Mesh independency tests were conducted for achieving numerical stability during the steady-state simulation. The model was validated using the static pressure taps and airflow data measured in an on-farm grain storage silo.A 0.35 m mesh size was optimized using the static pressure and airflow data in the silo model. Least error for static pressure and airflow predictions were observed when horizontal airflow resistance was 50% of the vertical airflow resistance. Furthermore, the model predicted that 14.3% of the total grain volume exhibited a low airflow rate below the recommended value of 2 L s−1 t−1 including a significant proportion of the top grain volume above the eave height. Due to 85% of the non-perforated section on the silo floor, 12.6% of the lower grain volume up to a maximum height of 4.4 m above the floor exhibited the low airflow regime. As physical experimentations are tedious, the proposed physical velocity based model could be extended for simulating different options for minimizing dead zone proportions for better grain storage management.

Experimental investigation of the tip leakage flow in a low-speed multistage axial compressor.

Casing pressure measurements and Stereoscopic Particle-Image Velocimetry (SPIV) measurements are used together to characterize the behavior of the rotor tip leakage flow at both the design and near-stall conditions in a low-speed multistage axial compressor. A three-dimensional Navier-Stokes solver is also performed for the multistage compressor and the prediction of tip leakage flow is compared with SPIV data and casing dynamic static pressure data. During the experiment 10 high-frequency Kulite transducers are mounted in the outer casing of the rotor 3 to investigate the complex flow near the compressor casing and Fourier analyses of the dynamic static pressure on the casing of the rotor 3 are carried out to investigate the tip leakage flow characteristics. At the same time, the two CCD cameras are arranged at the same side of the laser light sheet, which is suitable for investigating unsteady tip leakage flow in the multistage axial compressor. The SPIV measurements identify that the tip leakage flow exists in the rotor passage. The influence of tip leakage flow leads to the existence of low axial velocity region in the rotor passage and the alternating regions of positive and negative radial velocity indicates the emergence of tip leakage vortex (TLV). The trajectory of the tip leakage vortex moves from the suction surface toward the pressure surface of adjacent blade, which is aligned close to the rotor at the design point (DP). However, the tip leakage vortex becomes unstable and breaks down at the near-stall point (NS), making the vortex trajectory move upstream in the rotor passage and causing a large blockage in the middle of the passage.

NARMAX Identification Based Closed-Loop Control of Flow Separation over NACA 0015 Airfoil

A closed-loop control algorithm for the reduction of turbulent flow separation over NACA 0015 airfoil equipped with leading-edge synthetic jet actuators (SJAs) is presented. A system identification approach based on Nonlinear Auto-Regressive Moving Average with eXogenous inputs (NARMAX) technique was used to predict nonlinear dynamics of the fluid flow and for the design of the controller system. Numerical simulations based on URANS equations are performed at Reynolds number of 106 for various airfoil incidences with and without closed-loop control. The NARMAX model for flow over an airfoil is based on the static pressure data, and the synthetic jet actuator is developed using an incompressible flow model. The corresponding NARMAX identification model developed for the pressure data is nonlinear; therefore, the describing function technique is used to linearize the system within its frequency range. Low-pass filtering is used to obtain quasi-linear state values, which assist in the application of linear control techniques. The reference signal signifies the condition of a fully re-attached flow, and it is determined based on the linearization of the original signal during open-loop control. The controller design follows the standard proportional-integral (PI) technique for the single-input single-output system. The resulting closed-loop response tracks the reference value and leads to significant improvements in the transient response over the open-loop system. The NARMAX controller enhances the lift coefficient from 0.787 for the uncontrolled case to 1.315 for the controlled case with an increase of 67.1%.

Formation pressure prediction technology of infill point in low permeability oilfield

Poor reservoir physical property which leads to low rate of water injection pressure decline after the shut-in because of drilling control is the main characteristic of Daqing peripheral oilfields. To reduce reservoir energy loss, ensure the effect of infilling well, it is necessary to study the formation pressure of infill well point. However, there is no formation pressure prediction formula for infill well point in low permeability reservoir. In this article, combined with detailed reservoir description results, the effective characteristics of formation with different permeabilities are analyzed, the range of effective displacement permeability are defined, and the formation pressure of infill well point is calculated based on reservoir engineering method. Meanwhile, according to the actual injection pressure, produced liquid volume and partial static pressure data, numerical simulation pressure prediction is presented to simulate infill well point pressure. Considering to both prediction results, formation pressure at infill well point can be determined. Field test verifies that the predicted pressure is close to the actual pressure with an error rate within ± 10%, wells with pressure coefficients less than 1.80mpa/100m can be drilled, and those with the pressure coefficients greater than 1.80mpa/100m, drilling should be processed after depressurization.

