Farooq Saeed

Numerical Heat Transfer Correlation for Array of Hot-Air Jets Impinging on 3-Dimensional Concave Surface

Numerical heat transfer correlations established from a numerical computational fluid dynamics (CFD) study of a three-dimensional hot-air jet array impinging on curved (circular) surface are presented. The results are in the form of numerical correlations for the average and maximum Nusselt number for different nozzle-to-nozzle spacing, nozzle-to-surface height, and hot-air jet Mach numbers typical of those in an hot-air antiicing system employed on aircraft wings. A validation case is presented, and it is shown that the results obtained from the CFD study are in good agreement with experimental data found in the literature. An interpolation technique, the Dual-Kriging method, that makes use of the numerical database for antiicing simulation on aircraft wings is presented. The benefit of using the Dual-Kriging method is that it preserves the nonlinear nature of the heat transfer distribution from a hot-air jet impinging on a curved surface.

Numerical Simulation of Surface Heat Transfer from an Array of Hot Air Jets

A numerical study was conducted to simulate the heat transfer from an array of jets onto an impingement surface typical of those found on aircraft wing/slat surfaces. The study used commercially available CFD software, FLUENT, to model the different hot-jet arrangements that included: (a) a single array of jets, (b) two staggered arrays of jets at different stagger angle (10 and 20 deg), and (c) a case with an etched surface. The main findings of the study reveal that the single array and the array with a 20-deg stagger yield better surface heat transfer than the 10-deg stagger. The etched surface or inner liner yields almost 2-3 times better surface heat transfer than the others thus making it a favorable choice for increasing surface heat transfer. Nomenclature A = surface area or reference area based on hole diameter, m 2 a = piccolo tube diameter (0.05m) cn = spanwise distance between holes or spanwise hole spacing (0.015m) D = diameter of impingement wall semi-cylinder (0.075m) d = jet hole diameter (0.025m) dn = jet-to-jet distance taking into account the stagger hn = jet exit height, m hc = local convection heat transfer coefficient, W/m 2 -K k = thermal conductivity or air, W/m-K kw = thermal conductivity of impingement wall (Aluminum), W/m-K Lref = reference length (0.0025m) M = jet Mach number m& = mass flow rate, ρAvave, kg/s Nu = Nusselt number, hcLref/k p = pressure, Pa q = convective heat flux, hc(Tw – Tref), W/m 2 q&

Design of Subscale Airfoils with Full-Scale Leading Edges for Ice Accretion Testing

A design procedure for subscale airfoils with full-scale leading edges that exhibit full-scale water droplet impingement characteristics in an incompressible, inviscid e ow is presented. The design procedure uses validated airfoil design, e ow analysis, and water droplet impingement simulation codes to accomplish the task. To identify and isolate important design variables in the design, numerous trade studies were performed. This paper presents the results of the trade studies and briee y discusses the role of important design variables in the subscale airfoil design. The effect of these design variables on circulation, velocity distribution, and impingement characteristics is discussed along with the accompanying implications and compromises in the design. A strategy to incorporate viscous effects into the design is also presented. This article also presents the design of a half-scale airfoil model with a 5% upper and 20% lower full-scale surface of the Learjet 305 airfoil leading edge and compares its aerodynamic as well as the droplet impingement characteristics with that of the Learjet 305 airfoil.

Analysis Method for Inertial Particle Separator

4Re 5 10 5 ).Alimitationsoftheanalysistoolisthatitlacksanappropriateparticlereboundmodelforthe treatment of particle-wall collisions. The usefulness of the analysis tool is its use in conjunction with a multipoint inverse design tool for the design of a multi-element airfoil based inertial particle separator system model in an inverse fashion as opposed to the direct design methods being employed currently for this task. With such a design andanalysistoolathand,thedesignspacecanbeexploredaswellastradeoffstudiescanbeperformedthatcanaidin the development of a more efficient design methodology for multi-element airfoil based inertial particle separator systems.

