A Theoretical Analysis of Rotating Cavitation in Inducers

Tsujimoto, Yoshinobu; Kamijo, Kenjiro; Yoshida, Yoshiki

doi:10.1115/1.2910095

Cited by 98 publications

(27 citation statements)

References 2 publications

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“…As observed in the experiments, this value slightly decreases with cavitation parameter. However, the numerical frequencies of that supersynchronous phenomenon remain about 25% larger than experimental values, as already observed in analytical models by Tsujimoto et al 10 and Joussellin and de Bernardi. 11 For a lower cavitation parameter (σ = 0.08), a stable configuration appears (Fig.…”

Section: Four-blade Cascade Computation: Unsteady Behaviormentioning

confidence: 48%

“…They are based on stability analyses and linear approach and take into account the total flow rate variations through a cavitating blade-to-blade channel, 10,11 or calculate the flow around attached cavities. 12,13 To improve the understanding and the prediction capability of cavitation instabilities, numerical and experimental analyses are carried out in France through collaborations between the Laboratoire des Ecoulements Géophysiques et Industriels, the Rocket Engine Division of SNECMA Moteurs and the French space agency Centre National d'Etudes Spatiales.…”

Section: Introductionmentioning

confidence: 99%

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Nurmerical Simulation of the Unsteady Cavitation Behavior of an Inducer Blade Cascade

et al. 2004

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One source of unsteadiness in turbopump inducers consists in a rotating cavitation behavior, characterized by different cavity shapes on the different blades, which leads to super-or subsynchronous disturbances. This phenomenon is simulated for the case of a simple two-dimensional blade cascade corresponding to a typical fourblade inducer. A numerical model of unsteady cavitating flows was adapted to take into account nonmatching connections and periodicity conditions. Single-channel and four-channel computations were performed, and in the latter case, nonsymetrical unstable flow patterns were obtained. Limits of stability according to the mass flow rate and the cavitation number are presented. Qualitative comparisons with experiments, instability criterion, and the mechanisms of instabilities are also investigated. NomenclatureA min = minimum speed of sound in the two-phase mixture, m/s C(C m , C u ) = velocity vector in fixed frame, m/s C p = dimensionless static pressure,= total pressure, P + 1 2 ρC 2 , Pa P 1 , P 2 = total pressure at inlet and outlet, Pa p = local static pressure, Pa p ref , p vap = reference pressure (inlet pressure), vapor pressure, Pa p 1 , p 2 = static pressure at inlet and outlet, Pa r, R c , R = inducer radius, radius corresponding to the blade cascade, tip radius, m S = nondimensional surface of a grid cell S flow = cross section of the blade-to-blade channel, m 2 T ref = time corresponding to the passage of one blade in the fixed frame, s U = training velocity at inducer radius R c , R c , m/s W(W m , W u ) = relative velocity vector, m/s α = flow incidence at the blade leading edge, rad α v = local void fraction ρ l , ρ v , ρ = nondimensional density of the liquid, of the vapor, of the mixture ρ ref = reference density ρ l σ = cavitation number, ( p 1 − p vap )/( 1 2 ρU 2 ) , ref = flow coefficient, C m /(U ), and reference flow coefficient ., ref = head coefficient (P 2 − P 1 )/(ρ l U 2 ), head coefficient at cavitation inception = inducer angular velocity, rad/s

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Section: Four-blade Cascade Computation: Unsteady Behaviormentioning

confidence: 48%

Section: Introductionmentioning

confidence: 99%

Nurmerical Simulation of the Unsteady Cavitation Behavior of an Inducer Blade Cascade

et al. 2004

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“…Furthermore, it has been also shown that other forms of flow instabilities, like rotating cavitation, are promoted by particular combinations of the values of the dynamic transfer matrix elements. 2 Under this point of view, the cavitation compliance and, more so, the mass flow gain factor play a crucial role, as clearly shown by a number of analytical and experimental analyses. 6,7 It is therefore apparent that the characterization of the dynamic matrices of cavitating inducers and turbopumps is a necessary step for the prediction and control of the unstable behavior of this kind of machinery.…”

Section: Introductionmentioning

confidence: 95%

“…In the linearized approximation for incipent small-amplitude flow oscillations this issue is traditionally realized by means of the dynamic transfer matrix, which relates the complex amplitudes of the pressure and flow oscillations at the inlet and outlet crosssections of the machine. [1][2][3][4][5] The close connection between the elements of the dynamic matrix of inducers and turbopumps and the occurrence of potentially dangerous flow instabilities has been widely illustrated in the open literature. The pump resistance, as an example, plays a central role in determining the quasi-static unstable behavior of the machine.…”

