Measurement Techniques and Data Presentation

Surface static pressure distributions on the fat plate were measured by using a Scanivalve system. The isentropic static pressure coefficient is defined as:

Cp = (Poi – Ps )/(Poi – P97%,s) (1)

where Ps is the measured surface static pressure, Pg7%,s is the static pressure at 97% S0 on the fkt plate surface and P01 is the inlet total pressure after the moving bars.

A constant temperature anemometry system was used for hot-wire measure­ments with an overheat ratio of 1.8 . For each measurement, 128 ensembles of AC data and 32 ensembles of DC data were taken. Each ensemble consists 4096 samples covering at least three wake passing periods.

A Dantec single-wire 55P15 boundary layer probe was used to make the boundary layer traverses. The hot-wire was calibrated in a suction calibration facility in accordance with a modified form of King’s Law. The effects of the ambient temperature drift were taken into account using the correction of Bearman (1971).

Hot-wire traverses were performed normal to the plate surface. Typically, 34 positions were used through the boundary layer with the distance between positions increasing exponentially as the probe left the plate surface. In order to account for the infhence of the plate surface proximity on the cooling of the heated wire, the Cox correction was applied to the measured data.

The suction surface profile loss coefficient can be determined according to the approximal expression given by Denton (1993)as:

£ = 20/(p* cos(a>2)) (2)

where в is the trailing edge momentum thickness calculated from the hot-wire traverses at 97%So, p is the equivalent pitch of the pressure distribution under investigated calculated from the T106C linear cascade pitch and surface length ratio and a2 is taken the value of T106C linear cascade exit fhw angle.