Modeling Activities on Cavitating Flows at Centrospazio

The present paper illustrates recent theoretical and numerical activities on cavitating flows carried out at CENTROSPAZIO in the last few years. Specifically, it deals with the development and application of a modified isenthalpic cavitation model that accounts in an approximate but physical way for the occurrence of thermal cavitation effects and the concentration of active cavitation nuclei in the liquid. Expanding on the work of Brennen (1994), the model leads to a quasi-homogeneous barotropic description of cavitating flows, whose sound speed smoothly reduces to that of the liquid in the limit for low void fractions, thus eliminating the inconsistencies of previous formulations. Thermal effects are accounted for by assigning a single parameter expressing the nondimensional thickness of the thermal boundary layer in the liquid surrounding the growing cavities. The value of this parameter is related to the concentration of active cavitation nuclei, whose value can therefore be alternatively used to specify the impact of thermal cavitation effects. Applications to cavitating journal bearings, hydrofoils and helical inducers relevant to space engineering are presented

Cavitation and Rotordynamic Activities at Centrospazio

Centrospazio has long been carrying out an articulated program of experimental, theoretical and numerical research on cavitation and two-phase flow dynamics in connection with liquid propellant rocket fuel feed systems. The areas of involvement dealt with in recent years range from the modeling and simulation of cavitation to the study of rotordynamic fluid forces in whirling and cavitating axial inducers and journal bearings. Specifically, this paper illustrates the development of a new cavitation model accounting in an approximate but physical way for the occurrence of thermal cavitation and liquid quality effects, and the realization of the CPRTF (Cavitating Pump Rotordynamic Test Facility), a water loop for the measurement of rotordynamic fluid forces on whirling and cavitating turbopump impellers, and the TCT (Thermal Cavitation Tunnel), a modified version of the CPRTF for cavitation experiments in fluid dynamic and thermal cavitation similarity. Representative results of the application of cavitation model to journal bearings, hydrofoils and helical inducers and the typical performance of the CPRTF and TCT are presented

A New Cavitating Pump Rotordynamic Test Facility

The present paper illustrates the operational characteristics of the CPRTF (Cavitating Pump Rotordynamic Test Facility), an experimental apparatus specifically designed for the measurement of rotordynamic fluid forces acting on turbopump impellers in fluid dynamic and inertial/thermal cavitation similarity conditions. The realization of the CPRTF is currently in progress under ASI (Agenzia Spaziale Italiana) funding and consists in the upgrade of the CPTF (Cavitating Pump Test Facility), already available at Centrospazio, Consorzio Pisa Ricerche, Pisa, Italy. The experimental apparatus, operating in water, will be capable of carrying out the measurement of the steady and unsteady forces exerted by the flow on the impellers of cavitating/noncavitating turbopumps. More generally, the facility is designed as a flexible, versatile and inexpensive apparatus that can be readily be adapted to carry out detailed experimental investigations on practically any kind of fluid dynamic phenomena relevant to high performance turbopumps. The main operational requirements, development choices and design trade-offs that led to the final configuration of the facility are illustrated and its performance in testing of cavitating/noncavitating turbopumps under fluid dynamic and thermal cavitation similarity are discussed. Experimental results from a number of turbopump configurations and operational conditions are presented to illustrate the present capabilities of the facility

Experimental Activities on Liquid Propellant Turbopumps at Centrospazio

The present paper reviews recent experimental activities at Centrospazio on cavitation in liquid propellant turbopumps. These activities have been carried out in a dedicated, low-cost, versatile and easily instrumentable test facility, designed in 1996 under ESA (European Space Agency) funding and later refined and realized in 1999-2000 under a 1998/99 Fundamental Research contract by ASI (Italian Space Agency). The first part of the paper describes the characteristics and performance of the three alternative configurations of the facility: the CPTF (Cavitating Pump Test Facility), for general experimentation on cavitating/non-cavitating turbopumps under fluid dynamic and thermal cavitation similarity; the CPRTF (Cavitating Pump Rotordynamic Test Facility), capable of investigating rotordynamic fluid forces under forced vibration experiments on turbopump rotors of adjustable eccentricity and sub-synchronous or super-synchronous whirl speeds; and the TCT (Thermal Cavitation Tunnel), specifically designed for the investigation of 2D or 3D cavitating flows over test bodies in thermal cavitation similarity conditions. The second part of the paper presents some recent results of cavitation tests on helical inducers and hydrofoils. Future activities in this field at Centrospazio are illustrated

