Antonio Carlos de Oliveira

Bow Shock Wave Mitigation by Laser-Plasma Energy Addition in Hypersonic Flow

Experimental results of bow shock wave mitigation by laser-plasma energy addition in a low-density Mach 7 hypersonic flow conducted in a shock tunnel are presented. A high-power pulsed CO2 laser operating with 7 J of energy and 30 MW of peak power was used to generate the plasma ahead of a hemispherical model installed in the tunnel test section. The schlieren technique was used to visualize the time evolution of energy addition to the flow by laser-induced plasma and the interaction between this disturbed region and the inherent bow shock formed on the model by hypersonic flow. A complete mitigation of the bow shock profile under action of the energy addition was observed. The impact pressure on the hemispherical model measured at the stagnation point reveals the correlation between the schlieren images and the pressure reduction.

Flow Characterization of the T3 Hypersonic Shock Tunnel

Flight-tests, computational fluid dynamic facilities and ground-based test facilities are the hypersonic methodologies used to define and to quantify the aerothermodynamic environments that exist during the fly of the aerospace vehicle into the Earth’s atmosphere at hypersonic flight speeds.

2‐D Airbreathing Lightcraft Engine Experiments in Quiescent Conditions

Ground‐breaking laser propulsion (LP) experiments were performed under quiescent conditions with a 25 cm wide, two‐dimensional Lightcraft model using a Lumonics TEA‐622 CO2 laser emitting ∼ 1 μs pulses. In preparation for subsequent hypersonic experiments, this static test campaign was conducted at ambient pressures of 0.06, 0.15, 0.30 and 1 bar with laser pulse energies of 150 to 230 J. Time‐variant pressure distributions, generated over engine “absorption chamber” walls, were integrated to obtain total impulse and momentum coupling coefficients (Cm) representative of a single propulsion cycle. Schlieren visualization of laser‐induced air breakdown and expanding blast waves was also accomplished. Surprisingly, the Cm results of 600‐3000 Ns/MJ were 2.5x to 5x greater than previous results from smaller Lightcraft models; this suggests that higher static Cm performance can likely be achieved in larger scale LP engines. This research collaboration, forged between the USAF and Brazilian Air Force, was carried...

Experimental Analysis of a 2‐D Lightcraft in Static and Hypersonic Conditions

Aiming at the hypersonic phase of the Earth‐to‐Orbit trajectory for a laser propelled vehicle, a 2‐D Lightcraft model was designed to be tested at the T3 Hypersonic Shock Tunnel at the Henry T. Nagamatsu Laboratory for Aerodynamics and Hypersonics. A high energy laser pulse was supplied by a Lumonics TEA 620 laser system operating in unstable resonator cavity mode. The experiments were performed at quiescent (no flow) conditions and at a nominal Mach number of 9.2. A Schlieren visualization apparatus was used in order to access both the cold hypersonic flowfield structure (without laser deposition) and the time dependent flowfield structure, taking place after the laser induced breakdown inside the absorption chamber. The model was fitted with piezoelectric pressure transducers and surface junction thermocouples in an attempt to measure pressure and heat transfer time dependent distributions at the internal surfaces of the model’s absorption chamber. The 2‐D model followed a modular design for flexibility...

New Hypersonic Shock Tunnel at the Laboratory of Aerothermodynamics and Hypersonics Prof. Henry T. Nagamatsu

The new 0.60‐m. nozzle exit diameter hypersonic shock tunnel was designed to study advanced air‐breathing propulsion system such as supersonic combustion and/or laser technologies. In addition, it may be used for hypersonic flow studies and investigations of the electromagnetic (laser) energy addition for flow control. This new hypersonic shock tunnel was designed and installed at the Laboratory for of Aerothermodynamics and Hypersonics Prof. Henry T. Nagamatsu, IEAv‐CTA, Brazil. The design of the tunnel enables relatively long test times, 2–10 milliseconds, suitable for the experiments performed at the laboratory. Free stream Mach numbers ranging from 6 to 25 can be produced and stagnation pressures and temperatures up to 360 atm. and up to 9,000 K, respectively, can be generated. Shadowgraph and schlieren optical techniques will be used for flow visualization.

