BHR Group Research Articles

Improvement of a multiphase flow model for wellhead chokes under critical and subcritical conditions using field data

The characterization of the multiphase flow through valves and orifices is a problem yet to be solved in engineering design, and there is a need for a prediction model able to simulate the complexity of this kind of flow in relation to fluid thermodynamic behaviour, and applicable to different incoming stream conditions and compositions. The present paper describes the development of a global model for the calculation of the discharge coefficient of orifices and choke valves operating under two- and three-phase flow as well as critical and subcritical conditions. The model generalizes the hydrovalve model developed by Selmer-Olsen et al. (in: Wilson (ed) Proceedings of 7th international conference on Multiphase Production, BHR Group, pp 441–446, 1995) and the Henry–Fauske (J Heat Transfer 93: 179–187, 1971. https://doi.org/10.1115/1.3449782) non-equilibrium model on the basis of an updated definition of the discharge coefficient. The model has been adapted to real choke valve geometries, by fitting the discharge coefficient and model parameters using field data from three production wells. The model developed is a global quartic function with different constants for the different valve geometries. The new discharge coefficient allows to simulate field data with high accuracy.

Process intensification in chemical engineering: general trends and Russian contribution

AbstractMinimization of the costs with simultaneous increase in the raw materials and energy use efficiency is a challenge for the modern world. One of the most effective tools to solve this task is the use of process intensification (PI), first proposed by Ramshaw C. The incentive for process intensification, Proceedings, 1st Intl. Conf. Proc. Intensif. for Chem. Ind., 18, BHR Group, London, 1995, p. 1. and then extended by Stankiewicz AI, Moulijn JA. Process intensification: transforming chemical engineering. Chem Eng Prog 2000: 22–34. In the presented review, some principles of PI in chemical engineering and their application for wide variety of processes is discussed. The role of the Russian scientist with a research background is carried out in other countries.

Flow of non-Newtonian fluids in open channels

This report details progress made in a Maths in Industry Study Group Project. The key conclusions of the study group were that correctly choosing an appropriate rheological model, and using appropriate data to compute the parameters of that model, is vital in recovering the correct fluid behaviour; and that exact mathematical solutions that exist for simplistic channel shapes can be used to approximate the flow in more complicated geometries. The problems of accurate numerical computation for highly non-Newtonian channel flow, as well as the complications that arise from turbulence, were identified as important areas of further research. References N. J. Alderman and R. Haldenwang, ``A review of Newtonian and non-Newtonian flow in rectangular open channels.'' Hydrotransport 17: The 17th International Conference on the Hydraulic Transport of Solids , The Southern African Institute of Mining and Metallurgy and the BHR Group, 2007. http://hdl.handle.net/11189/5192 J. Burger, R. Haldenwang and N. Alderman, ``Experimental database for non-Newtonian flow in four channel shapes.'' Journal of Hydraulic Research , 48 (2010): 363–370. doi:10.1080/00221686.2010.481849 P. Coussot, ``Steady, laminar, flow of concentrated mud suspensions in open channel.'' Journal of Hydraulic Research , 32 (1994): 535–559. doi:10.1080/00221686.1994.9728354 D. A. Rojas and R. H. A. Janssen, ``Design of open channels for non-Newtonian fluids'', in Proceedings of the 16th International Seminar on Paste and Thickened Tailings , Eds R. J. Jewell, A. B. Fourie, J. Caldwell and J. Pimenta, Australian Centre for Geomechanics, 2013. S. W. McCue, J. R. King and D. S. Riley, ``Extinction behaviour for two-dimensional inward-solidification problems.'' Proceedings of the Royal Society of London A , 459 (2003): 977–999. doi:10.1098/rspa.2002.1059 C. C. Mei and M. Yuhi, ``Slow flow of a Bingham fluid in a shallow channel of finite width.'' Journal of Fluid Mechanics , 431 (2001): 135–159. doi:10.1017/S0022112000003013 H. Schlichting and K. Gersten, Boundary-Layer Theory . Springer-Verlag, Berlin Heidelberg, 2000. doi:10.1007/978-3-662-52919-5 K. X. Whipple, ``Open-channel flow of Bingham fluids: applications in debris-flow research.'' The Journal of Geology , 105 (1997): 243–262. doi:10.1086/515916 R. Chhabra and J. F. Richardson, Non-Newtonian Flow: Fundamentals and Engineering Applications , Butterworth-Heinemann, 1999. P. Coussot, Mudflow rheology and dynamics , Balkema, 1997. F. Holland and R. Bragg, Fluid Flow for Chemical and Process Engineers , Butterworth-Heinemann, 1995. E. Mitsoulis, Flows of viscoplastic materials: models and computations, Rheology reviews , 2007 (2007), pp. 135–178. http://www.bsr.org.uk/rheology-reviews/RheologyReviews/viscoplastic-materials-Mitsoulis.pdf D. Pritchard, B. R. Duffy, and S. K. Wilson, Shallow flows of generalised Newtonian fluids on an inclined plane, Journal of Engineering Mathematics , 94 (2015), pp. 115–133. doi:10.1007/s10665-014-9725-2 J. N. Reddy and D. K. Gartling, The finite element method in heat transfer and fluid dynamics , CRC press, 2010.

