DURIP Upgrading of Model Rotor Rig for Testing of Tip-Propeller-Driven Rotor in the Glenn L. Martin Wind Tunnel
Abstract
The objective is to generate a comprehensive set of measurements of the blade structural loads, hub loads, blade deflections, bladepressures, propeller torque, main rotor performance, rotor/propeller wake interference and motor characteristics of dynamically-scaled tip-propellerdriven rotor consisting of a two-bladed main-rotor, two compact electric motors and a stream-lined nacelle for a range of flight conditions. These datasets are vital to validate advanced CFD/CSD tools as well as gain improved understanding of the fundamental physics of the tip-driven rotor system using compact propellers. The objective is to systematically characterize the performance of (1) isolated propellers in hover and in wind tunnel (axial flow), (2) isolated shaft-driven rotor in hover and edge-wiseforward flight, and (3) coupled rotor with tip-propellers in the wind tunnel for different wind speeds. The scaled rotors and propellers are built in-house (at the Alfred Gessow Rotorcraft Center) using advanced composite materials and these will be characterizedfor structural and dynamic characteristics at different scales. The 6-ft diameter dynamically-scaled 2-bladed tip-propeller-driven rotor using compact electric motors will be fabricated inhouse and systematically tested on our hover stand and in the Glenn Martin wind tunnel for a range of flight conditions, and test data will be acquired using two tip load cells (compact balances), one 6-component hub balance and blade structural loads using strain gages. The power input to the motors will be acquired for each flight condition. Data acquisition and power input to motors will be carried out using the slipring. In parallel, the objective is to develop prediction methodology, starting from legacy methodology of conventional rotors to a detailed finite-element based comprehensive analysis using inhouse code UMARC as a baseline platform and validate it systematically with acquired test data for a range of flight conditions. The end-goal is to identify pros and cons of tip-propeller-driven rotor with respect to a conventional shaft-driven rotor.The power loading (thrust/power) in hover and L/D (Lift/Drag) in forward speed will be compared for different flight conditions.Some of these activities are already in progress in terms of testing of tip-propeller-driven rotors on our hover tower at the University of Maryland under the ONR program, but we are experiencing some deficiencies in data acquisition and processing due to inadequate instrumentation. Fundamental understanding of aeromechanics of tip-proper-driven rotor systems is a key to the development of next-generation advanced tip-propeller-driven rotors for naval resupply logistics. At the University of Maryland, we have a state-of-the-art model rotor rig that can be used only to test conventional hingeless and articulated rotors in the Glenn L. Martin (GLM) windtunnel. The objective is to acquire key supporting equipment and instrumentation to upgrade theexisting model rotor rig to undertake tests of tip ropeller-driven scaled model rotors in the GLM wind tunnel and acquire the much-needed precise test data. Key proposed items include: one specialized slipring with 128 channels, 15 ultra miniature pressure sensors, two specialized compact balances for propellers, input modules for pressure data acquisition, one strobe light for model-rotor tracking, 100 strain gages and 125 hours of precision machining work. The requested equipment will directly complement an existing ONR grant at the University of Maryland. It will result in an upgraded research facility for our students, and will also be made available to rotorcraft industry and federal laboratories. The upgrading cost will be $184,688.
Document Details
- Document Type
- DoD Grant Award
- Publication Date
- May 15, 2024
- Source ID
- N000142412321
Entities
People
- Inderjit Chopra
Organizations
- Office of Naval Research
- United States Navy
- University of Maryland