Study of intermittent flow characteristics experimentally and numerically in a horizontal pipeline

The gas-liquid intermittent flow regime is the dominant flow pattern, which significantly occurs in the oil and gas industries. The intermittent flow is challenging in the hydrocarbon transportation systems and separators operation. The present investigation aims to comprehend the behavior of intermittent flow characteristics using experimental and numerical methods simultaneously. Superficial velocities of water and air were set in ranges of (0.18–0.84 m/s) and (1.22–4.9 m/s), respectively. The research was conducted in a horizontal pipe with a diameter of 44 mm and 147D long to study slug frequency, slug length, translational slug velocity, pressure drops, as well as slug's initiation location using static pressure data and high-speed camera tools. In this regard, the volume of fluid (VoF) method and SST k-ω model were also applied to specify film thickness, maximum Taylor bubble velocity, and to grasp behaviors of the flow field in more detail. The results revealed that liquid superficial velocity has more effects on slug frequencies than gas superficial velocity. On the other hand, slug initiation location, as well as slug fully developed length, is affected by the gas superficial velocity more than liquid superficial velocity. Moreover, both the gas and liquid superficial velocities have the same effects on translational slug velocities. The obtained experimental results were also employed to define a distinctive inlet boundary condition in the numerical simulation, which leads to a 65 percent reduction in the computational domain.

Assessment of Cavity Covered with Porous Surface in Controlling Shock/Boundary-Layer Interactions in Hypersonic Intake

The supersonic/hypersonic flow through an aircraft intake must be decelerated before entering the combustion chamber to ensure efficient combustion. Retardation in the flow speed is achieved through a progression of oblique and normal shock waves in the isolator region of the intake. However, the advantages of speed reduction in intake are usually accompanied by huge losses due to the shock wave and boundary-layer interactions (SBLIs). These losses may include, inlet-unstart, abrupt thickening or separation of the boundary layer, unsteady shock oscillations, etc. Clearly, the SBLIs must be controlled to minimize the losses and improve the performance of the complete vehicle. Control of these interactions by manipulating the strength of the shock using a shallow cavity with wall ventilation has gained prominence. In this study, the efficacy of a thin porous surface deployed over shallow cavity in the higher adverse pressure gradient regions of Mach 5.7 and Mach 7.9 mixed-compression intakes, is experimentally investigated. With the variation of diameter and pitch of the pores, the porosity in Mach 5.7 intake is varied as; 4.5%, 7.5%, 17%, 21.6%, and 25%. A maximum of 20.53% drop in static pressure in the Mach 5.7 intake controlled by the cavity covered with 25% surface perforation, at a near-reattachment location (x/L = 0.73), is observed. However, the separation bubble in Mach 5.7 intake is suppressed most efficiently, when the cavity is covered with 17% porous surface. For Mach 7.9 intake also, the 25% surface perforation has maintained its superiority in reducing the wall static pressure to a maximum of 20.20% at x/L = 0.73. Once again, the 17% porous surface controlled configuration is found to be quite effective in suppressing the bubble. A qualitative investigation of the Schlieren images supports the findings of wall static pressure data.

Energy efficiency overestimated by classic affinity laws: relation between volumetric flow rate and static pressure of an axial mine fan adjusted by a variable frequency driver

ABSTRACTA significant problem with operating a coal mine fan is finding ways to save energy while still maintaining the required air supply to working faces. The authors developed and tested the performance of a K45-4-№9/18.5 kW axial mine fan adjusted by a variable frequency driver set to different fractions of a typical national electric grid frequency of 50 Hz. Its volumetric flow-rate and static pressure (Q-H) data were fitted with fifth-order polynomial equations using least-squares regression. The extremes of the Q-H curves descend with decreasing frequency and differ significantly from the predictions of classic affinity laws (CAL) in fluid dynamics. The air-flow power predicted by CAL theory deviates from the baseline of the fifth-order polynomial extremes by a maximum of 48%. Interestingly, the deviation between theoretical and experimental values increases with decreasing power frequency. These results are evidence of the theoretical overestimation of energy efficiency of an AMF adjusted by a VFD.

