scholarly journals Sabot Discard Characteristics under Different Spin Rates of the Rifled Barrel Launching APFSDS

2021 ◽  
Vol 2021 ◽  
pp. 1-18
Author(s):  
Chengqing Zhang ◽  
Huiyuan Wang ◽  
Ting Liu ◽  
Yingxian Duo
Keyword(s):  
Surface Pressure ◽  
Aerodynamic Characteristics ◽  
Intensity Change ◽  
Monitoring Point ◽  
Choked Flow ◽  
Optimal Value ◽  
Perfect Symmetry ◽  
Computational Fluid Dynamics Cfd ◽  
Aerodynamic Parameters ◽  
Quantization Parameters

The sabot discard asymmetry caused by spinning affects the exterior ballistic characteristics and shooting accuracy of a gun with the rifled barrel. To gain a deeper understanding of the complex sabot discard performance for the armor-piercing, fin-stabilized discarding sabot (APFSDS), a numerical investigation is performed to assess the effects of the spin rate on the sabot discard characteristics. We obtain the calculation boundary by the interior ballistics and the firing conditions and carry out a numerical simulation under different spin rates using computational fluid dynamics (CFD) and a dynamic mesh technique. We analyze four aspects of sabot discard characteristics, namely, sabot separation, rod surface pressure, rod aerodynamic parameters, and discarding quantization parameters. Computational results show that the sabot separation nearly presents perfect symmetry at 0 rad/s, and when the initial rate of the sabot increases, there is more obvious separation asymmetry, and it contributes to the relative position variation among the sabots and the rod. The distinction of rod surface pressure indicates that the choked flow is the strongest flow source, and the spin rate has almost no effect on the pressure of the rod front part. When the monitoring point moves towards the fins, the pressure distribution and intensity change more dramatically. The initial spin rate and separation asymmetry produce a variation in the surface pressure, which further influences the rod aerodynamic characteristics. The discarding quantization parameters exhibit a certain variation rule with its spin rate. 2,000 rad/s has a significant influence on the rod aerodynamic coefficients during the weak coupling phase. When the spin rate is in the range of 0–900 rad/s, the discarding characteristics remain the same. However, when the spin rate exceeds 900 rad/s, the separation time and aerodynamic impulse have a quadratic polynomial relationship with the rate. Additionally, a spin rate of 1,000 rad/s is the optimal value for a rifled barrel gun.

The Effects of Different Support Forms on the Aerodynamic Characteristics of the High-Speed Train Model

2012 ◽  
Vol 246-247 ◽  
pp. 461-465
Author(s):  
Bao Yu Li ◽  
Xi Zhuang Shan ◽  
Zhi Gang Yang
Keyword(s):  
Flow Field ◽  
High Speed ◽  
Aerodynamic Characteristics ◽  
Operating Conditions ◽  
High Speed Train ◽  
Reference Velocity ◽  
Computational Fluid Dynamics Cfd ◽  
Aerodynamic Parameters ◽  
Support Interference ◽  
Good Support

By the method of computational fluid dynamics (CFD), this paper calculates the aerodynamic parameters of one complex high-speed train model which adopts different support forms when the reference velocity is 70m/s under different operating conditions. It also analyses the support interference mechanism from the point of flow field structure. The results show that the distributed cylinder support form causes least interference on the model, while the single big cylinder support forms change the flow field structures much which leads to much change of the aerodynamic parameters of the model. The distributed cylinder support form can be applied as a good support form for the high-speed train wind tunnel tests.

EFFECT OF SKIRT ANGLE AND FEATHERS FORMATION ON SHUTTLECOCK AERODYNAMICS PERFORMANCE

2015 ◽  
Vol 76 (8) ◽  
Author(s):  
Tajuddin Md. Jahi ◽  
Haziq Ikhwan Zawawi ◽  
Norazah Abd Rahman
Keyword(s):  
Aerodynamic Drag ◽  
Aerodynamic Characteristics ◽  
Spin Rotation ◽  
Design Parameters ◽  
World Federation ◽  
Cfd Analysis ◽  
Optimal Value ◽  
Computational Fluid Dynamics Cfd ◽  
Α Angle ◽  
Very High

