Prediction of Turbulent Jet Mixing Noise Reduction by Water Injection

Abstract

A one-dimensional control volume formulation is developed for the determination of jet mixing noise reduction due to water injection. The analysis starts from the conservation of mass, momentum and energy for the confrol volume, and introduces the concept of effective jet parameters (jet temperature, jet velocity and jet Mach number). It is shown that the water to jet mass flow rate ratio is an important parameter characterizing the jet noise reduction on account of gas-to-droplet momentum and heat transfer.

Broadband shock noise reduction in turbulent jets by water injection

“…near the exit are obtained from the theoiy proposed in Kandula and Lonergan [13] In the present context, the effective jet Mach number is obtained as a function of the water to jet mass flow rate ratio. Thus the reduction in the overall sound pressure level (OASPL) can be estimated as…”

“…In the following, we briefly review the results for the effective jet properties derived in Kandula and Lonergan [13] on the basis of a control volume fonnulation (Fig. 3).…”

“…In view of the complexity with regard to the knowledge of droplet diameter and drop Reynolds number, it is postulated that the constants c1 and c2 are invariant [13]. These constants may be established by a correlation with available test data.…”

“…A correlation of the analysis with the test data of Norum [9] for hot supersonic turbulent mixing noise reduction at M =1.45 yields the values of the invariants c1 and c2 as [13] = 5, c2 = 0.05 (14) These values for the constants c1 and c2 are considered here. The ratio of water jet mass flow rate to the jet mass flow rate (m /th i ) is varied to a maximum value of about 0.825.…”

“…Based on control volume formulation a simple one-dimensional analytical model has been recently reported by Kandula and Lonergan [13] for estimating jet mixing noise suppression due to water injection. The method is based on the conception of effective jet properties in conjunction with the scaling laws developed by Kandula'4 for shock-free jet noise.…”