Aerodynamic Test Results Research Articles

Investigating the effect of axial fan shrinkage obtained by centrifugal casting technology on aerodynamic characteristics

Centrifugal casting technology was developed for the application of manufacturing axial fans. In the literature, these fans were usually manufactured by injection molding, mechanical processing or heat pressing. The main characteristic of this molding technology allows the creation of thick and hollow blades. This characteristic of the blades gives useful advantages of the fan that cannot be achieved by conventional methods. The centrifugal casting technology has been applied to fabricate axial fans in recent research. However, the issue of quality control and especially the shrinkage of the resulting fan compared to the molding has not yet been considered. Therefore, more in-depth studies and approaches are required. In this study, 3D scanning method is used to evaluate the shrinkage of the blades. The used 3D scanner is the Comet L3D 5M type based on structured light (blue LED) with a 5-megapixel sensor. This device achieves high accuracy and reliability (resolution 18 μm). The theoretical basis for determining fan shrinkage compared to CAD molds is based on the following main parameters: Chord line L (mm), relative thickness Emax (%), and stagger angle ( (degrees). In addition, the aerodynamic characteristics of the proposed fan are compared to those of a fan made of aluminum (blades are identical, but different in fabricating technology). Characteristics of this aluminum rigid-fan are assumed as reference. The results showed that the difference was not large between the blades. Besides, the results of aerodynamic testing on the test bench of the two fans are almost similar. This indicates the good adaptability of the axial fan received by the centrifugal casting technology.

Experimental Study of Air-Assisted Rocket System Models for Launching Payloads into a Low Earth Orbit

This paper presents the results of aerodynamic testing of air-launch rocket kit models for launching payloads into a low Earth orbit. The work was performed in a low-speed wind tunnel at the Military University of Technology (MUT, Warsaw, Poland)), using symmetrical airflow. Two carrier aircraft models were tested, i.e., Su-22 and MiG-29 aircraft without launched payloads and with these payloads at a dynamic pressure of q = 500 [Pa] and the range of angles of attack at α = -2828. The values obtained related to the aerodynamic drag coefficient, aerodynamic lift coefficient, pitching moment coefficient and lift to drag ratio, and are given in tabular and graphic forms. The tests were primarily used to validate the numerical results obtained during implementation of the project “Air-assisted rocket system for launching payloads into low Earth orbit - feasibility study”.

Оптимизация аэродинамических характеристик высокоскоростного юнимобиля струнного транспорта Юницкого

The paper describes technical solutions aimed at improving the aerodynamics of vehicles; the engineering specifics of high-speed models of the vehicles of the string transport by Unitsky (uST), their advantages in aerodynamics and ergonomics are presented; the design of unimobile (steel wheeled electric rail car) is proposed, which ensures the configuration of the wheeled vehicle of uST with advanced aerodynamic characteristics and having improved dynamic stability; the methods of analysis of optimal dimensions of the main elements of the unimobile are indicated. The presented data were proven by the results of aerodynamic tests. The results of the research constitute the foundation for the elaboration of the high-speed unimobile - uniflash.

Aerodynamic test results of bicycle helmets in different configurations: Towards a responsive design

Within the sport of cycling, aerodynamic efficiency is a fundamental criterion for equipment such as bicycle frames, wheels, clothing and helmets. Emerging technologies continually challenge the rules governing the sport as designers, engineers, sports scientists and athletes attempt to gain the edge on their competition. This study compares three-dimensional (3D) printed bicycle helmet prototypes with three commercially available helmets via aerodynamic testing in a wind tunnel. One 3D printed helmet featured a mechanical mechanism allowing two states of ventilation closure to be examined for aerodynamic efficiency, while the other featured electronically adjustable ventilation openings tested at five different states of ventilation closure. Data were collected using an anthropometrically accurate mannequin sitting atop a bicycle in a road-cycling position. The results found that the mechanically controlled prototype offered a 4.1% increase in overall drag experienced by the mannequin with ventilation in the open position compared to the closed position. The electronic prototype showed an increase in drag as ventilation openings increased through the five states, with an overall difference in drag of 3.7% between closed and the maximum opening. These experimental findings indicate that the responsive helmet prototypes can significantly affect the drag force on a cyclist between their closed and open positions and, when understood as being adaptable using sensors and automated controls, may provide new opportunities to modify athlete performance throughout varying stages of training and competition.

Shifts in stability and control effectiveness during evolution of Paraves support aerial maneuvering hypotheses for flight origins.