Section: Introductionmentioning

confidence: 99%

Experimental Characterization of the Dynamic Transfer Matrix of Cavitating Inducers

Pace

Torre

Pasini

et al. 2013

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

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The present paper illustrates and discusses the first results of the characterization of the dynamic transfer matrix of cavitating turbopumps by means of a series of forced-vibration tests carried out on a high-head three-bladed inducer in the CavitatingPump Rotordynamic Test Facility (CPRTF) at Alta, Pisa, Italy. The flow has been excited by vertically vibrating with adjustable frequency and intensity the free-surface tank used to close the loop of the suction and discharge lines of the inducer. The pressure and flow rate fluctuations for the determination of the dynamic transfer matrix have been obtained from unsteady pressure measurements at suitable locations on the inlet/outlet lines of the inducer. Two loop configurations with different inlet/outlet impedances to/from the test inducer have been used in order to obtain at each excitation frequency a set of four linearly independent measurements for the detetermination of the four elements of the dynamic transfer matrix. The preliminary results are in qualitative agreement with the scant data available in the literature for comparable inducers. Nomenclature A = Cross-sectional area  = Head coefficient ( 22 T pr     )  = Flow density r = Radius of the pump  = Oscillating frequency ( 2 f   )  = Impeller rotational speed  = Euler (or cavitation) number (   22 1 1 2 VT p p r    )  = Flow coefficient ( 3 / T Qr    ) 1 Junior Research Engineer, Alta S.p.A.; Ph. D. Student, Pisa University, g.pace@alta-space.com 2 p = Static pressure Q = Flow rate i = Immaginary unit R = Pipe resistence I = Pipe inertance T = Temperature S = Real part of the pressure gain factor X = Imaginary part of the pressure gain factor C = Compliance of the pump M = Mass flow gain factor of the pump Superscripts p = Pressure oscillations Q = Flow rate oscillations m = Mass flow rate oscillations Subscripts 1 = Pump inlet 2 = Pump outlet v = Vapour condition t = Total quantity T = Tip dimension u = Upstream d = Downstream nom = Nominal condition Acronyms CPRTF = Cavitating Pump Rotordynamic Test Facility S = Surge SRC = Synchronous Rotating Cavitation

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“…Virtually all of the experimental work on the dynamics of pumps has been necessarily conducted in ground-based test facilities (see, for example, [10][11][12]14]), and much attention has therefore focused on the instabilities that are observed in pumping systems in a nonaccelerating environment (for example, [16][17][18][19][20][21]). Among these much-studied instabilities are those caused by cavitation in the pump: for example, rotating cavitation [18][19][20][21] and cavitation surge [16,20].…”

mentioning

confidence: 99%

Dynamic Response to Global Oscillation of Propulsion Systems with Cavitating Pumps

Hori

Brennen

2011

Journal of Spacecraft and Rockets

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A time-domain model was developed to evaluate the dynamic response of pumping systems in the accelerating environment of rockets with a focus on cavitation. The model was first verified by comparing the results with measurements in ground-based tests of an LE-7A rocket engine. In these tests, various resonances occurred and levels of pump cavitation or incorporation of an accumulator altered them. The model results simulated the test data well, matching both the frequency and the amplitude. The test and model results also demonstrated the stability of the LE-7A propulsion system within nonaccelerating environments. Then, the model was used to examine the response of the propulsion system in accelerating frames; sinusoidal vehicle oscillations over a range of frequencies were explored. Under noncavitating conditions, the pressure amplitudes within the propulsion system did not substantially exceed the quasi-static acceleration head response ah. However, under cavitating conditions ( 0:02), the same accelerations produced violent responses with pressure and flow amplitudes about 2 orders of magnitude greater than in noncavitating conditions. The obvious conclusion is that vehicle oscillations can cause substantial pressure and flow amplitudes, particularly when the pump is cavitating, even if the ground-based tests and the calculations in static frames indicate stable and well-behaved responses. = pertaining to accumulator cc = pertaining to combustion chamber or terminating reservoir e = pertaining to end of discharge line p = pertaining to pump s = pertaining to suction line sc = pertaining to short column of liquid between pump and accumulator t = pertaining to tank tip = pertaining to pump tip u = pertaining to ullage gas in tank 1 = inlet to component 2 = discharge from component

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A Theoretical Analysis of Rotating Cavitation in Inducers

Cited by 98 publications

References 2 publications

Nurmerical Simulation of the Unsteady Cavitation Behavior of an Inducer Blade Cascade

Nurmerical Simulation of the Unsteady Cavitation Behavior of an Inducer Blade Cascade

Experimental Characterization of the Dynamic Transfer Matrix of Cavitating Inducers

Dynamic Response to Global Oscillation of Propulsion Systems with Cavitating Pumps

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