Experimental analysis of cell pattern on grid fin aerodynamics in subsonic flow

2019 ◽  
Vol 234 (3) ◽  
pp. 537-562
Author(s):  
Manish Tripathi ◽  
Mahesh M Sucheendran ◽  
Ajay Misra
Keyword(s):  
Subsonic Flow ◽  
Lift Coefficient ◽  
Aerodynamic Performance ◽  
Aerodynamic Efficiency ◽  
Grid Fin ◽  
Stall Angle ◽  
The Individual ◽  
The Impact ◽  
Control Surfaces

Grid fins consisting of a lattice of high aspect ratio planar members encompassed by an outer frame are unconventional control surfaces used on numerous missiles and bombs due to their enhanced lifting characteristics at high angles of attack and across wider Mach number regimes. The current paper accomplishes and compares the effect of different grid fin patterns on subsonic flow aerodynamics of grid fins by virtue of the determination of their respective aerodynamic forces. Furthermore, this study deliberates the impact of gap variation on aerodynamics of different patterns. Results enunciate enhanced aerodynamic efficiency, and lift slope for web-fin cells and single diamond patterns compared to the baseline model. Moreover, the study indicates improved aerodynamic performance for diamond patterns with higher gaps by providing elevated maximum lift coefficient, delayed stall angle, and comparable drag at lower angles. The study established the presence of an additional effect termed as the inclination effect alongside the cascade effect leading to deviations with respect to lift, stall, and aerodynamic efficiency amongst different gap variants of the individual patterns. Thus, optimization based on the aerodynamic efficiency, stall angle requirements, and construction cost by optimum pattern and gap selection can be carried out through this analysis, which can lead to elevated aerodynamic performance for grid fins.

Effect of aspect ratio variation on subsonic aerodynamics of cascade type grid fin at different gap-to-chord ratios

2019 ◽  
Vol 124 (1274) ◽  
pp. 472-498
Author(s):  
M. Tripathi ◽  
M.M. Sucheendran ◽  
A. Misra
Keyword(s):  
Aspect Ratio ◽  
Performance Enhancement ◽  
Aerodynamic Performance ◽  
Aerodynamic Efficiency ◽  
Grid Fin ◽  
Stall Angle ◽  
Control Surfaces ◽  
Cascade Type ◽  
Limiting Value ◽  
Selection Of

ABSTRACTThis paper dwells upon investigating the effect of aspect ratio (AR) variation on the aerodynamic performance of unconventional control surfaces called grid fins by virtue of a series of subsonic experiments on a simplified grid fin variant called the cascade fin. Wind tunnel tests were performed for different AR (variable span) grid fins. The same had been investigated for different gap-to-chord ratio (g/c) variants. Results demonstrated a tangible increase in the aerodynamic efficiency as well as stall angle reduction for higher AR. Moreover, higher AR leads to increased pitching moment, which emphasizes elevated hinge moment requirements. The study ensued the presence of higher deviation between the low AR fins, that is $AR<2$ compared to the pertinent deviations between the high AR fins, that is $AR\geq2$ . The effect associated with these variations was termed as span effect in this paper. It was established that, the deviations arising due to this phenomena were lesser for higher g/c and higher AR. The analysis of AR variation for different g/c presented a limiting value of AR reduction for stall performance enhancement. Thus, optimised selection of the g/c and AR values can lead to enhanced aerodynamic efficiency alongside an improved stalling characteristic.

scholarly journals Expressionism in European and Chinese painting (late XIX – early XXI centuries)

2020 ◽  
pp. 27-46
Author(s):  
Jitai Wang
Keyword(s):  
Comparative Analysis ◽  
Mutual Influence ◽  
Cultural Factors ◽  
Chinese Painting ◽  
Oil Painting ◽  
New Concepts ◽  
Similarities And Differences ◽  
The Individual ◽  
The Impact

This article examines the impact of Chinese traditional painting upon the formation of Western expressionism, as well as interprets the influence of Western expressionism upon Chinese painting in expressionist manner of different periods. The author reveals the mutual influence, similarities and differences between Western expressionism and Chinese painting in expressionist manner, Chinese imagery oil painting, Chinese colored ink painting, and Chinese imagery painting in Western style. Based on correlation between the spiritual ideology of painting and artistic form, the author carries out a comparative analysis of spiritual and formal factors of Chinese and Western painting systems for the purpose of determination of their mutual influence, and how it affects the emergence of new concepts in painting. The structure of brush stroke of the artist defines his aesthetic spirit. The article determines the &ldquo;cyclic&rdquo; nature of interinfluence processes between Chinese and Western painting systems that stimulate the development of human civilization. The analysis of corresponding cultural factors allows assessing the individual artistic characteristics of painting. Both, Chinese and Western painting systems entered the period when spiritual ideology of painting interacts with the artistic forms, opening the era of &ldquo;globalization&rdquo; of the language of painting.

