Wind tunnel and flight testing of a lamb wave based ice accretion sensor

Abstract

Severe icing conditions is still a risk in avtiation since heavy icing on aircraft can affect mass and aerodynamic performance in a way, that a catastrophic loss of control may occur. Detecting icing conditions and the extent of ice accretion is therefore essential to react instantly and to assess the severity. This eases the decision to either activate ice protection systems and continue the flight or to leave the icing conditions immediately. These functions can be provided by an icing sensor. Within the SENS4ICE project, such an icing sensor is developd which is able to detect ice accretion on aircraft surfaces which are prone to ice accretion. This so-called Local Ice Layer Detector (LILD) uses Lamb waves which are guided by the aircraft structure. If an ice accretion happens, the wave guide behavior is affected which can be measured. Within the project, the sensor hard- and software have been developed and wind tunnel as well as flight tests have been undertaken. In this paper, an overview about the function of the sensor as well as the general signal behavior are given. Finally the results of the wind tunnel test and some preliminary results from the flight tests will be shown. In both tests, the sensor was able to detect even very thin ice layers with minimum delay from the beginning of the ice accretion.