Comparative performance of in-line rotor-stators for deagglomeration processes

In-line rotor-stators are used for a wide range of power intensive dispersion applications, including the breakup of immiscible liquid droplets or agglomerates. This study, performed within the DOMINO project at BHR Group, aimed at studying the performance of three different rotor-stator head designs for deagglomeration processes. A given test system, nanoscale silica particles-in-water, was used to identify the mechanism and kinetics of break-up and determine the smallest attainable size. Three rotor-stator head designs used were the GPDH-SQHS and EMSC screens from Silverson and Ytron Z-Lab from Ytron. These in-line rotor-stators were used in the recirculation loop of a stirred tank with a total dispersion volume of 100l. Power input and residence time were varied by changing the rotor speed and dispersion flow rate. Breakup was found to occur through erosion regardless of the operating conditions or rotor-stator design. The smalleachieves a higher fraction of finesst fragments obtained were aggregates, rather than primary particles, and these were of a mean diameter of 150–200nm; also independent of the operating conditions or rotor-stator head design. With a given rotor-stator operated at a given flow rate, increasing the rotor speed and hence the power input increased the break up kinetics. For a given design at a given specific power input, whilst the break up rate per tank turnover decreased when the flow rate was increased, the total processing time could be reduced. There were differences in the volume of the mixer head and chamber volumes; in addition, a smaller flow rate range could be covered with the Ytron design. Comparison of the different designs was therefore not straightforward. It could however be shown that the rotor-stator designs with a high number and small size of holes and/or gaps have a faster break up rate.

The Effectiveness of Blood Metal Ions in Identifying Patients with Unilateral Birmingham Hip Resurfacing and Corail-Pinnacle Metal-on-Metal Hip Implants at Risk of Adverse Reactions to Metal Debris.

