Development of a Sensor for Total Temperature and Humidity Measurements under Mixed-Phase and Glaciated Icing Conditions

Fuleki, Dan; Mahallati, Ali; Currie, Thomas E.; MacLeod, J. D.; Knezevici, D. C.

doi:10.2514/6.2014-2751

Cited by 15 publications

(9 citation statements)

References 12 publications

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“…A gas velocity at the tunnel exit of ve = 85 m/s was specified as a model parameter input. Liquid water was injected with an initial temperature of 280.4 K (45 °F) at a bulk total water content of TWCbulk = 2.26 g/m 3 . The value of TWCbulk was calculated as the ratio of water mass flow rate to volumetric gas flow rate at the test section and is calculated using Eq.…”

Section: Model Sample Resultsmentioning

confidence: 99%

Numerical Analysis of Mixed-Phase Icing Cloud Simulations in the NASA Propulsion Systems Laboratory

Bartkus

Tsao

Struk

et al. 2016

8th AIAA Atmospheric and Space Environments Conference

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This paper describes the development of a numerical model that couples the thermal interaction between ice particles, water droplets, and the flowing gas of an icing wind tunnel for simulation of NASA Glenn Research Center's Propulsion Systems Laboratory (PSL). The ultimate goal of the model is to better understand the complex interactions between the test parameters and have greater confidence in the conditions at the test section of the PSL tunnel. The model attempts to explain the observed changes in test conditions by coupling the conservation of mass and energy equations for both the cloud particles and flowing gas mass. The model uses isentropic relations to relate gas temperature, velocity, density and pressure with respect to the PSL geometry. Measurements were taken at the PSL during wind tunnel tests simulating ice-crystal and mixed-phase icing that relate to ice accretions within turbofan engines in May 2015. The model was compared to experimentally measured values, where test conditions varied gas temperature, pressure, velocity and humidity levels, as well as the cloud total water content, particle initial temperature, and particle size distribution. Wet-bulb temperatures were generally within a few degrees of freezing. The model showed good agreement with experimentally measured values, to within approximately 30% of the measured change in gas temperature and humidity at the tunnel test section. The model did reasonably well in predicting melt content (liquid mass to total mass) at the test section, especially for clouds with larger particle sizes. In addition, the model predicted particle size at the tunnel exit with good agreement, however, the comparison was limited to clouds consisting of a small particle size distribution. One of the key findings from this work is that there was a nearly constant but slight increase in total wet-bulb temperature when the spray cloud was activated for every test and simulation. In addition, the total wet-bulb temperature in the tunnel plenum was a large factor in determining cloud phase.

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Section: Model Sample Resultsmentioning

confidence: 99%

Numerical Analysis of Mixed-Phase Icing Cloud Simulations in the NASA Propulsion Systems Laboratory

Bartkus

Tsao

Struk

et al. 2016

8th AIAA Atmospheric and Space Environments Conference

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“…Increases from the other energy sources mentioned have been estimated for runs at the ends of the plateau in Fig. 23 using T o , ω measured under wet conditions 19 and a stagnation point heat transfer coefficient obtained from the correlation of Kestin and Wood 20 with the measured tunnel turbulence intensity of 7.75% 4 . The impinging water droplet temperature was assumed to equal the wet value of T wb , and changes in the sensible heat of the ice crystals between M=0.25 and M=0.4 were ignored.…”

Section: Effect Of Pressurementioning

confidence: 99%

Experimental Studies of Mixed-Phase Sticking Efficiency for Ice Crystal Accretion in Jet Engines