Aerodynamic characteristics of badminton shuttlecock are significantly different from balls used in other sports. Shuttlecock can achieve a very high initial speed and at the same time, it can decelerate very fast. This is due to the significant aerodynamic drag it experiences during its in-flight motion. A computational fluid dynamics (CFD) analysis was carried out to understand the aerodynamics of a feathers shuttlecock approved by Badminton World Federation (BWF) for international tournaments. The aerodynamics performance of a standard shuttlecock at steady-state flight was investigated. The shuttlecock was assumed to be rigid and have no spin rotation; and velocity considered was 92 m/s. Effects of parameters such as angle of attack, α; angle of skirt, Ɵ; and angle of feathers, β; on the shuttlecock drag coefficient, Cd; were studied. It is found that smaller Ɵ leads to smaller Cd. Analysis shows that the Cd is the largest when the shuttlecock is at α = 0°. Besides that, the Cd is also influenced by β which the standard shuttlecock has fairly small Cd. Formation of feathers of the standard shuttlecock may be further twisted to the optimal value of β in order to increase its drag. As a result, Ɵ and β may be considered as design parameters in order to obtain the desired aerodynamics performance.

scholarly journals Research on aerodynamic characteristics of two-stage axial micro air turbine spindle for small parts machining

2020 ◽  
Vol 12 (12) ◽  
pp. 168781402098437
Author(s):  
Liu Jiang ◽  
Guo Zhiping ◽  
Miao Shujing ◽  
He Xiangxin ◽  
Zhu Xinyu
Keyword(s):  
High Speed ◽  
Aerodynamic Characteristics ◽  
Maximum Efficiency ◽  
Two Stage ◽  
Output Torque ◽  
Air Turbine ◽  
Solid Foundation ◽  
Computational Fluid Dynamics Cfd ◽  
Micro Machine ◽  
Small Parts

In order to meet the requirements of output torque, efficiency and compact shape of micro-spindles for small parts machining, a two-stage axial micro air turbine spindle with an axial inlet and outlet is proposed. Based on the k-ω turbulence model of SST, the flow field and operation characteristics of the two-stage axial micro air turbine spindle were studied using computational fluid dynamics (CFD) combined with an experimental study. We obtained the air turbine spindle under different working conditions of the loss and torque characteristics. When the inlet pressure was 300 KPa, the output speed of the two-stage turbine was 100,000 rpm, 9% higher than that of a single-stage turbine output torque. The total torque reached 6.39 N·mm, and the maximum efficiency of the turbine and the spindle were 42.2% and 32.3%, respectively. Through the research on the innovative structure of the two-stage axial micro air turbine spindle, the overall performance of the principle prototype has been significantly improved and the problems of insufficient output torque and low working efficiency in high-speed micro-machining can be solved practically, which laid a solid foundation for improving the machining efficiency of small parts and reducing the size of micro machine tool.

scholarly journals Pipeline Compressor Redesign With the Consideration of Both Noise and Performance

2000 ◽  
Author(s):  
Yuri I. Biba ◽  
Zheji Liu ◽  
D. Lee Hill
Keyword(s):  
High Efficiency ◽  
Aerodynamic Characteristics ◽  
The Body ◽  
Design Parameters ◽  
Original Design ◽  
Tonal Noise ◽  
Experimental Performance ◽  
Expected Performance ◽  
Computational Fluid Dynamics Cfd ◽  
And Performance

A complete effort to redesign the aerodynamic characteristics of a single-stage pipeline compressor is presented. The components addressed are the impeller, diffuser region, and the volute. The innovation of this effort stems from the simultaneous inclusion of both the noise and aerodynamic performance as primary design parameters. The final detailed flange-to-flange analysis of the new components clearly shows that the operating range is extended and the tonal noise driven by the impeller is reduced. This is accomplished without sacrificing the existing high efficiency of the baseline machine. The body of the design effort uses both Computational Fluid Dynamics (CFD) and vibro-acoustics technology. The predictions are anchored by using the flange-to-flange analysis of the original design and its experimental performance data. By calculating delta corrections and assuming that these deltas are approximately the same for the new design, the expected performance is extrapolated.