We investigated whether blood metal ions could effectively identify patients with metal-on-metal hip implants with two common designs (Birmingham Hip Resurfacing [BHR] and Corail-Pinnacle) who were at risk of adverse reactions to metal debris. This single-center, prospective study involved 598 patients with unilateral hip implants (309 patients with the BHR implant and 289 patients with the Corail-Pinnacle implant) undergoing whole blood metal ion sampling at a mean time of 6.9 years. Patients were classified into two groups, one that had adverse reactions to metal debris (those who had to undergo revision for adverse reactions to metal debris or those with adverse reactions to metal debris on imaging; n = 46) and one that did not (n = 552). Three metal ion parameters (cobalt, chromium, and cobalt-chromium ratio) were compared between groups. Optimal metal ion thresholds for identifying patients with adverse reactions to metal debris were determined using receiver operating characteristic analysis. All ion parameters were significantly higher (p < 0.0001) in the patients who had adverse reactions to metal debris compared with those who did not. Cobalt maximized the area under the curve for patients with the BHR implant (90.5%) and those with the Corail-Pinnacle implant (79.6%). For patients with the BHR implant, the area under the curve for cobalt was significantly greater than that for the cobalt-chromium ratio (p = 0.0005), but it was not significantly greater than that for chromium (p = 0.8483). For the patients with the Corail-Pinnacle implant, the area under the curve for cobalt was significantly greater than that for chromium (p = 0.0004), but it was similar to that for the cobalt-chromium ratio (p = 0.8139). Optimal blood metal ion thresholds for identifying adverse reactions to metal debris varied between the two different implants. When using cobalt, the optimal threshold for identifying adverse reactions to metal debris was 2.15 μg/L for the BHR group and 3.57 μg/L for the Corail-Pinnacle group. These thresholds had good sensitivities (88.5% for the BHR group and 80.0% for the Corail-Pinnacle group) and specificities (84.5% for the BHR group and 76.2% for the Corail-Pinnacle group), high negative predictive values (98.8% for the BHR group and 98.1% for the Corail-Pinnacle group), and low positive predictive values (34.3% for the BHR group and 20.0% for the Corail-Pinnacle group). The authority thresholds proposed by the United States (3 μg/L and 10 μg/L) and the United Kingdom (7 μg/L) missed more patients with adverse reactions to metal debris at 2.0% to 4.7% (twelve to twenty-eight patients) compared with our implant-specific thresholds at 1.2% (seven patients missed). Patients who underwent metal-on-metal hip arthroplasty performed with unilateral BHR or Corail-Pinnacle implants and who had blood metal ions below our implant-specific thresholds were at low risk of adverse reactions to metal debris. These thresholds could be used to rationalize follow-up resources in asymptomatic patients. Analysis of cobalt alone is acceptable. Implant-specific thresholds were more effective than currently recommended fixed authority thresholds for identifying patients at risk of adverse reactions to metal debris requiring further investigation. Diagnostic Level II. See Instructions for Authors for a complete description of levels of evidence.

BHR Group’s 18th International Conference on Pipeline Protection: calls for papers

BHR Group’s 18th International Conference on Pipeline Protection: calls for papers

Sealing conference set for Nottingham BHR Group’s 20th International Fluid Sealing Conference Call for Papers

Sealing conference set for Nottingham BHR Group’s 20th International Fluid Sealing Conference Call for Papers

H 034 SPIRONOLACTONE LOWERS BLOOD PRESSURE IN RESISTANT HYPERTENSIVE PATIENTS WITH LOW PLASMA RENIN ACTIVITY

The purpose of this study was to examine the systolic blood pressure and plasma renin activity (PRA) responses to chronic stress in normotensive rats and in rats with one hypertensive parent. Twenty-four male Wistar-Kyoto (WKR) and 24 male F1 offspring of spontaneously hypertensive and WKY rats (BHR) were randomly assigned to 3 groups of 8 each. Experimental (E) animals were subjected to 2 hr daily of shock-shock conflict. Each response produced a 0.2 sec, 0.2–0.4 mA cutaneous electric shock. Failure to respond in 10 sec resulted in a train of 5 shocks (0.2 sec each sec). Yoked animals (Y) received the same shocks as E but had no control over their presentation. Finally, a control group (C) for maturation received no shocks. The E and Y animals were subjected to 14 weeks of conflict and were then monitored an additional 14 weeks in the absence of shock. All animals had their tail cuff blood pressures taken weekly except for 3 times when bloods were obtained for PRA assays. Analysis of blood pressure data revealed that: (1) BHR animals showed more of a blood pressure response to shock than WKY animals; (2) Y animals showed more of a response to conflict than E, especially for the BHR group; and (3) BHR shocked animals remained permanently elevated compared to BHR control animals even in the 14 week post-conflict period during which no shocks were given. Although PRAs for BHR animals were significantly higher than for WKY at the beginning of study, the stress-induced hypertension was associated with either normal or suppressed PRA values, suggesting that the hypertension in these animals is not a high renin hypertension.

