A Reduced Order Model for Preliminary Design and Performance Prediction of Radial Turbopumps

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

Pace

et al. 2013

Self Cite

The paper illustrates the experimental validation of the reduced order model recently developed at Alta, Pisa (Italy), for the simultaneous and preliminary geometrical definition and non-cavitating performance prediction of centrifugal turbopumps. The proposed model has been employed to size and design the test machine, named VAMPIRE and equipped with a six-bladed radial impeller, a vaneless diffuser and a single-spiral volute. The pumping and suction performance of the machine have been determined in a series of tests in Alta's Cavitating Pump Rotordynamic Test Facility (CPRTF). The measured pumping characteristic proved to be in excellent agreement with the model predictions, thus effectively validating the design model. In addition, the experimental determination of the pump's cavitation characteristic is fully consistent with the expected suction performance of comparable machines, confirming the capability of the proposed model to generate hydrodynamically efficient turbopump designs. Nomenclatureb blade height c blade chord % c tip clearance/mean blade height ratio % m c h δ = m h mean blade height ( ) 1 2 2 m h b b = + N number of blades p , t p static and total pressures r radial coordinate, radius S r specific radius Re Reynolds number 2 Re 2 T r Ω ν = T temperature V volumetric flow rate z axial coordinate γ blade angle from axial direction ρ flow density σ blade solidity =; cavitation number ( ) 2 2 1 0.5 v T p p r σ ρΩ = − ϕ flow angle w.r.t. the radial direction Φ flow coefficient: ( ) 3 2 V r Φ Ω = ɺ χ backsweep angle from radial direction Ω impeller rotational speed

Section: Discussionsupporting

confidence: 70%

Section: Non-cavitating Performancementioning

confidence: 99%

Section: Introductionmentioning

confidence: 98%

Section: Introductionmentioning

confidence: 99%

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Experimental Validation of a Reduced Order for Radial Turbopump Design

Valentini

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

Pace

et al. 2013

Self Cite

“…The DAPROT3 high-head, tapered-hub, three-bladed inducer, is also manufactured in 7075-T6 aluminum alloy. The test articles, whose relevant geometrical and operational data are reported in Table 2, have been designed by means of two reduced order model developed at ALTA and described in [15,16] (inducer) and in [17,18,19] (centrifugal pump). The two machines operate at the same design flowrate allowing for coupling in the resulting VAMPDAP configuration.…”

Section: Test Articlesmentioning

confidence: 99%

Inducer and Centrifugal Pump Contributions to the Rotordynamic Fluid Forces Acting on a Space Turbopump

Pace¹,

Valentini²,

Journal of Fluids Engineering

et al. 2017

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The fluid induced rotordynamic forces acting on a whirling space turbopump composed by an inducer and a radial impeller have been compared to the same forces measured on each single component of the turbomachine (i.e. on the inducer and on the radial impeller). The experimental campaign has been carried out in cold water at design and off-design conditions (80%, 100% and 120% of the design flow rate) both in non-cavitating and cavitating regimes. The paper illustrates the different trends of the rotordynamic forces on the axial and radial pumps and highlights their contributions on the overall turbomachine. At positive whirl ratios, the behavior of the inducer is dominant while, at negative ones, both the pumps show the same trends in such a way that the overall behavior is roughly the sum of each single component.

On the Preliminary Design and Performance Prediction of Centrifugal Turbopumps—Part 1

d’Agostino

Valentini

Cavitation Instabilities and Rotordynamic Effects in Turbopumps and Hydroturbines

et al. 2017

A reduced order model for the preliminary design and performance prediction of radial turbopumps is illustrated. The model expresses the 3D, incompressible, inviscid, irrotational flow through helical blades with slow axial variations of their pitch and backsweep angles by superposing a 2D axial vorticity correction to a fully-guided forced-vortex flow with axisymmetric stagnation velocity in the meridional plane. Application of the relevant governing equations allows for the closed form definition of the impeller geometry and flowfield in terms of a reduced number of controlling parameters. Mass and momentum conservation are used for coupling the flow leaving the impeller with the 2D reduced order models of the flow in the diffuser and/or the volute, as well as for the evaluation of the mixing losses in the transfer between successive components of the machine. This information completes the geometric definition of the turbopump and determines its ideal noncavitating performance in accordance with the resulting flowfield. As a consequence of the neglect of viscous effects, the slip factor predicted by the present model exceeds those obtained from theoretical/ semi-empirical formulas reported in literature for centrifugal pumps, but correctly captures their trends