Thermal Cavitation Experiments on a NACA 0015 Hydrofoil

The present paper illustrates the main results of an experimental campaign conducted in the Thermal Cavitation Tunnel of the CPRTF (Cavitating Pump Rotordynamic Test Facility) at Centrospazio. Experiments were carried out on a NACA 0015 hydrofoil at various incidence angles, cavitation numbers and freestream temperatures, in order to investigate the characteristics of cavitation instabilities and the impact of thermal cavitation effects. Measured cavity length, surface pressure coefficients and unsteady pressure spectra are in good agreement with the data available in the open literature and suggest the existence of a strong correlation between the onset of the various forms of cavitation and instabilities, the thermal cavitation effects, and the effects induced by the presence of the walls of the tunnel. Further analytical investigations will be carried out in order to provide a better interpretation of the above results

A New Cavitation Test Facility at Centrospazio

The present paper illustrates the result of the trade-offs between operational requirements and practical limitations leading the final design of the CPTF (Cavitating Pump Test Facility), the CPRTF (Cavitating Pump Rotordynamic Test Facility) and the related TCT (Thermal Cavitation Tunnel). The CPTF is an experimental apparatus specifically designed for the performance analysis of turbopumps in fluid dynamic and inertial/thermal cavitation similarity conditions. The apparatus, operating in water up to 90°C, is capable of controlling the pump’s operational conditions and carrying out the measurement of the steady and/or unsteady flow parameters (pressure, velocity, temperature) at the inlet and discharge of full-scale cavitating/noncavitating turbopumps for space propulsion applications. More generally, the CPTF is designed as a flexible, versatile and inexpensive facility that can be readily be adapted to carry out detailed experimental investigations on practically any kind of fluid dynamic phenomena relevant to high performance turbopumps. The CPRTF is currently being completed under ASI (Agenzia Spaziale Italiana) funding and consists in an upgraded version of the CPTF capable of carrying out the measurement of the steady and unsteady rotodynamic forces exerted by the flow on whirling impellers of cavitating/noncavitating turbopumps using an especially designed rotating dynamometer. To this purpose the CPRTF can operate the pump under forced whirl conditions on a circular orbit with assigned eccentricity and angular speed. The TCT is a small-scale water tunnel that can be installed on the suction line of the CPTF, with the specific capability of running tests under thermal cavitation similarity conditions. The main operational requirements and development choices that led to the final configurations of the CPTF, CPRTF and TCT are illustrated and their performance in testing cavitating/noncavitating turbopumps and hydrofoils under fluid dynamic and thermal cavitation similarity are illustrated. Experimental results are presented to document the present capabilities of the facility in a number of typical configurations and operational conditions

Cavitation Experiments on Turbopump Inducers and Hydrofoils at Alta/Centrospazio: Overview and Future Activities

The aim of the present paper is to provide some highlights about the most interesting experimental activities carried out during the years 2000-2004 through the CPRTF (Cavitating Pump Rotordynamic Test Facility) at Centrospazio/Alta S.p.A. After a brief description of the facility, the experimental activities carried out on a NACA 0015 hydrofoil for the characterization of the pressure coefficient on the suction side and evaluation the cavity length and oscillations are presented. Then, the results obtained to characterize the performance and the cavitation instabilities on three different axial inducers are showed: in particular, a commercial three-bladed inducer, the four-bladed inducer installed in the LOX turbopump of the Ariane Vulcain MK1 rocket engine and the “FAST2”, a twobladed one manufactured by Avio S.p.A. using the criteria followed for the VINCI180 LOX inducer. The ..