Pipeline protection headed for Edinburgh BHR Group's 17th International Conference Calls for Papers

Pipeline protection headed for Edinburgh BHR Group's 17th International Conference Calls for Papers

Current in vivo wear of metal‐on‐metal bearings assessed by exercise‐related rise in plasma cobalt level

Baseline metal ion levels are elevated in patients with metal-on-metal (MOM) hip arthroplasty. Interpretation of baseline levels is difficult as measurements are influenced by wear, corrosion, and metal ion release from stored metal in the body. Schmalzried et al. demonstrated that "wear is the function of use, not time." The specific research question we asked was: Does physiological exercise increase the wear of metal-on-metal articulation which can be measured from the plasma metal ion levels? Patients with three different well functioning MOM bearings [two types of resurfacing (BHR 46.8 mm and Cormet 48 mm) and Metasul 28 mm] were included. Blood samples were taken immediately before, immediately after, and 1 h after exercise to determine cobalt and chromium levels. A significant increase (p<0.005) in serum cobalt and chromium of 13% and 11%, respectively, was noticed after the exercise. Rise of cobalt levels in patients with a resurfacing MOM was 8.5 times (BHR group) or 6.5 times (Cormet group) larger than in those with a Metasul MOM (p=0.021 and p=0.047). Neither rise of metal levels nor baseline levels correlated with any other factor (p>0.27). Exercise-related elevations of plasma cobalt level provides information on current in vivo wear production that cannot be inferred from a baseline measurement of cobalt levels. Chromium levels cannot provide reliable information on the in vivo wear of the devices. Diameter was the important feature of the implant in determining exercise-related elevations of plasma cobalt level. Exercise-related elevations of plasma cobalt level is a potential in vivo tool to understand and improve the tribology of metal-metal bearings.

Changes in BMD in the Proximal Femur after Cementless Total Hip Arthroplasty and Resurfacing Arthroplasty: Prospective, Longitudinal, ComparativeStudy

Purpose : This study analyzed the differences in bone remodeling and stress shielding between cementless total hip arthroplasty and resurfacing arthroplasty by examining the serial bone mineral density around the prosthesis. Materials and Methods : Fifty total hip arthroplasty procedures and 50 resurfacing arthroplasty procedures, which were performed between July 2002 and June 2003, were examined to this comparative study. The mean age at surgery was 44 years in the THA group and 36 years in the resurfacing arthroplasty group. The bone mineral density was measured by the DEXA at preoperation and 3 months, 6 months, 12 months after surgery in zone I-III of the acetabulum (classified by DeLee & Charnley) and zone I-VII of the femur (classified by Gruen), and the medial and lateral side of the femoral neck in the resurfacing arthroplasty group. Results : In the acetabulum, zones I and II of both groups showed a significant decrease in the BMD 12 months after surgery but the level of bone loss in the resurfacing arthroplasty group was relatively small compared with those in the THA group. In the proximal femur, the overall amount of bone loss at 3, 6 and 12 months postoperatively were 0.7%, 5%, and 2.6% respectively, and those in zones I and VII at 12 months postoperatively in the THA group were 7.8% and 7.7%, respectively. In the BHR group, the overall bone loss in the proximal femur at 3, 6 and 12 months postoperatively were 5.8%, 4.4%, and 2.9%, respectively. However, those Gruen zones I and VII at 12 months postoperatively were 2.6% and 0.6%, respectively. Conclusion : The level of bone loss in Gruen zones I and VII of the resurfacing arthroplaty group was much lower, which suggests that resurfacing arthroplasty can prevent stress shielding and preserve the proximal bone stock around the femoral stem.

Sealing technology course to be held at Georgia Tech, 2–4 December 2003

The next in the regular series of sealing technology courses at Georgia Institute of Technology has been announced. The course, which has been presented at Georgia Tech since 1988, utilizes the fluid sealing and tribology expertise of Georgia Tech, BHR Group and independent consultants to provide an extensive introduction to fluid sealing. This is a short news story only. Visit www.worldpumps.com for the latest pump industry news.

Sealing electronic equipment casings

Dr Emily Ho, BHR Group Ltd, Cranfield, Bedford, UK A number of recent news items in Sealing Technology have featured seal developments by manufacturers of seals for electronic equipment, particularly for communications. The sealing of casings for communication equipment may sound at first to be relatively simple, but this is far from the case as this feature article explains.

IMechE awards prize to shaft seal paper

The Fluid Machinery Group of the Institution of Mechanical Engineers (IMechE) has just presented a Donald Julius Groen prize to Dr Simon Leefe of BHR Group. This prize was for a paper that Dr Leefe, manager of engineering analysis at BHR, presented to the IMechE conference Advances of CFD in Fluid Machinery Design during June 2001.