scholarly journals Critical Distance of the Seismic Waves’ Impact in Disintegration of Rock Blasting

2019 ◽  
Vol 2019 ◽  
pp. 1-8
Author(s):  
Dušan Kudelas ◽  
Blažej Pandula ◽  
Michal Cehlár ◽  
Marcela Taušová ◽  
Ján Koščo
Keyword(s):  
Critical Point ◽  
Seismic Waves ◽  
Critical Distance ◽  
Rock Blasting ◽  
Significant Difference ◽  
Explosive Charges ◽  
Speed Of Propagation ◽  
The Individual ◽  
The Impact

The presented paper deals with attenuation of seismic waves, which depends on the degree of disintegration of the rock environment in which seismic waves are propagated due to the explosion of explosive charges during blasting operations. Measurements of the impact of seismic waves were conducted to determine the best possible way to absorb these waves. The aim of the article is to identify the existence of a critical distance and the determination of the critical point from which the propagation of the velocity is not dependent on the type of deposit and the environment in which the seismic wave propagates. Statistical methods were used for these findings. The result is the determination of the distance of 80 m in which the speed on the individual deposits varied. From this limit on, there was no significant difference in the speed of propagation on the individual deposits.

Diagnosis of the Operation of Power Plants

2007 ◽  
Author(s):  
Jose´ Miguel Gonza´lez-Santalo´ ◽  
Abigail Gonza´lez-Di´az ◽  
Carlos Alberto Marin˜o-Lo´pez
Keyword(s):  
Power Plants ◽  
Environmental Changes ◽  
Environmental Parameters ◽  
Combined Cycle ◽  
Characteristic Parameters ◽  
Operating Variables ◽  
Design Values ◽  
The Individual ◽  
The Impact

A system was developed to diagnose the operation of combined cycle power plants and to determine, when deviations are found, which components are causing the deviations and the impact of each component deviation. The system works by comparing the values of the actual operating variables with some reference values that are calculated by a model that was adjusted to the design heat balances. The model can use the actual values of the environmental parameters as well as the design values, so the effect of environmental changes can be quantified and separated. The determination of the individual equipment impacts is done by adjusting the equipment parameters in order to reproduce the values of the measured variables. The adjustment is done by varying the values of the characteristic parameters of the equipment in order to minimize the sum of the squares of the differences between the values of the measured variables and the calculated values from the model.

Aerodynamic Performance of Turbine Center Frames With Purge Flows—Part I: The Influence of Turbine Purge Flow Rates

2018 ◽  
Vol 140 (6) ◽  
Author(s):  
Stefan Zerobin ◽  
Andreas Peters ◽  
Sabine Bauinger ◽  
Ashwini Bhadravati Ramesh ◽  
Michael Steiner ◽  
...  
Keyword(s):  
Measurement Data ◽  
Leading Edge ◽  
Aerodynamic Performance ◽  
Flow Structures ◽  
Flow Rates ◽  
Purge Flow ◽  
Mass Flows ◽  
The Individual ◽  
The Impact ◽  
First Time

This two-part paper deals with the influence of high-pressure turbine (HPT) purge flows on the aerodynamic performance of turbine center frames (TCF). Measurements were carried out in a product-representative one and a half-stage turbine test setup. Four individual purge mass flows differing in flow rate, pressure, and temperature were injected through the hub and tip, forward and aft cavities of the unshrouded HPT rotor. Two TCF designs, equipped with nonturning struts, were tested and compared. In this first part of the paper, the influence of different purge flow rates (PFR) is discussed, while in the second part of the paper, the impact of the individual hub and tip purge flows on the TCF aerodynamics is investigated. The acquired measurement data illustrate that the interaction of the ejected purge flow with the main flow enhances the secondary flow structures through the TCF duct. Depending on the PFR, the radial migration of purge air onto the strut surfaces directly impacts the loss behavior of the duct. The losses associated with the flow close to the struts and in the strut wakes are highly dependent on the relative position between the HPT vane and the strut leading edge (LE), as well as the interaction between vane wake and ejected purge flow. This first-time experimental assessment demonstrates that a reduction in the purge air requirement benefits the engine system performance by lowering the TCF total pressure loss.

scholarly journals Impact of the Winding Angle of the Auger Blade on the Loading Process With Milling Auger Drums

2020 ◽  
Vol 3 (1) ◽  
pp. 241-250
Author(s):  
Tomasz Wydro
Keyword(s):  
Milling Process ◽  
Design Parameters ◽  
Mining Machine ◽  
Loading Process ◽  
Auxiliary Process ◽  
Correct Determination ◽  
The Individual ◽  
The Impact ◽  
Winding Angle

