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Buttsworth, David
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Microwave Technique for Liquid Water Detection in Icing Applications

University of Oxford-Matthew McGilvray, David Gillespie
University of Southern Queensland-John Leis, David Buttsworth, Ramiz Saeed, Khalid Saleh
Published 2019-06-10 by SAE International in United States
The partial melting of ingested ice crystals can lead to ice accretion in aircraft compressors, but accurately measuring the relatively small fraction of liquid water content in such flows is challenging. Probe-based methods for detecting liquid water content are not suitable for deployment within turbofan engines, and thus alternatives are sought. Recent research has described approaches based on passive microwave sensing. We present here an approach based on active microwave transmission and reflection, employing a vector network analyzer. Utilization of both transmission and reflection provides additional data over and above emission or transmission only, and permits a more controllable environment than passive sensing approaches. The paper specifically addresses the question of whether such an approach is viable within the context of representative icing wind tunnel and engine flow conditions. A quasi-thermal equilibrium approach is presented herein to estimate the melting ratio during microwave analysis of samples at 0 °C. Experimental results using microwaves in the 2.45GHz region are presented, and post-processing methods investigated. This is followed by an investigation of detection limits for ice accretion…
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A New Wind Tunnel Facility for Ice Crystal Icing Experiments

University of Southern Queensland-Ramiz Saeed, David Buttsworth, Khalid Saleh
Published 2019-06-10 by SAE International in United States
The design and characterization of a new ice crystal icing wind tunnel facility is introduced through this work. The arrangement proposed in this work involves water droplet freeze-out using liquid nitrogen evaporation followed by natural particle melting through dilution with warm air. The viability of the concept was first demonstrated theoretically using a conservation of energy analysis. Thermodynamic performance of the facility is dictated largely by the availability of the liquid nitrogen, and in order to establish a facility with modest operating costs, the proposed operation specified using a maximum of 20 liter of liquid nitrogen per run with a maximum duration of two minutes. The target operating conditions for the facility were: flow speed around 50 m/s, temperatures around 0 °C, and total water content up to 10 g/m3 with melting ratio up to 0.2. Experimental results have demonstrated a generally favorable agreement with the energy equation analysis, and with results from Computational Fluid Dynamics (CFD) simulations. Experiments have demonstrate sufficient uniformity of flow speed and temperature for the facility to be regarded as…
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Finite Element Analysis of Eroding Type Surface Thermocouple with Application to Engine Heat Flux Measurement

University of Oxford-Xiaowei Wang, Richard Stone, Robert Stevens, Yoshi Arita
University of Southern Queensland-David Buttsworth
Published 2006-04-03 by SAE International in United States
A two-dimensional finite element model has been used to analyze the unsteady heat conduction behavior of an eroding type of surface thermocouple. The impulse response of the thermocouple was analyzed by using both a one-dimensional solution and a two-dimensional model. The experimental impulse response of the thermocouple was investigated by a laser impulse excitation experiment to validate the modeling results. The modeling results showed that there was a significant difference between the two-dimensional modeling and the one-dimensional analytical solution, especially before 1 ms. The two-dimensional modeling result is closer to the laser impulse experiment result, which implies the existence of a multi-dimensional effect on the transient heat conduction within the eroding thermocouple. Engine heat flux measurements were obtained using the impulse response analysis, and a comparison of the computed heat flux has been made using the experimental impulse response and the different models. The use of a laser impulse calibration is recommended. If a model is to be used then it should be a 2-D model, but if only a 1-D model is available, then…
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