Bandra Pumping Station, Bombay: re-design of Bandra influent pumping station

The Bandra Influent Pumping Station (referred to subsequently as the IPS), at Mumbai (Bombay) in India, is a key element in the Bandra drainage area of Mumbai. Construction of the whole scheme started in the mid 1980s but by the early 1990s had run into construction and financial difficulties. Binnie & Partners (India) Ltd (referred to subsequently in this paper as Binnie and now part of the Black & Veatch group) were commissioned to redesign the IPS, with the assistance of Tata Consulting Engineers of Mumbai (TCE). This paper discusses the details of the changes and the development of what is thought to be a unique layout for a major sewage pumping station. As part of the re-design process, the station was model-tested at the BHr Group laboratories and the model and the modifications required to the station as a result of the testing are also discussed.

Bronchial Hyperresponsiveness and Exhaled Nitric Oxide in Patients with Cardiac Disease

Background: Increased concentrations of exhaled nitric oxide (NO) correlate with increased airway inflammation and measurement of exhaled NO is a noninvasive method for the management of bronchial asthma. In various cardiac diseases, bronchial hyperresponsiveness is observed, as is bronchial asthma. However, there have been few studies on the relationship between exhaled NO and bronchial responsiveness in cardiac diseases. Objective: The aim of this study was to clarify the association between exhaled NO and bronchial hyperresponsiveness in patients with cardiac disease. Methods: We measured expired NO and bronchial responsiveness to inhaled methacholine in 19 patients with cardiac diseases and 17 with bronchial asthma. We divided the cardiac disease patients into two groups according to their bronchial responsiveness to inhaled methacholine: BHR(+) group consisted of 12 patients with bronchial hyperresponsiveness and BHR(–) group consisted of 7 patients without bronchial hyperresponsiveness. Results: The concentration of exhaled NO in the asthmatic patients was significantly higher than that in the BHR(+) and BHR(–) groups (142.0 ± 17.0, 33.6 ± 6.4 and 42.3 ± 10.3 ppb, respectively, p < 0.01). There was no significant difference in exhaled NO between BHR(+) and BHR(–) groups. There were also no significant differences in the parameters of bronchial hyperresponsiveness between the cardiac BHR(+) and bronchial asthma groups. These results indicate that bronchial hyperresponsiveness in patients with cardiac diseases is not a consequence of eosinophilic inflammation or of exhaled NO. Conclusion: We conclude that bronchial hyperresponsiveness in patients with cardiac diseases can occur independently of NO production.

New testing facility at BHR Group

New testing facility at BHR Group

Seals research to boost rocket engines into the 21st century

The move towards reusable launcher vehicles, coupled with the need for increased payload in rocket powered space vehicles is driving rocket engine development to produce smaller and more durable turbopumps, operating at higher speeds and pressures. Seals in these future turbopumps, which supply high pressure liquid oxygen and hydrogen to the combustion nozzle, will be required to operate under more stringent conditions, whilst wearing less. This enormous design challenge, requiring improvements in seal materials and new seal design strategies, is the subject of a current consortium project using BHR Group's sealing expertise.

On impeller circulation and mixing effectiveness in the turbulent flow regime

Impeller effectiveness has often been evaluated via either mixing time, θ m , or flow number, Fl; and a direct connection between the two has also been assumed in some cases. Here, these concepts are considered in the light of recent theoretical and experimental work. It is shown that an equation for mixing time recently published by BHR Group can be related to a basic turbulence model. It is also shown that this equation is superior to those based on a theory linking mixing time to the flow generated by the impeller. The new equation and theory implies that all impeller types of equal impeller-to-tank diameter ratio are equally energy efficient in achieving overall homogenisation. On the other hand, impeller efficiency based on the flow generated, as measured by laser Doppler anemometry at equal measured power, suggests a significant difference between impeller types.

Sealing performance prediction software

Elastomer seals are widely used throughout industry and seal failure can be very expensive, in both financial and safety terms. One failure mode causing major concern is progressive degradation. It is generally of a long term nature and its extent and consequences in service can be particularly difficult to predict. BHR Group has developed seal-life prediction software in a user friendly, Windows format to address the problem of progressive seal degradation.