Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Experimental validation of the hybrid scattering model of installed jet
  noise   Jet installation causes jet noise to be amplified significantly at low
frequencies and its physical mechanism must be understood to develop effective
aircraft noise reduction strategies. A hybrid semi-empirical prediction model
has recently been developed based on the instability-wave-scattering mechanism.
However, its validity and accuracy remain to be tested. To do so, in this paper
we carry out a systematic installed jet-noise experiment in the laboratory
using a flat plate instead of an aircraft wing. We show that reducing $H$ (the
separation distance between the flat plate and jet centreline) causes stronger
low-frequency noise enhancement while resulting in little change to the noise
shielding and enhancement at high frequencies. Decreasing $L$ (the axial
distance between the jet exit plane and the trailing edge of the plate) results
in reduced noise amplification at low frequencies and also weakens both the
shielding and enhancement at high frequencies. Increasing the jet Mach number
abates the installation effects. It is shown that the hybrid model developed in
the earlier work agrees with experimental measurements and can capture the
effects of varying $H$, $L$ and jet Mach number extremely well. It is concluded
that the model captures the correct physics and can serve as an accurate and
robust prediction tool. This new physical understanding provides insights into
innovative strategies for suppressing installed jet noise.

4
The categories of this paper are: cond-mat
37
The categories of this paper are: supr-con
28
The categories of this paper are: alg-geom
18
The categories of this paper are: econ
14
The categories of this paper are: math-ph
0
The categories of this paper are: hep-ph
29
The categories of this paper are: funct-an
32
The categories of this paper are: atom-ph
9
The categories of this paper are: nlin
27
The categories of this paper are: comp-gas
35
The categories of this paper are: mtrl-th
34
The categories of this paper are: chem-ph
5
The categories of this paper are: gr-qc
24
The categories of this paper are: dg-ga
10
The categories of this paper are: q-bio
17
The categories of this paper are: q-fin