Numerical simulation of a hot-air anti-icing system

The paper presents results of the numerical simulation of a hot-air anti-icing system model. A 20 Navier-Stokes CFD code is used to simulate jet impingement on (a) a flat plate and (b) th e inner surface a slat of a multi-element airfoil, a modified RAE 2822 airfoil. The j?at plate case is used to validate numerical predictions by comparison with known empirical conelations. Since these correlations are being used in most of the anti-icing simulation codes, the slat case is used to determine their applicability to concave surfaces. The results indicate that the empirical correlations are not n&able enough for use in anti-icing simulations. The CFD code is then coupled to an ice accretion and antiicing simulation code, CANICE. The overall computational prvcedum is presented with the help of an example. The merits of using the CFD tool in conjunction with the CANICE code are discussed. NOMENCLATURE c, = specific heat of air = airfoil chord length ii slot-tc+wall distance/height h = heat-transfer coefficient k = thermal conductivity L W C = liquid water content M = freestream Mach number MVD = median volumetric droplet diameter ti ?z mass flow rate NZ6 = Nusselt number, hs/kf Pr = Prandtl number, pk/Cp ke = heat flux = freestream Reynolds number, V,c/v Res = jet Reynolds number, isS/~ S = hydraulic diameter of slot, 2x width St = Stanton number, h/pre,VrerCP FL = surface arc length measured from origin = temperature Tf = film temperature, (Tw + Tin)/2 V = airspeed, velocity Q = angle of attack relative to chord line P = fluid viscosity v = kinematic viscosity, p/p P = fluid density i.2 = mean velocity at the inlet slot * Postdoctoral Fellow. Member AIAA. t Ph. D. Student Member AIAA. 4 Bombardier Aeronautical Chair Professor. Associate Fellow AIAA. Copyright @ 2000 by Farooq Saeed, FranGois Morency, and Ion Paraschivoiu. Published by the American Institute of Aeronautics and Astronautics, Inc. with permission. Subscripts: anti = anti-icing f = fluid, film in = inlet out = outlet ref = reference s = static t = total w = wall X = local 00 = freestream value INTRODUCTION Atmospheric icing presents a major hazard to aircraft operat ing under natural icing condit ions and is a cause of major concerns for the certification authorities as well as the aircraft manufacturers. The steady rise in the global aviation traffic means an increased likelihood of encounter ing natural icing conditions. This suggest an increased frequency of icing related accidents unless a considerable amount of effort is focused on the various safety issues concerning in-flight aircraft icing. To enhance flight safety under natural icing conditions, FAA has recently initiated a multi-year icing plan’>’ to address the various issues related to in-flight aircraft icing. One of the several key tasks outl ined in the plan is to ensure the validity and reliability of icing simulation/modeling methods currently being used/developed. In an effort to support the objectives of the FAA Icing Plan, and facilitate Bombardier Aerospace in the certification process, the main focus of research under the Bombardier Aeronautical Chair at l?cole Polytechnique, MontrCal, has been the development of a reliable ice accretion and anti-icing simulation code CANICE.3-5 The development of CANICE has

Experimental and Numerical Investigation of 65 Degree Delta and 65/40 Degree Double-Delta Wings

In this study, an experimental and numerical investigation was carried out to obtain lift, drag, and pitching moment data on 65 degree delta and 65/40 degree double-delta wings. The experimental tests were conducted at the King Fahd University of Petroleum and Minerals low-speed wind-tunnel facility, whereas the numerical tests were performed using the commercial computational fluid dynamics software FLUENT. Results from both experiments and numerical predictions were compared to other experimental data found in literature as well as to the theory of Polhamus. The results of comparison of surface pressure coefficient distribution and vortex breakdown location show good agreement with experiments. Overall, the comparison of result shows good agreement between different experimental studies as well as good agreement with the computational fluid dynamics predictions and the theoretical calculations.

