Simultaneous analysis of all four vane relative measurement planes allows circumferential flow variations to be determined. Accurate spacing measurements between vane-relative positions allow all four planes to be referenced to a point in time specified by rotor position. Plane to plane spacing is 2 7/32 ±1/64 degrees. At the design speed of 2500 rpm, it thus takes a rotor blade 148 ±1^s to sweep from one measurement plane to the next. Thus, for the purposes of simultaneously analyzing all four measurement planes, a traverse time was taken at A=150^,s. Table 3.3 shows the timing sequence for comparison of all vane positions. Each row represents a single instant in physical time or, equivalently, a given rotor blade position. The specified acquisition delay time provided in each cell of that row ensures that the rotor blade is in the proper position relative to that specific measurement plane. For example, if Plane A was imaged at a delay time t=450 ^s then Planes B, C and D would be at the proper distance from the rotor at delay times t=300, 150, and 0 ^s, respectively. This allows information to be displayed at of all four vane positions at a single instance in time, for example as shown in Figure 3.4

0 0

Post a comment