Currie

Fuleki

Mahallati

2014

6th AIAA Atmospheric and Space Environments Conference

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Aircraft jet engines operating at high altitudes in ice crystal clouds can experience operational problems and/or damage resulting from accretion of ingested ice crystals within the compressor. It is believed the ice crystals partially melt, allowing them to stick to internal components. A method for modelling such mixedphase accretion is required to de-risk new engine designs, modify existing designs with such icing issues and define critical operating points for scrutiny in proposed ice crystal certification tests. This paper presents preliminary results for a modelling approach which treats the accretion process as strictly a sticking phenomenon, largely ignoring heat transfer, phase change, runback and other location-dependent effects commonly used in the analysis of supercooled water icing. Ice-on-ice growth is described by a sticking efficiency, defined as the fraction of the mixed-phase impinging mass flux which remains on the surface (i.e. sticks). Experimental results are presented for 3 test articles tested in a small mixed-phase icing tunnel located in an altitude chamber (Research Altitude Test Facility or RATFac) at the National Research Council of Canada. These results show that the sticking efficiency is highly correlated with the ratio of liquid water content (LWC) to total water content (TWC) in the freestream, reaching a maximum value of 0.4-0.5 at melt (LWC/TWC) ratios in the approximate range 10-20%, as measured with a multi-element probe. It is shown that sticking efficiencies are largely independent of TWC, Mach number (M) and particle size at normal incidence (i.e. at the stagnation point) at these melt ratios, at least in the limited ranges of these variables investigated, but are strongly dependent on these parameters at oblique impingement angles. It is also shown that accretions can grow to a very large size at an almost constant rate at high levels of TWC. The experimental results are used to develop an erosion-based semi-empirical accretion model which at least partially explains this super-growth phenomenon and predicts most of the experimental results with acceptable fidelity. The model predicts that the almost unlimited growth observed in the experiments is possible at lower Mach numbers (e.g. 0.25) for TWC levels exceeding ~10g/m 3 , when the sticking efficiency remains finite at all particle impingement angles. The model also predicts that such growth is unlikely for higher Mach numbers (e.g. 0.4), at least for the 45μ (MVD) particles to which the model is applied. Smaller particles will likely extend the Mach number range over which the sticking efficiency remains finite. Nomenclature a, b = TWC-dependent coefficients in relation for t & a f = coefficient in expression for flux reduction factor f A,B = constants dependent on mechanical, physical properties of eroded material and erodent particles D = diameter D xx = particle diameter below which the cumulative particle volume is xx% of the total particle volume DSD = droplet size distribution E = erosion function (of γ) f = eros...

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“…More details on the TAT & RH probe can be found elsewhere. 8 When the cloud is activated, a temperature change (T) and humidity change is typically measured by the TAT & RH probe. That T is applied to the dry (cloud off) measurement from P0 & T0 probe to establish the total temperature at the test section with the cloud on, T0,on.…”

Section: Aerothermal Measurementsmentioning

confidence: 99%

“…During all the previous testing, air temperature and humidity measurements showed changes at the test section when the cloud was active compared to when the cloud was off. The most recent joint NASA and NRC test 7 in March 2012 included a traversable total air temperature (TAT) & relative humidity (RH) probe 8 which allowed measurements at tunnel centerline. Subsequent modelling showed that a decreasing air temperature was due to the energy exchange from the partial evaporation of the cloud [9][10][11] .…”

Section: Introductionmentioning

confidence: 99%

Ice Crystal Icing Physics Study using a NACA 0012 Airfoil at the National Research Council of Canada’s Research Altitude Test Facility

Struk

King

Bartkus

et al. 2018

2018 Atmospheric and Space Environments Conference

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This paper presents results from a study of the fundamental physics of ice-crystal ice accretion using a NACA 0012 airfoil at the National Research Council of Canada (NRC) Research Altitude Test Facility in August 2017. These tests were a continuation of work which began in 2010 as part of a joint collaboration between NASA and NRC. The research seeks to generate icing conditions representative of those that occur inside a jet engine when ingesting ice crystals. In this test, an airfoil was exposed to mixed-phase icing conditions and the resulting ice accretions were recorded and analyzed. This paper details the specific objectives, procedures, and measurements which included the aero-thermal and cloud measurements. The objectives were built upon observations and hypothesis generated from several previous test campaigns regarding mixed-phase ice-crystal icing. The specific objectives included (A) ice accretions under different wet-bulb temperatures, (B) investigations of steady-state ice shapes previously reported in the literature, (C) total water content variations in search of a threshold for accretion, and (D) probe characterization related to measuring melt fraction which is important to characterize the mixed-phase condition. The resulting ice accretions and conditions leading to such accretions are intended to help extend NASA's predictive iceaccretion codes to include conditions occurring in engine ice-crystal icing.

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Development of a Sensor for Total Temperature and Humidity Measurements under Mixed-Phase and Glaciated Icing Conditions

Cited by 15 publications

References 12 publications

Numerical Analysis of Mixed-Phase Icing Cloud Simulations in the NASA Propulsion Systems Laboratory

Numerical Analysis of Mixed-Phase Icing Cloud Simulations in the NASA Propulsion Systems Laboratory

Experimental Studies of Mixed-Phase Sticking Efficiency for Ice Crystal Accretion in Jet Engines

Ice Crystal Icing Physics Study using a NACA 0012 Airfoil at the National Research Council of Canada’s Research Altitude Test Facility

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