Hybrid Airfoil Design Procedure Validation for Full-Scale Ice Accretion Simulation

This paper presents results of the ice accretion tests performed to validate the hybrid airfoil design method. The hybrid airfoil design method was developed to facilitate the design of hybrid airfoils with full-scale leading edges and redesigned aft sections that simulate full-scale ice accretion simulation for a given ® range. Icing tests in the NASA Lewis Icing Research Tunnel were conducted with test conditions representative of e ight. A twodimensional half-scale hybrid airfoil was designed and built with a 20% plain e ap and a 5% upper and 20% lower full-scale leading-edge surface of a modern business jet wing section. This paper presents a comparison between the ice shapes accreted on the business jet and hybrid airfoil models during the tests. The test results show that ice accretion simulation could be predicted in terms of the droplet-impingement simulation alone and cone rm the assumption that the leading-edge ice accretion will be the same for the full-scale and hybrid airfoils if icing cloud properties, droplet impingement, local leading-edge e owe eld, model surface characteristics, and geometry are held constant. This assumption was found to be valid when tested under the most severe conditions of glaze ice accretion over a large time interval. A comparison between the actual ice shapes and those predicted by LEWICE 1.6 under similar conditions is also shown. The results suggest that the hybrid airfoil design method has signie cant application potential for tests where leading-edge ice accretion is desired because it provides an alternative to the myriad of issues related to ice accretion scaling.

Simulation of Heat Transfer From Hot-Air Jets Impinging a Three-Dimensional Concave Surface

a, b = coefficients d = piccolo-hole (jet) diameter e = eccentricity of a conical curve H = nozzle-to-surface distance h = heat-transfer coefficient k = thermal conductivity M = Mach number Nu = Nusselt number based on the hole diameter, hd=k n = empirical coefficient p = focal point of a conical curve _ q = heat flux Rejet = Reynolds number based on jet diameter and mean jet velocity, ud= s = coordinate along the surface with its origin aft of the center of the jet axis, y 0 plane T = temperature, K u = velocity along the jet axis u = mean jet velocity W = nozzle-to-nozzle distance x, y, z = coordinate system with its origin aft of the center of the jet exit = dynamic viscosity = kinematic viscosity, = = orientation angle of the jet = fluid density

Surface Heat Transfer Study for Ice Accretion and Anti-Icing Prediction in Three Dimension

This paper present CANICE-3D, a three dimensional ice-accretion prediction code. This code can predict ice shape over a complete aircraft. The external pow field is based on a potential formulation using commercial CMARC panel code. Droplet trajectories are calculated in 9D considering the potential solution, the atmospheric liquid water content and a mean volumetric diameter distribution of water droplets. Boundary layer correction is added on surface streamlines starting from stagnation points. Thermodynamic balance is performed to predict surface temperature and freezing fraction of water mass which considers running back water. An Anti-Icing model has been coupled in an aim to predict optimal design for its configuration. Emphasis will be presented for thermodynamics and ice accretion formulation as well as anti-icing prediction. The integration of the surface roughness for convective heat transfer coefficient calculation within the boundary layer is described. Implementation of CANICE-3D and comparison of surface heat transfer coefficient and ice accretion prediction in conjunction with experimental data.

A Three-Dimensional Water Droplet Trajectory and Impingement Analysis Program

The paper presents the details of the development of a three-dimensional panel method based droplet impingement analysis code. The code is based on the low-order three-dimensional panel method code CMARC which is the commercially available ANSI C language version of PMARC (Panel Method Ames Research Center) code. With modern PCs, low-order panel methods can provide nearly the same level of accuracy as higher-order methods as long as sufficient panels are added in areas of high curvature with significant savings in computational time. The paper gives details of the three-dimensional droplet trajectory calculation and impingement analysis. The paper compares the impingement characteristics with those obtained from the two-dimensional code CANICE. The effect of important flow and icing variables on impingement characteristics is presented to highlight some of the effects of finite aspect ratio on droplet impingement characteristics. A comparison of droplet impingement efficiency with the two-dimensional version of CANICE shows that the threedimensional effects result in an increase in impingement limits as well as the maximum impingement efficiency value.