Concept and design of extended hybrid laminar flow control suction panels

Fully laminar aircraft are one step towards reaching eco-efficient aviation. However, high system complexity and significant manufacturing effort prevent the wide usage of existing laminarisation concepts such as laminar flow control, which are rarely found in commercial aircraft. Hybrid laminar flow control concepts reduce the manufacturing effort significantly at the cost of only achieving partial laminar flow. This paper presents extended hybrid laminar flow control concepts for fully laminar wings, with reduced system complexity. A detailed study of structural and aerodynamic requirements provides the foundation for partial design solutions of active suction structures. The authors derive two concepts for active suction panels from the structural design space. While the first concept relies on state of the art manufacturing techniques, the focus of the second concept is on additive manufacturing technologies. Based on these concepts, it is feasible to design fully laminar wings with structurally integrated active suction systems. The authors propose an aerodynamic test strategy for further developing extended hybrid laminar flow control.

Study and Design a Spoiler to Understand Aerodynamics with Various Angle of Attack at Different speeds

In this scope of study, various type of spoiler is researched out of which a pedestal spoiler is chosen to design as it generates a very good downforce and also has good aesthetic appeal to it, spoiler is designed considering actual scaled dimensions. Analysis on the designed pedestal spoiler is carried out to get to know how much the downforce is generated and at the same time how much drag coefficient is produced. Also, angle of attack of the spoiler in various degrees (9, 6, 4, 3, 2, 0, -2, - 3, -4, -6, -9, -12, -15) is carried out to know downforce at various angle of attack with various velocity (10, 15, 20, 25, 30, 35, 40, 45, 50) inputs in meter per seconds. After carrying out more than 80 analysis, found that highest downforce generated by the spoiler’s angle of attack is at (-6) degree with a 400 N of downforce and also with low drag. Velocity magnitude contour plot of each angle is provided to understand the air flow around each angle of attack. To validate the results given by the simulation tool a mathematical/analytical calculation are carried out for four angles of attack with a good result and also graphs are plotted for each validation to figure out the variation in them. Observing the validation’s graphs and calculations the difference between computational results and mathematical/analytical results is less than 5% indicating a proper process carried out in simulation and approximately giving realistic values that can be given in a wind tunnel aerodynamic test. Keywords: Spoiler, Aerodynamics, CAD, CFD, Drag coefficient, Lift coefficient, angle of attack.

Development of cost-effective shock tube based on experimental and numerical analysis

Purpose The purpose of the study is to design economical shock tube. It is an instrument used for experimental investigations not only related to shock phenomena but also for the behavior of the material when it is subjected to high-speed flow. The material used here in this shock tube is stainless steel ss304 and aluminum. A shock tube consists of two sections, namely, the driver and the driven. The gas in the driven and driver is filled with atmospheric air and nitrogen, respectively, under the predominant condition. Design/methodology/approach The focus of the study is on the design and fabrication of shock tubes. a shock tube is a research tool to make an aerodynamic test in the presence of high pressure and temperature by generating moving normal shock waves under controlled conditions. Findings The main necessity for instrumentation in the shock tube experiment is to know the velocity of the moving shock wave from which the other parameters can be calculated. the pressure transducers are located in the shock tube in various locations to measure aerodynamic parameters in terms of pressure. Originality/value The main objective of this project work is to make an experimental setup to produce supersonic velocity with the readily available material in the market in a highly safe manner.