Evaluation of Aerodynamic Characteristics of Mega-Yacht Superstructures by CFD Simulations

2020 ◽  
Vol 36 (04) ◽  
pp. 259-270
Author(s):  
Ahmet Ziya Saydam ◽  
Serhan Gokcay ◽  
Mustafa Insel
Keyword(s):  
Aerodynamic Characteristics ◽  
Temperature Gradients ◽  
Time Dependent ◽  
Navier Stokes ◽  
Noise Generation ◽  
Velocity Data ◽  
Cfd Simulations ◽  
Recent Developments ◽  
Computational Fluid Dynamics Cfd

Air wake distribution around the superstructure of a mega-yacht is a key concern for the designer because of various reasons such as comfort expectations in recreational deck areas, self-noise generation, air pollution and temperature gradients due to exhaust interactions, and safety of helicopter operations such as landing/take off and hovering. The Reynolds-averaged Navier-Stokes (RANS) technique in computational fluid dynamics (CFD) is frequently used in studies on mega-yacht hydrodynamics and aerodynamics with satisfactory results. In this article, a case study is presented for the utilization of CFD in a mega-yacht's superstructure design. The flow field in recreational open areas has been analyzed for the increase in velocity due to the existence of the superstructure. A reduction in self-noise of the mast structure has been aimed by reducing flow separation and vorticity. Time-dependent velocity data obtained with scale-resolving simulations are presented for the evaluation of helicopter landings. The capabilities and limitations of the RANS technique are discussed along with recent developments in modeling approaches.

scholarly journals The Effects of Icing on Aircraft Longitudinal Aerodynamic Characteristics

Mathematics ◽  
2020 ◽  
Vol 8 (7) ◽  
pp. 1171
Author(s):  
Yihua Cao ◽  
Wenyuan Tan ◽  
Yuan Su ◽  
Zhongda Xu ◽  
Guo Zhong
Keyword(s):  
Prediction Method ◽  
Flight Test ◽  
Aerodynamic Characteristics ◽  
Identification System ◽  
Narrow Strip ◽  
Aerodynamic Derivatives ◽  
Strip Theory ◽  
Aerodynamic Parameters ◽  
Flight Dynamics Model ◽  
Derivatives Of

To study the effects of ice accretion on the longitudinal aerodynamic characteristics of an aircraft, a two-part method for predicting longitudinal aerodynamic derivatives of iced aircraft is proposed. For the aircraft with a flight test, a parameter identification system based on maximum likelihood criterion and a longitudinal nonlinear flight dynamics model is established. For the aircraft without a flight test, an engineering prediction method of aerodynamic derivatives based on an individual component CFD calculation and narrow strip theory is established. According to the flight test data of DHC-6 Twin Otter aircraft from NASA, the longitudinal aerodynamic parameters of both clean and artificially iced aircraft are obtained. Additionally, the longitudinal aerodynamic derivatives of the iced aircraft are calculated. Then, the correctness of the prediction method is verified by comparing the calculated results with the identification results. The comparison of these results shows that the prediction method is correct and accurate, and it can be used to calculate the effects of icing on the aircraft longitudinal aerodynamic parameters.

AERODYNAMIC OF UITM'S BLENDED-WING-BODY UNMANNED AERIAL VEHICLE BASELINE-II EQUIPPED WITH ONE CENTRAL VERTICAL RUDDER

2015 ◽  
Vol 75 (8) ◽  
Author(s):  
Wirachman Wisnoe ◽  
Rizal E.M. Nasir ◽  
Ramzyzan Ramly ◽  
Wahyu Kuntjoro ◽  
Firdaus Muhammad
Keyword(s):  
Unmanned Aerial Vehicle ◽  
Cfd Simulation ◽  
Aerodynamic Characteristics ◽  
Control Surface ◽  
Wind Tunnel Experiments ◽  
Aerodynamic Parameter ◽  
Aerial Vehicle ◽  
Computational Fluid Dynamics Cfd ◽  
Blended Wing Body ◽  
Lift And Drag

In this paper, a study of aerodynamic characteristics of UiTM's Blended-Wing-Body Unmanned Aerial Vehicle (BWB-UAV) Baseline-II in terms of side force, drag force and yawing moment coefficients are presented through Computational Fluid Dynamics (CFD) simulation. A vertical rudder is added to the aircraft at the rear centre part of the fuselage as yawing control surface. The study consists of varying the side slip angles for various rudder deflection angles and to plot the results for each aerodynamic parameter. The comparison with other yawing control surface for the same aircraft obtained previously are also presented. For validation purpose, the lift and drag coefficients are compared with the results obtained from wind tunnel experiments. 

scholarly journals Computational Evaluation of Surgical Design for Multisegmental Complex Congenital Tracheal Stenosis

