Liquid Oxygen Cooling of Hydrocarbon Fueled Rocket Thrust Chambers

Rocket engines using liquid oxygen (LOX) and hydrocarbon fuel as the propellants are being given serious consideration for future launch vehicle propulsion. Normally, the fuel is used to regeneratively cool the combustion chamber. However, hydrocarbons such as RP-1 are limited in their cooling capability. Another possibility for the coolant is the liquid oxygen. Combustion chambers previously tested with LOX and RP-1 as propellants and LOX as the collant demonstrated the feasibility of using liquid oxygen as a coolant up to a chamber pressure of 13.8 MPa (2000 psia). However, there was concern as to the effect on the integrity of the chamber liner if oxygen leaks into the combustion zone through fatigue cracks that may develop between the cooling passages and the hot gas side wall. In order to study this effect, chambers were fabricated with slots machined upstream of the throat between the cooling passage wall and the hot gas side wall to simulate cracks. The chambers were tested at a nominal chamber pressure of 8.6 MPa (1247 psia) over a range of mixture ratios from 1.9 to 3.1 using liquid oxygen as the coolant. The results of the testing showed that the leaking LOX did not have a deleterious effect on the chambers in the region of the slots. However, there was unexplained melting in the throat region of both chambers, but not in line with the slots

Cooling of rocket thrust chambers with liquid oxygen

Rocket engines using high pressure liquid oxygen (LOX) and kerosene (RP-1) as the propellants have been considered for future launch vehicle propulsion. Generally, in regeneratively cooled engines, the fuel is used to cool the combustion chamber. However, hydrocarbons such as RP-1 are limited in their cooling capability at high temperatures and pressures. Therefore, LOX is being considered as an alternative coolant. However, there has been concern as to the effect on the integrity of the chamber liner if oxygen leaks into the combustion zone through fatigue cracks that may develop between the cooling passages and the hot-gas side wall. To address this concern, an investigation was previously conducted with simulated fatigue cracks upstream of the thrust chamber throat. When these chambers were tested, an unexpected melting in the throat region developed which was not in line with the simulated fatigue cracks. The current experimental program was conducted in order to determine the cause for the failure in the earlier thrust chambers and to further investigate the effects of cracks in the thrust chamber liner upstream of the throat. The thrust chambers were tested at oxygen-to-fuel mixture ratios from 1.5 to 2.86 at a nominal chamber pressure of 8.6 MPa. As a result of the test series, the reason for the failure occurring in the earlier work was determined to be injector anomalies. The LOX leaking through the simulated fatigue cracks did not affect the integrity of the chambers

Bearing optimization for SSME HPOTP application

The space shuttle main engine (SSME) high-pressure oxygen turbopumps (HPOTP) have not experienced the service life required of them. To improve the life of the existing turbopump bearings, modifications to the bearings that could be retrofitted into the present bearing cavity are being investigated. Several bearing parameters were optimized using the computer program SHABERTH, which performs a thermomechanical simulation of a load support system. The computer analysis showed that improved bearing performance is feasible if low friction coefficients can be attained. Bearing geometries were optimized considering heat generation, equilibrium temperatures, and relative life. Two sets of curvatures were selected from the optimization: an inner-raceway curvature of 0.54, an outer-raceway curvature of 0.52, and an inner-raceway curvature of 0.55, an outer-raceway curvature of 0.53. A contact angle of 16 deg was also selected. Thermal gradients through the bearings were found to be lower with liquid lubrication than with solid film lubrication. As the coolant flowrate through the bearing increased, the ball temperature decreased but at a continuously decreasing rate. The optimum flowrate was approximately 4 kg/s. The analytical modeling used to determine these feasible modifications to improve bearing performance is described

The Value of Milk

Milk is increasingly recognized as an important factor in the diet of children and adults. In the past, milk was considered a mere incidental in the diet, desirable if it could be easily and cheaply obtained. Today it is classed as a necessity and old slip-shod methods of caring for the milk are rapid}y being surplanted by new, sanitary and scientific methods

Watch out for Measles

Why is it we seem to take measles so calmly? We merely regard them as one of the disagreeable but unavoidable things which parallel youth. So many take little precaution to keep their children from contracting the disease. And often they forget the whole incident as soon as the rash is gone, overlooking, or failing to realize, the great number of physical ailments of later life which have their origin in a neglected case of measles

So, Your Favorite Therapist is........a Horse?