AbstractThis publication addresses the impact of selected design parameters of milling auger cutting drums on the loading process, and above all the winding angle of the auger blade. The loading process is often referred to as an auxiliary process because the milling process is considered to be the dominant throughout the work of the cutting drum. The correct determination of the relationship between the mining process and the loading process allows to understand how the individual design and kinematic parameters of the mining drums and the mining machine on which they are installed affect each other. The publication discusses the problem of loading with milling cutting drums and ways to increase its efficiency. The research results of the loading process have been presented, affecting the efficiency of this process in the aspect of various angles of inclination of the auger blades. Based on the tests, conclusions have been formulated that allow for the possible selection of an appropriate winding angle for the auger blade, depending on the granulation of spoil.

scholarly journals Experimental and Computational Investigation of Spoiler Deployment on Wing Stall

2021 ◽  
Author(s):  
Scott Lindsay
Keyword(s):  
Wind Tunnel ◽  
Drag Coefficient ◽  
Computational Study ◽  
Lift Coefficient ◽  
Wind Tunnel Experiment ◽  
Chord Length ◽  
Aerodynamic Efficiency ◽  
Stall Angle ◽  
Wing Stall ◽  
High Angles Of Attack

Upper surface flaps commonly referred to as spoilers or drag brakes can increase maximum lift, and improve aerodynamic efficiency at high, near-stall angles of attack. This phenomenon was studied experimentally and computationally using a 0.307626 m chord length NACA 2412 airfoil in six different configurations, and one baseline clean configuration. A wind tunnel model was placed in the Ryerson Low Speed Wind Tunnel (atmospheric, closed-circuit, 3 ft × 3 ft test section) at a Reynold’s number of approximately 780,000 and a Mach number of 0.136. The wind tunnel study increased the lift coefficient by 0.393%-2.497% depending on the spoiler configuration. A spoiler of 10% chord length increased the maximum lift coefficient by 2.497 % when deflected 8º, by 2.110% when deflected 15º, and reduced the maximum lift coefficient by 2.783% when deflected 25º. A spoiler of 15% chord length produced smaller maximum lift coefficient gains; 0.393% when deflected 8º, by 1.760% when deflected 15º, and reduced the maximum lift coefficient by 4.475% when deflected 25º. Deflecting the spoiler increased the stall angle between 37.658% and 87.544% when compared with the clean configuration. The drag coefficient of spoiler configurations was lower than the clean configuration at angles of attack above 18º. The combination of the increased lift and reduced drag at angles of attack above 18º created by the spoiler configurations resulted in a higher aerodynamic efficiency than the clean configuration case. A 10% chord length spoiler deflected at 8º produced the highest aerodynamic efficiency gains. At low angles of attack, the computational study produced consistently higher lift coefficients compared with the wind tunnel experiment. The lift-slope was consistent with the wind tunnel experiment lift-slope. The spoiler airfoil stall behaviour was inconsistent with the results from the wind tunnel experiment. The drag coefficient results were consistent with the wind tunnel experiment at low angles of attack. However, the spoiler equipped airfoils did not reduce drag at high angles of attack. Therefore, the computational model was not valid for the spoiler configurations at high angles of attack.

scholarly journals Aerodynamic Performances of Paper Planes

2020 ◽  
Vol 77 (1) ◽  
pp. 124-131
Author(s):  
Noor Iswadi Ismail ◽  
Zurriati Mohd Ali ◽  
Iskandar Shah Ishak ◽  
R.M. Noor ◽  
Rosniza Rabilah
Keyword(s):  
Lift Coefficient ◽  
The Other ◽  
Navier Stokes ◽  
Navier Stokes Equation ◽  
Aerodynamic Efficiency ◽  
Ansys Cfx ◽  
Wide Range ◽  
Aerodynamic Performances ◽  
Paper Plane ◽  
Stall Angle