A Three-Zone Modeling Approach for Centrifugal Compressor Slip Factor Prediction

Accurate estimation of slip factor is of paramount importance to ensure centrifugal compressor work input is adequately predicted during the preliminary design process. However, variations in the flow field at impeller exit in both the pitchwise and spanwise directions complicate the evaluation procedure considerably. With the increasing implementation of engine downsizing technologies in the automotive sector, achieving a wide operating range has become a factor of prime importance for centrifugal compressors used in automotive turbocharging applications. As a result of the design features required to achieve this aim, modern impeller geometries have been shown to exhibit an approximately parabolic variation in slip factor across their respective operating maps. By comparison, traditional slip correlations typically exhibit a constant, or at best monotonic, relationship between slip factor and impeller exit flow coefficient. It is this lack of modeling fidelity which the current work seeks to address. In order to tackle these shortcomings, it is proposed that the impeller exit flow should be considered as being made up of three distinct regions: a region of recirculation next to the shroud providing aerodynamic blockage to the stage active flow, and a pitchwise subdivision of the active flow region into jet and wake components. It is illustrated that this hybrid approach in considering both spanwise and pitchwise stratification of the flow permits a better representation of slip factor to be achieved across the operating map. The factors influencing the relative extent of each of these three distinct regions of flow are numerous, requiring detailed investigations to successfully understand their sources and to characterize their extent. A combination of 3D computational fluid dynamics (CFD) data and gas stand test data for six automotive turbocharger compressor stages was employed to achieve this aim. Through application of the extensive interstage static pressure data gathered during gas stand testing at Queen's University Belfast, the results from the 3D CFD models were validated, thus permitting a more in-depth evaluation of the flow field in terms of locations and parameters that could not easily be measured under gas stand test conditions. Building on previous knowledge gained about the variation in shroud side recirculation with geometry and operating condition, the characteristic jet/wake flow structure emanating from the active flow region of the impeller was represented in terms of area and mass flow components. This knowledge allowed individual slip factor values for the jet and wake to be calculated and combined to give an accurate passage average value which exhibited the distinctive nonlinear variation in slip across the operating map which is frequently absent from existing modeling methods. Fundamental considerations of the flow phenomena in each region provided explanation of the results and permitted a modeling approach to be derived to replicate the trends observed in both the experimental data and the CFD simulations.

Active Stall Control of an Airfoil Using Synthetic Jets

Flow separation is mostly an undesirable phenomenon and flow separation control is very important on airfoils. The synthetic jet is one of the effective techniques for active flow control. The synthetic jet actuator is composed of a speaker or a piezoelectric diaphragm. The purpose of this study is to develop the active stall control system of NACA0012 airfoil’s upper surface. The system detects the flow conditions (stall or unstalled) by two static pressure data alone on the airfoil. When the system detects the stall, synthetic jets automatically operate to control the stall. The maximum lift increases 16 ％ and the stall angle can improved at 3 ° by using synthetic jet actuator at Re = 1.5×105 based on the chord length of the airfoil. Our proposed system can enhance the aerodynamic performance of the airfoil and separation control is always attained with no stall for all flow fields produced by changing the angle of attack examined in the present study.

Inference of Global Reservoir Connectivity from Static Pressure Data with Fast Coarse-Scale Simulation Models

