Investigation of Supersonic Jet Noise at Afterburner Conditions
Abstract
The proposed research program consists of a two-year base program, and a one-year optional program. The objective of the two-year base program is to determine the impact of indirect combustion noise and TTRs up to 7.0 on the noise spectra and compare these results with past laboratory experiments and full scale afterburning engine tests. The objective of year three is to determine the effect of indirect combustion noise and TTRs up to 7.0 on the turbulent eddyconvection velocities and turbulent statistics of the flow field. The program is broken down into 3 main tasks, which coincide with each year of the program. The scope of work for each tasks andsubtasks are as follows:Task 1: Design, construction, and commissioning of afterburner test rig.Subtask 1.1: Design and manufacture afterburner test section.Subtask 1.2: Design and manufacture supersonic nozzles.Subtask 1.3: Commission Supersonic Jet Noise Rig.Task 2: Experimentally determine the effect of indirect combustion noise and TTR on the noisespectra.The primary objective for task one is to commission a supersonic jet noise rig, which can reach TTRs of 7.0 and acoustically force entropy waves. To achieve the objective, the HPC rig shown in Figure 6 will be modified to include an air quench system, a secondary combustion zone with acoustic drivers in the fuel lines, and a supersonic biconic nozzle. All the design work, manufacturing, and rig shakedown will be performed in this task. A preliminary representation of the supersonic jet noise rig is shown in Figure 7. Careful consideration of the design constraints isrequired to achieve the objectives of task 1, as well as the overall objectives of the proposal.Therefore, it is expected the entire year-one of the program will be required to successfully commission the rig.Subtask 1.1: Design and manufacture afterburner test section.The afterburner module will consist of a combustion chamber with connecting flanges, optical acess for OH* chemiluminescence images, and two independently controlled fuel injectors each with an independently controlled acoustic driver. The overall length of the combustor will be adjustable, and if a thermoacoustic mode is observed, the afterburner can be relocated near the pressure node to mitigate thermoacoustic excitation. The acoustic drivers will allow operation fora range of frequencies (or broadband noise) and desired temperature fluctuations (entropy waves).Subtask 1.2: Design and manufacture supersonic nozzles.Two converging diverging nozzle design will be constructed. Both nozzles will be designed tooperate as a fully expanded jet conditions to reduce unwanted shock associated jet noise. A biconicnozzle (~~ ~ 1.65~ design based on the work by Ecker et. al. [5], which was originally adaptedfrom the geometry studied by Powers et. al. [10] for military style nozzles, will be used for the proposed research; however, feedback from the Office of Naval Research on the design will be taken into account in order to achieve Navy relevant afterburner exhaust nozzle conditions. An example of the biconic nozzle used by Ecker et. al. [5] is shown in figure 8. Nozzle 1 will not have any active cooling, but may have ceramic or thermal barrier coating (TBC)/ceramic coatingand back side insulation to mitigate heat loss through the nozzle. Nozzle 2 will be designed with a water cooling circuit, ceramic or TBC coating, and back side insulation. Temperature measurements at the cooling water inlet and exit will be measured to quantify heat loss.
Document Details
- Document Type
- DoD Grant Award
- Publication Date
- Jun 13, 2019
- Source ID
- N000141912430
Entities
People
- Joseph Meadows
Organizations
- Office of Naval Research
- United States Navy
- Virginia Tech