Paper plane has a high potential to be upgraded as a Micro Air Vehicle (MAV). Due to its simplicity, paper plane offers easier design option compared to the biological inspired designs as shown in recent MAV development. However, researchers have underestimate and overlook the basic aerodynamic performance induced by these paper planes. This is due to its common usage as toys and wide range of paper plane design. Thus, the objective for current work is to analyse and compare the aerodynamics forces and its performance for selected paper plane design known as Glider, Wide Stunt Glider Plane and Stunt plane. A series of CFD simulations on each paper plane was executed by using ANSYS-CFX module. A steady state, incompressible flow Navier-Stokes equation (RANS) combined with Shear Stress Turbulence (SST) model were used in this works to solve flow problem over the paper planes. The analysis is mainly conducted to study and compare the lift coefficient (), drag coefficient ()and aerodynamic efficiency () performances for each paper planes. The results show that the Glider paper plane has managed to produce better performances in terms overall magnitude, stall angle, wider angle of attack (?) envelope and higher maximum lift coefficient magnitude compared to the other paper plane design. However, Glider paper plane has the least distributions by producing at least 14.3% larger magnitude compared to the other plane design at certain ? region. Instead, The Wide Stunt has promisingly produced better distribution by producing lower value compared to the other plane design. Based on performance, the Wide Stunt paper plane has produced better and maximum aerodynamic efficiency () magnitudes compared to the other design. Wide Stunt paper plane induced at least 6.4% better magnitude compared to the other paper plane design. Based on these results, it can be concluded that Wide Stunt paper plane has promising advantages which are very crucial for the paper plane especially during hovering operation, take-off and landing manoeuvre.

scholarly journals Amplitude Modulated Noise for Tinnitus Suppression in Tonal and Noise-Like Tinnitus

2019 ◽  
Vol 24 (6) ◽  
pp. 309-321 ◽  
Author(s):  
Stefan Schoisswohl ◽  
Johannes Arnds ◽  
Martin Schecklmann ◽  
Berthold Langguth ◽  
Winfried Schlee ◽  
...  
Keyword(s):  
Past Research ◽  
Acoustic Stimulation ◽  
Short Term ◽  
Novel Approach ◽  
Different Types ◽  
Pure Tones ◽  
Residual Inhibition ◽  
The Individual ◽  
The Impact

Background: The phenomenon of short-term tinnitus suppression by different forms of acoustic stimulation is referred to as residual inhibition (RI). RI can be triggered in the majority of tinnitus cases and was found to be depending on the used intensity, length or types of sounds. Past research already stressed the impact of noise stimulation as well as the superiority of amplitude modulated (AM) pure tones at the individual tinnitus frequency for RI in tonal tinnitus. Recently a novel approach for the determination of noise-like tinnitus characteristics was proposed. Objectives: The aim of the present study was to investigate whether in participants with noise-like tinnitus RI can be increased by AM noise stimuli according to the individual tinnitus frequency range. Methods: For this purpose the individual tinnitus characteristics (noise-like and tonal tinnitus) of 29 people affected by tinnitus (mean age = 55.59, 7 females, mean tinnitus duration = 159.97 months) were assessed via customizable noise-band matching. The objective was to generate bandpass filtered stimuli according to the individual tinnitus sound (individualized bandpass filtered [IBP] sounds). Subsequently, various stimuli differing in bandpass filtering and AM were tested with respect to their potential to induce RI. Participants were acoustically stimulated with 7 different types of stimuli for 3 min each and had to rate the loudness of their tinnitus after each stimuli. Results: Results indicate a general efficacy of noise stimuli for the temporary suppression of tinnitus, but no significant differences between AM and unmodulated IBP. Significantly better effects were observed for the subgroup with noise-like tinnitus (n = 14), especially directly after stimulation offset. Conclusions: The study at hand provides further insights in potential mechanisms behind RI for different types of tinnitus. Beyond that, derived principles may qualify for new or extend current tinnitus sound therapies.

Flow Field Characterization and Visualization of Grid Fin Subsonic Flow

2019 ◽  
Vol 141 (10) ◽  
Author(s):  
Manish Tripathi ◽  
Mahesh M. Sucheendran ◽  
Ajay Misra
Keyword(s):  
Flow Field ◽  
Pressure Coefficient ◽  
Aerospace Applications ◽  
Planar Surfaces ◽  
Coefficient Distribution ◽  
Grid Fin ◽  
Layer Velocity ◽  
Stall Angle ◽  
High Mach ◽  
Control Surfaces

Grid fins are unconventional control surfaces consisting of an outer frame supporting an inner grid of intersecting planar surfaces. Although afflicted with higher drag, these have been credited for their enhanced lifting characteristics at high angles of attack and high Mach numbers, alongside reduced hinge moments accounting for the recent upsurge in their usage on numerous aerospace applications. Present investigations carry out elaborate flow field visualization and characterization underlining the rudimentary physics through a sequence of subsonic numerical simulations performed at different angles of attack and different gap (between the members) to chord ratios on a simplified grid fin variant called cascade fin. The study makes use of a new nondimensionalization technique called cumulative nondimensionalization to decipher the effect of cascading on individual members of the fin. Hence, after a comprehensive examination of the aerodynamic coefficients, pressure coefficient distribution, pressure gradient, velocity gradient, boundary layer velocity profile, and flow field visualization, the study elucidates physics associated with hastened stall angle, augmented lift-drag, and bounded efficiency accretion for gap increment.

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