cases:case015

# Transitional Cascade Blade

Flow around a highly loaded compressor blade in cascade at three different incidence angles.

2D flow with constant temperature.

#### Geometry

Domain around a double-circular-arc blade.

The double-circular-arc blade geometry is shown in figure 1. Equations for the pressure surface, suction surface and camberline are given by $x_p^2 + (y_p + 219.7)^2 = 246.8^2$ $x_s^2 + (y_s + 149.5)^2 = 189.1^2$ $x_c^2 + (y_c + 179.4)^2 = 212.8^2$ where the origin is taken at the mid-point of the chord line, and all dimensions are in millimetres. The leading and trailing edges were machined to be circular, with radii of $0.9144$ mm, meeting the two blade surfaces at the tangency points. The chord length $c=228.6$ mm is measured from the centre of the leading edge circle to the centre of the trailing edge one.

The blades are arranged in a cascade, as shown in figure 2. Fig. 2: Blade cascade geometry

Features of the blades separated by a distance of $s=106.8$ mm:

• centreline curvature radius: $212.8$ mm
• camber angle: $\phi=65$o
• stagger angle: $\gamma=20.5$o
• chord length: $c = 228.6$ mm
• solidity: $c/s=2.14$
• radius of both the leading and the trailing edges: $0.9144$ mm

#### Flow Characteristics

A periodic, two-dimensional cascade flow has been developed without the use of continuous side wall suction.

Near the leading edge, the incidence angle causes the stagnation point to lie on either the pressure or suction surface of the blade. On this stagnation surface, the streamwise pressure gradient begins as favourable and results in a region where the boundary layer is laminar. Further downstream, an adverse streamwise pressure gradient either causes the laminar boundary layer to separate or initiate natural transition. On the surface opposite of the stagnation point, a severe adverse pressure gradient results in the presence of a separation bubble'' which transitions the flow to turbulence.

After the trailing edge, the near wake structure shows no similarity or self-preservation characteristics. Downstream, the far wake velocity profile shows Gaussian similarity.

#### Flow Parameters

Air with a kinematic viscosity $\nu = 1.5 \times 10^5$ m2/s and a density $\rho = 1.205$ kg/m2.

Inlet mean velocity: $U_{ref} = 33$ m/s.

Reynolds number based on the chord: $Re_c = U_{ref}c/\nu$.

Three different incidence angles have been imposed to the inlet flow: 5.0o, -1.5o and -8.5o.

#### Inflow Conditions

Constant mean velocity profile and turbulent quantity levels compatible with a free-stream turbulence intensity level of $0.18\% \pm 10\%$.

Velocity measurements using a one-component LDV system.

Static pressure measurements.

#### Measurement Errors:

The standard deviations are provided for each velocity measurement in the data files.

For the three different incidence angles, the following measurements are provided:

• Pressure distribution around the blade.
• Profiles at selected positions around the blade and across the wake of:
• First order moment: $U$
• Second order moment: $\overline{u^2}/U_{ref}^2$
• Skewness and Flatness: $S_u$, $F_u$

The data can be downloaded as compressed archives from the links below, or as individual files.

Sample plots of selected quantities are available.

#### Pressure Measurements

 Incidence Angle $5^o$ $-1.5^o$ pdistp050.dat pdistm015.dat pdistm085.dat

#### Velocity Measurements

$5^o$ Incidence Angle
Pressure Surface Suction Surface Wake
Location (%chord) File Location (%chord) File Location (%chord) File
2.7 tabp50p0027.dat 2.6 tabp50s0026.dat 105.4 tabp50w1054.dat
5.9 tabp50p0059.dat 7.6 tabp50s0076.dat 109.6 tabp50w1096.dat
14.4 tabp50p0144.dat 12.7 tabp50s0127.dat 152.6 tabp50w1526.dat
25.1 tabp50p0251.dat 23.0 tabp50s0230.dat
35.8 tabp50p0358.dat 33.2 tabp50s0332.dat
46.5 tabp50p0465.dat 43.3 tabp50s0433.dat
57.2 tabp50p0572.dat 53.6 tabp50s0536.dat
68.0 tabp50p0680.dat 63.2 tabp50s0632.dat
78.6 tabp50p0786.dat 74.0 tabp50s0740.dat
89.3 tabp50p0893.dat 84.2 tabp50s0842.dat
97.9 tabp50p0979.dat 94.9 tabp50s0949.dat
$-1.5^o$ Incidence Angle
Pressure Surface Suction Surface
Location (%chord) File Location (%chord) File
55.1 tabm15p0551.dat 7.3 tabm15s0073.dat
9.4 tabm15s0094.dat
14.5 tabm15s0145.dat
$-8.5^o$ Incidence Angle
Pressure Surface Suction Surface Wake
Location (%chord) File Location (%chord) File Location (%chord) File
4.3 tabm85p0043.dat 10.4 tabm85s0104.dat 106.0 tabm85w1060.dat
9.7 tabm85p0097.dat 19.7 tabm85s0197.dat 109.7 tabm85w1097.dat
20.5 tabm85p0205.dat 30.1 tabm85s0301.dat 131.9 tabm85w1319.dat
30.3 tabm85p0303.dat 40.5 tabm85s0405.dat
40.0 tabm85p0400.dat 49.8 tabm85s0498.dat
49.7 tabm85p0497.dat 55.0 tabm85s0550.dat
60.5 tabm85p0605.dat 60.2 tabm85s0602.dat
70.3 tabm85p0703.dat 70.6 tabm85s0706.dat
80.0 tabm85p0800.dat 80.0 tabm85s0800.dat
89.7 tabm85p0897.dat 90.3 tabm85s0903.dat
98.4 tabm85p0984.dat 97.6 tabm85s0976.dat
1. Zierke, W.C., Deutsch, S. (1989). The measurement of boundary layers on a compressor blade in cascade - Vols. 1 and 2. NASA CR 185118.

Indexed data:

case015 (dbcase, flow_around_body)
case015
titleTransitional Cascade Flow
authorZierke, Deutsch
year1989
typeEXP
flow_tag2d, streamlined_body