scholarly journals Computing Measured Spectra from Hypersonic Pitot Probes with Flow-Parallel Freestream Disturbances

AIAA Journal ◽  
2017 ◽  
Vol 55 (12) ◽  
pp. 4155-4166 ◽  
Author(s):  
Ross S. Chaudhry ◽  
Graham V. Candler
Keyword(s):  
Pitot Probes

scholarly journals Inventive nesting behaviour in the keyhole wasp Pachodynerus nasidens Latreille (Hymenoptera: Vespidae) in Australia, and the risk to aviation safety

2019 ◽  
Author(s):  
Alan P.N. House ◽  
Jackson G. Ring ◽  
Philip P. Shaw
Keyword(s):  
Central America ◽  
Seasonal Pattern ◽  
Aviation Safety ◽  
Nesting Success ◽  
Native Range ◽  
Probe Volume ◽  
Nesting Behaviour ◽  
Mesh Bags ◽  
The Caribbean ◽  
Pitot Probes

AbstractThe keyhole wasp (Pachodynerus nasidens Latreille 1812), a mud-nesting wasp native to South and Central America and the Caribbean, is a relatively recent (2010) arrival in Australia. In its native range it is known to use man-made cavities to construct nests. A series of serious safety incidents Brisbane Airport related to the obstruction of vital airspeed measuring pitot probes on aircraft possibly caused by mud-nesting wasps at prompted an assessment of risk. An experiment was designed to determine the species responsible, the types of aircraft most affected, the seasonal pattern of potential risk and the spatial distribution of risk on the airport. A series of replica pitot probes were constructed using 3D-printing technology, representing aircraft with high numbers of movements (landings and take-offs), and mounted at four locations at the airport. Probes were monitored for 39 months. Probes blocked by mud nesting wasps were retrieved and incubated in mesh bags. Emerging wasps were identified to species. Results show that all nests in probes were made by P. nasidens, and peak nesting occurs in the summer months. Nesting success (as proportion of nests with live adult emergents) was optimal between 24 and 31°C and that probes with apertures of more than 3 mm diameter are preferred. Not all areas on the airport are affected equally, with the majority of nests constructed in one area. The proportion of grassed areas within 1000 m of probes was a significant predictor of nesting, and probe volume may determine the sex of emerging wasps.

Experimentally Measured Effectiveness of Different Shroud Swirl Brake Profiles in a Centrifugal Compressor

2019 ◽  
Author(s):  
Jason Wilkes ◽  
Natalie Smith ◽  
Balaji Venkataraman ◽  
Marco Vagani ◽  
Sara Goucher
Keyword(s):  
Centrifugal Compressor ◽  
Flow Characteristics ◽  
Specific System ◽  
Depth Of Knowledge ◽  
Art Form ◽  
Swirl Velocity ◽  
Technical Innovations ◽  
Swirl Vane ◽  
Pitot Probes ◽  
The Impact

Abstract As centrifugal compressors are pushed to operate at higher pressures and higher power levels, destabilizing gas forces often increase the challenge of designing a stable rotordynamic system. While technical innovations like damper seals, swirl brakes, and damper bearings that help stabilize compressors are numerous, predicting the impact that these improvements will have on a specific system is somewhat of an art form. To this end, researchers are constantly improving the depth of knowledge on these features so that the impact of these improvements is well defined. In the current work, the authors experimentally measured the impact of different swirl brake/vane concepts on the flow characteristics of a centrifugal compressor shroud cavity. The eye seal configuration studied here is a tooth on rotor labyrinth eye seal. The different shroud swirl vane geometries considered consist of various castellated features, each having the intent to reduce swirl velocity in the shroud cavity prior to entering the seal. The purpose of the testing was to determine whether a significant reduction in swirl velocity entering or exiting the seal could be measured with the different anti-swirl vane profiles over a conventional shroud cavity that was tested with the same setup. The metrics that determine the effectiveness of the swirl brake were based on upstream and downstream measurements of swirl velocity using pitot-probes at different depths in the shroud cavity, and measurements of seal exit angle and velocity using a traversing cobra-probe. The test data presented herein show definitively that the different swirl brake designs, including a slotted seal, a long vane, and a short vane, have a major impact on swirl velocities relative to the conventional shroud design. The most effective at reducing swirl entering/leaving the seal is the slotted seal, while the concepts employing shroud vanes were more effective at reducing swirl in the shroud cavity.

