Recommendations

On the basis of the issues raised in this report, the panel recommends continued or increased emphasis by AEAP on the areas noted below.

EMISSIONS CHARACTERIZATION

  1. Some revisions are recommended to the existing prioritization of the engine emissions to be measured. Specifically, measurements of SO2, SO3, and OH levels should be changed from second to first priority.

  2. An increased emphasis on conducting tests of civil subsonic engines at cruise-altitude operating conditions, and a corresponding decreased reliance on combustor-rig testing, are recommended. Aggressive efforts to seek out and capitalize on opportunities for conducting such tests on a piggyback basis are strongly encouraged. To the extent possible, these tests should involve engine models that have been recently introduced into operational service. One important product of such tests should be validated procedures for calculating NOx, CO, and hydrocarbon emission indices at cruise by adjusting the emission-index values contained in the International Civil Aviation Organization (ICAO) emissions database. This extensive database contains emission-index data, acquired at sea-level operating conditions, for a large number of in-service engines. In the case of the HSCT engine-emission-characterization effort, prime reliance should be placed on the planned tests of the demonstrator engine that will embody the ultra-low-NOx combustor concept. This test series is a planned task of the HSRP. Prior to this dedicated-demonstrator test, engine tests at cruise-altitude operating conditions to assess the degrees of SOx oxidation occurring within engines should



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OCR for page 13
An Interim Assessment of AEAP's Emissions Characterization and Near-Field Interactions Elements Recommendations On the basis of the issues raised in this report, the panel recommends continued or increased emphasis by AEAP on the areas noted below. EMISSIONS CHARACTERIZATION Some revisions are recommended to the existing prioritization of the engine emissions to be measured. Specifically, measurements of SO2, SO3, and OH levels should be changed from second to first priority. An increased emphasis on conducting tests of civil subsonic engines at cruise-altitude operating conditions, and a corresponding decreased reliance on combustor-rig testing, are recommended. Aggressive efforts to seek out and capitalize on opportunities for conducting such tests on a piggyback basis are strongly encouraged. To the extent possible, these tests should involve engine models that have been recently introduced into operational service. One important product of such tests should be validated procedures for calculating NOx, CO, and hydrocarbon emission indices at cruise by adjusting the emission-index values contained in the International Civil Aviation Organization (ICAO) emissions database. This extensive database contains emission-index data, acquired at sea-level operating conditions, for a large number of in-service engines. In the case of the HSCT engine-emission-characterization effort, prime reliance should be placed on the planned tests of the demonstrator engine that will embody the ultra-low-NOx combustor concept. This test series is a planned task of the HSRP. Prior to this dedicated-demonstrator test, engine tests at cruise-altitude operating conditions to assess the degrees of SOx oxidation occurring within engines should

OCR for page 13
An Interim Assessment of AEAP's Emissions Characterization and Near-Field Interactions Elements be conducted. For this purpose, piggybacked tests of an advanced military supersonic aircraft engine are recommended. Intensification of current efforts to develop or refine methods for adequately measuring SO2, SO3, and OH concentrations, as well as soot-particulate characteristics, is recommended. In all cases, emphasis should be focused on measurements at the engine-exit plane, rather than at the combustor-exit plane. NEAR-FIELD INTERACTIONS Aggressive efforts to complete at least first-cut versions of the three plume and wake models are recommended, so that the integration of these models into a set can be initiated. The promptest possible dissemination of the various flight-test datasets to the interested modelers is recommended, so as to expedite individual model development and validation tasks and to permit identification of possible needs for additional data.