scholarly journals Development of an Analytic Convection Model for a Heated Multi-Hole Probe for Aircraft Applications

Sensors ◽  
2021 ◽  
Vol 21 (18) ◽  
pp. 6218
Author(s):  
Pablo Nieto Muro ◽  
Florian M. Heckmeier ◽  
Sean Jenkins ◽  
Christian Breitsamter
Keyword(s):  
Wind Tunnel ◽  
Analytical Model ◽  
Heating System ◽  
Real System ◽  
Measuring System ◽  
Prediction Tool ◽  
Ice Accretion ◽  
Heating Performance ◽  
Convection Model ◽  
Air Speed

Ice accretion or icing is a well-known phenomenon that entails a risk for the correct functioning of an aircraft. One of the areas more vulnerable to icing is the air data measuring system. This paper studies the icing protection offered by a heating system installed inside a multi-hole probe. The problem is initially solved analytically, creating a tool that can be used in order to predict the heating performance depending on the flying conditions. Later, the performance of the real system is investigated with a heated five-hole probe prototype in a wind tunnel experiment. The measured results are compared with the predictions made by the analytical model. Last, the icing protection provided by the system is estimated with respect to flying altitude and speed. As a result, a prediction tool that can be used in order to make quick icing risk predictions for straight cylindrical probes is delivered. Furthermore, the study provides some understanding about how parameters like altitude and air speed affect the occurrence of ice accretion.

Numerical Investigation on Transmission Line Conductor Icing

2014 ◽  
Vol 672-674 ◽  
pp. 1105-1108
Author(s):  
Xian Yi ◽  
Han Jie Huang ◽  
Zhi Hong Zhou
Keyword(s):  
Wind Tunnel ◽  
Transmission Line ◽  
Numerical Method ◽  
Liquid Water ◽  
Droplet Diameter ◽  
Liquid Water Content ◽  
Ice Thickness ◽  
Ice Accretion ◽  
Protection Technology ◽  
Air Speed

Ice accretion on transmission line conductor exists widely in nature, which can bring a lot of hazards. It is important and necessary to obtain characteristics of ice on different conductors for analyzing ice hazards or developing ice protection technology. A numerical method based on CFD technology for predicting ice accretion on transmission line conductor was presented in the present paper. Ice accretion on a conductor with a diameter of 26 mm was then predicted with the numerical method and an icing wind tunnel experiment. The results showed that it was acceptable to use clear cylinder as actual conductor for icing study, and the numerical results were credible. The effects of droplet diameter, liquid water content, air speed and time on icing were then investigated with the numerical method. The law that ice thickness, limit and volume varied with different icing conditions was obtained, which built a good foundation for further research.

scholarly journals Constant Raindrop Fall Speed Profiles Derived from Doppler Radar Data Analyses for Steady Nonconvective Precipitation

2005 ◽  
Vol 62 (1) ◽  
pp. 220-230 ◽  
Author(s):  
Robert Nissen ◽  
Roland List ◽  
David Hudak ◽  
Greg M. McFarquhar ◽  
R. Paul Lawson ◽  
...  
Keyword(s):  
Doppler Radar ◽  
Free Fall ◽  
Radar Data ◽  
Measuring System ◽  
Doppler Velocity ◽  
Light Rain ◽  
Fall Speed ◽  
Air Speed ◽  
Velocity Moments ◽  
Rain Rates

Abstract For nonconvective, steady light rain with rain rates <5 mm h−1 the mean Doppler velocity of raindrop spectra was found to be constant below the melting band, when the drop-free fall speed was adjusted for pressure. The Doppler radar–weighted raindrop diameters varied from case to case from 1.5 to 2.5 mm while rain rates changed from 1.2 to 2.9 mm h−1. Significant changes of advected velocity moments were observed over periods of 4 min. These findings were corroborated by three independent systems: a Doppler radar for establishing vertical air speed and mean terminal drop speeds [using extended Velocity Azimuth Display (EVAD) analyses], a Joss–Waldvogel disdrometer at the ground, and a Particle Measuring System (PMS) 2-DP probe flown on an aircraft. These measurements were supported by data from upper-air soundings. The reason why inferred raindrop spectra do not change with height is the negligible interaction rate between raindrops at low rain rates. At low rain rates, numerical box models of drop collisions strongly support this interpretation. It was found that increasing characteristic drop diameters are correlated with increasing rain rates.