Detection and warning of ice crystals clogging pitot probes from total air temperature anomalies

2020 ◽  
Vol 102 ◽  
pp. 105874 ◽  
Author(s):  
Eduardo S. Ayra ◽  
Álvaro Rodríguez Sanz ◽  
Rosa Arnaldo Valdés ◽  
Fernando Gómez Comendador ◽  
Javier Cano
Keyword(s):  
Air Temperature ◽  
Ice Crystals ◽  
Temperature Anomalies ◽  
Pitot Probes ◽  
Air Temperature Anomalies

scholarly journals Inventive nesting behaviour in the keyhole wasp Pachodynerus nasidens Latreille (Hymenoptera: Vespidae) in Australia, and the risk to aviation safety

PLoS ONE ◽  
2020 ◽  
Vol 15 (11) ◽  
pp. e0242063
Author(s):  
Alan P. N. House ◽  
Jackson G. Ring ◽  
Phillip P. Shaw
Keyword(s):  
Central America ◽  
Seasonal Pattern ◽  
Aviation Safety ◽  
Nesting Success ◽  
Native Range ◽  
Probe Volume ◽  
Nesting Behaviour ◽  
Mesh Bags ◽  
The Caribbean ◽  
Pitot Probes

The keyhole wasp (Pachodynerus nasidens Latreille 1812), a mud-nesting wasp native to South and Central America and the Caribbean, is a relatively recent (2010) arrival in Australia. In its native range it is known to use man-made cavities to construct nests. A series of serious safety incidents Brisbane Airport related to the obstruction of vital airspeed measuring pitot probes on aircraft possibly caused by mud-nesting wasps, prompted an assessment of risk. An experiment was designed to determine the species responsible, the types of aircraft most affected, the seasonal pattern of potential risk and the spatial distribution of risk on the airport. A series of replica pitot probes were constructed using 3D-printing technology, representing aircraft with high numbers of movements (landings and take-offs), and mounted at four locations at the airport. Probes were monitored for 39 months. Probes blocked by mud nesting wasps were retrieved and incubated in mesh bags. Emerging wasps were identified to species. Results show that all nests in probes were made by P. nasidens, and peak nesting occurs in the summer months. Nesting success (as proportion of nests with live adult emergents) was optimal between 24 and 31°C and that probes with apertures of more than 3 mm diameter are preferred. Not all areas on the airport are affected equally, with the majority of nests constructed in one area. The proportion of grassed areas within 1000 m of probes was a significant predictor of nesting, and probe volume may determine the sex of emerging wasps.

THERMAL ANALYSIS OF HEATED PITOT PROBES IN ATMOSPHERIC CONDITIONS OF ICE ACCRETION

2015 ◽  
Author(s):  
Ali Allahyarzadeh Bidgoli ◽  
José Roberto Brito de Souza ◽  
Kleber Marques Lisboa ◽  
Renato Machado Cotta
Keyword(s):  
Thermal Analysis ◽  
Ice Accretion ◽  
Atmospheric Conditions ◽  
Pitot Probes

Numerical and experimental characterisation of an aeronautic Pitot probe

2019 ◽  
Vol 123 (1264) ◽  
pp. 890-911
Author(s):  
R. Jäckel ◽  
G.L. Gutiérrez Urueta ◽  
F. Tapia Rodríguez ◽  
C. Monreal Jiménez
Keyword(s):  
Thermal Performance ◽  
Thermal Response ◽  
Heating System ◽  
Operating Conditions ◽  
Heating Element ◽  
Conventional Heating ◽  
Ice Formation ◽  
Composition Material ◽  
Failure Data ◽  
Pitot Probes

AbstractAeronautic Pitot probes (PPs) are extremely important for airspeed and altitude measurements in aviation. Failure of the instrument due to clogging caused by ice formation can lead to dangerous situations. In this work, a commercial aeronautic PP was characterised experimentally regarding its inner composition, material properties and its thermal performance in a climatic wind tunnel. Performance runs were taken out in order to analyse the thermal response of the PP under various operating conditions with a particular emphasis on the cooling process in the case of a heating element failure. Data for the thermal conductivity, diffusivity and specific heat for each material forming the PP were obtained. A numerical model to simulate the thermal behaviour of the PP was created using Comsol Multiphysics (CM). Experimental data were compared with their numerical counterparts for model validation purposes. After the model was validated, the operation of the PP in flight conditions was simulated. The failure of the conventional heating system was analysed to obtain the time until the PP reaches a tip temperature where ice formation can be expected. The tip temperature undercut the zero degrees Celsius mark 165 seconds after the heating element was switched off. The data collected in this work can be used to implement and validate mathematical models in order to predict the thermal performance of Pitot probes in flight conditions.

