NASA SBIR 02-1 Solicitation


PROPOSAL NUMBER:02- A4.01-8734 (For NASA Use Only - Chron: 023265 )
SUBTOPIC TITLE: Space Transportation Architecture Definition
PROPOSAL TITLE: Dynamic Transfer Function Measurements for Cavitating Pumps

SMALL BUSINESS CONCERN (Firm Name, Mail Address, City/State/Zip, Phone)
Concepts ETI, Inc.
217 Billings Farm Road
White River Jct , VT   05001 - 9486
(802 ) 296 - 2321

PRINCIPAL INVESTIGATOR/PROJECT MANAGER (Name, E-mail, Mail Address, City/State/Zip, Phone)
Daniel O. Baun
217 Billings Farm Road
White River Jct , VT   05001 - 9486
(802 ) 296 - 2321

There are no analytical tools or experimental facilities in the world today that can quantify the dynamic transfer function for a cavitating inducer. The goal of this research is to fill this void. An innovative experimental technique is proposed where by a cavitating inducer's dynamic transfer function is quantified by mapping the flow and pressure fluctuations at the inducer exit as a function of harmonic perturbations at the inlet. A cavitating inducer can be a source of instability in a rocket engine. Due to cavitation dynamics, inlet flow perturbations maybe amplified by the inducer resulting in very large flow and pressure fluctuations in the fuel system. The resulting dynamic couplings can lead to vehicle instability (POGO) as well as generate intense dynamic loadings on the turbopump. The feasibility of implementing the technique on the Concepts NREC water flow test rig will be demonstrated in Phase I of the project. Implementation of the technique and inducer transfer function identification will occur in Phase II. The proposed dynamic transfer function characterization methodology is applicable to any high energy density turbomachine subject to impeller induced flow instabilities, such as boiler feed pumps or re-injection pumps and compressors.

High energy density turbomachines such as gas re-injection pumps and compressors, and high-energy industrial pumps, are a source of instability. Accurate dynamic characterizations of these machines are required to ensure safe and reliable operation of the systems into which they are installed. In addition to understanding the dynamic attributes of these machines under cavitation or stalled conditions, the dynamic transfer function under normal operating conditions are also required. The methodology proposed to measure the dynamic transfer function of a cavitating inducer is transferable. The proposer is well-positioned to commercialize the technology to both aerospace and industrial customers.

As mission requirements lead to higher power density turbopumps with lower specific weights and higher suction specific speed requirements the potential for flow-induced dynamic instabilities, both at the turbopump level and at the system level, increase. Rocket vehicle dynamic models require an accurate dynamic characterization for the inducer. The proposed experimentally measured dynamic transfer functions will provide accurate and reliable pump dynamic attributes which are necessary to assess the probability of destructive flow instabilities, such as cavitation surge and rotating cavitation, and their effect on engine component or integrated vehicle system instability.

Form Printed on 09-05-02 10:10