Wingbeat frequency of barn swallows and house martins: a comparison between free flight and wind tunnel experiments

2002 ◽  
Vol 205 (16) ◽  
pp. 2461-2467 ◽  
Author(s):  
Felix Liechti ◽  
Lukas Bruderer
Keyword(s):  
Wind Tunnel ◽  
Single Pulse ◽  
Free Flight ◽  
Wind Tunnel Experiments ◽  
Wingbeat Frequency ◽  
Flight Costs ◽  
Radar Echo ◽  
The Mean ◽  
Barn Swallows ◽  
Air Speed

SUMMARYThe flight paths and wingbeat patterns of 39 barn swallows (Hirundo rustica) and 26 house martins (Delichon urbica) were recorded by tracking radar during the spring migration. Depending mostly on flight angle,hirundines performed anything from continuous flapping flight during climbing to single pulse-like wing beats during descent. Unlike most other passerines,hirundines rarely showed regular flapping and rest phases, allowing them to be distinguished from other bird migrants by radar echo signatures. Effective wingbeat frequency (Feff) was calculated as the mean number of wing beats per second, including non-flapping phases. Under comparable flight conditions, Feff was higher in house martins than in barn swallows. Within species, Feff values were higher during climbing and slow flying than during descent. Of the variance in Feff, 71 % could be explained by climb rate,air speed and species; similar results were obtained in the wind tunnel. Under comparable flight conditions, barn swallows and house martins in free flight had significantly lower values of Feff than individuals in wind tunnel experiments (by 40 % and 32 %, respectively). This difference may at least partly be due to the shorter wings of the juveniles tested in the wind tunnel during autumn. However, it seems unlikely that this can account for all of the large difference. It is suggested that wind tunnel experiments might overestimate birds' flight costs compared with free flight.

Aerodynamics of Gliding Flight of a Black Vulture Coragyps Atratus

1970 ◽  
Vol 53 (2) ◽  
pp. 363-374 ◽  
Author(s):  
G. CHRISTIAN PARROTT
Keyword(s):  
Wind Tunnel ◽  
Wing Area ◽  
Drag Coefficients ◽  
Wing Span ◽  
Drag Forces ◽  
Gliding Flight ◽  
Black Vulture ◽  
Air Speed

1. A black vulture (mass = 1.79 kg) gliding freely in a wind tunnel adjusted its wing span and wing area as its air speed and glide angle changed from 9.9 to 16.8 m/s and from 4.8° to 7.9°, respectively. 2. The minimum sinking speed was 1.09 m/s at an air speed of 11.3 m/s. 3. The maximum ratio of lift to drag forces was 11.6 at an air speed of 13.9 m/s. 4. Parasite drag coefficients for the vulture are similar to those for conventional airfoils and do not support the contention that black vultures have unusually low values of parasite drag.

Suggestions to the test procedure for technical means of protection of steel welded domestic LPG gas cylinders from physical destruction in fire

2021 ◽  
pp. 67-72
Author(s):  
Владимир Леонидович Малкин ◽  
Владимир Александрович Угорелов ◽  
Петр Алексеевич Леончук ◽  
Руслан Андреевич Загуменников
Keyword(s):  
Coming Out ◽  
Test Procedure ◽  
Video Recording ◽  
Heating System ◽  
Measuring System ◽  
Cylinder Surface ◽  
In Fire ◽  
Gas Leaks ◽  
The Impact ◽  
Gas Cylinders