Characterization of field-scale reservoir connectivity is critical for production optimization and field development planning. The information content of the data corresponding to different physical processes, coupled with the discrepancy in production data and geologic model resolutions, complicate the estimation of global field connectivity. Due to its diffusive nature, pressure varies smoothly in the reservoir, a characteristic that can be adequately captured using coarse-scale description of the connectivity in the reservoir model. On the other hand, flowrate and watercut information are relatively more localized and require higher-resolution models to adequately describe their variations. Hence, pressure and flowrate data carry information pertinent to their respective scales. In this paper, a fast workflow is presented for estimating large-scale reservoir connectivity from static reservoir pressure measurements. For this purpose, a coarse-scale grid system with Delaunay triangulation is developed to represent the global reservoir connectivity. Flow-based upscaling is applied to create the initial coarse-scale static simulation models from geological or simulation models. The ensemble Kalman filter is then applied to calibrate the initial models against static pressure data and to identify field-scale connectivity parameters that control the global pressure distribution, such as aquifer strength, continuity/discontinuity in reservoir properties, and fault transmissibilities. This approach enables fast characterization of field-scale reservoir connectivity from pressure data with a coarser description of the reservoir connectivity, which offers a parameterization level that is commensurate with the resolution and information content of the static pressure measurements. The proposed calibration approach can serve as preconditioning to generate initial reservoir models with consistent global connectivity patterns for full-scale history matching. To illustrate the feasibility and performance of the method, examples are drawn from real field cases in which static pressure data are integrated to infer global reservoir connectivity maps. In this paper, the resulting connectivity maps are used to obtain facies probability maps to generate initial facies models for full-scale history matching.

RX-320 Rocket Static Pressure Combustion Chamber Prediction and Validation by Using Invers Method

The static pressure data of the combustion chamber which can generally be obtained by performing direct measurements when static test is performed on the rocket is an important parameter in predicting the thrust and design of the combustion chamber of the rocket. However, there is a model rocket for flight test that is used in static test. Thus, there is no mounting for static pressure sensors (for measurement) are made. To solve the problem, then the inverse method is used as an iterative solution for the basic equations of the rocket thrust force in the nozzle by guessing the value of the static pressure of the combustion chamber firstly and calculate the iteration by including the value of the rocket thrust from static test data and the efficiency variation of the nozzle. The results of this calculation are then validated by using a 3D-CFD numerical simulation to obtain a more detailed comparison on the nozzle. In this research RX 320 LAPAN rocket nozzle with focus on maximum static thrust data of static test results is used. The 3-D numerical simulation is performed using Numeca CFD software, with k-extended wall extended turbulent model, numerical multigrid level 3 scheme, center based, and convergence criteria of 10 e-05. The result of calculation by inverse method and its comparison with numerical simulation shows that the smallest difference of the combustion chamber static pressure between inverse method and numerical simulation is 0.017%, that is achieved at 92% nozzle efficiency. At this point, the static pressure of the combustion chamber is 57.94 bar. From this point of view, the results of this comparison indicate that the inverse method can be used accurately for static pressure of the combustion chamber prediction, if the nozzle efficiency is given correctly. Furthermore, with given static pressure of the combustion chamber correctly, it will be very helpful in the design of the more optimum combustion chamber.

UAV flight test of plasma slats and ailerons with microsecond dielectric barrier discharge**Project supported by the National Natural Science Foundation of China (Grant Nos. 51336011 and 51607188), the China Postdoctoral Science Foundation (Grant No. 2014M562446), and the PhD Research Startup Foundation of Xi’an University of Technology (Grant No. 256081802).

Plasma flow control (PFC) is a promising active flow control method with its unique advantages including the absence of moving components, fast response, easy implementation, and stable operation. The effectiveness of plasma flow control by microsecond dielectric barrier discharge (μs-DBD), and by nanosecond dielectric barrier discharge (NS-DBD) are compared through the wind tunnel tests, showing a similar performance between μs-DBD and NS-DBD. Furthermore, the μs-DBD is implemented on an unmanned aerial vehicle (UAV), which is a scaled model of a newly developed amphibious plane. The wingspan of the model is 2.87m, and the airspeed is no less than 30m/s. The flight data, static pressure data, and Tufts images are recorded and analyzed in detail. Results of the flight test show that the μs-DBD works well on board without affecting the normal operation of the UAV model. When the actuators are turned on, the stall angle and maximum lift coefficient can be improved by 1.3° and 10.4%, and the static pressure at the leading edge of the wing can be reduced effectively in a proper range of angle of attack, which shows the ability of μs-DBD to act as plasma slats. The rolling moment produced by left-side μs-DBD actuation is greater than that produced by the maximum deflection of ailerons, which indicates the potential of μs-DBD to act as plasma ailerons. The results verify the feasibility and efficacy of μs-DBD plasma flow control in a real flight and lay the foundation for the full-sized airplane application.