2020 ◽  
Vol 2020 ◽  
pp. 1-10
Author(s):  
Limin Zhu ◽  
Xiaolei Gong ◽  
Jinlong Liu ◽  
Youjin Li ◽  
Yumin Zhong ◽  
...  
Keyword(s):  
Tracheal Stenosis ◽  
Computer Aided Design ◽  
Surgical Correction ◽  
Patient Specific ◽  
Congenital Tracheal Stenosis ◽  
Computational Evaluation ◽  
Life Threatening ◽  
Computational Fluid Dynamics Cfd ◽  
Aerodynamic Parameters ◽  
Aided Design

Multisegmental complex congenital tracheal stenosis (CTS) is an uncommon but potentially life-threatening malformation of the airway. Staged surgery is indicated for the complex pathophysiology of the abnormal trachea. Surgical intervention to fix the stenotic segments may result in different postoperative outcomes. However, only few studies reported the design of surgical correction for multisegmental CTS. We used computer-aided design (CAD) to simulate surgical correction under different schemes to develop a patient-specific tracheal model with two segmental stenoses. Computational fluid dynamics (CFD) was used to compare the outcomes of different designs. Aerodynamic parameters of the trachea were evaluated. An obvious interaction was found between the two segments of stenosis in different surgical designs. The surgical corrective order of stenotic segments greatly affected the aerodynamic parameters and turbulence flows downstream of tracheal stenosis and upstream of the bronchus. Patient-specific studies using CAD and CFD minimize the risk of staged surgical correction and facilitate quantitative evaluation of surgical design for multiple segments of complex CTS.

Correlations for the Choked Mass and Momentum Flux Density Considering Real-Gas Thermodynamics

2019 ◽  
Vol 141 (8) ◽  
Author(s):  
Matthias Banholzer ◽  
Michael Pfitzner
Keyword(s):  
Flux Density ◽  
Mass Flux ◽  
Momentum Flux ◽  
Second Phase ◽  
Cfd Simulations ◽  
Choked Flow ◽  
Saturation Properties ◽  
Isentropic Flow ◽  
Computational Fluid Dynamics Cfd ◽  
Reduced Pressures

The choked mass flux density and the choked momentum flux density for the nonideal fluids methane and nitrogen have been calculated using the Soave–Redlich–Kwong equation of state (EoS). For the computation a steady, one-dimensional (1D), isenthalpic and isentropic flow is assumed. The developed algorithm for the calculation of the choked flow properties includes a bounded multidimensional Newton method. A possible second phase emerging in the critical nozzle area is excluded using the saturation properties of the considered fluids. The critical ratios of pressure, density, temperature, and speed of sound are discussed and compared to other publications. Formulations of the choked mass flux density and the choked momentum flux density explicit in Tr, pr, and Zr are given valid for different reduced pressures and temperatures depending on the fluid. Additional computational fluid dynamics (CFD) simulations are carried out in order to validate the findings of the algorithm and the proposed correlations.

Numerical Prediction of Blended Wing Body Aerodynamic Characteristics at Subsonic Speed

2014 ◽  
Vol 71 (2) ◽  
Author(s):  
Pang Jung Hoe ◽  
Nik Ahmad Ridhwan Nik Mohd
Keyword(s):  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
High Performance ◽  
Aerodynamic Characteristic ◽  
Aerodynamic Characteristics ◽  
Numerical Prediction ◽  
Navier Stokes ◽  
Subsonic Speed ◽  
Computational Fluid Dynamics Cfd ◽  
Blended Wing Body

The need for high performance and green aircraft has brought the blended wing (BWB) aircraft concept to the centre of interest for many researchers. BWB is a type of aircraft characterized by a complex blending geometry between fuselage and wing. Recently, many researches had been performed to unlock its aerodynamic complexity that is still not well understood. In this paper, aerodynamic characteristic of a baseline BWB configuration derived from simple conventional aircraft configuration was analysed using the Reynolds-averaged Navier-Stokes computational fluid dynamics (CFD) solver. The main objectives of this work are to predict the aerodynamic characteristics of the BWB concept at steady flight conditions and at various pitch angles. The results obtained are then compared against a simple conventional aircraft configuration (CAC). The results show that the BWB configuration used has 24% higher L/D ratio than the CAC. The increment to the L/D however is mainly due to lower drag than the improvement in the lift. 

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