Разработана методика проведения испытаний технических средств защиты стальных сварных бытовых баллонов для сжиженных углеводородных газов (СУГ) от физического разрушения при воздействии на них пожара. В методике содержатся требования к отбору газовых баллонов, рассматриваемым модельным сценариям, установке для испытаний, мероприятиям по подготовке испытаний, порядку их проведения, к отчету о проведении испытаний. Использование предлагаемой методики позволит с высокой степенью достоверности оценивать эффективность применения технических средств защиты стальных бытовых баллонов для СУГ от физического разрушения при воздействии пожара. The paper contains proposals for inclusion in the testing methodology for technical means of protecting gas cylinders from physical destruction. The proposals relate to the choice of typical scenarios characteristic for emergencies and fire development in a room with LPG cylinders: the ingress of cylinders into the fire center, the impact on the cylinder surface of the heat flow of the adjacent fire center; the impact on the surface of the cylinder of LPG vapors jet combustion, simulating the effect of combustion of LPG vapors coming out of the outlet of the valve (safety valve or membrane) of the adjacent cylinder. The design of the installation for testing cylinders in accordance with the above scenarios is presented. There are given requirements for the test preparation procedure, including the verification of documentation, installation of technical protective equipment, filling and delivery of cylinders, checking for gas leaks from cylinders after delivery, installation for testing. A detailed description of the installation procedure is given in accordance with the presented diagrams for various test scenarios. The basic diagrams of the measuring system for the pressure inside the cylinder, mounting of thermocouples on the wall of the cylinder, and remote supply of liquid fuel to trays are described. There is described the test procedure, which consists of turning on the recording systems, gas supplying to the installation, activating the cylinder heating system, video recording of the experiment with timing, closing the valve in front of the pressure sensor after the end of combustion, discharging LPG from the sealed cylinder to the burner. The requirements for the composition of the test report are given, which make it possible to confirm the reliability of the experiments.

Aerodynamics of Gliding Flight in a Falcon and Other Birds

1970 ◽  
Vol 52 (2) ◽  
pp. 345-367 ◽  
Author(s):  
VANCE A. TUCKER ◽  
G. CHRISTIAN PARROTT
Keyword(s):  
Wind Tunnel ◽  
High Performance ◽  
Lift Coefficient ◽  
Aerodynamic Characteristics ◽  
Wing Span ◽  
Technical Errors ◽  
Gliding Flight ◽  
Air Speed ◽  
D Values ◽  
D Value

1. A live laggar falcon (Falco jugger) glided in a wind tunnel at speeds between 6.6 and 15.9 m./sec. The bird had a maximum lift to drag ratio (L/D) of 10 at a speed of 12.5 m./sec. As the falcon increased its air speed at a given glide angle, it reduced its wing span, wing area and lift coefficient. 2. A model aircraft with about the same wingspan as the falcon had a maximum L/D value of 10. 3. Published measurements of the aerodynamic characteristics of gliding birds are summarized by presenting them in a diagram showing air speed, sinking speed and L/D values. Data for a high-performance sailplane are included. The soaring birds had maximum L/D values near 10, or about one quarter that of the sailplane. The birds glided more slowly than the sailplane and had about the same sinking speed. 4. The ‘equivalent parasite area’ method used by aircraft designers to estimate parasite drag was modified for use with gliding birds, and empirical data are presented to provide a means of predicting the gliding performance of a bird in the absence of wind-tunnel tests. 5. The birds in this study had conventional values for parasite drag. Technical errors seem responsible for published claims of unusually low parasite drag values in a vulture. 6. The falcon adjusted its wing span in flight to achieve nearly the maximum possible L/D value over its range of gliding speeds. 7. The maximum terminal speed of the falcon in a vertical dive is estimated to be 100 m./sec.

A new low-turbulence wind tunnel for bird flight experiments at Lund University, Sweden

1997 ◽  
Vol 200 (10) ◽  
pp. 1441-1449 ◽  
Author(s):  
C J Pennycuick ◽  
T Alerstam ◽  
A Hedenström
Keyword(s):  
Wind Speed ◽  
Wind Tunnel ◽  
Test Section ◽  
Safety Net ◽  
Turbulence Level ◽  
Bird Flight ◽  
Contraction Ratio ◽  
Unrestricted Access ◽  
Side Walls ◽  
Air Speed

