Icing Wind Tunnels

ICING WIND TUNNELS3938 C/Sgt DMCD DissanayakeENG/AE/12/0009 WN KaushalyaOUTLINEHistoryProblems regarding aircraft icingIntroduction of IWTOperation Components of IWTChallengers in IWTIWT FacilitiesConclusion

HISTORYThere were many aircraft accidents due to ice formation583 crashes were happened819 people diedNASA, NRI, CIRA and many universities researched for de-icing and anti icing systemsIWT is the testing equipment for those systemsNASA has the first icing research tunnel since WW CIRA has the biggest IWT

PROBLEMS REGARDING AIRCRAFT ICINGLoss of inherent stabilityLoss of lift and thrustIncrease weight of the aircraftMiscalculations of instrumentsProblems in enginesLoss of communicationLoss of control and visibility

INTRODUCTION OF IWTIcing wind tunnels are used to simulate In-flight atmospheric icing conditionsViewing of the microphysical processes of ice accretionCheck anti icing and de icing systemsThere are two features mainlyA refrigeration system is implemented to cools the air to well below freezing temperatureA water spray system is used to injects water droplets into the air stream creating a super cooled cloud These are usually closed loop wind tunnels6OPERATIONAir flow introduced by a fanRefrigeration system that can cool the air down to around - 40 FWater vapor and droplets added to the air to condense and freeze on the aircraft surfaces by the spray bars Then supersaturated cloud of air resulting in rapid ice buildup on the aircraftCameras record the whole sequence to show engineers where to make improvements in the de-icing system

Finally heating elements are activated for deicing

There the similarity ends. The first departure from conventionality is the 2100-ton refrigeration system that can cool the air down to - 40 F. However, cold air by itself cannot produce icing. There must be water vapor and droplets in the air to condense and freeze on the aircraft surfaces. The appropriate atmospheric conditions are created by a battery of atomizers upstream of the test section. The aircraft in the test section is thus forced to fly through a cold, supersaturated cloud of air resulting in rapid ice buildup on the craft. As the deadly layers grow, heating elements in the crucial aircraft components go into action, and the detached ice shards fly off downstream. Cameras record the whole sequence to show engineers where to make improvements in the de-icing system.

7OPERATION Contd.

OPERATION Contd.

COMPONENTS OF IWTCooling SystemsRemove the heat generated by the different heat sources and to keep constant temperature valuesTwin row Heat ExchangersThe function of the Cooling System is to remove the heat generated by the differentheat sources and to keep constant temperature values. Air flow refrigeration is obtainedvia a twin row Heat Exchangers located in the back leg, upstream the third corner, andback stream the main fan.10COMPONENTS OF IWT Contd.Air PlantFully dedicated to the IWT in order to provide facility operation support A centrifugal compressor unit allows the pressure to be regulatedSafety valves allow a fast tunnel evacuation and pressurization 11COMPONENTS OF IWT Contd.Fan SystemDriven at the desired airspeed A grid avoids that major ice blocks could impinge on the blades of the fanSpray Bar SystemGenerate water dropletsAlso it capable to generate super-cooled large droplets within the range of freezing drizzle conditions

12COMPONENTS OF IWT Contd.Test Sections

13COMPONENTS OF IWT Contd.Engine Flow Simulator Reproduce the air intake flow inside an engineHigh pressure fans are used to extract the flow through an engine installed in the test sectionCHALLENGES IN IWTThe introduction of the water droplets should not produce tunnel turbulenceAdequate size of water dropletsThe water droplets should supercool without freezingCorrosion due to water accumulation inside the wind tunnelIWT FACILITIESNASA Lewis Icing Research TunnelCIRA Icing Wind TunnelNRC Altitude Icing Wind TunnelThe Boeing Research Aero-Icing Tunnel

IWT FACILITIES Contd.NASA Lewis Icing Research TunnelAirspeed is from 50 to 350 knots Temperature is as low as -25CIt can rotate horizontally +/-20 degrees for various angles of attack

IWT FACILITIES Contd.CIRA Icing Wind TunnelAirspeed is up to 0.8 M Temperature is as low as -40CIt is the largest modern IWTIt is capable to do engine icing facilities and low velocity facilities in addition to IWT facilities.

IWT FACILITIES Contd.NRC Altitude Icing Wind TunnelAirspeed is up to 0.6 M Simulate flight as altitude as 30,000 ftThe Boeing Research Aero-Icing TunnelIt used to create ice shapes and test de-icing systemsfor further developing of Boing aircraftsSpeed range is up to 250 knotsTemperature range is -25 to 50F

CONCLUSIONEnabling analysis of inflight ice formationHelp manufacturers to check there designs are good enough to face extreme weather conditionsTest anti-icing ,de-icing equipment's and ice detectorsAircraft certification tests for newly designed aircrafts and enginesStudy microscopic ice forming in different shapesSimulations for investigations of aircrafts due to IcingThank You