Influence of Scaling Rules on the Loss of Acoustic Energy

Morgenweck, Daniel; Sattelmayer, Thomas; Fassl, Felix; Kaess, R.

doi:10.2514/1.48334

Cited by 12 publications

(11 citation statements)

References 11 publications

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“…As shown by 9 and, 3 PIANO is capable of capturing the nozzle impedance correctly. Based on that result, 10 show that the damping of longitudinal waves by the nozzle is high, while transverse modes are damped rather weakly, see Fig. 6.…”

Section: A Nozzlementioning

confidence: 79%

A Conceptional Approach for the Prediction of Thermoacoustic Stability in Rocket Engines

Schulze

Schmid

Morgenweck

et al. 2013

49th AIAA/ASME/SAE/ASEE Joint Propulsion Conference

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A methodology to predict thermoacoustic stability in rocket engines is presented. It is based on a divide and conquer principle. The central elements, consisting of the combustion chamber and the nozzle are calculated together directly by a hybrid approach using an extended version of the DLR's acoustic solver PIANO. Beside these central elements, the different components affecting the overall thermoacoustic stability are simulated separately and their properties are lumped into an adequate mathematical description, which is then integrated into PIANO. Each component is analyzed and optimized in its individual environment to reduce the complexity of the interaction processes, which govern thermoacoustics. The challenging step however is the incorporation of all components into a complete stability analysis and thereby keep the computational cost within reasonable limits to make this approach attractive for industrial purposes. In this report the fundamental approach is explained as well as the different components are described by means of their relevance for thermoacoustics and used modelling approaches are shown. Finally the strengths of the approach are confronted with its disadvantages. Especially its realizability and future prospects are discussed.

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Section: A Nozzlementioning

confidence: 79%

A Conceptional Approach for the Prediction of Thermoacoustic Stability in Rocket Engines

Schulze

Schmid

Morgenweck

et al. 2013

49th AIAA/ASME/SAE/ASEE Joint Propulsion Conference

Self Cite

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“…[4,9], that the time domain LEE solver provides sufficiently low numerical damping properties to perform meaningful acoustic investigations. So far, the frequency based method including stabilization techniques, has not been analyzed in terms of numerical dissipation.…”

Section: General Considerationsmentioning

confidence: 99%

A comparison of time and frequency domain descriptions of high frequency acoustics in rocket engines with focus on dome coupling

Schulze

Sattelmayer

2015

Aerospace Science and Technology

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“…As shown for example in [5], longitudinal modes at high frequency are heavily damped by the thrust nozzle and cannot sufficiently be amplified to reach dangerous amplitudes. Transversal modes, however, are far less damped by the nozzle.…”

mentioning

confidence: 98%

Impact of Absorber Ring Position and Cavity Length on Acoustic Damping

Schulze

Kathan

Sattelmayer

2015

Journal of Spacecraft and Rockets

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The influence of axial position and cavity length of an absorber ring with grazing flow on damping of acoustic amplitudes in a rocket combustion chamber is experimentally investigated under nonreactive ambient temperature conditions. At the perforated inlet, high-bias flow velocities are present, providing strong damping. On the basis of power spectral densities gained from flow noise excitation, damping rates for the first transverse mode are derived using a Lorentzian profile fitting procedure. Results show that an absorber ring located in close proximity to the nozzle leads to enhanced damping, whereas in the case of a ring placed closely to the inlet, damping rates are reduced. Absorption coefficients show that an isolated absorber ring is not capable of acoustic amplification. It is concluded that reduced damping originates from weaker impact of the perforated inlet on the acoustics, resulting from a shielding effect by the absorber ring. The highest damping rate is found for a cavity length below the theoretically predicted optimum length for an absorber ring located close to the nozzle. Nomenclature c = speed of sound, m∕s D = diameter, m F,Ĝ = characteristic wave amplitude, m∕s f = frequency, Hz hIi = acoustic intensity averaged over one acoustic period, W∕m 2 J 1 = Bessel function of first kind and order 1 k = wave number, 1∕m L = length, m Ma = Mach number _ m = mass flow, kg∕s p = pressure, Pâ p = complex amplitude of pressure, Pa R = radius, m s 10 = zeroth root of first-order Bessel function derivative x, r, ϕ = axial, radial, and circumferential position; m, m, rad α = damping rate, rad∕s δ = offset angle with respect to frame of reference, rad λ = wavelength, m ξ = absorption coefficient ρ = density, kg∕m 3 ρ = mean density, kg∕m 3 φ = phase, rad 1T = first transverse mode for a system with absorber ring 1T − = additional transverse mode for a configuration with absorber ring 1T∕2T = first/second transverse mode 1T1L = first transverse and first longitudinal coupled mode 1T2L = first transverse and second longitudinal coupled mode Subscripts A = absorber ring cavity length C = chamber co = cut-on e = effective i = ith measurement location num = numerical Optimal = optimal (highest) damping t = nozzle throat u, d = upstream/downstream λ∕4 = property of λ∕4 absorber I = case I, absorber ring located closely to the face plate II = case II, absorber ring located closely to the nozzle * = complex conjugation Superscripts A, B = excitation states u, d = upstream/downstream x = in positive/negative axial direction * = complex conjugation

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Influence of Scaling Rules on the Loss of Acoustic Energy

Cited by 12 publications

References 11 publications

A Conceptional Approach for the Prediction of Thermoacoustic Stability in Rocket Engines

A Conceptional Approach for the Prediction of Thermoacoustic Stability in Rocket Engines

A comparison of time and frequency domain descriptions of high frequency acoustics in rocket engines with focus on dome coupling

Impact of Absorber Ring Position and Cavity Length on Acoustic Damping

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