Icing Research Wind Tunnel Research Articles

Hot-Air Anti-Icing Heat Transfer and Surface Temperature Modeling

An inlet strut with a hot-air anti-icing system is studied experimentally and numerically to understand the heat transfer between impinged supercooled water droplets and solid surfaces. Experiments were performed in an icing research wind tunnel for dry (without water droplets) and sprayed cases. The results show that the impinged droplets can decrease the surface temperature, even on areas without droplet impingement or a water film. Theoretically, the impinged droplets exchange heat with solid surfaces through two heat flow rate terms: , which contains the kinematic and internal energies of the impinged droplets; and the evaporation energy . Adding these two terms to the solid surface when simulating the dry case provides a method to predict the surface temperature after spraying. Calculations for depend on the film coverage that varies due to different operating conditions. However, calculating for the impinged area or over the entire surface can give the upper and lower bounds of the prediction for surface temperature. The results show that both methods can give predictions with errors that are below 5% for all cases studied. The numerical results also show that both and decrease the surface temperature, whereas the effect of is neglectable when compared with .

Numerical Study of Atmospheric Icing on Non Rotating Circular Cylinders in Tandem Arrangement

Numerical study of atmospheric ice accretion on two non-rotating circular cylinders in tandem arrangement was carried out at different operating and geometric conditions. To validate the numerical model, initially the results of ice accretion on single circular cylinder were compared with the experimental data obtained from CIGELE atmospheric icing research wind tunnel (CAIRWT) [1, 2]. A good agreement was found between experimental and numerical results. Numerical analyses of ice accretion on two circular cylinders in tandem arrangement showed that accreted ice loads decreases with the increase in distance between the cylinders and also affects the rate and shape of ice accretion. Parametric study at different droplet sizes and temperatures showed a significant change in ice accretion. This research work provides a useful base for better understanding and further investigation of atmospheric ice accretion on circular overhead power network cables in tandem arrangement, installed in the cold regions.

Atmospheric Ice Accretion on Non-Rotating Circular Cylinder

Numerical study of atmospheric ice accretion on a non-rotating circular cylinder was carried out at dry rime ice conditions. To validate the numerical model, results were compared with the experimental data obtained from CIGELE atmospheric icing research wind tunnel (CAIRWT). A good agreement was found between experimental and numerical results. Numerical study showed that selection of appropriate numerical model of ice density and droplet size distribution is important, as these can significantly varies the simulated ice growth. Parametric study at different air flow velocities and angles showed a significant change in ice accretion on circular cylinder. This research work provides a useful base for further numerical investigation of atmospheric ice accretion on circular power network cables installed in the cold regions like arctic and alpine.

Measuring temperature of the ice surface during its formation by using infrared instrumentation

A non-destructive remote sensing technique was used to measure the surface temperature of a thin macroscopic water film flowing on a growing asymmetric ice accretion during its formation inside an icing research wind tunnel. Given the underlying thermodynamic conditions of this experimental series, the recorded surface temperature was always below the temperature of water fusion, T m = 273.15 K, even when water shedding from growing ice accretions was observed visually. The surface temperature of ice accretions, T s, ranged from −1 °C, for angular positions near the stagnation line, down to a certain minimum above the ambient temperature, T a, for the greater angular positions, i.e. T m > T s > T a.

Two-dimensional modelling of the ice accretion process on transmission line wires and conductors

The main objective of this paper is to introduce a new 2-D icing model, of which the primary purpose is the simulation of the ice accretion process on overhead power line cables. The parameters of the model, such as the Local Collision Efficiency (LCE) and the local Heat Transfer Coefficient (HTC), were evaluated on the basis of time-dependent airflow computations and water droplet trajectory calculations. For wet accumulations, the movement of a surface water film was monitored at each time step so as to obtain the film's thickness and direction. In order to validate the present model, a number of experimental tests were carried out at the CIGELE Atmospheric Icing Research Wind Tunnel (CAIRWT). The results show that, on the whole, the proposed ice model performed well in simulating and predicting ice-grown shapes under dry and wet icing conditions.

Icing research wind tunnel opened

Icing research wind tunnel opened

Aerodynamic effects of aircraft ground deicing/anti-icing fluids

This article presents the results of flight and wind-tunnel investigations of the aerodynamic effects of aircraft ground deicing/anti-icing fluids on a Boeing 737-200ADV. The flight tests were performed in Kuopio, Finland, and the wind-tunnel tests were performed at the NASA Lewis Research Center Icing Research Wind Tunnel (IRT). Both types of commonly used fluids, those characterized by Newtonian and nonNewtonian viscosity behavior, were evaluated. Results of the tests indicate that the fluids remain on aircraft surfaces until well after liftoff and may cause measurable lift loss and drag increase, depending on the temperature, dilution, and specific characteristics of each fluid. A secondary wave of fluid which occurred at takeoff rotation was observed. Capillary wave action within the secondary wave is considered to be the source of the fluid's adverse aerodynamic effects at high angles of attack. Wind-tunnel testing and computational fluid dynamics analysis indicate that the fluid effects are airplane configuration dependent. This article also describes how results from these tests, other data, and airplane performance analyses were used to define an aerodynamic acceptance test for the fluids.

Investigation of the diffuser flow quality in an icing research windtunnel

In this paper, the flow in the diffuser section of the Icing Research Tunnel at the NASA Lewis Research Center is both numerically and experimentally investigated. To accomplish the numerical portion of the work, and existing computer code is utilised. The code, known as PARC3D, is based on the Beam-Warming algorithm applied to the strong conservation law form of the complete Navier-Stokes equations. Following a brief description of the diffuser geometry, the measured flow characteristics are described. A brief discussion of the code work is also provided. The flow measurements show a highly nonuniform velocity profile across the diffuser exit with boundary-layer growth more prevalent near the centres of the walls rather than in the corners of the diffuser. Predicted velocity profiles at the centreline are similar to those measured; however, the code did not accurately predict the boundary-layer behaviour near the corners.