Supersonic Combustion Experimental Investigation at T2 Hypersonic Shock Tunnel

The aerospace technological products have grown that one cannot conceive of putting payloads (satellites) into Earth orbit or beyond using technologies in operation (rockets carry out solid or liquid fuel). The knowledge required to keep the current launching vehicles is already so high that if the countries do not have a technological support for their own industry, they will depend on of the supplier countries and not have independent capacity sustained. Aerospace vehicle limitations for launching payloads into orbit or beyond require a continuous reduction in size, weight and power consumption of launch vehicles. Some solutions to these challenges require paradigm shifts, new production methods, and new technologies of strategic nature. The requirements of platformslaunched satellites, high performance and reliability, as well as the strict limitations of fuel (reduction of size, weight and power consumption) for launching payloads into orbit or beyond provide the development of hypersonic aircraft using hypersonic airbreathing propulsion based on supersonic combustion.

Supersonic Combustion Flow Visualization at Hypersonic Flow

Currently, a new generation of scientific aerospace vehicles, using advanced hypersonic airbreathing propulsion based on supersonic combustion technology, is in development at several research centers [1].

2‐D Air‐Breathing Lightcraft Engine Experiments in Hypersonic Conditions

Experiments were performed with a 2‐D, repetitively‐pulsed (RP) laser Lightcraft model in hypersonic flow conditions. The main objective was the feasibility analysis for impulse generation with repetitively‐pulsed air‐breathing laser Lightcraft engines at hypersonic speeds. The future application of interest for this basic research endeavor is the laser launch of pico‐, nano‐, and micro‐satellites (i.e., 0.1–100 kg payloads) into Low‐Earth‐Orbit, at low‐cost and on‐demand. The laser propulsion experiments employed a Hypersonic Shock Tunnel integrated with twin gigawatt pulsed Lumonics 620‐TEA CO2 lasers (∼ 1 μs pulses), to produce the required test conditions. This hypersonic campaign was carried out at nominal Mach numbers ranging from 6 to 10. Time‐dependent surface pressure distributions were recorded together with Schlieren movies of the flow field structure resulting from laser energy deposition. Results indicated laser‐induced pressure increases of 0.7–0.9 bar with laser pulse energies of ∼ 170 J, o...

EXPERIMENTAL RESULTS OF A MACH 10 CONICAL-FLOW DERIVED WAVERIDER TO 14-X HYPERSONIC AEROSPACE VEHICLE. doi: 10.5028/jatm.2011.03027510

This paper presents a research in the development of the 14-X hypersonic airspace vehicle at Institute for Advanced Studies (IEAv) from Department of Science and Aerospace Technology (DCTA) of the Brazilian Air Force (FAB). The 14-X project objective is to develop a higher effi cient satellite launch alternative, using a Supersonic Combustion Ramjet (SCRAMJET) engine and waverider aerodynamics. For this development, the waverider technology is under investigation in Prof. Henry T. Nagamatsu Aerothermodynamics and Hypersonics Laboratory (LHTN), in IEAv/DCTA. The investigation has been conducted through ground test campaigns in Hypersonic Shock Tunnel T3. The 14-X Waverider Vehicle characteristic was verifi ed in shock tunnel T3 where surface static pressures and pitot pressure for Mach number 10 were measured and, using Schlieren photographs Diagnostic Method, it was possible to identify a leading-edge attached shock wave in 14-X lower surface.

Laboratory Facilities and Measurement Techniques for Beamed‐Energy‐Propulsion Experiments in Brazil

Laser propulsion is an innovative concept of accessing the space easier and cheaper where the propulsive energy is beamed to the aerospace vehicle in flight from ground—or even satellite‐based high‐power laser sources. In order to be realistic about laser propulsion, the Institute for Advanced Studies of the Brazilian Air Force in cooperation with the United States Air Force and the Rensselaer Polytechnic Institute are seriously investigating its basic physics mechanisms and engineering aspects at the Henry T. Hamamatsu Laboratory of Hypersonic and Aerothermodynamics in Sao Jose dos Campos, Brazil. This paper describes in details the existing facilities and measuring systems such as high‐power laser devices, pulsed‐hypersonic wind tunnels and high‐speed flow visualization system currently utilized in the laboratory for experimentation on laser propulsion.