Response of Pitot probes in turbulent streams

1974 ◽  
Vol 62 (1) ◽  
pp. 85-114 ◽  
Author(s):  
H. A. Becker ◽  
A. P. G. Brown
Keyword(s):  
Static Pressure ◽  
Transverse Velocity ◽  
Turbulent Shear ◽  
Turbulent Shear Flow ◽  
Probe Signal ◽  
Turbulence Scale ◽  
The Mean ◽  
Reference Pressure ◽  
Pitot Probes ◽  
Probe Geometry

The response of a Pitot probe in a uniform laminar stream is commonly expressed in the form\[ P_s = P+{\textstyle\frac{1}{2}}C_{\rho} U^2, \]wherePsis the probe signal pressure,Pis the stream static pressure,Uis the stream speed and ρ is the fluid density. It has been found that for ordinary sphere-nosed, round-nosed and square-nosed probes\[ 1-C = K(\sin^2\theta)^m = K(U^2_n/U^2)^m, \]where θ is the angle between the velocity vector and the probe axis, andUn≡Usin θ is the transverse velocity component. The parametersmandKare functions of the probe geometry. These formulae also describe the performance in a turbulent stream when the probe is small compared with the turbulence scale. The evaluation of the time-averaged response is treated, and an answer is developed to the question of what it is that a Pitot probe measures in a turbulent stream. In a turbulent shear flow having the properties of a boundary layer, the reference pressure is best taken to be the static pressure at the shear-layer edge. It is shown that round-nosed probes withDi/D≃0·45 and square-nosed probes withDi/D≃0·15 then detect${\textstyle\frac{1}{2}}\rho\overline{U}^2_x$with good accuracy, whereDi/Dis the ratio of the inside and outside diameters of the Pitot tube. When measurements are made with two probes of dissimilar geometry, the differential response can be used to find the mean-square level of the transverse velocity fluctuations. Turbulence levels so measured agree closely with results from hot-wire anemometry.

Conjugated Heat Transfer Analysis of Heated Aeronautical Pitot Probes With Flight Tests Experimental Validation

2015 ◽  
Vol 36 (11) ◽  
pp. 991-1000 ◽  
Author(s):  
José Roberto Brito De Souza ◽  
Kleber Marques Lisboa ◽  
Ivana Gabriela Cerqueira ◽  
José Luiz Zanon Zotin ◽  
Carolina P. Naveira-Cotta ◽  
...  
Keyword(s):  
Heat Transfer ◽  
Experimental Validation ◽  
Heat Transfer Analysis ◽  
Flight Tests ◽  
Conjugated Heat Transfer ◽  
Pitot Probes

Condensation in Jet Engine Intake Ducts During Stationary Operation

1995 ◽  
Vol 117 (2) ◽  
pp. 227-236 ◽  
Author(s):  
J. B. Young
Keyword(s):  
Relative Humidity ◽  
Industrial Test ◽  
Condensation Process ◽  
Test Results ◽  
Jet Engines ◽  
Local Flow ◽  
Jet Engine ◽  
Homogeneous Condensation ◽  
Stationary Operation ◽  
Pitot Probes

The paper describes an analysis of the condensation of moist air in very long intake ducts of jet engines during stationary operation. Problems arising from such condensation include fan overspeed and increased stagnation pressure loss in the intake duct. The analysis demonstrates that, for moderate values of relative humidity, homogeneous condensation will occur in an outer annulus adjacent to the intake cowling if the local flow Mach number attains values of about 1.0. In the central region of the intake duct, where design Mach numbers of 0.8 may be attained, homogeneous condensation is unlikely to occur except, possibly, when the relative humidity is close to 100 percent and the ambient temperature very high. However, if the intake duct is very long, significant heterogeneous condensation on foreign particles present in the atmosphere is possible. The concentration of foreign nuclei required for this type of condensation is comparable to the likely levels of contamination at many industrial test sites. The effects of condensation on engine test results are twofold. First, condensation is a thermodynamically irreversible process and results in an increase of entropy and hence loss of total pressure in the intake duct. Uncorrected measurements using Pitot probes may not record this loss correctly. Second, the mass and energy transfer between the phases during the condensation process has a tendency to accelerate the flow approaching the engine, an effect that may be counteracted by a reduction in mass flow rate in order to maintain the static pressure constant. These conclusions are in agreement with experimental results obtained on-site during the testing of a jet engine fitted with a very long intake duct.

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