The capacity for aerial maneuvering was likely a major influence on the evolution of flying animals. Here we evaluate consequences of paravian morphology for aerial performance by quantifying static stability and control effectiveness of physical models for numerous taxa sampled from within the lineage leading to birds (Paraves). Results of aerodynamic testing are mapped phylogenetically to examine how maneuvering characteristics correspond to tail shortening, forewing elaboration, and other morphological features. In the evolution of Paraves we observe shifts from static stability to inherently unstable aerial planforms; control effectiveness also migrated from tails to the forewings. These shifts suggest that a some degree of aerodynamic control and capacity for maneuvering preceded the evolution of a strong power stroke. The timing of shifts also suggests features normally considered in light of development of a power stroke may play important roles in control.

Study of the Aerodynamics of a Regular Liner Made of Polymer Mesh Fabric

This article presents the results of aerodynamic tests on a new liner made from polymer mesh. The potential for use of this liner for evaporation cooling processes is demonstrated.

Aerodynamic tests of new regular cellular packings for mass-transfer towers

The results of aerodynamic tests of new regular cellular packings for mass-transfer towers are reported. The key geometric and aerodynamic characteristics of the test cellular packings are compared with the characteristics of similarly designed regular packings that are widely used in the industry.

Correlation between the Voice Handicap Index and Voice Laboratory Measurements after Phonosurgery

Phonosurgery is an effective treatment for some vocal fold pathologies, and the Voice Handicap Index (VHI) survey has been shown to be a useful instrument for evaluating treatment effectiveness. We conducted a nonrandomized, prospective study of 21 patients who underwent phonosurgery for the treatment of non-neoplastic vocal fold lesions at our academic tertiary-care referral center. Our goals were to compare pre- and postoperative VHI scores (subjective assessments) and pre- and postoperative results of acoustic and aerodynamic tests (objective assessments). We sought to determine if there was any correlation between the subjective and objective findings. We looked for differences between professional voice users (n = 10) and nonprofessional voice users (n = 11) in both subjective and objective measures. We found statistically significant differences between pre- and postoperative values in three of four VHI parameters, but in only one of 13 objective measures. There was no correlation between preoperative VHI scores and preoperative acoustic and aerodynamic test results. The professional voice users expressed greater postoperative improvement as reflected by lower VHI scores than did the nonprofessional voice users, confirming that the former are more negatively affected by a voice disability.

Experimental investigation of aerodynamic characteristics of the laser guided bomb model

Aerodynamic test results and boundary layer flow visualization on the wings and fins of laser guided bomb model are presented in this article. Test was performed in the T-38 wind tunnel. Influence of fin position relative to conic top of the model on aerodynamic characteristics was analyzed. Analysis was performed on aerodynamic characteristics of the model for two Mach numbers M∞ = 0,8 and 0,9 and fin deflection δ=15°. Normal forces present on the model and fin were measured by internal strain gauge balances. Obtained test results of normal force on the model and especially on the fin were associated with flow visualization results, which were performed by oil emulsion method. Presented images of flow visualization show changes of the flow around the model and confirm the results of the aerodynamic measurements. .

Aerodynamic experimentation with ducted models as applied to hypersonic air-breathing vehicles

A methodology of experimentation in high supersonic wind tunnels for studying aerodynamic characteristics of hypersonic flying vehicles powered by air-breathing engines is discussed. Investigations of such total aerodynamic forces as drag, lift and pitching moment at testing the models are implicit when the air flow through the model ducts is accomplished so that to provide the simulation of the external flow around the airplane and flow over the inlets, but the operating engines and, hence, the exhaust jets are not modeled. The methods used for testing such models are based on the measurement of duct stream parameters alongside with the balance measurement of aerodynamic forces acting on the models. In the tests, aerometric tools are used such as narrow metering nozzles (plugs), pitot and static pressure probes, stagnation temperature probes and pressure orifices in walls of the model duct. The aerometric data serve to determine the flow rate and momentum of the stream at the duct exit. The internal non-simulated forces of the model ducts are also determined using the conservation equations for energy, mass flow and momentum, and these forces are eliminated from the aerodynamic test results. The techniques of the said model testing have been well developed as applied to supersonic aircraft, however their application for hypersonic vehicles whose models are tested at high supersonic speeds, Mach number M∞>4, implies some specific features. In the present paper, the results of experimental and theoretical study of these features are discussed. Some experimental data on aerodynamics of hypersonic aircraft models received in methodological tests are also presented. The tunnel experiments have been carried out in the Mach number range M∞=2–6.

An aerodynamic investigation for the suspended structure of the proposed Tsing Ma bridge

Aerodynamic test results, important to the design of a long-span suspension bridge subject to typhoon winds, were recorded. Classical flutter oscillations were found to be of major concern and it is shown that these can be avoided by openings in the lower and upper surfaces of the suspended structure.

Effect of dust content of the flow on test results in hypersonic wind tunnels

The nature and character of the effect of dust content of the working flow of hypersonic wind tunnels on the results of aerodynamic tests are considered. It is shown that dustiness causes an increase of the drag of slender models and, conversely, a decrease of the drag and damping coefficient of the longitudinal moment of blunt models.