LAS EDIFICACIONES QUE SE EFECTUARÁN EN EL PREDIO CON EXPEDIENTE CATASTRAL 13-019-007, DE CONFORMIDAD CON EL REGLAMENTO DE ZONIFICACIÓN Y USOS DEL SUELO DEL MUNICIPIO DE SAN

Constant-percentage-bandwidth, 1/3-octave, far-field noise data were obtained in the EVNERT program using ground- level microphones located along a circular arc from 5° to 160° with respect to the engine inlet direction, in 5° increments. The online data acquisition system also obtained narrowband data in parallel with the 1/3-octave data as well as sequentially (Ref 87, personal communication) obtained pressure-time history data at select locations. Only the 1/3-octave data will be used here, however.

A sequence of “standard” engine power settings, character- ized by the corrected fan speed, was used for the many configurations investigated during the EVNERT program.

NASA was provided select engine operational parameters for the power settings for EVNERT configuration 31. The required nondimensional ANOPP performance parameters (see Table 3.1) were constructed from those. Even though, they were obtained for one particular configuration, the ANOPP nondimensional performance parameters are also representative of many of the other configurations.

Comparisons between ANOPP predictions and the EVNERT 1/3-octave data were made on an actual-day basis in the present work rather than on a standard-acoustic-day basis. This choice was based on the fact that NASA has access to the uncorrected actual-day EVNERT 1/3-octave data and converting the data would add further uncertainties to the experimental data. Consequently, the ambient (reference) conditions varied between cases (configurations and power settings) to reflect the actual conditions of the day. However, the same values of the nondimensional performance parame- ters were used in all cases for the ANOPP predictions carried out here.

Comparisons for configurations 25 and 31 are described in separate subsections below. Configuration 25 (October 2005) is a baseline case without any fan-noise acoustic treatment; that is, the fan flow path has all hard-wall conditions. Configu- ration 31 (March 2006) is identical except single-degree-of- freedom acoustic liners are installed in the inlet, aft-fan c-duct, and nozzle. Configurations 25 and 31 will now be referred to as the “hard-wall” and “treated” cases, respectively.

3.4.1.1 Hard-Wall Case

To give a visual overview of the quality of the ANOPP predictions compared to the EVNERT measured data, side-by- side 1/3-octave SPL carpet plots of predictions and test results are shown in Figure 3.4 for the approach, cutback, and takeoff conditions (60-, 71-, and 87-percent corrected fan speed). The horizontal axes are the base-10 logarithm of the center-band frequency and the directivity angle, and the vertical axis is the 1/3-octave SPL. In general, the ANOPP predictions are in qualitative agreement with the EVNERT data. As can be seen in the figure, the EVNERT engine-test SPL values are higher than the ANOPP predictions for frequencies greater than about 6 kHz in the downstream direction. This is believed to be caused by an underprediction of the turbine noise (Ref. 57). The EVNERT data is also contaminated in the 315 to 630 Hz 1/3-octave frequency bands by an abnormal noise source. Honeywell (Ref. 57) identified this noise source to be case- radiated noise by using a tarmac-array beamforming tech- nique. They found that this unwanted noise source was present during the 2005 EVNERT configurations 13 to 28, but was not seen again after a partial engine rebuild for instrumentation in early 2006.

Figure 3.5 to Figure 3.7 show the 1/3-octave SPL spectra in the 30°, 60°, 90°, 120°, and 150° directions in parts (a) through (e) and the overall SPL (OASPL) versus polar directivity angle in part (f) for the approach, cutback, and takeoff conditions, respectively. The ANOPP predictions have

Figure 3.4.—Hard-wall case 1/3-octave surface plots comparing ANOPP predictions and EVNERT data of far-field sound from Honeywell TECH977 engine at various corrected fan speeds. SPL is sound pressure level, and f repre- sents frequency. (a) 60 percent (approach). (b) 71 percent (cutback). (c) 87 percent (takeoff).

Figure 3.5.—Comparison of ANOPP predictions and EVNERT data for hard-wall case of Honeywell TECH977 engine at approach condition, 60 percent corrected fan speed. Error bands for predictions are 1 and 3 percent uncertainties in performance parameters. Error bar for data is ±1.25 dB estimated uncertainty from calibration and instrumentation. (a) to (e) 1/3-octave sound pressure level (SPL) versus center frequency at different polar angles. (a) 30°. (b) 60°. (c) 90°. (d) 120°. (e) 150°. (f) Overall SPL (OASPL) versus polar directivity angle.

Figure 3.6.—Comparison of ANOPP predictions and EVNERT data for hard-wall case of Honeywell TECH977 engine at cutback condition, 71 percent corrected fan speed. Error bands for predictions are 1 and 3 percent uncertainties in performance parameters. Error bar for data is ±1.25 dB estimated uncertainty from calibration and instrumentation. (a) to (e) 1/3-octave sound pressure level (SPL) versus center frequency at different polar angles. (a) 30°. (b) 60°. (c) 90°. (d) 120°. (e) 150°. (f) Overall SPL (OASPL) versus polar directivity angle.

Figure 3.7.—Comparison of ANOPP predictions and EVNERT data for hard-wall case of Honeywell TECH977 engine at takeoff condition, 87 percent corrected fan speed. Error bands for predictions are 1 and 3 percent uncertainties in performance parameters. Error bar for data is ±1.25 dB estimated uncertainty from calibration and instrumentation. (a) to (e) 1/3-octave sound pressure level (SPL) versus center frequency at different polar angles. (a) 30°. (b) 60°. (c) 90°. (d) 120°. (e) 150°. (f) Overall SPL (OASPL) versus polar directivity angle.

uncertainty bands (1 and 3 percent performance parameter uncertainty in blue and orange, respectively) and the static- engine-test data have ±1.25-dB bars based on estimated calibration and/or instrumentation uncertainty. The abnormal case-radiated sound and the high-frequency underprediction of the turbine noise are clearly visible in the SPL spectra shown in these figures. Nevertheless, the OASPL directivity and value are relatively well predicted for the cutback and takeoff conditions, with discrepancies mainly occurring close to the upstream and downstream directions.

3.4.1.2 Treated Case

Figure 3.8 shows 1/3-octave SPL surface plots at the approach, cutback, and takeoff conditions of 60-, 71-, and 87-percent corrected fan speeds, respectively. The figure layout is the same as that used in Figure 3.4. The ANOPP predictions are in qualitative agreement with the EVNERT data, but with some exceptions. There is high-frequency noise, probably turbine-associated, present in the EVNERT data that is not reflected in the ANOPP predictions. In addition, there is a SPL peak in the EVNERT data at the compressor shaft frequency (≈400 Hz at approach). It is most visible in the data for the approach conditions and decreasingly so for the higher throttle settings. This spectral peak is most likely a compressor-disk tone.3 The effect of the acoustic treatment in the inlet, c-duct, and nozzle can clearly be seen by comparing these results with those in Figure 3.4. The fan blade-passing frequency tone and its harmonics have clearly been reduced. The takeoff condition is dominated by jet noise, which somewhat masks the fan-noise attenuation due to the acoustic liners.

Figure 3.9 to Figure 3.11 show the 1/3-octave SPL spectra in the 30°, 60°, 90°, 120°, and 150° directions in parts (a) through (e) and the OASPL versus polar directivity angle in part (f) for the approach, cutback, and takeoff conditions, respectively. The uncertainty bands and bars for the prediction and data, respectively, are the same as for the hard-wall case above. The compressor-disk tone and the high-frequency underprediction of the turbine noise are clearly visible in the SPL spectra shown in these figures. The OASPL directivity and value are relatively well predicted for all conditions.