Experimental Characterization of the Cavitation Instabilities in the Avio “FAST2” Inducer

The present paper illustrates the main results of an experimental campaign conducted using the CPRTF (Cavitating Pump Rotordynamic Test Facility) at Alta S.p.A. The tests were carried out on the FAST2 inducer, a two-bladed axial pump designed and manufactured by Avio S.p.A. using the criteria followed for VINCI180 inducer. The transparent inlet section of the facility was instrumented by several piezoelectric pressure transducers located at three axial stations: inducer inlet, outlet and at the middle of the axial chord of the blades. For each axial station at least two transducers were mounted at a given angular spacing, in order to cross-correlate their signals for coherence and phase analysis. The most interesting detected instabilities were: a cavitation auto-oscillation at about 5÷12 Hz, a high order cavitation surge having a frequency of about 4.4W and a rotating stall at about 0.31W. Some experiments were carried out under forced vibration cond..

Salicylaldoximes and anthranylaldoximes as alternatives to phenol-based estrogen receptor ligands

Estrogens play a crucial role in the development and function of female reproductive tissues. They have positive effects on the maintenance of bone mineral density, on the liver, and on the cardiovascular and central nervous systems. Selective Estrogen Receptor Modulators (SERMs) are particularly attractive as therapeutic agents because they are able to block estrogen action at those sites where stimulation would be undesirable, such as the breast and uterus, but at the same time stimulate estrogen actions in other tissues where they are desired, such as the bone and liver. Most synthetic estrogen receptor ligands possess a phenolic ring, mimicking the phenolic "Aring" of the natural ligand estradiol. In an attempt to increase the structural diversity of estrogen receptor (ER) ligands, we designed and synthesized molecules containing unprecedented replacements of the prototypical phenolic "A-ring" of estrogens with an oxime and a hydroxy- (salicylaldoximes) or aminomoieties (anthranylaldoximes), forming intramolecularly H-bonded pseudocycles. These new classes of compounds showed interesting ER binding properties on both receptor subtypes (ERα and ERβ). These results proved that the six-membered ring formed by an intramolecular hydrogen bond, and containing an exocyclic oxime OH, is an effective stereoelectronic replacement of the phenolic ring of typical ER ligands

Circulating Cancer Stem Cell-Derived Extracellular Vesicles as a Novel Biomarker for Clinical Outcome Evaluation.

The recent introduction of the "precision medicine" concept in oncology pushed cancer research to focus on dynamic measurable biomarkers able to predict responses to novel anticancer therapies in order to improve clinical outcomes. Recently, the involvement of extracellular vesicles (EVs) in cancer pathophysiology has been described, and given their release from all cell types under specific stimuli, EVs have also been proposed as potential biomarkers in cancer. Among the techniques used to study EVs, flow cytometry has a high clinical potential. Here, we have applied a recently developed and simplified flow cytometry method for circulating EV enumeration, subtyping, and isolation from a large cohort of metastatic and locally advanced nonhaematological cancer patients (N = 106); samples from gender- and age-matched healthy volunteers were also analysed. A large spectrum of cancer-related markers was used to analyse differences in terms of peripheral blood circulating EV phenotypes between patients and healthy volunteers, as well as their correlation to clinical outcomes. Finally, EVs from patients and controls were isolated by fluorescence-activated cell sorting, and their protein cargoes were analysed by proteomics. Results demonstrated that EV counts were significantly higher in cancer patients than in healthy volunteers, as previously reported. More interestingly, results also demonstrated that cancer patients presented higher concentrations of circulating CD31+ endothelial-derived and tumour cancer stem cell-derived CD133 + CD326- EVs, when compared to healthy volunteers. Furthermore, higher levels of CD133 + CD326- EVs showed a significant correlation with a poor overall survival. Additionally, proteomics analysis of EV cargoes demonstrated disparities in terms of protein content and function between circulating EVs in cancer patients and healthy controls. Overall, our data strongly suggest that blood circulating cancer stem cell-derived EVs may have a role as a diagnostic and prognostic biomarker in cancer