Auto-Yaw
An Auto-Yaw Pressure Transducer Module can be included in any Rotadata Combi Traverse Installation using a Rotadata RTA, RTC or RTM radial/yaw actuator to measure flow angle.
The auto-yaw pressure transducer module contains a differential
pressure transducer which can be connected through micro bore tubing
to the two outer test points on say a cobra probe which is the type of
probe often used in flow angle measurement. The length of the micro
bore tubing to be as short as possible (preferably not more than 0.5
metres). The pressure transducer module is contained within its own
enclosure and may require a supply of cooling air depending on the
ambient temperature in close proximity to the test engine.
The electrical output from the transducer is taken to the Combi controller through a multi-core cable, which also carries power supplies from the controller to the transducer.
Once the transducer module is connected to the Combi controller and to the probe it is a simple matter to measure the flow angle by selecting ‘Auto Yaw & Inc Rad’ operating mode on the traverse system.
The control software rotates the probe backwards and forwards between the actuator yaw limits until the transducer module detects a pressure null. The output from the transducer then stops the probe and only allows it to move again to follow changes in flow direction.
The probe angle at the null point (in relation to a known datum on the actuator) can be read directly from the yaw indicators on the Combi front panel. It is then a comparatively simple matter to calculate flow angle in the test area if the position of the datum and the aerodynamic alignment of the probe are known.
The use of RTRAV software enables automatic control of the process from the host computer.
Usually operators wishing to upgrade a Rotadata actuator/combi installation for auto yaw need buy only the pressure transducer and a multi-core connecting cable. The connectors, circuits and software needed to use the auto yaw facility are a standard fitting in the Combi so the controller will require no modification. Occasionally for some early combi’s an auto-yaw upgrade is necessary.
Like the micro bore tubing the pressure transducer module should be mounted within a short distance of the actuator/cobra probe and in an ambient environment.
The distance between the pressure transducer module and the combi controller can be a maximum distance of 100 metres (325 feet) but it is preferable to keep the distance below 70 metres (225 feet) when ever possible to avoid loss of power or signal strength.