The field of Equine Assisted Mental Health (EAMH) is both new and broad. The purpose of this paper is to explore justifications and methods for incorporating EAMH into practice; identify core concepts of an equine assisted therapy program for counselors; and describe the experience of learning within one of those programs. The method to accomplish this goal was a phenomenological account of finding, comparing and taking part in an EAMH training program. This account looks at the many ways EAMH can be applied within a counseling practice and describes the core concepts of a program that teaches counselors the EAMH process. The author also describes her experience of learning within a program

The Use of Fantasy Theme Analysis to Describe the Group Communication and Creative Problem-Solving Skills of University-Level Students as They Prepare for Destination Imagination Global Finals Competition

Problem and Purpose In order to meet the growing needs for efficiency in the workplace, industry is turning to group-work and collaboration. Successful teams are in demand because they not only meet the efficiency needs, but also provide the kind of bonding that creates convergence in the members. The chemistry or recipe for this kind of success is difficult to pinpoint, however, and several aspects of group communication and skills, need to be re-examined using communication theory. The purpose of this study is to describe one of those aspects—group creative problem-solving—in order to see how the communication used in that process affects the group dynamic. Method The research was a qualitative design based on a multiple or comparative case study. A theoretical/conceptual framework using Symbolic Convergence Theory and CAVE (Combine, Analogue, Visualize, Elaborate), an acronym that provides a way to describe in communication terms the creative problem-solving process, was applied to groups that were formed specifically to do competitive creative problem-solving. Fantasy Theme Analysis (FTA) is the method used to identify Symbolic Convergence Theory, and observation surveys were designed to note the occurrence of Fantasy Chains, Fantasy Themes, and Fantasy Types. The observation surveys also were designed to follow CAVE as it occurred. Three university-level Destination Imagination teams were observed as they prepared over a period of 3 months for Global Finals Creative Problem-solving Competition. Data were collected through video recordings, field notes, artifacts, and interviews. The teams were made up of five to seven members, and each, additionally, had a Team Manager. Using observation surveys, the teams’ communication patterns were noted and evaluated. The results were documented in case studies that were reported first individually, and then cross-case analysis was performed. Results Symbolic communication, described as Fantasy Chaining, Fantasy Theming, and Fantasy Types, was found to induce the creative process (CAVE), and the two occurred simultaneously. In addition to being interactive, a crucial piece of the symbolic conversion for the group was a crucial piece of the group creative problem-solving process. The use of analogue in both processes linked the two, and was seen as the element that tied the two processes together in these cases. Two of the cases gave clear evidence of how this works when both symbolic communication and creative process are present. The third case showed the results of a lack of use of symbolic communication, and its impact on the creative process. When symbolic communication processes occurred, bonding also occurred, which produced the skills that have been noted as being critical for synergy to happen in a group. When those symbolic communication processes were absent, as in the third case study, no bonding or synergy occurred. Conclusions Fantasy Chaining sparks CAVE, and works with it to fuel the creative process. The kind of communication uncovered with FTA is the same communication used in CAVE, and should be included in creative problem-solving models. The use of symbolic communication processes provides the climate for group bonding. Therefore, the type of communication in use is also seen as the way group creative problem-solving can aid the cohesion and synergy of the team, and thus the convergence of the team. And because all groups inherently problem-solve, group communication models need to recognize how group creative problem-solving communication affects the group dynamic. Skills that accompany this kind of communication are the skills that have been identified as necessary for cohesion and synergy to occur. Additionally, while the symbolic communication processes drove the creative process, the reverse was also true. So it was apparent that Symbolic Conversion and CAVE exist in a symbiotic relationship, which is needed for a group to truly converge