Aerodynamic characteristics of a free-flight scramjet vehicle in shock tunnel

A multi-component aerodynamic test for an airframe-engine integrated scramjet vehicle model was conducted in the free-piston shock tunnel HIEST. A free-flight force measurement technique was applied to the scramjet vehicle model named MoDKI. A new method using multiple piezoelectric accelerometers was developed based on overdetermined system analysis. Its unique features are the following: (1) The accelerometer’s mounting location can be more flexible. (2) The measurement precision is predicted to be improved by increasing the number of accelerometers. (3) The angular acceleration can be obtained with single-axis translational accelerometers instead of gyroscopes. (4) Through the averaging process of the multiple accelerometers, model natural vibration is expected to be mitigated. With eight model-onboard single-axis accelerometers, the three-component aerodynamic coefficients (Drag, Lift, and Pitching moment) of MoDKI were successfully measured at the angle of attack from 0.7 to 3.4 degrees under a Mach 8 free-stream test flow condition. A linear regression fitting revealed a 95% prediction interval as the measurement precision of each aerodynamic coefficient. Graphical abstract

Experimental Evaluation for The Feasibility of Test Chamber in The Open-Loop Wind Tunnel

The test chamber in an open-loop wind tunnel is a critical part for aerodynamic experiment. The study aims to assess the feasibility of the new design of test chamber for open–loop wind tunnel by studying the fluid characteristic and the average pressure in the test chamber. The study is done by a series experimental test for the test chamber. From experimental test, the downstream velocity in the test chamber is increased from 8.9 m/s to 12.72 m/s where the pressure gradient is ranging from 6.19 to 8.398 atm with the overall turbulence intensity for the test chamber is 0.749%. According to the results, the designed open-loop wind tunnel is acceptable to use for an aerodynamic test.

Aerodynamic and Micro-Fluidic Effect in Masks with Impact in Covid-19 and Other Pandemic Propagation

US has ignored the hierarchy of pandemic control, misinformed population on virus propagation needed protection by using masks and other complementary protection measures facilitating the human disaster. The population mindset was to dismiss science, the virus and hope to dodge the pandemic with a fabric over the mouth and a free vaccine that will result in more than 600,000 deaths, and over 30 Million infected. In fact, masks are filters, and have a limited protection factor, known when used in medical practice. The masks were mainly designed and measured for stopping solid particulates, but when used against aerosolized watery droplets loaded with bio-agents nano-fluidic effects are responsible for anomalous, nonlinear and unpredictable complex behavior. Using an aerodynamic test bench, and various sizes of radioactive nano-powders, we performed measurements on the retention factor dependence for various filter materials of airflow magnitude, temperature, airflow regime, and filter's load. The results showed that a retention function of particle magnitude, measured for particulates, vary with temperature and when filter is used for aerosolized loaded watery droplets, an "atomization" effect happens transforming larger aerosols in finer ones, due to micro-nano-fluidic and aerodynamic instabilities. The measurements showed that pulsed and reciprocating airflow regimes trigger loaded filters to release some of previously retained particles, making the masks offer a reduced protection factor, and imposing special rules of safe usage. It was not told to public that is a contagious person uses correctly a mask, without any lateral leakage, through the mask passes nano-sized, airborne aerosols, containing virioli that float in air for weeks, driven by air currents, and special complementary measures to sterilize or remove the air have to be taken for safety.

Review of research on high-speed railway aerodynamics in China

High-speed railway aerodynamics is the key basic science for solving the bottleneck problem of high-speed railway development. This paper systematically summarizes the aerodynamic research relating to China’s high-speed railway network. Seven key research advances are comprehensively discussed, including train aerodynamic drag-reduction technology, train aerodynamic noise-reduction technology, train ventilation technology, train crossing aerodynamics, train/tunnel aerodynamics, train/climate environment aerodynamics, and train/human body aerodynamics. Seven types of railway aerodynamic test platform built by Central South University are introduced. Five major systems for a high-speed railway network—the aerodynamics theoretical system, the aerodynamic shape (train, tunnel, and so on) design system, the aerodynamics evaluation system, the 3D protection system for operational safety of the high-speed railway network, and the high-speed railway aerodynamic test/computation/analysis platform system—are also introduced. Finally, eight future development directions for the field of railway aerodynamics are proposed. For over 30 years, railway aerodynamics has been an important supporting element in the development of China’s high-speed railway network, which has also promoted the development of high-speed railway aerodynamics throughout the world.

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.