A new wind tunnel for experiments on bird flight was completed at Lund University, Sweden, in September 1994. It is a closed-circuit design, with a settling section containing five screens and a contraction ratio of 12.25. The test section is octagonal, 1.20 m wide by 1.08 m high. The first 1.2 m of its length is enclosed by acrylic walls, and the last 0.5 m is open, giving unrestricted access. Experiments can be carried out in both the open and closed parts, and comparison between them can potentially be used to measure the lift effect correction. The fan is driven by an a.c. motor with a variable-frequency power supply, allowing the wind speed to be varied continuously from 0 to 38 m s-1. The whole machine can be tilted to give up to 8 ° descent and 6 ° climb. A pitot-static survey in the test section showed that the air speed was within ±1.3 % of the mean at 116 out of 119 sample points, exceeding this deviation at only three points at the edges. A hot-wire anemometer survey showed that the turbulence level in the closed part of the test section was below 0.04 % of the wind speed throughout most of the closed part of the test section, rising to approximately 0.06 % in the middle of the open part. No residual rotation from the fan could be detected in the test section. No decrease in wind speed was detectable beyond 3 cm from the side walls of the closed part, and turbulence was minimal beyond 10 cm from the walls. The installation of a safety net at the entrance to the test section increased the turbulence level by a factor of at least 30, to 1.2 % longitudinally and 1.0 % transversely.

Possible Implementation of Ex-core Measurement in TEPLATOR Graphite Reflector

2021 ◽  
Author(s):  
Eva Vilimova ◽  
Tomas Peltan ◽  
Jana Jiricková
Keyword(s):  
Neutron Flux ◽  
District Heating ◽  
Flux Measurement ◽  
Heating System ◽  
Fast Response ◽  
Reactor Power ◽  
Measuring System ◽  
Monte Carlo Code ◽  
District Heating System ◽  
And Control

Abstract An ex-core neutron flux measurement is a crucial system for all common power reactors. It is necessary to monitor the neutron flux and control the chain reaction, therefore the ex-core neutron flux measurement is one of the main safety and control systems. The main advantage of this arrangement of detectors is a fast response to neutron flux change, which determines the reactor power change. Regarding to the new reactor concepts, it is important to deal with improved detection systems suitable for these reactors. Many of the modern reactor concepts are based on a graphite moderator or reflector, which is also the case of the TEPLATOR. The TEPLATOR is a solution of a district heating system based on heavy water as a moderator and graphite as a reflector. The TEPLATOR is designed to use irradiated fuel from the commercial PWR or BWR reactors, which has low to intermediate burnup. This article is focused on the verification of the possible use of the special neutron measuring system placed in the graphite reflector. The Monte Carlo code Serpent was used for the calculations performed in this article.

Pressure Measurements on Yacht Sails: Development of a new system for wind tunnel and full scale testing

2016 ◽  
Author(s):  
Fabio Fossati ◽  
Ilmas Bayati ◽  
Sara Muggiasca ◽  
Ambra Vandone ◽  
Gabriele Campanardi ◽  
...  
Keyword(s):  
Wind Tunnel ◽  
Unsteady Aerodynamics ◽  
Research Field ◽  
Full Scale ◽  
Measuring System ◽  
Windward Side ◽  
Pressure System ◽  
Operational Conditions ◽  
Sailing Yacht ◽  
Full Scale Testing

The paper presents an overview of a joint project developed among Politecnico di Milano, CSEM and North Sails, aiming at developing a new sail pressure measurement system based on MEMS sensors (an excellent compromise between size, performance, costs and operational conditions) and pressure strips and pads technology. These devices were designed and produced to give differential measurement between the leeward and windward side of the sails. The project has been developed within the Lecco Innovation Hub Sailing Yacht Lab, a 10 m length sailing dynamometer which intend to be the reference contemporary full scale measurement device in the sailing yacht engineering research field, to enhance the insight of sail steady and unsteady aerodynamics [1]. The pressure system is described in details as well as the data acquisition process and system metrological validation is provided; furthermore, some results obtained during a wind tunnel campaign carried out at Politecnico di Milano Wind Tunnel, as a benchmark of the whole measuring system for future full scale application, are reported and discussed in details. Moreover, the system configuration for full scale testing, which is still under development, is also described.

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